Televue 85 vs 8" SCT
Gonzo Breath
to a 6" dob, but I have a further question for the list.
I am getting ready to spend the wad on a 'real' telescope.
When I got started, I figured the best scope for what I wanted
to do would be either a Meade LX50, or a Celestron C8 DX.
Then I started reading about the TV-85 APO. From what I
have read so far, I am seriously rethinking my decision. When
you look at the quality of the optics, the overall power of the
scope, and the PORTABILITY, the TV-85 is hard to beat.
According to the December article in Sky and Telescope,
there does not seem to be anything that the TV-85 scope
does not do well. And this from a scope you can transport
as carry-on luggage.
Is there something I am missing here? What are the weaknesses
of the TV-85? In general, I was under the impression that
refractors were not the best suited for deep space observing,
and yet, I have read articles saying that the TV-85 can pick
out some planetary nebulas that can only be seen through
mid-range reflectors with filters.
The only limitation here is that the scope is rated at only being
able to reach 12.0 mag. stars. How big a problem is that?
Anyone have any words of wisdom here? This will be my only
scope for a long time so I wanna make sure I get something
that is gonna max out bucks spent.
I am in an area with mountains behind me, and an ocean infront
of me, so I will have some fairly dark sky most of the time; but
if I am willing to commute about 20 mins and setup, I can have
extremely dark sky.
Thanks,
Mike.
Chris Marriott
Gonzo Breath wrote in message <78v5o9$1v$1...@remarQ.com>...
>Okay... I have read the recent thread on debating a TV-Ranger
>to a 6" dob, but I have a further question for the list.
>
>I am getting ready to spend the wad on a 'real' telescope.
>When I got started, I figured the best scope for what I wanted
>to do would be either a Meade LX50, or a Celestron C8 DX.
>
>Then I started reading about the TV-85 APO. From what I
>have read so far, I am seriously rethinking my decision. When
>you look at the quality of the optics, the overall power of the
>scope, and the PORTABILITY, the TV-85 is hard to beat.
>According to the December article in Sky and Telescope,
>there does not seem to be anything that the TV-85 scope
>does not do well. And this from a scope you can transport
>as carry-on luggage.
For most purposes, aperture wins. A 200mm telescope gathers more than 5x as
much light as an 85mm telescope, and will allow you to see much fainter
objects.
There are a few situations - eg planetary observing - when in SOME
atmospheric conditions the refractor would show you more "fine detail" than
the SCT, but again, in general, the 8" SCT will show you more.
If portability or terrestrial use is your primary concern then the TV85 may
be a winner, but there's no doubt that for the vast majority of astronmical
purposes the 8" will be a lot better.
Regards,
Chris
-----------------------------------------------------------------------
Chris Marriott, SkyMap Software, UK (ch...@skymap.com)
Visit our web site at http://www.skymap.com
Astronomy software written by astronomers, for astronomers
Les6767
have a friend who sold his 8 SCT after having owned both it and the TV85.
Having looked thru both and images looked brighter thru the TV85 and with more
color with stars actually looking like fine grains of sugar!. Refrator optics
will always beat an SCT's for sharpness. Just try splitting doubles to Dawes
limit in both and that will tell you. I know many 4in refrcator owners who
claim they can see to 14 mag. Portability is a major factor if you think
you'll only get out there often if its not a hassel to do so. You'd be
surprised how much more viewing small refractor owners do than SCT owners. The
TV85 is also made of better than the typical SCT.
MaxWebhead
said that I more often than not grab for the 85 when I go observing. I observe
on the fly most of the time & In my circumstances portability & convieniance
wins.
The origional poster made a referance to the "glowing S&T report , most of
which I find to be accurated. but the part about useing a 5X Powermate with a
2.5 vixen Lath sounded a little absurd to me, altho I never tried , I cant
think of an instance in which i would want to.
Both scopes are great & if I had to sell one it'd be the C8
~ Buddy from N.Y ~ "Serenity is just a level of Insanity thats pleasurable"
Capella
that matter:
1. Aperture
2. Aperture
3. Aperture
:^)
Capella
Gonzo Breath wrote:
>
> Okay... I have read the recent thread on debating a TV-Ranger
> to a 6" dob, but I have a further question for the list.
>
> I am getting ready to spend the wad on a 'real' telescope.
> When I got started, I figured the best scope for what I wanted
> to do would be either a Meade LX50, or a Celestron C8 DX.
>
> Then I started reading about the TV-85 APO. From what I
> have read so far, I am seriously rethinking my decision. When
> you look at the quality of the optics, the overall power of the
> scope, and the PORTABILITY, the TV-85 is hard to beat.
> According to the December article in Sky and Telescope,
> there does not seem to be anything that the TV-85 scope
> does not do well. And this from a scope you can transport
> as carry-on luggage.
>
Capella
I have to say that I disagree with this post. A 4" refractor may be
almost as good as a 6" newtonian and possibly better if well made in
some aspects, but in my personal experience, I have not seen a 4" that
can compete with an 8" SCT.
I own a TeleVue Genesis 101mm and although I love it, I am not
selling my 8" SCT.
I could understand if portability was the main concern, but performance
wise the 8" SCT wins easily. :^)
My opinion.
Capella.
Rich N.
apples and oranges comparison.
If you need a highly portable telescope the TV-85 is better.
An 8" SCT is certainly portable but nearly as portable TV-85.
If you don't mind a larger piece of equipment the 8" SCT will
give brighter deep sky images and should give better planetary
images. The SCT will need to time to cool down when you take
it outside, roughly 45 minutes.
M13 looks nice in my 4" Tak refractor but in an 8" SCT M13 is
a much more impressive "explosion" of stars.
Before you buy either one try looking through an 8" SCT and a
4" refractor (4" because it may be easier to find than a TV-85).
Rich
Gonzo Breath wrote in message <78v5o9$1v$1...@remarQ.com>...
Jim Wayda
use most often. I like small refractors because of the minimal setup
and cool down time. Therefore, the best scope is the scope that you will
use most often.
-jim
Capella wrote:
>
> If you plan to do any deep sky observing, there are three things
> that matter:
>
> 1. Aperture
> 2. Aperture
> 3. Aperture
>
> :^)
>
> Capella
>
> Gonzo Breath wrote:
> >
Capella
>
> Aperture does not always win! The best scope is the one that you will
> use most often. I like small refractors because of the minimal setup
> and cool down time. Therefore, the best scope is the scope that you will
> use most often.
>
> -jim
>
That's fine, but as an owner of a TeleVue Genesis 101mm and an 8"
SCT, for deep sky viewing, the 8" SCT gets used much more by me. ;^)
Capella
bro...@my-dejanews.com
The answer is the same as the Ranger vs. the 6". While the TV85 is one of
the best refractors of it's size that you can buy, 85mm of aperture is still
85mm and cannot circumvent the laws of physics. An 8" SCT will show far more
on all objects than an 85mm refractor no matter how good it is. So, you have
to decide what you are getting the scope for. If extreme portability is the
overriding concern than get the TV85. However, if you want the best views of
both planets and deep sky then it is no contest: the 8" SCT wins.
Kevin Brown
Burke, VA
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
GrapeApe
>use most often. I like small refractors because of the minimal setup
>and cool down time. Therefore, the best scope is the scope that you will
>use most often.
I prefer the Original Green mint flavor, though sometimes I use Blue
Listermint.
Peter Besenbruch
<stin...@intrex.net> wrote:
>When
>you look at the quality of the optics, the overall power of the
>scope, and the PORTABILITY, the TV-85 is hard to beat....
>this from a scope you can transport
>as carry-on luggage.
>
>Is there something I am missing here?
Two things. First, like the others say, aperture wins if the SCT
optics are up to snuff. Second, what are you going to mount the
Teleview 85 on? How portable is it?
Your best bet is to get both.
___________________________________________________
Hawaiian Astronomical Society http://www.hawastsoc.org
HAS Deepsky Atlas http://www.hawastsoc.org/deepsky
Delete the "nobulk." for the true e-mail address.
Capella
Yes, it would be a lot more "pleasant" at star parties if everyone
used their "scope". :^)
Capella
Neptune
>optics are up to snuff. Second, what are you going to mount the
>Teleview 85 on? How portable is it?
>
>Your best bet is to get both.
Or, take your $2000 that you are planning to spend and get a ETX, Ranger,
or a Pronto, and a 10" Dob. You'll have cash left over for some
accessories.
Stard...@webtv.net
all other scopes beat when it comes to having a comfortable position to
observe. Most SCTs and reflectors require standing while observing. I
can sit while viewing with a refractor, therefore I can observe for much
longer than I could with other scopes. Dark adaptation has a lot to do
with how much you see. I use red Astro Goggles for an hour before I
observe and it makes a huge difference.
Stard...@webtv.net
More tears have been shed from answered prayers than those unheard-----
Chris
>
>I think they key word is "grab"
>That's something you can't do with the 8 inch SCT.
>-Rich
>
>
>
>"To Hell with Pluto!" :)
No, grab is a 55mm vixen. I can lift my whole observing setup with one hand
and get the best darn images you can see. I can't wait to compare it to a
pronto!
Chris
Capella
>
> Something that hasn't been mentioned: viewing position. Refractors have
> all other scopes beat when it comes to having a comfortable position to
> observe. Most SCTs and reflectors require standing while observing.
Actually most SCTs, assuming that most are 8-10" on fork mounts,
can be used sitting down.
Many of the smaller dobs, 6-10" can also be used sitting down. They
even make special seats that can be quickly and precisely adjusted up
or down to keep you level with the eyepiece.
:^)
Capella
Stard...@webtv.net
cap...@airmail.net (Capella) wrote:
Actually most SCTs, assuming that most are 8-10" on fork mounts, can be
used sitting down.
Many of the smaller dobs, 6-10" can also be used sitting down. They even
make special seats that can be quickly and precisely adjusted up or down
to keep you level with the eyepiece.
:^)
Capella
The SCTs I've seen were on mounts that couldn't be lowered enough to
view from a sitting position and Dobs require an adjustment of position
every time you move the scope. I understand that refractors are the most
expensive per inch of aperture, but they do have their redeeming
qualities. I'll have to check on the adjustable seat you mentioned.
Rich N.
It sounds like you've been reading the old Uintion ads.
I love refractors but sorry to say they are not necessarily more comfortable
to use when it comes to eyepiece position.
Rich
Stard...@webtv.net wrote in message
<6557-36...@newsd-211.iap.bryant.webtv.net>...
Something that hasn't been mentioned: viewing position. Refractors have
all other scopes beat when it comes to having a comfortable position to
observe. Most SCTs and reflectors require standing while observing. I
can sit while viewing with a refractor, therefore I can observe for much
longer than I could with other scopes. Dark adaptation has a lot to do
with how much you see. I use red Astro Goggles for an hour before I
observe and it makes a huge difference.
AndersonRM
>Aperture does not always win! The best scope is the one that you will
>use most often.
Very true. It's a fact that if you could get a 20 inch scope
in a suitcase, we'd all own one. There's a personal "demarcation"
line for all of us. For me, it's an 8 inch SCT. Best combination
of portability, performance and aperture there is. However, in
terms of pure numbers, I probably have had my 80mm Vista out
more this winter than any other scope i've got.
AndersonRM
In article <19990130122650...@ng01.aol.com>, maxwe...@aol.com
(MaxWebhead) writes:
>I agree with Chris M. Aperture wins,, as I own both the TV85 & a C8,, having
>said that I more often than not grab for the 85 when I go observing
I think they key word is "grab"
That's something you can't do with the 8 inch SCT.
Jon Isaacs
>all other scopes beat when it comes to having a comfortable position to
>observe.
1. SCTs with fork mounts work best sitting down.
2. Some of us like to observe standing up. Sitting down is OK if you are
going to spend some time looking at one object. But then to find the next one,
you have to get up, find the thing, maybe move the chair and sit down again.
If you want to do a quick run through of various objects then I much prefer
standing. For standing I think a Newtonian is best.
3. A compromise between a C8 and a TV85 is the C5+/G5 series. Bit more
aperture, and still quite portable.
Jon Isaacs
AndersonRM
In article <6557-36...@newsd-211.iap.bryant.webtv.net>,
Stard...@webtv.net writes:
>Something that hasn't been mentioned: viewing position. Refractors have
>all other scopes beat when it comes to having a comfortable position to
>observe. Most SCTs and reflectors require standing while observing.
Putting an SCT in it's lowest tripod position will allow you to sit. It also
produces less eyepiece movement than a longer refractor tube, so
you won't have to move as much to accomodate different objects
being viewed.
AndersonRM
In article <790d9u$39le$1...@newssvr04-int.news.prodigy.com>, "Chris"
<ASTRO...@prodigy.net> writes:
>No, grab is a 55mm vixen. I can lift my whole observing setup with one hand
>and get the best darn images you can see. I can't wait to compare it to a
>pronto!
The Pronto has almost
twice the surface area and therefore will make objects look
alot brighter. Still, the 55 must be as portable as a finder, or
near that.
Jim Wayda
>
> >Something that hasn't been mentioned: viewing position. Refractors have
> >all other scopes beat when it comes to having a comfortable position to
> >observe.
>
>
> 2. Some of us like to observe standing up. Sitting down is OK if you are
> going to spend some time looking at one object. But then to find the next one,
> you have to get up, find the thing, maybe move the chair and sit down again.
> If you want to do a quick run through of various objects then I much prefer
> standing. For standing I think a Newtonian is best.
>
> 3. A compromise between a C8 and a TV85 is the C5+/G5 series. Bit more
> aperture, and still quite portable.
The C5 does not provide sharp planetary images like the TV85. I have
tried them side
by side.
-jim
>
> Jon Isaacs
Rich N.
Rich N. wrote in message <790uc2$o4b$1...@remarQ.com>...
>How many SCTs and reflectors have you looked through lately?
>
>It sounds like you've been reading the old Uintion ads.
make that.. Unitron
rn
>I love refractors but sorry to say they are not necessarily more
comfortable
>to use when it comes to eyepiece position.
>
>Rich
>
>Stard...@webtv.net wrote in message
><6557-36...@newsd-211.iap.bryant.webtv.net>...
>Something that hasn't been mentioned: viewing position. Refractors have
>all other scopes beat when it comes to having a comfortable position to
Eric Faust
position. Seated where? On the dirt? An observing chair, such as the starbound
chair is a valuable tool for any scope - refractor or reflector. A
refractor requires a taller tripod, a reflector a shorter tripod. Maybe you
are trying to use a reflector on a tall tripod? The shorter tripod , if
anything, is an advantage (sturdier). I also find the newt's higher eyepiece an
advantage over refractors since I have a starbound chair.
Eric
In article <6557-36...@newsd-211.iap.bryant.webtv.net>,
Stard...@webtv.net says...
Chris
expectations and from the time when I used the pronto for a night, the 55mm
is giving me a lot better image. When I do compare the 2 intensively, I
will post it on this newsgroup asap.
Chris Kline
AndersonRM wrote in message
<19990131022416...@ngol03.aol.com>...
Capella
>
> Group: sci.astro.amateur Date: Sat, Jan 30, 1999, 9:10pm (MST+1) From:
> cap...@airmail.net (Capella) wrote:
> Actually most SCTs, assuming that most are 8-10" on fork mounts, can be
> used sitting down.
> Many of the smaller dobs, 6-10" can also be used sitting down. They even
> make special seats that can be quickly and precisely adjusted up or down
> to keep you level with the eyepiece.
> :^)
> Capella
> ***********************************************
> The SCTs I've seen were on mounts that couldn't be lowered enough to
> view from a sitting position
Most fork mounts on equatorial wedges can be easily lowered for sitting
position. Up until I bought a Losmandy G-11 last year, my 8" SCT was on
a fork mount for 6 years and I used it almost exclusively sitting down.
Most of that sitting down was doing astrophotography, but for the
most part I had no trouble getting to the eyepiece sitting in a
regular folding chair.
I guess the lesson is that if you want to sit down and observe, then
the fork equatorially mounted is the way to go for the SCT.
> and Dobs require an adjustment of position
> every time you move the scope. I understand that refractors are the most
> expensive per inch of aperture, but they do have their redeeming
> qualities. I'll have to check on the adjustable seat you mentioned.
I'm not sure if it has a standard name. It has been around for at least
10 years as far as I know. I bought one last year at the Texas Star
Party.
You can find them advertised in astronomy magazines and someone brought
up a webpage that described how to make a home made version of it they
called the "Denver chair."
BTW, I have a TeleVue Genesis myself and I love it.
Take care,
Capella
Capella
>
> Group: sci.astro.amateur Date: Sat, Jan 30, 1999, 9:10pm (MST+1) From:
> cap...@airmail.net (Capella) wrote:
> Actually most SCTs, assuming that most are 8-10" on fork mounts, can be
> used sitting down.
> Many of the smaller dobs, 6-10" can also be used sitting down. They even
> make special seats that can be quickly and precisely adjusted up or down
> to keep you level with the eyepiece.
> :^)
> Capella
> ***********************************************
> The SCTs I've seen were on mounts that couldn't be lowered enough to
> every time you move the scope. I understand that refractors are the most
> expensive per inch of aperture, but they do have their redeeming
> qualities. I'll have to check on the adjustable seat you mentioned.
>
I found a website I mentioned in a previous post about one:
http://www.du.edu/~pryan/seat.html
Capella
Harry Pulley
cassegrain on a GEM, 6" newt as a dob (but soon to have a dovetail for
my GP so I can track) and a 50mm refractor on an alt-az mount. The
largest scope I will use is the best one for me. I'll take a more
informative view any day over a sharp contrasty one which actually shows
less detail.
The 50mm scope is the most portable. I'd be interested in seeing how
much larger a refractor could be while still being one-hand portable. I
use this little scope for solar projection and super-fast setup time
when I will only be out for 20 minutes or less, but really only for
projection as the dob is nearly as fast and easy to set up.
My 6" dob is in some ways not a prime example of its breed, as the base
is quite heavy. This means it is very stable but actually less portable
than my 200mm cassegrain with GP mount (where no piece is nearly as
heavy as my dob's base). The OTA cools in half the time of my
cassegrain so I really like this scope for morning views of the planets
and Moon where I'll only be out for an hour so my cass would barely cool
by the time I was done. I like tracking so I'm making a dovetail for
this OTA on my GP. With a small secondary, this scope provides
excellent views of planets and the Moon, equal to or better than all 4
and 5" refractors I've used (though it has never been compared to AP or
Tak scopes, just Meade and Vixen).
My 200mm cassegrain beats the 6" for deep sky by a mile and performs
extremely well on planets and the Moon too, even with a huge central
obstruction. I still find this scope to be extremely portable but the
setup and cooldown time is much longer. Once cooled, it is my preferred
scope for all targets. Since it is the only one on a mount that tracks
right now, it is my preferred scope for that reason too.
I can sit perfectly well with my 200mm cassegrain on the GP, either with
a diagonal or straight through. I find my newt must be used standing
up.
I really find an 8" scope to be a break point where you get a lot of
aperture. The cassegrain design keeps the length and weight down so it
is very portable. 10" SCTs are very heavy, much to heavy for me. 10"
newts are too big and long for me to transport easily with camping
equipment and a passenger. A 10" scope shows more than an 8" scope but
I find the 8" to be good enough that the extra size is not warranted FOR
ME.
So, I really find an 8" cassegrain to be the perfect scope FOR ME. Easy
enough to set up and cool down that it gets used a lot, small enough to
fit with camping gear and my wife and I in the car, big enough to show
lots of deep sky and shallow sky targets.
But I've kept my smaller scopes for good reasons. There is no way to
speed up the cooldown of my cass much, so I'll be keeping the newt. for
morning views at least. The 50mm refr is great for solar projection.
I might be in the market for a good quick look scope. The 80mm f/5
sounds nice but the newer f/7 model sounds even better. I don't want an
expensive portable scope, as I like something cheap enough I don't
really care about it falling in the lake. I like a scope that is
portable enough for trips to little islands riding in the bottom of a
boat -- having a Pronto or TV85 bouncing around with every wave would
give me an ulcer! They look rugged and well made but slinging around
that kind of money gives me the heebee geebees.
--
<:-{} Harry C. Pulley, IV, member RASC, ALPO, IOTA, TPS
\ mailto: hpu...@home.com
http://members.home.net/hpulley
Guelph, Ontario, Canada, 43.55N, 80.26W
Rich N.
The answer is, it depends. It depends on the way the OTA
of the scope is mounted and the distance the eyepiece will
travel as you move the scope. Quite a few SCTs, Dobs and
GE mounted reflectors and refractors can all be used over a
wide range of movement from an adjustable chair like the Starbound
deluxe model.
Rich
Stard...@webtv.net wrote in message
<6507-36B3FCEC-85@newsd-***********************************************
The SCTs I've seen were on mounts that couldn't be lowered enough to
view from a sitting position and Dobs require an adjustment of position
every time you move the scope. I understand that refractors are the most
expensive per inch of aperture, but they do have their redeeming
qualities. I'll have to check on the adjustable seat you mentioned.
Stard...@webtv.net
something to be considered. I have owned a 4 1/2 " reflector on a
tripod, an ETX and a 4" Celestron refractor. I've also had the
oportunity to view with a 12.5" and a 16" Dob as well as 8" and a 14"
SCT a few times. When I observe, I usually check out a section of sky
from Norton's, then go out and spend hours finding and attempting to
identify the interesting stuff there. My next major purchases will be a
SCT and a BIG Dob. I regularly post questions on this NG about scopes,
mounts, etc., that I don't know a lot about, but usually get few
responses.
If you post an opinion on this NG, you can count on 5X the number of
responses.
No, I don't sit in the dirt.
*&^%$#@#$%^&&%$&%#@$^*&^%$@##
eri...@hotmail.com (Eric Faust) wrote:
This is a rather prejudiced post. You state that a refractor offers a
seated position. Seated where? On the dirt? An observing chair, such as
the starbound chair is a valuable tool for any scope - refractor or
reflector. A refractor requires a taller tripod, a reflector a shorter
tripod. Maybe you are trying to use a reflector on a tall tripod? The
shorter tripod , if anything, is an advantage (sturdier). I also find
the newt's higher eyepiece an advantage over refractors since I have a
starbound chair.
Eric
Harald Lang
ander...@aol.com (AndersonRM) wrote in message
<news:19990131022416...@ngol03.aol.com>
>>No, grab is a 55mm vixen. I can lift my whole observing setup
>>with one hand and get the best darn images you can see. I can't
>>wait to compare it to a pronto!
>
> The Pronto has almost
>twice the surface area and therefore will make objects look
>alot brighter.
Almost twice? 62% ?
Cheers -- Harald
Frez
Gonzo Breath wrote in message <78v5o9$1v$1...@remarQ.com>...
>Okay... I have read the recent thread on debating a TV-Ranger
>to a 6" dob, but I have a further question for the list.
>
>I am getting ready to spend the wad on a 'real' telescope.
>When I got started, I figured the best scope for what I wanted
>to do would be either a Meade LX50, or a Celestron C8 DX.
>
>
>Thanks,
>Mike.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hi Mike I own an Celestar 8 dlx and really like it. The adjustable
tripod means I can stand for wide area star hopping or sit for lengthy
studying. At f10 it is good at planetary and dso. Setup is easy as it is
lightweight and takes about 10 min. After 8 months I got a yearning for
wider views and toyed with thoughts of focal reducers and/or 2" plumbing.
Instead I spent $250 on a Celestron 80EQ WA refractor. I find these
two scopes complement each other extremely well. The quick grab &
go of the 80mm has gotten me out on bitterly cold nights for an hour while
the 8" has provided unforgettably resolved views of many objects.
Sometimes I set them up side by side. The other night M81 & 82 were in
both scopes. With the 80mm at 22x and 2.3 deg true FOV, (Ultima 18mm),
the shape of these galaxies was pronounced and well placed in the
starfield. The 8" with same EP is 113x and .45 deg true FOV. Both
galaxies will not fit in the FOV but detail & resolution really kick up and
prolonged observing was very enjoyable. Considering dollars spent, I
couldn't
be happier. The 80mm is an inexpensive achromat and shows some
color. Upgrading this to an APO seems like a logical next step. Teleview
has a long waiting list for it's products, but I don't know if the TV85 is a
stock
item or part of the list. I am also unaware of its price. Surfing Markus
Ludes' APM website turned up two very interesting alternatives. They
are 80mm fluorite APOs at f6 or f7.5 and are priced under $1000 for OTA
only. The URL is:
http://www.apm-telescopes.com/index.html
My advice to you is purchase the 8 dlx and later consider an 80mm.
Good luck with whatever you do and please keep us informed.
Frez
fr...@greennet.net
Eric Faust
position as one of the refractors advantages. You said "Refractors have
all other scopes beat when it comes to having a comfortable position to
associated with SCT's are due to the fork mount, not the optical design. On
large dobs obviously eyepiece position can be a problem, but on similar focal
length reflectors and refractors, the eyepiece will move similar distances.
The reason for asking where you sit was to point out you need an observing
chair, since you said "Most SCTs and reflectors require standing while
observing". If you get to sit, why can't the reflector owner sit too? Please
don't think I was attacking you personally. I just thought the post was
prejudiced toward refractors, trying to say they enjoy an advantage in eyepiece
position, something I think is arguable. An overall observing system (mount,
tripod, scope, chair, etc.) may have an advantage, but it's not dependent on
whether it's a refractor or reflector. Also, I have no prejudice against
refractors. While my current scopes are an 8" newt and a 6" mak-newt, my next
purchase will probably be a small APO refractor. If I don't get a half pier for
my SP mount to go with the refractor, I'll be the one sitting on the ground.
Clear Skies,
Eric
In article <8643-36B...@newsd-211.iap.bryant.webtv.net>,
Stard...@webtv.net says...
>
> Prejudiced how? I merely stated that the viewing position of a scope is
>something to be considered. I have owned a 4 1/2 " reflector on a
>tripod, an ETX and a 4" Celestron refractor. I've also had the
>oportunity to view with a 12.5" and a 16" Dob as well as 8" and a 14"
>SCT a few times. When I observe, I usually check out a section of sky
>from Norton's, then go out and spend hours finding and attempting to
>identify the interesting stuff there. My next major purchases will be a
>SCT and a BIG Dob. I regularly post questions on this NG about scopes,
>mounts, etc., that I don't know a lot about, but usually get few
>responses.
>If you post an opinion on this NG, you can count on 5X the number of
>responses.
>No, I don't sit in the dirt.
>*&^%$#@#$%^&&%$&%#@$^*&^%$@##
>
Eric Faust
Christmas. They market it under the Orion label, but the papers in the box
called it a starbound observing chair.
Eric
In article
<C33E882ECF625946.CAE8C304...@library-proxy.airnews.net>,
cap...@airmail.net says...
>
>Stard...@webtv.net wrote:
>>
>> Group: sci.astro.amateur Date: Sat, Jan 30, 1999, 9:10pm (MST+1) From:
>> cap...@airmail.net (Capella) wrote:
>> Actually most SCTs, assuming that most are 8-10" on fork mounts, can be
>> used sitting down.
>> Many of the smaller dobs, 6-10" can also be used sitting down. They even
>> make special seats that can be quickly and precisely adjusted up or down
>> to keep you level with the eyepiece.
>> :^)
>> Capella
>> ***********************************************
>> The SCTs I've seen were on mounts that couldn't be lowered enough to
>> view from a sitting position
>
>Most fork mounts on equatorial wedges can be easily lowered for sitting
>position. Up until I bought a Losmandy G-11 last year, my 8" SCT was on
>a fork mount for 6 years and I used it almost exclusively sitting down.
>
>Most of that sitting down was doing astrophotography, but for the
>most part I had no trouble getting to the eyepiece sitting in a
>regular folding chair.
>
>I guess the lesson is that if you want to sit down and observe, then
>the fork equatorially mounted is the way to go for the SCT.
>
>
>> and Dobs require an adjustment of position
>> every time you move the scope. I understand that refractors are the most
>> expensive per inch of aperture, but they do have their redeeming
>> qualities. I'll have to check on the adjustable seat you mentioned.
>
JaePbond
>tried them side
I know that not all C5's are great, but after searching a while, my second C5+
has optics that would crush a TV85. It can keep up with 4 inch apo's.
Bert Geeslin
the zenith. Even with a star diagonal, you have to hunker down pretty
close to the ground, and getting a view through the Telrad or finderscope
requires some major neck bending.
Bert Geeslin
Rich N.
a pain in the neck.
You could add weight to the back of your OTA so that it will balance
with more of the tube forward of the tube ring. This would put the
diagonal a little farther off the ground.
Rich
Bert Geeslin wrote in message <01be4d69$3ae762a0$a28ccbd0@bgeeslin>...
JosephB41
the zenith. Even with a star diagonal, you have to hunker down pretty
close to the ground, and getting a view through the Telrad or finderscope
requires some major neck bending. >>
In a case like that, it's a good idea to mount the Telrad near the middle of
the tube, not down by the eyepiece.
Joe Bergeron (JABer...@aol.com)
tfla...@my-dejanews.com
Stard...@webtv.net wrote:
> If you post an opinion on this NG, you can count on 5X the number of
> responses.
Yes, but not one of them has agreed with you, which should tell you
something. I will add my voice to the dissent. In my opinion, taking
all things into account, refractors are the worst telescope design with
respect to viewing position. The combination of long tubes and viewing
from the bottom is particularly problematic, because it requires both
a tall, ultra-stable mount and a variable-height chair.
A 4" refractor may be marginally manageable, but that is only because
the size is so small. A 4" SCT or 4" Dob would be far more comfortable.
Conversely, a conventional 6" F/15 achromat, with similar performance
to an 8" SCT or an 8" Dob, varies the eyepiece height by several feet
when switching from the zenith to near the horizon.
- Tony Flanders
Cambridge, MA
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
tfla...@my-dejanews.com
"Gonzo Breath" <stin...@intrex.net> wrote:
> Then I started reading about the TV-85 APO...
> According to the December article in Sky and Telescope,
> there does not seem to be anything that the TV-85 scope
> does not do well...
I think you are misunderstanding the review. It seemed to me like
a perfectly fine and fair review, but that is only because the author
took for granted that all of his readers understood implicitly the
limitations of an 85 mm. telescope. Which is to say, that an
average 6-inch econo-Dob will provide significantly more detail
on each and every object in the sky. Let alone an 8-inch SCT
or a high-quality 6-inch Dob.
> Is there something I am missing here? What are the weaknesses
> of the TV-85? In general, I was under the impression that
> refractors were not the best suited for deep space observing,
> and yet, I have read articles saying that the TV-85 can pick
> out some planetary nebulas that can only be seen through
> mid-range reflectors with filters.
Possibly so. But the only reason that people mention this is because
the fact is so surprising. They don't talk about the 99% of all
deep-sky objects where the mid-range reflector beats the TV-85
handily, because that's just what you would expect. In any case,
what's wrong with using a filter? Put that same filter on the
TV-85, and the view will become so dark that you can't see anything.
To me, the TV-85 seems pretty unattractive. If you just want to
satisfy the craving for a high-quality portable instrument, why
not get a Ranger or a Pronto? They are nearly as classy as the
TV-85, and vastly cheaper. Or, if you want the best possible
ultra-portable instrument, get the AP Traveller. It is barely
larger than the TV-85, and 100 mm. is getting on towards serious
aperture. 85 mm. seems neither here nor there.
Rich N.
How many 6" f/15 achromats have you seen lately? I've seen 2 in
the last 9 years. You are right about the problems with a long OTA.
That is one of the reasons for the popularity of the modern fast APOs.
The AP 155EDF, 130EDF and 105Traveler are very compact. The diagonal does
not stick down as far with the APs as with my 4" f/8 Takahashi refractor.
Rich
>Yes, but not one of them has agreed with you, which should tell you
>something. I will add my voice to the dissent. In my opinion, taking
>all things into account, refractors are the worst telescope design with
>respect to viewing position. The combination of long tubes and viewing
>from the bottom is particularly problematic, because it requires both
>a tall, ultra-stable mount and a variable-height chair.
>
>A 4" refractor may be marginally manageable, but that is only because
>the size is so small. A 4" SCT or 4" Dob would be far more comfortable.
>Conversely, a conventional 6" F/15 achromat, with similar performance
>to an 8" SCT or an 8" Dob, varies the eyepiece height by several feet
>when switching from the zenith to near the horizon.
>
dj...@psu.edu
>
> "To Hell with Pluto!" :)
>
Rich,
There was a 16" suitcase Dob at Stellafane last year (see
http://www.stellafane.com under 1998 Mechanical Competition winners)
Dave Mitsky
ASH, DVAA
"Pluto, go to Hades!" :>)
Clive Gibbons
<tfla...@my-dejanews.com> wrote:
>
>To me, the TV-85 seems pretty unattractive. If you just want to
>satisfy the craving for a high-quality portable instrument, why
>not get a Ranger or a Pronto? They are nearly as classy as the
>TV-85, and vastly cheaper. Or, if you want the best possible
>ultra-portable instrument, get the AP Traveller. It is barely
>larger than the TV-85, and 100 mm. is getting on towards serious
>aperture. 85 mm. seems neither here nor there.
>
> Cambridge, MA
Just a few comments, Tony.
I don't think a Ranger or Pronto is really comparible to a TV-85.
The 85 has *much* better colour correction and nearly 50% more light
grasp. It is alot pricier than a Pronto, but the performance difference
might justify this.
As far as getting an AP Traveler is concerned, you'll probably find the
TV-85 is alot easier to find! ;)
Cheers,
--
Clive Gibbons * *
Technician, McMaster University, * "Good, Fast, Cheap... *
School of Geography and Geology. * ...pick any two." *
JosephB41
comfortable overall because of the limited eyepiece movement and the ease of
rotating the tube or diagonal. I find using my 6" f/9 refractor is pretty comfy
with a good chair though, even though I wind up moving that chair around quite
a bit. I had to stick a 12" extension on the G-11 tripod to make it usable when
pointed at the zenith.
Lou L.
Lou L.
AndersonRM
In article <8643-36B...@newsd-211.iap.bryant.webtv.net>,
Stard...@webtv.net writes:
> Prejudiced how? I merely stated that the viewing position of a scope is
>something to be considered. I have owned a 4 1/2 " reflector on a
>tripod, an ETX and a 4" Celestron refractor.
Viewing position variations equal the circle circumscribed by the
telescope tube. A 40 inch long refractor is going to have a far
greater position change going from object to object than a
18 inch long SCT 8" tube. Point an 8 inch SCT on a fork
at Rigel, then point it at Castor. The change is about an 8 inch
drop followed by a rightward (at the eyepiece) swing of about
6 inches. The diagonal eyepiece position change is only about
10 inches or so. A 4 inch F`10 refractor eyepiece swings about
20 inches.
The shorter the tube, the easier to observe.
AndersonRM
>
>Rich,
>
>There was a 16" suitcase Dob at Stellafane last year (see
>http://www.stellafane.com under 1998 Mechanical Competition winners)
>
>
I remember a military guy in Sky and Tel who had a 12 inch
Cassegrain in a suitcase, but i'll bet it and the 16 weigh an
awful lot.
Richard DeLuca
(JosephB41) wrote:
> I think a stubby telescope like a C-8 or a Questar is probably the most
> comfortable overall because of the limited eyepiece movement and the ease of
> rotating the tube or diagonal.
Agreed,
Nothing's more comfortable than a Questar, especially on a sturdy picnic
table. I've wasted (enjoyed) lots of time over the years, both daytime
and night, with just such an instrument.
Best Regards,
Rich
Stard...@webtv.net
tfla...@my-dejanews.com wrote:
Yes, but not one of them has agreed with you, which should tell you
something. I will add my voice to the dissent. In my opinion, taking all
things into account, refractors are the worst telescope design with
respect to viewing position. The combination of long tubes and viewing
from the bottom is particularly problematic, because it requires both a
tall, ultra-stable mount and a variable-height chair.
It's O.K. that no one has agreed with me. Although I have been observing
for several years, there is a lot I need to learn. For example, from
this thread I've realized the need for a variable height chair. I never
considered getting one. Although you disagreed, you've been polite
about it.
+++++++++++++++++++++++++++++++
A 4" refractor may be marginally manageable, but that is only because
the size is so small. A 4" SCT or 4" Dob would be far more comfortable.
If the ETX counts, the tripod trial didn't go so well. When sitting, my
knees sort of get in the way, I'm 6' 1".
+++++++++++++++++++++++++++++++
Conversely, a conventional 6" F/15 achromat, with similar performance
to an 8" SCT or an 8" Dob, varies the eyepiece height by several feet
when switching from the zenith to near the horizon.
Cambridge, MA
I agree with your assesment of the 6" achromat ( those suckers get huge
) and the problem I had with the Dobs would be solved with a proper
chair. With the SCTs however, the problem I had was bumping into the
tripod, and without a barlow, bumping against the back of the OTA when
viewing near the zenith. Ouch! I better learn to overcome this.
Stard...@webtv.net
circumscribed by the telescope tube. A 40 inch long refractor is going
to have a far greater position change going from object to object than a
18 inch long SCT 8" tube. Point an 8 inch SCT on a fork at Rigel,
then point it at Castor. The change is about an 8 inch drop followed by
a rightward (at the eyepiece) swing of about 6 inches. The diagonal
eyepiece position change is only about 10 inches or so. A 4 inch F`10
refractor eyepiece swings about 20 inches.
The shorter the tube, the easier to observe. -Rich
O.K. I have a problem. ( sob ) I'm 6' 1" and ( sob ) my knees stick out
and I tend to bump the tripod unless I can set back away from it. I feel
so much better now.
william meyers
In choosing between a small refractor and a larger Dob or SCT on the
basis of portability, you might want to distinguish between portability
in an airplane and portability onto your patio or back yard. I keep a 10"
dob with a wooden truss tube cage in my garage, fully set up; when I want
to observe, I don't "grab" it and lift it in one hand, I don't lift it at
all. I wheel it (it has wheels) out onto my driveway in back of my house.
I then start observing: no setup time beyond loosening two sliding bolts
to free the altitude axis. So, for me, it is as portable as any smaller
scope, and gives great views compared to my 6" dob.
But if stairs, or narrow doorways were involved, the story would be very
different. If you have wheels on it, and a patio or deck on the same level
where you keep the scope, you are in good shape.
My scope breaks down readily into three components that fit into my
minivan, even though it is an f6.4. I can lift all three components myself
bu usually have a bit of help. Bigger than 10" I find some components get
harder to lift, in truss tube Dobs.
If you live in an apartment that is not on the ground floor, consider
seriously something like a small refractor or a C5.
If your scope has a tripod, JMI makes wheelie bars for many sorts of
tripods. But this presumes ground level living.
It might be hard to wheel a telescope across a lawn if the earth is soft
and the telescope is large, even if you use large balloon wheels.
If you have a picnic table that is sturdy, a 6"f5 dob or smaller can
easily be set up on it instead of a tripod. Small refractors and small
SCT's will probably work from this position also, as will the ETX,
although I don't like the small field of view of the ETX considering its
modest aperture. But it would doubtless be great if you travel by plane
with a telescope.
I think the difficulty or easy of getting the telescope into the viewing
area is far more important than eyepiece position; the observing chair
sold by Pocono Optics can handle lots of different eyepiece situations
pretty comfortably. Yes, it does have to be adjusted as you move a Dob
from one object to another.
Just my personal experience; your situation may give you a different
range of choices. Hope this helps,
Bill Meyers
In article <91779851...@math.kth.se>,
--
~5E:
Gerh3150
don't forget about cool down time
Chris Gerh...@aol.com
I am Spartacus!
tfla...@my-dejanews.com
"Rich N." <rn...@znet.com> wrote:
> How many 6" f/15 achromats have you seen lately? I've seen 2 in
> the last 9 years. You are right about the problems with a long OTA.
> That is one of the reasons for the popularity of the modern fast APOs.
Rich,
Thanks for keeping me honest. Of course I agree, and knew so at the time
that I posted, but I omitted this piece of information because it didn't
agree with the flow of my argument.
Fact remains that an SCT is even more compact than an APO, and that the
price of a large APO puts it in a class all of its own, not really comparable
with any other telescope.
- Tony Flanders
Cambridge, MA
-----------== Posted via Deja News, The Discussion Network ==----------
Todd Gross
>From: jaep...@aol.com (JaePbond)
>Subject: C5 vs Televue 85 (was vs 8 inch Sct.)
>Date: 31 Jan 1999 23:30:09 GMT
Well, now you are in there with a possible comparison that is realistic. Let's
examine that.
My televue85 (bizarro) has given me what I consider the BEST possible view of
the planets for it's aperture. A great star test, plus extraordinary detail on
Saturn including a very clear shot at the cassini division, and on Jupiter,
numerous festoons and views of some of the white ovals, etc. (the red spot is
EASY, can make out limited detail within the GRS) The view however does not
hold a candle to the 5" A/P , nor the 7" starmaster reflector. I have tried
the TV85 in florida and Cayman stability too, where I reaped the max out of
it.
However, that second C5+ of yours.. I'd bet if the optics really were great,
it could out-do the TV 85 despite my testament above. DID YOU TRY the televue
85 in optimal conditions .. or are you speaking off the cuff?
To newcomers: Mini-reviews of these scopes can be found at
http://www.weatherman.com/wxastrob.htm
Todd Gross
JaePbond
>it could out-do the TV 85 despite my testament above. DID YOU TRY the televue
>
>85 in optimal conditions .. or are you speaking off the cuff?
>Todd Gross
Todd, you got me. I'm guilty of speaking off the cuff.
However not without some basis. I have compared it to 80mm Brandon APO ('97),
Brandon 94, and the AP Traveler, plus a really good ETX. I'm so amazed at
the performance of this C5+ so far, that I think the Better View Desired
article on Cat scopes is right on (you must have read it?). I questioned his
findings when I got my first C5+ a couple of years ago. He said he was
impressed and it performed at least as well as the Questar during daytime.
The background sky is nice and dark. Lunar images along the terminator at
high power shows lots of contrast & resolution. I guess I am more surprised
than anything.
I had to twist the owner's arm to get the scope. He was waffling as he wasn't
sure he could get one that good again based on his 4 other larger SCT's.
I'd like to think it may be like your comparison of the recent ETX to the TV85
but with the extra aperture tacked on. When we get some really good seeing,
I'll be able to give you some more updates.
Jae P
Rich N.
very well against a smaller refractor. It would be interesting
to know if this C5 shows Jupiter's 4 largest moons as discs.
Rich
Les6767 wrote in message <overlook
-snip
>If you do get around to comparing the TV85 with your C5 see if your C5 show
>stars like fine grains of sugar on a black velvet background, planets like
>round balls, and the color of a blue star as vibrant as the refractor...
>
>
Stard...@webtv.net
+++++++++++++++++++++++++++++++
(Rich N.) wrote:
I'm sure a C5 with outstanding optics would perform very well against a
smaller refractor. It would be interesting to know if this C5 shows
Jupiter's 4 largest moons as discs.
Rich
Les6767
have never compared it to, but also going from "keeping up" on a 4in to "crush"
on the vernable TV85 shows your "aperature obsessed" attitude. The TV85 is not
that far of a performer behind other 4in APOs......I consequently think you're
the type to want to concentrate on aperature realted strengths and overlook
refractor strengths "sharpness" and color
JaePbond
>on the vernable TV85 shows your "aperature obsessed" attitude.
Hmm...interesting newsgroup response but the spelling could be better..
> The TV85 is not that far of a performer behind other 4in APOs......I
consequently think you're the type to want to concentrate on aperature realted
strengths and overlook refractor strengths "sharpness" and color>
Is that green, blue or purple strengths ?
>If you do get around to comparing the TV85 with your C5 see if your C5 show
>stars like fine grains of sugar on a black velvet background, planets like
>round balls, and the color of a blue star as vibrant as the refractor...
>
No question, refractors are king.
Jae P
Eric Faust
lower power but I've not tried it. It's great to watch the moons as the are
occulted and sliced cleanly in half by jupiter. One of those sights that keeps
you looking.
Eric
In article <12728-36...@newsd-214.iap.bryant.webtv.net>,
Stard...@webtv.net says...
>
>How much magnification do you need to see Jupiter's moons as discs?
>+++++++++++++++++++++++++++++++
Rich N.
moons as discs. When I observe Jupiter I'm usually using between
150x and 250x.
Rich
--
How much magnification do you need to see Jupiter's moons as discs?
+++++++++++++++++++++++++++++++
Todd Gross
>I think you're just bias...not only saying "crush" the optics of something you
>have never compared it to, but also going from "keeping up" on a 4in to "crush"
>on the vernable TV85 shows your "aperature obsessed" attitude. The TV85 is not
>that far of a performer behind other 4in APOs......I consequently think you're
>the type to want to concentrate on aperature realted strengths and overlook
>refractor strengths "sharpness" and color
>If you do get around to comparing the TV85 with your C5 see if your C5 show
>stars like fine grains of sugar on a black velvet background, planets like
>round balls, and the color of a blue star as vibrant as the refractor...
Well, in all fairness, he did compare it to a 4" Traveler, and the 4" traveler
is better overall in performance than the TV85..due to the aperture. Both
scopes basically give you 100% of what one can expect from that aperture.
As for the other refractor attributes, almost all can be achieved with proper
design of newtonians, and other scopes from what I understand and have seen,
but I know where you are coming from. - Todd G
Todd Gross
>From: "Rich N." <rn...@znet.com>
>Subject: Re: C5 vs Televue 85 (was vs 8 inch Sct.)
>Date: Tue, 2 Feb 1999 16:51:07 -0800
>I'm sure a C5 with outstanding optics would perform
>very well against a smaller refractor. It would be interesting
>to know if this C5 shows Jupiter's 4 largest moons as discs.
>Rich
FWIW.. In refractors I have tested this anyway. The discs are actually airy
discs once you get to 3" and below...therefore not really the discs of the
Jovian moons themselves. However, from my recollection, I can just barely make
out Ganymede as larger in the Televue 85 (3.35"), and by the time you get to
the 4" and on up refractor, the moons start to take on different sizes. Did
not look for this when I had the C5+ myself, didn't really know what I was
doing at the time. TG
Todd Gross
>From: Stard...@webtv.net
>Subject: Re: C5 vs Televue 85 (was vs 8 inch Sct.)
>How much magnification do you need to see Jupiter's moons as discs?
150-200x
Todd Gross
>>If you do get around to comparing the TV85 with your C5 see if your C5 show
>>stars like fine grains of sugar on a black velvet background, planets like
>>round balls, and the color of a blue star as vibrant as the refractor...
>>
>No question, refractors are king.
>Jae P
but aperture is the emperor
(you know I love both)
Todd Gross
>I don't know what the minimum magnification would be to see the
>moons as discs. When I observe Jupiter I'm usually using between
>150x and 250x.
Hi Rich! Interesting. That's the second time you dropped a hint about that.
(150x)
Most of my Jovian observation is in that range too (175x-300x) due to seeing,
but any fruitfull observation of small features (I like to call them ALPO
worthy features, to do transit timing, etc.) is generally done at 250x and on
up. Saturn even higher. One thing i have noticed is that the clarity of
Jupiter and Saturn ismore easily discerned at high power in larger aperture.
That is, given great seeing, the view seems to be as good in smaller aperture
refractors at something like 200x, but pump it up to 400x or more, and it's
the larger aperture that is flashing periods of sharp clarity my way, not the
5.1" APO. The image doesn't seemingly "break down" in the 5" refractor, but
eventually just doesn't seem to get very much better with magnification, while
it can get better and better in the larger scope(s).
Rich N.
I asked because comparing my 4" Tak FC-100 to several
3.5" Questars. The 4" refractor consistently showed the
moons as discs while the Questars consistently show
the moons as points.
It would be interesting to know if a good C5 shows the
moons as discs.
Rich
Todd Gross wrote in message ...
>In article <7986ds$7fu$1...@remarQ.com> "Rich N." <rn...@znet.com> writes:
>>From: "Rich N." <rn...@znet.com>
>>Subject: Re: C5 vs Televue 85 (was vs 8 inch Sct.)
Harry Pulley
disk. Theoretically, a 5" scope should be able to resolve two double
stars 1.0" apart. If the Dawes limit also shows the size of object you
are able to resolve, then the 5" is not quite enough to resolve Europa
but is enough to tell that the other three satellites are larger than
the airy disk. A 6" scope, with a limit of 0.8" shows them all as
disks.
Next time you are out with your 5-6" scope, look for background stars
near the Jovian system. It is interesting to compare the apparent size
of stars compared to the satellites. I think the Dawes limit is
pessismistic in this regard and bet a 4" scope can actually tell Jovian
satellites from stars.
Really interesting was last January's conjunction of Mars with Jupiter.
Mars was really small in size at just over 4" but looked HUGE compared
to the satellites.
Even though magnification doesn't matter, I'd suggest at least 100x to
see the Galilean Moons as disks, and 150x is better.
Stard...@webtv.net wrote:
>
> How much magnification do you need to see Jupiter's moons as discs?
> +++++++++++++++++++++++++++++++
> (Rich N.) wrote:
> I'm sure a C5 with outstanding optics would perform very well against a
> smaller refractor. It would be interesting to know if this C5 shows
> Jupiter's 4 largest moons as discs.
> Rich
> +++++++++++++++++++++++++++++++
>
> Stard...@webtv.net
> More tears have been shed from answered prayers than those unheard-----
--
<:-{} Harry C. Pulley, IV, member RASC, ALPO, IOTA, TPS
\ mailto: hpu...@home.com
http://members.home.net/hpulley
Guelph, Ontario, Canada, 43.55N, 80.26W
Rich N.
This last year the seeing was seldom good enough to use much
power. At a star party I would rather show a smaller "nicer looking"
image if the seeing is not very good. Jupiter is large enough to
see interesting features using less than 200x.
When the seeing is really good I will use well over 250x (depending
on the telescope). A few years ago using 300x to 450x to good
advantage wasn't unusual. Once or twice 700x and 800x.
You're right, Jovian features like thin festoons, white ovals, barges,
etc. are easier to see using 250x and up. But you do need good seeing.
Rich
Todd Gross wrote in message ...
>
Rich N.
Rich
Harry Pulley wrote in message <36B84FDF...@home.com>...
-snip
>Next time you are out with your 5-6" scope, look for background stars
>near the Jovian system. It is interesting to compare the apparent size
>of stars compared to the satellites. I think the Dawes limit is
>pessismistic in this regard and bet a 4" scope can actually tell Jovian
>satellites from stars.
-snip
JaePbond
>
>(you know I love both)
>
"Never met a scope I didn't like, just a matter of how much"
Jae P
AndersonRM
In article <7997vo$mb7$1...@remarQ.com>, "Rich N." <rn...@znet.com> writes:
>I don't know what the minimum magnification would be to see the
>moons as discs. When I observe Jupiter I'm usually using between
>150x and 250x.
Below about 8 inches, my guess is your seeing diffraction discs
and not actual moon discs.
-Rich
I ask that everyone to boycott the movie now being made from on of
Scientologist
founder, L. Ron Hubbard's books. Paying to see it only supports a CULT
that is ultimately dangerous.
Richard DeLuca
> I asked because comparing my 4" Tak FC-100 to several
> 3.5" Questars. The 4" refractor consistently showed the
> moons as discs while the Questars consistently show
> the moons as points.
>
> It would be interesting to know if a good C5 shows the
> moons as discs.
>
My own Questar 3.5 doesn't show them as discs either, although I've tried
many times over the years. I'm very pleased wit the scope- just not QUITE
enough aperture. I've seen them as discs in several 4" apos.
In my 6" AP Starfire they are very obvious, and on a decent night one can
easily identify them by size and color.
Best Regards,
Richard DeLuca
Brian Tung
> I can confirm that my C5+ shows the moons as discs. They appear
> distinctly different from stars. This is at 167x (15 mm Plossl plus
> Barlow). The seeing need only be of average quality.
I should qualify this.
For the sake of reference, the Airy disc in a C5+ (and presumably the
new G5 too) is about 1.7 seconds of arc wide, give or take. Ganymede,
the largest of the moons, is about 5300 km wide; at its average distance,
some 800 million km away, it subtends about 1.3 seconds of arc.
It is not then the case, however, that the Airy disc completely overwhelms
the moon's disc. I don't know for sure, but I would guess that the Airy
pattern is convolved over the surface of the moon to produce the final
image. It is true that the image of Ganymede, when it appears, is a
visible disc with a distinct cutoff at the edges, but still a reasonably
bright halo around it. It is also true that this disc appears larger than
the discs of, say, Io and Europa, which subtend about 0.9 and 0.8 seconds
of arc, respectively, and certainly larger than the discs of stars, which
are just the Airy discs.
A star does *not* show a halo, as surrounds the moons. It shows a set of
diffraction rings. This may be the reason I perceive the images of the
moons as distinctly different from those of stars.
It is a very rough rule of thumb that the diameter of the visible disc in
arc seconds is approximately equal to 1.7 arc seconds (the Airy disc) plus
the true angular width of the moon. That would yield the picture which I
see in my eyepiece, at least.
Brian Tung / byron elbows
br...@isi.edu (What, me worry about spam?)
Astronomy Corner at http://gost.isi.edu/brian/astro/
C5+ Home Page at http://gost.isi.edu/brian/astro/c5plus/
Jim Van Nuland
>Date: Wed, 3 Feb 1999 02:23:47 -0800
>I don't know what the minimum magnification would be to see the
>moons as discs. When I observe Jupiter I'm usually using between
>150x and 250x.
>Rich
>--
>How much magnification do you need to see Jupiter's moons as discs?
I had suspected discs at 61x, and confident at 122x.
One night when S&T mentioned that there would be a field star was among
the moons, I went to see whether I could tell the difference. In an 8
inch Newtonian at 61x, it was instantly obvious which was the imposter,
this based on size. After another look, I realized that the star was
distinctly bluer than the moons.
* SLMR 2.1a * Save some stars...kill a light.
__
| Internet: Jim.Van...@sjpc.org
| Fidonet: Jim Van Nuland 1:143/11
|
| A service of the San Jose IBM PC Club, running OS/2 Warp
JosephB41
rings. In my 6" refractor, they are 4 perfect little disks, without diffraction
rings, with varying colors and levels of surface brightness.
Joe Bergeron (JABer...@aol.com)
Todd Gross
>When the seeing is really good I will use well over 250x (depending
>on the telescope). A few years ago using 300x to 450x to good
>advantage wasn't unusual. Once or twice 700x and 800x.
>You're right, Jovian features like thin festoons, white ovals, barges,
>etc. are easier to see using 250x and up. But you do need good seeing.
100% agree
Todd Gross
discern Ganymede as larger (only ganymede, not the others) Will re-check
that down the road. Thanks much.
(would be interesting to see if that was a function of aperture or scope type,
etc)
AndersonRM
In article <toddg.118...@weatherman.com>, to...@weatherman.com (Todd
Gross) writes:
>This is interesting, as I could swear the Televue 85mm was able to
>discern Ganymede as larger (only ganymede, not the others) Will re-check
>that down the road. Thanks much.
Maybe because it is brighter, it looked larger.
Sue and Alan French
I am surprised that you see such a difference between a 3.5" Questar and a
6" APO. In some Questar literature they say that the 3.5" Questar
approaches the performance of a fine 6-inch Apochromat <G>.
Clear skies, Alan
JosephB41 wrote in message <19990203201945...@ng-fu1.aol.com>...
JosephB41
approaches the performance of a fine 6-inch Apochromat >>
Well, it does. In the same vein, I approach the wisdom and benevolence of the
Dalai Lama. Just not all that closely.
AndersonRM
In article <O#2KNpKU#GA.265@upnetnews05>, "Sue and Alan French"
<sue_and_a...@msn.com> writes:
> 3.5" Questar vs. 6" APO
Stop! It's too funny!!
samw...@my-dejanews.com
jose...@aol.com (JosephB41) wrote:
> << In some Questar literature they say that the 3.5" Questar
> approaches the performance of a fine 6-inch Apochromat >>
>
> Well, it does. In the same vein, I approach the wisdom and benevolence of the
> Dalai Lama. Just not all that closely.
Just checked that Questar lit that Alan referenced. Already got a Questar.
Anybody out there I can unload this now redundant AP 155 EDF on?
Thanks Alan ;-}
-----------== Posted via Deja News, The Discussion Network ==----------
http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
Rich N.
>
>Just checked that Questar lit that Alan referenced. Already got a Questar.
>Anybody out there I can unload this now redundant AP 155 EDF on?
>
>Thanks Alan ;-}
You could dump the Questar for a TV Ranger. Their performance
is very close to the Q3.5.
Rich
Richard DeLuca
>
> You could dump the Questar for a TV Ranger. Their performance
> is very close to the Q3.5.
>
> Rich
Tell you what..........;->
For every Questar 3.5 you send me, I'll send TWO Rangers back to you. Okay??
Best Regards,
Richard DeLuca
Rich N.
Richard DeLuca wrote in message ...
That's right. They're less expensive and perform nearly as well. ;-)
Rich
Clive Gibbons
Ummm, I guess that depends on how you define "nearly", Rich. :)
From comparisons I've made, they do have about the same light grasp.
However, the colour correction of the Ranger isn't anywhere near as good
as the Questar and because it has less aperture, it can't split doubles
down to the same limit as the Q. The Ranger is tougher to focus, because
of it's slightly stiff helical action.
Of course, the Questar is essentially a complete, ultra-portable
observatory, with many neat user-friendly features, while the Ranger is an
OTA, sans mount, drive, slow motions, finderscope and Barlow.
That's gotta account for some of the price diff, huh? ;)
Cheers,
--
Clive Gibbons * *
Technician, McMaster University, * "Good, Fast, Cheap... *
School of Geography and Geology. * ...pick any two." *
Michael Edelman
As for the comparison betwene a Ranger and a Questar, uh-uh. Don't think so. I own
a Q and a Pronto, and there's quite a bit of difference in both contrast and
resolution between them..not to mention chromatic error. But the two compliment
each other very nicely.
-- mike
Rich N.
cost quite a bit to manufacture.
Rich N.
a 3.5" Questar and a 155EDF. Both comparisons were
with tongue in cheek.
Questar vs a TV-85? ;-)
Rich
Michael Edelman wrote in message
Stewart Squires
>
> Well the Pronto and Questar are closer in performance than
> a 3.5" Questar and a 155EDF. Both comparisons were
> with tongue in cheek.
>
> Questar vs a TV-85? ;-)
Seriously, the problem I have with this comparison is that it's really
no different than the Pronto/Questar comparison. Or my Questar compared
to my Traveler. Slow optics versus fast. Not the same-use scopes.
It's why they were both on my list :-}
But to address the original comment by Alan, yes, Braymer was a
salesman. He was a commercial artist prior to building telescopes. And
there are some things that have remained (survived)in Questar literature
that probably ought not to be there based on what we know now. We have
to date (1) 4" seeing cells, (2) glass flowage, and now we have (3) an
89mm obstructed cat that provides views of a 6" APO. I really didn't
buy my Questars based on this, nor did anyone I know with one at this
point in time.
Still, it's a nice telescope that makes a lot of folks very happy.
Stew
Rich N.
was a kid I would read and re-read the Questar and Unitron ads.
The Questar is functional art.
Rich
Stewart Squires wrote in message <36BBB5...@tar-palantir.com>...
AndersonRM
In article <79ftrs$251$1...@remarQ.com>, "Rich N." <rn...@znet.com> writes:
>Questar vs a TV-85? ;-)
Planetary detail, probably the TV85 by a slim margin, if any.
Deepsky, the TV85 by a pretty wide margin owing
to a substantially brighter image.
Stewart Squires
>
> One of these days I want to own a 3.5" Questar. When I
> was a kid I would read and re-read the Questar and Unitron ads.
> The Questar is functional art.
Actually, so are the Unitrons in their own way. Certainly they were
meant to be complete observing products as well. I own both 3" and 4",
f/16 and f/15, respectively. They both have superb optics, are
mechanically solid on well built EQ mounts, and have tons of accessories
(toys) that make them fun to observe with in their own right.
Stew
Del Johnson
>6" APO. In some Questar literature they say that the 3.5" Questar
>approaches the performance of a fine 6-inch Apochromat <G>.
>
>Clear skies, Alan
>
>is very close to the Q3.5.
>
>Rich
>
Do we conclude that the TV Ranger is about as good as a fine 6" apo :^) ?
Del Johnson
Rich N.
bruce...@hotmail.com
"Rich N." <rn...@znet.com> wrote:
> >>
> >>You could dump the Questar for a TV Ranger. Their performance
> >>is very close to the Q3.5.
> >
> >
> >Del Johnson
>
> Ouch!
>
> Rich
Ouch is right! Rich, don't you think overall that a scope like the 102
fluorite Vixen would easily outperform the 3.5" Questar, even if it is not a
6" AP?
Best regards,
Bruce Jensen