Looking for advice on finderscopes.
Bill Cotten
right angle model with a correctly oriented image. I want the image to be
sharp right to the edge of the field and bright. Thanks.
Bill
Mark S. Holden
Unfortunately, it seems makers tend to cut corners on finder scopes to
keep the price in the range folks are willing to pay.
Vic at Stellarvue tells me his F50 finder will perform better if you
replace the eyepiece, but I've yet to identify a suitable replacement.
A direction I've considered is building a finder using the Borg system.
George Hein
and an old 30mm Plossl. I live in a suburb and am nearsighted. Also,
after some 55 years of casual telescope observing I am used to a normal
finder. I moved my red-laser pointer to my smaller Borg77-acromat which
lacked a finder.
The only problem with Borg is that it is expensive and you must also
purchase a couple extra parts (which I already had left over from my
Borg77. If you want perfection, you need to get an apochromatic lens.
jameswill...@yahoo.com
Engineering Company have Japanese finderscopes. University Optics'
finders have had a good rep for a long time. Built in USA. Machined
aluminum. Lumicon, too. You could also use a 50 - 60mm Borg achro -
great quality and light. Also, the new Williams Optics 60mm achro. Then
you have Antares (Sky Instruments) and Orion. Not as good but a great
value for the money. If you can get an Intes 10x50 - 5mm exit pupil,
great optics, they are very good (I have one) - not sure if they have a
RA option.
Jim Johnson
Ed T
<jameswill...@yahoo.com> wrote in message
news:1121438344.5...@o13g2000cwo.googlegroups.com...
> If money is no object, go Takahashi.
My thoughts too. The 7x50 is very nice, haven't tried the bigger one. Add
an illuminator if you're under dark skies.
Ed T.
Mitch...@aol.com
Seriously, I got rid of all my finderscopes after using a telrad* for a
while, and picked up a 31mm Nagler. This enables me to use the whole
main optical system as a finder! and the telrad to point close enough
that the main scope can pan around to find the dim object. Try it , you
will like it. Our hit rate went up markedly after switching from
finders to zero power pointers.
[*] telrad is one zero power finder, there are several others of
similar construction.
Morris Jones
On Jane's 17.5-inch Litebox dob, she uses an Orion Short-Tube 80, with
an erecting prism and a crosshair eyepiece for 16x. On my 14.5-inch
Litebox I have a Lumicon super 80mm finder with the same prism and
eyepiece for 12x.
Both work out very nicely. We don't have a ring mounting for the ST-80,
but Jane doesn't have much trouble aligning it.
You can see pictures of both on this page:
<http://www.otastro.org/2005-07-sfaa-yosemite/pg01.html>
One of my favorite star party tricks is to put an O-III filter on the
finderscope eyepiece and show the North America nebula NGC7000. It's
much easier to see with the erecting diagonal giving a proper view.
Best regards,
Mojo
--
Morris Jones
Monrovia, CA
http://www.whiteoaks.com
Old Town Astronomers: http://www.otastro.org
Doink
to which I added an adapter for 1.25" eyepieces. The rings are the same as
Orions 80mm APO or their 100mm OTA so I had rings laying around. Piggy
backed onto any ota it makes a cool finder. And, it's about the price of a
decent finder! Look around, you can get these CHEAP
Doink
<Mitch...@aol.com> wrote in message
news:1121441293.7...@g14g2000cwa.googlegroups.com...
Mark S. Holden
Takahashi doesn't seem to be offering right angle finders though.
Actually, if money (and weight) is no object, go for an 80mm f6 apo. :)
William Hamblen
Lumicon and University Optics have nice finders with Amici right angle
prisms.
--
e-Harmony.com called the cops after I sent in my personality profile.
Michael McCulloch
wrote:
>Vic at Stellarvue tells me his F50 finder will perform better if you
>replace the eyepiece, but I've yet to identify a suitable replacement.
What's wrong with the StellarVue F50? I own it and love it.
The only possible shortcoming I can think of is that the finder
crosshairs are not illuminated and can be difficult to see under some
conditions.
I did try to use the Lumicon illumated reticle with the F50 and could
not get it to focus.
---
Michael McCulloch
Mark S. Holden
I'm still using my F50, and feel it does well in terms of bang for the
buck.
If you want a white right angle finder with a focuser that'll fit in a
50mm finder bracket, your options seem to be the F50 or building your
own with the Borg system.
The cross hairs in the f50 are remarkably easy to see because they're
quite thick. They can cover Jupiter.
My only real complaint is stars away from the center of the field start
looking like M objects. I'd like pinpoint stars across the field.
I'm picky.
I understand they can't afford to include a $150-$200 eyepiece as part
of a $100 finder.
But it would be great if Vic offered a high quality IR eyepiece as an
upgrade.
Chris L Peterson
>[*] telrad is one zero power finder, there are several others of
>similar construction.
I think I'd call it a unit power finder. A zero power finder seems like
it would be a particularly useless device! <g>
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
Bill Cotten
"Bill Cotten" <bill_cotte...@ANDTHIScomcast.net> wrote in message
news:goWdnYHSYNb...@comcast.com...
> Who makes the best quality finderscopes? I'm looking for atleast an 8x50,
> right angle model with a correctly oriented image. I want the image to be
> sharp right to the edge of the field and bright. Thanks.
Re hi all,
Thanks for all the responses. I've decided to go with a University Optics
8x50 Amici finder. It's not illuminated but I have several illuminators
laying around and I can easily drill and tap a hole in a suitable location
to remedy that. I have an old beat up UO finder that is very sharp to the
edge and seems to have a bright image. For this new project I' looking for
something that looks nicer.
I'll be using the finder in conjunction with a Telrad. I've never had a need
to use a finderscope in the past but this new scope will probably be used to
observe the Herschel 400 and I want something that will provide a correctly
oriented image to match Uranometria.
I do have one more question about these correct image finders.......are all
amici prisms created equal? What kind of light loss can I expect compared to
a high quality mirror diagonal? Who makes the best amici prisms? That's
three questions! ;-)
Thanks again,
Bill
William Hamblen
> I do have one more question about these correct image finders.......are all
> amici prisms created equal? What kind of light loss can I expect compared to
> a high quality mirror diagonal? Who makes the best amici prisms? That's
> three questions! ;-)
Amici prisms have to be silvered on the roof because the angles aren't
right for total internal reflection, so you lose a little light compared
to a plain 90 degree diagonal. I have an Edmund Scientific Amici
diagonal that I use in a Tuthill 50 mm finder. I haven't noticed the
image being dimmer than with a plain 90 degree diagonal, although I know
that has to be the case. You do get a diffraction spike from the roof,
which is the only obvious visual difference apart from the image being
the right way around.
Axel
> right angle model with a correctly oriented image. I want the image to be
> sharp right to the edge of the field and bright. Thanks.
The best one I've used is a Takahashi straight-through 7x50, it was a
superb match for my 8" Dob. But when I upgraded to a 14.5" Dob, I
needed a larger finder and had to go right angle to make it safer to
starhop while on a ladder. ;-) I wasn't able to hunt down an RA finder
with the same quality of optics and construction as the Tak, so I
settled on a Lumicon 11x80 RA and have been reasonably pleased. My
only gripes are that the optics aren't pinpoint sharp across the field
and the crosshairs are rather thick and not illuminated. Takahashi
does make an awesome 11x70 finder but it's not RA.
Cheers,
Ritesh
William C. Keel
A question that come to my mind - how well does this work from
light-polluted locations? Where I usually gaze from, there may
be few enough stars for naked-eye hopping that I've always
favored 50mm finders. (But then again, with our summer haze,
I've been stuck trying to teach constellations when Albireo
is a very tough naked-eye tartet...)
Bill Keel
tony_f...@yahoo.com
> Seriously, I got rid of all my finderscopes after using a telrad* for a
> while, and picked up a 31mm Nagler. This enables me to use the whole
> main optical system as a finder! and the telrad to point close enough
> that the main scope can pan around to find the dim object.
That works fine as long as the target is nice and bright,
so that it's readily visible even when you pan over it at
the lowest possible magnification. Difficult objects are
usually completely invisible unless you use medium to high
power, and even then, you need to know where *within* the
field of view to look for them. Otherwise, scanning an
80-degree apparent FOV with averted vision could take a
sizeable fraction of an hour.
Obviously, if the object's tough in the main scope, it's
going to be invisible in a finderscope too. But I do find
that a finderscope allows me to locate the surrounding star
field a whole lot faster than I can using just a low-power
eyepiece.
Mind you, given a choice between a unit-power finder *or*
a finderscope, I'd choose the former, as long as my main
scope had a reasonably wide maximum FOV. But if weight and
tube real-estate aren't issues, I really love the combination
of a unit-power finder *and* a right-angle finderscope.
- Tony Flanders
Brian Tung
> Mind you, given a choice between a unit-power finder *or*
> a finderscope, I'd choose the former, as long as my main
> scope had a reasonably wide maximum FOV.
I'm sure Tony knows this, but this is a personal choice, of course. I'd
make the opposite choice myself, because I'm able to use my finder as a
unit-power finder, too, simply by keeping both eyes open and watching
the crosshairs. It's a bit tough to do from dark skies, since it's easy
to lose the crosshairs, but I've learned to watch for stars being occulted
by the crosshairs to get them back again.
It seems this is not a universal skill, so those who find it hard to do
will probably prefer a unit-power finder. (I do have a Telrad on my dob,
and while I enjoy using it, I'd enjoy using an optical finder more. Not
enough for me to swap it out, so far, though.)
--
Brian Tung <br...@isi.edu>
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt
William Hamblen
> It seems this is not a universal skill, so those who find it hard to do
> will probably prefer a unit-power finder. (I do have a Telrad on my dob,
> and while I enjoy using it, I'd enjoy using an optical finder more. Not
> enough for me to swap it out, so far, though.)
It's useful to have both, even in a bright sky area. With a short
scope like an SCT it is hard to sight down the tube in order to get a
target into the field of the finder. The Telrad will get you in the
neighborhood and the finder scope will get you close enough to see the
target in a low power eyepiece.
--
The night is just the shadow of the Earth.
Brian Tung
> It's useful to have both, even in a bright sky area. With a short
> scope like an SCT it is hard to sight down the tube in order to get a
> target into the field of the finder.
I don't sight down the tube. I use the finder exactly as I would a
Telrad. If the crosshairs were illuminated, the connection would be
easier to see, but it's there all the same.
Of course, I don't dispute that it would be useful to have both. The
question is whether it's worth the purchase. For me, it would not be;
for others, the answer might be different.
tony_f...@yahoo.com
> It's useful to have both [a 1X finder and a finderscope],
> even in a bright sky area. With a short scope like an SCT
< it is hard to sight down the tube in order to get a
> target into the field of the finder.
Brian's point is that there's no need to sight along
the tube. Indeed, I find it quite easy to point a
conventional straight-through finderscope wherever
I want by keeping one eye open to look at the sky
while I look through the finderscope with the other.
As Brian says, the ability to do this varies quite a
lot from one person to another.
The main reason that I prefer a unit-power finder for
this purpose is that it has infinite eye relief. A
finderscope requires you to stick your eye right
against it, which is invariably awkward and/or
painful with a straight-through unit when pointed
near the zenith. That's doubly true for me, since
I favor low telescopes and a seated observing
position.
Also, I find that the discomfort factor makes it
hard or impossible for me to do extended star hops
through a straight-through finderscope. That's why
I like right-angle finderscopes so much. But with
a right-angle view, I really do need a supplemental
finder.
- Tony Flanders
Brian Tung
> The main reason that I prefer a unit-power finder for
> this purpose is that it has infinite eye relief. A
> finderscope requires you to stick your eye right
> against it, which is invariably awkward and/or
> painful with a straight-through unit when pointed
> near the zenith. That's doubly true for me, since
> I favor low telescopes and a seated observing
> position.
It's only necessary to put your eye up against it when you're using
it as an optical finder. If you use it like a Telrad, you only need
the very center of the field of view and can pull your eyeball back
away from it to a comfortable distance. (Well, comfortable to me,
anyway, except near the poles.)
The same tactic is used by quite a folks when using short focal length
orthos or Plossls on planets in a driven scope. Since the motor drive
keeps the target centered, the size of the field of view is less
important (it still makes it easier to find the target, of course) and
you can use only the central 20 degrees of the AFOV, say, and observe
in relative comfort.
Pursuant to another thread, pulling back from the eyepiece to improve
comfort at the expense of AFOV is one thing I'd consider to be a useful
astronomy hack.