18" Obsession or 18" Starmaster
Doug Healy
For all you Truss Tube Dob guys (Gals) out there.
I beleive that the 18" is the perfect size for my needs. I can get the
Obsession quicker and cheaper , but I have read such great things about
the CZ mirrors
and Rick's customer service
that I would be willing to wait the extra couple of months for the SM.
Does anyone have any Technical "gotchas" that they can list between the
2 brands.
Any feedback would be greatly appreciated.
Doug H
jar...@my-deja.com
Check out the recent thread on Obsession vs. Starmaster vs.
Starsplitter. Several posts there about this question.
Jarad
> Does anyone have any Technical "gotchas" that they can list between
the
> 2 brands.
Starmaster has GOTO (if you want it). I also like the 4 triangular
trusses (SM) better than 8 poles (OB) for ease of set up.
> Any feedback would be greatly appreciated.
> Doug H
>
>
Sent via Deja.com http://www.deja.com/
Before you buy.
Kurtis
wrote:
You might like to get the book the Dobsonian Telescope and consider
building your own. You'll get lots of technical info here as well as
see that many things affect your image. Optics are one. If not the
book will most likely see you on the Obsession. Rick does some
fundamental things different than Dave. Dave looks at strength of the
scope to keep distortion out. Rick believes in quick cool times, he
uses thinner mirrors. They cool faster. I feel you would do well to
spend the time and money on the book.
Kurtis
Please remove the "X" from my email address.
SaundersErineliz
of the primary mirror cell. It allows you to transport the scope without the
need for ramps.
Take care,
Pat Saunders
Paul Roy
Doug Healy <dhe...@teleglobe.net> wrote:
Doug,
Each scope has it's good points, and both scopes perform quite
well, however..each design has it's own points that make it unique.
The SMstr for instance has a removable mirror cell. This has it's good
points and bad points, and it really depends on what you're personal
prefrences are. I didn't like that as much as to me as it's just
another thing that you have to move....that is it's heavy, plus there
is always the increased chance you could drop it..you know it's dark,
you're tired, it's wet with dew..etc..
Plus, I like the wood the Obsession employs which has a far greater
weight to strength ratio then oak that is used in the SMstrs. Also,
IMHO..I have never met a SM that moves as well as an Obssn.
Cosmetically I think the Obssn. looks better as well, but that again is
matter purely of taste.
As far as optics are concerned, Obssn. can be acquired with optics as
good as CZ puts out. John Hall of Pegasus makes outstanding mirrors,
and was CZs mentor (many few know that) You can also get optics from
Galaxy and Swyaze (forgive me for spelling if not correct!)that are
superb as well. The Obssn. also comes standard with 99% endurobright
coatings on the secondary that will virtually never wear out. The
SMstr though has some newer ideas employed that the Obssn. does not.
One is a goto system (which in my opinion sort of negates the dob idea
in the first place..BUT the tracking is nice) The also have those neat
triangular trusses that make set-up time quicker, however take up more
room in you're vehicle.
So either way it's personal prefrence, and what appeals to you and
you're specific needs. You couldn't go wrong purchasing either scope.
I purchased the Obsession because of the reasons above that I FELT was
important. Plus, you can save one hell of alott of money by picking it
up yourself instead of having it crated and shipped. I think the
going rate for an 18" is close to $400.00. That could buy you 1 or two
very nice eyepieces to compliment you're new KILLER big eye.
pr
Kurtis
I spoke with both, and both could be picked up. Rick is close to a
state boarder and will meet you across the line to avoid the sales
tax! I don't know if this can be done with OB. I too like the OB
they do move great!
John J. Kasianowicz
Ian Turner
wrote:
http://www.mindspring.com/~skyshooter/Telescopes.html
David
I first saw a large Star Master with the new GoTo drive system at the
Chief land FL. Star Party in Oct. 99. It was
amazing to see a 22" scope slewing quietly from object to object.
Recently the thought of owning a large Dob has captured my attention.
Like most
Dobs Star Master designs there large scopes to be taken apart and
stacked together so transporting it is easier. There are differences
between Dob
manufactures and here are some I noticed. The quality of the wood and
fit and finish is very good not as excellent as the finish on a
Obsession but
hey it's a telescope not a piece of furniture. The mirror cell design
is the best Dob system I have seen to date. Rick uses a heavy steel
frame with 18
mirror support pads safety wired together. Over the past two nights
slewing the scope all over the sky the mirror has never required
recollimation.
This attest to the excellent mirror and truss design Rick Singmaster
employs. I have friends that must recollimation after several hours
with there
Obsession sling mirror design. The encoder system is 4000 tick high
resolution encoders coupled with the Sky Commander its pointing
accuracy is
excellent. The Scopes positions easily from object to object with a
fluid like motion. My scope has a two speed JMI focuser, Secondary
mirror
heater, Wheel barrel handles and the Sky Commander. In Oct. 2000 I
will have the GoTo system installed by Star Master look for an
additional
review.
I didn't mention optical quality in this review because mirrors can be
purchased from different companies. My mirror is made by Carl Zambuto.
I
have not seen many large mirrors made with this level of quality. The
Star test is perfect both sides of focus and a Ronchi screen show an
excellent
mirror. If you can get a Zambuto I would encourage you to do so they
are that good. My mirror specifications are P-V 0.183, RMS 0.057 and
the
Strehl Ratio 0.988.
CCD Imaging & Astrophoto Site
http://www.mindspring.com/~skyshooter/
John J. Kasianowicz
I've owned a 20" Obsession Dob for a few years and have had good experiences
interacting w/Dave Kriege.
I've made a few minor changes to the scope after I bought it (e.g. I
installed an FPI ProtoStar secondary mirror holder and spider vanes). I'm
sure Dave could build a scope w/parts other than those specified on his web
pages (assuming the owner is willing to pay any differential increase in
cost).
While I have no experience w/StarMaster instruments, I would rather keep the
mirror safe in the primary box (I'd guess one still could do this w/a SM
scope). Although ramps take additional space, I'd prefer to move a
relatively large box w/wheels on handles than lift the box into my car.
Lifting a mirror box incorrectly just once can hurt your back for a
lifetime.
When you compare the two manufacturer's scopes (you might want to check out
Tectron too), make sure they are similarly configured instruments.
FWIW, I prefered to put my money into the optics, not DSCs. I have no
regrets whatsoever.
Chris Adamson
>The SMstr for instance has a removable mirror cell. This has it's good
> points and bad points, and it really depends on what you're personal
> prefrences are. I didn't like that as much as to me as it's just
> another thing that you have to move....that is it's heavy, plus there
> is always the increased chance you could drop it..you know it's dark,
> you're tired, it's wet with dew..etc..
The cell on the SM is much better in my opinion. First, it holds the mirror
all night, not needing recollimation during the night. The Obsession sling
does not do this. The removable cell also makes it easier to transport and
makes the arrangement lighter. It is lighter than carrying the mirror and
box together, so I am not sure how this would be a risk of dropping but the
other is not.
> Plus, I like the wood the Obsession employs which has a far greater
> weight to strength ratio then oak that is used in the SMstrs. Also,
> IMHO..I have never met a SM that moves as well as an Obssn.
> Cosmetically I think the Obssn. looks better as well, but that again is
> matter purely of taste.
As for movement, I think that is an Urban Legend, generally propagated by
those who have never used a SM. The SM is as smooth as the Obsession. They
are both excellent in movement. Try them both and you will see. The SM is
larger per size, but I like the larger footprint, which to me makes it more
steady.
> As far as optics are concerned, Obssn. can be acquired with optics as
> good as CZ puts out. ....
While this is probably true that you 'can' acquire such optics, it is
definitely more hit and miss than with CZ. Carl's mirrors are consistently
top quality, with not a single deviation ever reported. His mirrors are
simply consistently the best that can be purchased for large Newts. There
is a reason behind his reputation and the popularity of SM's now (just as
their is a reason behind AP's popularity). It is called top quality. See
both Ed Ting and Todd Gross' comments on the SM optics (for that matter
their comments on CZ's optics on Portaball and Teleport also). Until you
have viewed through a CZ mirror, you really cannot imagine how good they
are. You have to see to believe.
> One is a goto system (which in my opinion sort of negates the dob idea
> in the first place..BUT the tracking is nice)
I do not know how this negates the dob idea. What it does is significantly
improve upon it, IMO. I do not care how smooth these scopes are, tracking
at 500x is one hell of a lot easier with the tracking on a SM. Basically,
it eliminates the main reason not to buy a dob. It is as good as can be on
planetary because of the tracking and the CZ optics. If you do not like the
goto, just do not engage the drives. It does not lose itself (the DSC's
still work with the drives disengaged).
> So either way it's personal preference, and what appeals to you and
> you're specific needs. You couldn't go wrong purchasing either scope.
That I agree with. Both scopes are the best you can get in high end dobs.
But, IMO, the CZ optics, the tracking capability and Rick's famous customer
and quality service, puts SM over the top. IMO, SM are as good as it gets.
Thanks,
Chris
Paul Roy <pro...@my-deja.com> wrote in message
news:8omk61$iqo$1...@nnrp1.deja.com...
SaundersErineliz
and cell weigh 50 lbs.
Pat
Attilla Danko
I agree the manual movement on a starmaster are just as usable as the
movement on the Obsession.
But the Obsession feels so much nicer. Obsession (comaring a 25"
obsession and a 18" GOTO starmaster) has a much lighter feel.
Most people who use my scope for the first time are astonished
as to how beautifully the scope moves.
For some, the delicate feel of the obsession is a disadvantage
since it requires more carefull balancing.
For a purely manual telescope, I would choose obsession bearings
over the goto starmaster. However, this is largely a matter of taste since
the Starmaster has perfectly good manual motions.
Actually, the manual mode of the goto starmaster is incredibly good
if you consider that its a tracking dob. Starmsters have the best
manual feel of any tracking dob I have tried. The mechanics are
also very clever in that Rick Singmaster has managed to find a
spur gear material that also works as a good bearing with teflon.
For a dob with tracking, I would pick starmaster over obsession.
Try both. See what you like. Both are very fine instruments.
The differences are in the details. Get picky if you care about
details. If not, you will most likely be delighted with both
scopes.
Clear skies.
-ad
Morris Jones
>When you compare the two manufacturer's scopes (you might want to check out
>Tectron too), make sure they are similarly configured instruments.
I guess people really like heavy dobs. :)
Jane and I are quite fond of our Litebox truss-tube dobs. We can pack
both the 18" and the 12.5" in the back of a station wagon, with camping
gear, and head off to the Sierras for a weekend of observing.
Or we can pack the 12.5" in a box, take the mirror cell and mirror
as a briefcase-size carry-on, and haul the whole telescope to Hawaii,
Australia, or Florida.
But I guess priorities are different. :)
Mojo (expecting my 15" Litebox in a couple of weeks)
http://www.litebox-telescopes.com/
--
Morris Jones <*>
San Rafael, CA
mo...@whiteoaks.com
http://www.whiteoaks.com
John J. Kasianowicz
Chris Adamson wrote:
> The cell on the SM is much better in my opinion. First, it holds the
mirror
> all night, not needing recollimation during the night. The Obsession
sling
> does not do this. The removable cell also makes it easier to transport
and
> makes the arrangement lighter. It is lighter than carrying the mirror and
> box together, so I am not sure how this would be a risk of dropping but
the
> other is not.
I've read that replacing the standard sling with a $2 piece of Kevlar solves
one source or collimation shift.
> I do not know how this negates the dob idea. What it does is
significantly
> improve upon it, IMO. I do not care how smooth these scopes are, tracking
> at 500x is one hell of a lot easier with the tracking on a SM. Basically,
> it eliminates the main reason not to buy a dob. It is as good as can be
on
> planetary because of the tracking and the CZ optics. If you do not like
the
> goto, just do not engage the drives. It does not lose itself (the DSC's
> still work with the drives disengaged).
Does the tracking feature increase the cost of SM compared to the price of a
non-tracking Obsession?
John J. Kasianowicz
was easy to get and use (e.g. an Obsession). I've recently seen interesting
lightweight Dob projects on the web, but I'm too busy (i.e. too lazy) to
design and make my own instrument.
BTW, the LiteBoxes still seem fairly heavy. I wouldn't want to schlep a
60#-75# box into my car at 6 am.
Jeffrey S. Setzer
news:8opso6$770$1...@bob.news.rcn.net...
> Does the tracking feature increase the cost of SM compared to the price of
a
> non-tracking Obsession?
Yes, but it's an OPTION. One has the ability to choose the drive, or not.
You can add it later, or not. On an Obsession, you have no choice.
(And yes, I know about Equatorial Platforms. You can get them for either
scope. But it's not the same thing as the SkyTracker GOTO system, which you
can only get on Starmaster).
Same for the mirror cell. On a Starmaster, you can CHOOSE to remove it for
transport, or not. On an Obsession you have no choice.
One major part of the telescope you don't really have a choice for with
Starmaster is the optics. You can only get Pegasus or Zambuto :-) And that
IS part of the regular price, instead of being an extra expense.
Likewise for the shroud. Standard equipment with Starmaster, and they never
drip dew onto your primary mirror, BTW. And the Astrosystems secondary
mirror holder, standard with Starmaster, is sometimes seen as a "field
replacement" for the Novak unit sold with Obsessions.
And I have no choice when it comes to quality control, either: I can't buy a
Starmaster that hasn't been tested as an assembled unit, optics and all,
under a real night sky, by Rick Singmaster himself.
--
-Jeffrey S. Setzer
Astro(v1.1):LD(Starmaster)A(22") r- l+++ c- OT+ OB++(++++)
DS+>+++ PL+ F+(++) M+(++) P+ T++ D+ U+(++) S++>+++ W+ E++
(see http://www.xmission.com/~dnash/astrodir/astrogeek.html for details)
John J. Kasianowicz
Hi Jeff,
Thanks for the info.
For my purposes, I can't see the virtue of taking the mirror out of the
primary mirror box. However, I'm sure that some folks want to do this.
I can also understand why someone would want a GO-TO system on a scope.
Personally, I have no desire to have one on my Dob.
I played with DSCs and a JMI NGC-Max on my A-P 400QMD German Equatorial
mount. I felt that the resolution of those DSCs (4196 steps per 360 degrees)
was not particularly great and not worth the bother (I sold the NGC-Max to
someone for a very low price). My TelRad and some NGCView 32 star charts
w/TelRad indicators printed out get me where I have to go pretty quickly.
That said, we all have different TQs (i.e. Toy Quotients!). My wife is
starting to question why my TQ has to be so high (I've got a third scope and
mount on order and I can easily see buying and using two more scopes).
I've never had problems with dew dripping off the shroud onto the primary. I
tilt the scope down and tap the shroud before I lift the shroud. This gets
rid of most of the water that might drip down on its own. I also cover the
primary w/the lid before I disassemble the scope. Of course, if someone
prefers a more absorbent shroud, that's cool.
I didn't like the Novak secondary mirror holder and spider vanes that were
stock items on my Obsession 20. Replacing it was no big deal. I suspect that
Dave will install whatever holder/vanes someone wants in their scope.
I ordered an upgrade set of optics for my scope. Dave shipped the scope to
me and Galaxy optics sent the mirror straight to my home too. While I'm no
craftsman, I was able to trim the poles to the right height (it took two
tries because my 35mm TV PanOptic requires more in-focus than I thought). I
felt competent enough to evaluate the scope myself. I've been happy with the
instrument.
Perhaps I'll build a motor control system for my Obsession someday. Until
then, I'm enjoying the light show whenever the skies are clear (which has
been rather infrequent here this Spring and Summer).
I certainly look forward to seeing the views through a StarMaster scope
sometime soon.
Best,
John