The perfect refractor?

Moderators: Erik, Chopin
Post Reply   Page 2 of 3  [ 70 posts ]
Jump to page « 1 2 3 »
Author Message
Erik
Post subject:
Posted: Sun Mar 30, 2008 6:32 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
Hey David,

Glad you're here! :)

Yeah, 66mm may be a bit small for a primary scope, but it would probably make a great finder. I often wish for something bigger than my 50mm.

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
Gary
Post subject:
Posted: Sun Mar 30, 2008 7:58 pm
molecule
User avatar
Offline
 
Posts: 134
Joined: Thu Feb 14, 2008 8:17 am
Location: USA Louisiana
 
After much trial and error, I've settled on f/7 to f/10 4" refractors as the best balance of aperture vs low magnification exit pupil and overall utility for me. I'm most comfortable with an exit pupil of no more than 4-mm and the 4-inch produces that at 25x, still low enough to deliver a wide 3?+- field of view. 4 inches of aperture resolves enough planetary detail to keep me entertained, but isn't so much that I have to resort to more than 4-mm of exit pupil to enjoy that 3? field.

I suppose I could move up to a 110-mm refractor now that they're available and still achieve the same thing. Or I could invest in a Dioptrx and move up to a 5-mm exit pupil (my aging right eye's max on most nights) and that 140-mm Apo that's so popular. I guess that means that there is no "perfect" refractor?


Top
Profile Quote
ANDY
Post subject:
Posted: Wed Apr 02, 2008 6:18 am
atom
User avatar
Offline
 
Posts: 36
Joined: Thu Feb 14, 2008 7:11 pm
Location: SACRAMENTO, CA U.S.A.
 
Is exit pupil a function of the telescope? I thought it only had to do with the eyepiece being used. Its very confusing, ANDY

_________________

ANDY S


Top
Profile Quote
Chopin
Post subject:
Posted: Wed Apr 02, 2008 8:07 am
Velocepedist
User avatar
Online
 
Posts: 6704
Joined: Tue Mar 18, 2008 6:28 pm
Location: In search of the ultimate switchbacks and single tracks
 
Andy, no worries. Optical mathematics all seem very confusing at first. There are many factors to consider. The exit pupil is a function of both the scope and the eyepiece.

The easiest way to calculate the exit pupil is to first know the ?/number (focal ratio) of the scope. For example, my most used newtonian reflector has a ratio of ?/5. This is calculated by taking the focal length of the scope (1500mm) and dividing by the aperture of the primary objective, in this case a 300mm mirror. Thus 1500mm ? 300mm = 5, or ?/5.

Now that you have your scope's ?/number you can divide this into the focal length of the eyepiece. Let's say i have a 25mm pl?ssl eyepiece, a common style of eyepiece, often sold with telescope packages, and a very good starter eyepiece. I divide the 25mm by the ?/number of my scope. So, 25mm ? ?/5 (or 25 ? 5) = 5mm. This is the exit pupil now created by the combo of the scope and eyepiece. If I were to put this same eyepiece in a new telescope with a focal ratio of ?/10, my exit pupil would be 25mm ? ?/10 = 2.5mm. So the same eyepiece produces a different sized exit pupil because the focal ratio of the new scope is different.

Basic rule of thumb: the larger the exit pupil, the brighter the image. However, there is little use in having a scope and eyepiece combo that produces an exit pupil larger than 7mm, because this is about the maximum size of the dilated young adult human pupil, thus larger exit pupils put light from the scope's image beyond your own pupil, essentially wasting that unused light. This number decreases with age, down to about a maximum of 4-5mm. This is why you will often find veteran observers who prefer to have a lower power eyepiece that does not produce an exit pupil larger than 4-5mm. So, in the end, no matter how large your exit pupil, even beyond 7mm, it will never be brighter than your own dilated pupil will allow.

OTOH, exit pupils smaller than 1mm will cast an image so small, that the image becomes relatively dark, while floaters in your eye can become readily visible in the background of the image. The long accepted perfect compromise is a 2mm exit pupil, which matches the resolution maximum of the human eye (a measurement of visible arc seconds), enables enough light from the original image to reach the eye, while also eliminating the visibility of anatomical artifacts like floaters. Meaning the perfect compromise eyepiece for that same ?5 reflector would be a 10mm eyepiece (10mm ? ?/5 = 2mm).

Perfectly confused now? :lol:

_________________

Jason® (Admin...and spoke-folk)
[ img ]
[ img ]
[ img ]
[ img ]
Veritable Imagery
Single ride personal records: Distance-76.7miles, Max Speed-50.4mph, Max sustained speed (20miles) 19.5mph
“Life is like riding a bicycle. To keep your balance, you must keep moving.” ― Albert Einstein


Top
Profile Quote
Gary
Post subject:
Posted: Wed Apr 02, 2008 1:20 pm
molecule
User avatar
Offline
 
Posts: 134
Joined: Thu Feb 14, 2008 8:17 am
Location: USA Louisiana
 
My bad Andy.

I should have thought to explain my cryptic shorthand and Jason did a great job of correcting my oversight.

I suffer a bad case of eye "floaters" and, as Jason explained, very small exit pupils tend to do little more than highlight individual floaters. For me, this is particularly bad with an exit pupil smaller than 0.8 mm. I try to stick with exit pupils greater than 1.0 mm and, if I want to use high magnifications, that means more aperture. 300x in a 12.5" (317.5 mm) scope produces an exit pupil that's still larger than 1.0 mm, while the same magnification in a 6" (150 mm) scope yields a 0.5 mm exit pupil - too small for my comfort. Most folks find images produced by exit pupils smaller than 0.5 mm to be too dark to bother, with few exceptions such as some lunar features.

Some people accommodate the floaters problem by using binoviewers for high magnification viewing instead of mono-viewing and it does work. If a floater in one eye is highlighted, but the other eye has a relatively floater free view, our amazing brains merge the two and essentially filter out the floater. Our brains even throw in the bonus of the perception of 3D effect when we use both eyes.

On the other end of the exit pupil spectrum, my comfort zone tops out at around 4.0 mm, even though my aging eyes still dilate to around 5.0 mm. The problem in my case is that I suffer a still fairly minor astigmatism of around. 0.25 diopter. That causes stars to tend to look more like little sea gulls than the crisp pinpoints of light we all prefer. For me, this phenomena kicks in at around 4.0 mm and that will probably worsen as my eye ages further - to bad I took 20/20 for granted when I was younger! Tele Vue produces an astigmatism corrector that it calls the "Dioptrx" (short for "Diopter Rx" I assume), which fits over the eye lens of many of its wide-field eyepieces. It basically does the job of eyeglass astigmatism correction without having to try viewing with eyeglasses. I'd rather not wear eyeglasses when viewing through eyepieces or binoculars, but many who've been doing it for years aren't bothered by having extra optics hanging on their noses.


Top
Profile Quote
Gary
Post subject:
Posted: Wed Apr 02, 2008 1:37 pm
molecule
User avatar
Offline
 
Posts: 134
Joined: Thu Feb 14, 2008 8:17 am
Location: USA Louisiana
 
Andy,

I intended to also reinforce Jason's conclusion that a 2-mm exit pupil is, for many (including me), optimum. In fact, I rarely think in terms of magnification, but choose scope/eyepiece combinations based upon the exit pupil they produce within the extreme range of 1- to 4-mm exit pupil and more ideally 1.5- to 3-mm exit pupil. That means that I'm more likely to change scopes to accommodate my viewing goals than to change eyepieces.

If that sounds needlessly extravagant, consider that premium ultra wide-field eyepieces often cost more than the scopes we use them with. These days, you can pick up a perfectly competent used 12" Dob for about what the amazing 31-mm Nagler costs new. In keeping with my earlier example, if I want to view a planet at 300x, what I really need is a 12" (1.0-mm exit pupil) or larger telescope, with a 24" scope being optimum, because it produces that magic 2.0-mm exit pupil at 300x (using very rough math, of course).

If I want to view the widest field comfortably possible, I need to use the smallest scope that will still gather enough light to match the true magnitude of my target. Consequently, I spend an undue amount of time pearing through a little 60-mm refractor and a very wide 4?+ true field of view (with an exit pupil of no more than 4 mm).


Top
Profile Quote
Erik
Post subject:
Posted: Wed Apr 02, 2008 5:41 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
I have a real problem with floaters as well. Even a 2mm exit pupil makes them fairly visible. Maybe a reason to use binoviewers.

Light pollution is another factor to consider when trying to determine the optimum exit pupil. In my mag 4 skies, anything over a 5mm exit pupil is usually wasted.

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
GeneralRageSC
Post subject:
Posted: Mon Jun 02, 2008 10:03 am
atom
User avatar
Offline
 
Posts: 44
Joined: Sun May 25, 2008 10:14 pm
Location: NorCal
 
Andy,

I see that you are from the Sac area. I am too. Have you heard of TAC-Sac? www.tac-sac.org We are a group of active observers who goes out to a couple dark sites just east of Sac on third and new moon weekends. Most of us are very experienced observers, but welcome newcomers as well. Many newcomers become serious observers too. Go ahead, check us out and sign up if you can. Come on out and view through some serious aperture (there are more than 15 of us with 18" or larger scopes). Be forewarned, you might catch aperture fever.

The other group, SVAS (Sacramento Valley Astronomical Society) www.svas.org is a good group to hang with as well.

Back on topic. Im my personal experience, I think the perfect refractor would be the Antares 6" f/6.5 refractor http://tinyurl.com/52utzg One can get one for a little over a grand with mount. Enough glass for DSOs and good enough for planets without going APO. Also fast enough for wide-field views with aperture. It gives a 2.5 degree field with a 31mm Nagler.

I'm very surprised at its planetary performance, it is actually very good for a relatively fast achromat. And I own a 5" APO and used to own a 4 and 8" APOs, so I've observed through those quite a bit.

The 6" may be a bit heavy, the difference between a 4" and 6" is very significant. On DSO's, my 5" APO doesn't come close to the 6" achromat.

APO or Achro - Aperture wins for DSO's.

So for a little over a grand, the 6" Antares is tough to beat.

_________________

Clear Skies,
Alvin #26
22" f/4.1 reflector, 30" f/4.3 StarMaster and Antares 6" f/6.5 on Orion SVP, 28" f/3.275 (under construction)
[url=http://www.faintfuzzies.com]FaintFuzzies[/url] | [url=http://www.observers.org]TAC[/url] | [url=http://www.tac-sac.org]TAC-Sac[/url]


Top
Profile Quote
Square_peg
Post subject:
Posted: Sat Jun 14, 2008 10:00 am
The Blacksmith
User avatar
Offline
 
Posts: 3055
Joined: Sat Feb 16, 2008 11:51 am
Location: Maple Valley, WA
 
I'd take a TV-85. Just the right blend of aperture and portability. Plus great optics.

_________________

Tom (Pegster)

subvert the dominant paradigm


Top
Profile Quote
Erik
Post subject:
Posted: Sat Jun 14, 2008 6:21 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
I'm pretty enamored with the SV 80mm ED. Great build quality, and very little color. The Orion ED80 is a bit better in terms of color correction, but the build quality is nowhere near the SV. Of course, if money were no object, I'd look at the Televue as well- though maybe the NP-101. ;)

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
Chopin
Post subject:
Posted: Mon Jun 16, 2008 1:46 pm
Velocepedist
User avatar
Online
 
Posts: 6704
Joined: Tue Mar 18, 2008 6:28 pm
Location: In search of the ultimate switchbacks and single tracks
 
Square_peg wrote:
I'd take a TV-85. Just the right blend of aperture and portability. Plus great optics.


Mmmm. This and the Tak Sky-90 are on my short list (read: dream) for a grab n' go refractor.

_________________

Jason® (Admin...and spoke-folk)
[ img ]
[ img ]
[ img ]
[ img ]
Veritable Imagery
Single ride personal records: Distance-76.7miles, Max Speed-50.4mph, Max sustained speed (20miles) 19.5mph
“Life is like riding a bicycle. To keep your balance, you must keep moving.” ― Albert Einstein


Top
Profile Quote
Erik
Post subject:
Posted: Wed Jun 18, 2008 8:19 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
The 80mm Celestron Onyx is another one on my wish list. Great optics and build quality, and reasonably priced. :cool:

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
Erik
Post subject:
Posted: Wed Jun 18, 2008 8:27 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
For $3800, this looks pretty hard to beat:
http://www.williamoptics.com/telescopes ... atures.php

It appears to just use ED glass, though the "FLT" makes me think flourite? Man, flourite for that price would be just about unheard of...

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
Chopin
Post subject:
Posted: Wed Jun 18, 2008 9:28 pm
Velocepedist
User avatar
Online
 
Posts: 6704
Joined: Tue Mar 18, 2008 6:28 pm
Location: In search of the ultimate switchbacks and single tracks
 
Man, forget looking through William Optics gear. Just looking AT their stuff make me drool. That is probably one of the sexiest refractors I've ever seen.

_________________

Jason® (Admin...and spoke-folk)
[ img ]
[ img ]
[ img ]
[ img ]
Veritable Imagery
Single ride personal records: Distance-76.7miles, Max Speed-50.4mph, Max sustained speed (20miles) 19.5mph
“Life is like riding a bicycle. To keep your balance, you must keep moving.” ― Albert Einstein


Top
Profile Quote
GeneralRageSC
Post subject:
Posted: Thu Jun 19, 2008 6:29 am
atom
User avatar
Offline
 
Posts: 44
Joined: Sun May 25, 2008 10:14 pm
Location: NorCal
 
If you really want APO, take a look at the TEC 140. I was about to get that 'till a great deal on a Tak TOA-130S came by and I couldn't pass that up. Got it for more than 2 grand les than a new price and it is fairly new when I got it.

I'll restate the Antares 6" f/6.5. I'll take on any APO under 5 grand with that scope for DSO's, including my very own 5" Tak APO. Best bang for the buck. IMO

I did own a TEC200ED at one point, but that thing is HUGE. So I dumped it, but kept the mount. Now I have a oversized mount for the Tak.

_________________

Clear Skies,
Alvin #26
22" f/4.1 reflector, 30" f/4.3 StarMaster and Antares 6" f/6.5 on Orion SVP, 28" f/3.275 (under construction)
[url=http://www.faintfuzzies.com]FaintFuzzies[/url] | [url=http://www.observers.org]TAC[/url] | [url=http://www.tac-sac.org]TAC-Sac[/url]


Top
Profile Quote
Erik
Post subject:
Posted: Thu Jun 19, 2008 8:27 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
The Antares looks really cool- I don't remember seeing that one before. It's advertised as using a "low dispersion" lens assembly. How's the CA on bright objects, Alvin? Is it comparable to the 6" Meade AR6? $780.00 is a heck of a price, and it's more compact than the f/8 variety. Here's a link I found:
http://www.agenaastro.com/Antares-1529- ... n-1529.htm

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
GeneralRageSC
Post subject:
Posted: Fri Jun 20, 2008 6:21 am
atom
User avatar
Offline
 
Posts: 44
Joined: Sun May 25, 2008 10:14 pm
Location: NorCal
 
Erik,

I have no first hand experience between the Antares 6" f/6.5 versus the AR6. But one Sac Astro member told me that my scope looks better than his AR6. That's all I have. I did look through the older Celestron 6" f/8 and the Antares has less CA. So Antares (whatever lens maker) did a great job on the non-ED doublet. The mechanics of the scope is very nice. Now I wish I have the new sliding dewshield option of the newer scopes. But I have what I have. :)

_________________

Clear Skies,
Alvin #26
22" f/4.1 reflector, 30" f/4.3 StarMaster and Antares 6" f/6.5 on Orion SVP, 28" f/3.275 (under construction)
[url=http://www.faintfuzzies.com]FaintFuzzies[/url] | [url=http://www.observers.org]TAC[/url] | [url=http://www.tac-sac.org]TAC-Sac[/url]


Top
Profile Quote
Seantóir
Post subject:
Posted: Fri Jun 20, 2008 8:56 am
left
User avatar
Offline
 
Posts: 4297
Joined: Wed Mar 05, 2008 3:13 pm
Location: Area 14, Kildare, Ireland
 
I think the perfect refractor is the one you will use whenever you can - whatever it happens to be. An expensive, high quality APO would probably not be my choice for the accolade because I would be too careful with it to take it when conditions were not perfect.

_________________

John

[quote]The Irish Constitution... is written in the present tense. You reason it in light of this year, not in light of the year in which it was adopted by the people. You don't need to hark back to what some people thought thirty or forty years ago. [/quote]Brian Walsh, Supreme Court Justice 1961-90

O....o?oo


Top
Profile Quote
Erik
Post subject:
Posted: Fri Jun 20, 2008 1:35 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
GeneralRageSC wrote:
Erik,

I have no first hand experience between the Antares 6" f/6.5 versus the AR6. But one Sac Astro member told me that my scope looks better than his AR6. That's all I have. I did look through the older Celestron 6" f/8 and the Antares has less CA. So Antares (whatever lens maker) did a great job on the non-ED doublet. The mechanics of the scope is very nice. Now I wish I have the new sliding dewshield option of the newer scopes. But I have what I have. :)
thanks for the info, Alvin! Those sound like a real steal. Must be why they're out of stock at Agena. At some point after we move to Hawaii, I'd really like to get a large refractor. Hopefully, the Antares will be available then. :)

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
deefrey
Post subject:
Posted: Thu Jul 10, 2008 11:41 am
molecule
User avatar
Offline
 
Posts: 78
Joined: Sun Feb 17, 2008 6:48 pm
 
Well, I recently got my "TMB92SS". It is probably the most beautiful scope I've owned (hopefully the TAK and SV didn't hear that). I have only had it out one time so far, it's been very cloudy here and I've been too exhausted to do much lately. It may very well qualifly as my "perfect" refractor. We'll see!!!


Top
Profile Quote
Erik
Post subject:
Posted: Thu Jul 10, 2008 8:30 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
Congratulations Dee! Looking forward to hearing more about your new scope! :cool:

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
deefrey
Post subject:
Posted: Thu Aug 21, 2008 12:40 pm
molecule
User avatar
Offline
 
Posts: 78
Joined: Sun Feb 17, 2008 6:48 pm
 
I've gotten the TMB92SS out only on a few occasions so far. Unfortunately the marine layer seems to roll in almost every night. I love the small size of the scope, however I just got the extension tube that screws into the scope and it is sorta heavy. I'll see how I like it compared to just using the temporary one. I did get a chance to view Jupiter and I am happy to report that the GRS was obvious to me which was sort of what I was looking for in terms of defining my "perfect" size refractor.


Top
Profile Quote
Stacy Jo
Post subject:
Posted: Thu Aug 21, 2008 9:56 pm
star
Offline
 
Posts: 296
Joined: Fri Mar 28, 2008 11:52 am
Location: Oakland, CA
 
Way groovy...can you post photos of new said telescope?! :grin:

_________________

Clear skies, Stacy

StellerVue 80mm Nighthawk
Orion Starblast 6" Newtonian
Old Jason 3" reflector
Orion 8x50 binoculars (which need some re-alignment)
Two wonderful and beautiful hazel green eyes


Top
Profile Quote
deefrey
Post subject:
Posted: Thu Aug 21, 2008 11:52 pm
molecule
User avatar
Offline
 
Posts: 78
Joined: Sun Feb 17, 2008 6:48 pm
 
I'll try! This is a picture of the TMB92SS with the SV80S in the foreground. The 92 appears shorter because it's 2" extension is not in place. In fact I havent' threaded it on yet.
[ img ]


Top
Profile Quote
deefrey
Post subject:
Posted: Thu Aug 21, 2008 11:56 pm
molecule
User avatar
Offline
 
Posts: 78
Joined: Sun Feb 17, 2008 6:48 pm
 
Here's my attempt at putting it on the Voyager mount. I've been using an extension tube added to the back of this configuration.
[ img ]


Top
Profile Quote
pollux
Post subject:
Posted: Fri Oct 24, 2008 5:04 pm
atom
Offline
 
Posts: 18
Joined: Sun Jul 27, 2008 4:32 pm
 
Not totally perfect for me (want more aperture!) but close.

[ img ]


Top
Profile Quote
Erik
Post subject:
Posted: Fri Oct 24, 2008 10:03 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
Nice! I like the case modification. :cool:

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
Kawx4d
Post subject:
Posted: Thu Nov 06, 2008 8:28 am
Steely-Eyed Missile Man
User avatar
Offline
 
Posts: 5075
Joined: Tue Nov 04, 2008 1:18 pm
Location: According to Heisenberg, I'm uncertain...
 
Perfect refractor? Tough call. Depends on whether we're talking dream scope or one that can get used all the time without chopping off an arm and a leg to pay for it and the mount.

Dream refractor - 8" -12" APO from TMB, Tak, or AP, permanently mounted in a nice observatory.

Reality - Actually I could not ask for more than what I already have..........well I'd love to have another refractor or two, but the the 92mm f/7 Stowaway is easy to use, easy to mount and continually amazes me with the images it puts up. Yes it's aperture-challenged, but I've never seen a scope in its size class even come close to it.

_________________

Kerry

[ img ]


Oh, yeah. The Stifmeister's coming back to Grand Harbor. Deck the halls. Bye-bye, Great Falls. Wipe my a$$ and lick my ba!!s It's Stifler time, baby. Whoo-hoo-hoo. Whoo-hoo-hoo. ~Steve Stifler-American Pie 2 :lol: :lol: :lol:


Top
Profile Quote
Erik
Post subject:
Posted: Thu Nov 06, 2008 12:43 pm
Site Admin
User avatar
Offline
 
Posts: 12643
Joined: Tue Feb 12, 2008 4:58 pm
Location: Off Grid in Paradise... Mag 7 skies
 
Youve got quite a nice list of gear there, Kerry. Changing the subject, but how do you like that Tom O platform? I need to get tracking for my dob at some point. :)

_________________

-Erik Wilcox
Homebuilt 16" Truss Dob
8" Antares f/5 Newt
SV 80mm ED Nighthawk NG on M1 ALT/AZ
Nikon Prostaff 65mm spotter on Trekpod
Konusvue 20x80 binos/Peterson PipeMount


"Newt Gingrich is what stupid people think smart people sound like."
-The Great Paul Krugman

Evolution is both fact and theory. Creationism is neither. -Anonymous


Top
Profile Quote
Kawx4d
Post subject:
Posted: Thu Nov 06, 2008 2:38 pm
Steely-Eyed Missile Man
User avatar
Offline
 
Posts: 5075
Joined: Tue Nov 04, 2008 1:18 pm
Location: According to Heisenberg, I'm uncertain...
 
Hi Erik,

Thanks, but I really do miss my 14.5" Starmaster I sold about 18 months ago. Intended on replacing it with an 18 or 20, and have not been able to justify it yet since I'm not traveling to dark skies much right now. Not to mention needing to be a little careful these days with the economy the way it is........... :shock:

Anyway, the Tom O. platform I bought used and it was around 4 years old at the time. It performed well for about three years, but I'm going to need to take the motor assembly off and send it back to Tom for some maintenance - it's just wearing some and won't track at the proper speed. But it's seen a lot of use over it's 7 or 8 years.

Personally I believe Tom O. makes the best platforms out there and the new compact models are much smaller than mine. If I were ordering one today I'd go with Tom O. I guess Round Table does a good job too, and they are quite a bit less, but a friend of mine has one that's less than a year old and he's already had to send it back once. Guess that happens.

My preferred tracking option for big dobs is really an on-board drive like a Stellar Cat if you want GOTO, or a Dob Driver II if you don't need GOTO, mainly because it eliminates a bulky piece of equipment, and keeps the eyepiece height where it belongs. I've never used a Dob Driver, but from everything I've heard they are pretty solid performers for alt-az tracking. Hope this helps.

_________________

Kerry

[ img ]


Oh, yeah. The Stifmeister's coming back to Grand Harbor. Deck the halls. Bye-bye, Great Falls. Wipe my a$$ and lick my ba!!s It's Stifler time, baby. Whoo-hoo-hoo. Whoo-hoo-hoo. ~Steve Stifler-American Pie 2 :lol: :lol: :lol:


Top
Profile Quote
Display: Sort by: Direction:
Post Reply   Page 2 of 3  [ 70 posts ]
Return to “Telescopes and Binoculars” | Jump to page « 1 2 3 »
Jump to:
cron