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What is a similar scope to the Questar optics wise?

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#1 Stargazer3236

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Posted 21 July 2019 - 11:04 AM

I am on the cusp of barely able to afford a Questar, pointing more towards "out of my league" budget wise. What would be a similar telescope as far as optics goes? I heard the ETX 90 was once compared to the Questar in terms of optics.



#2 Optics Patent

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Posted 21 July 2019 - 12:33 PM

I trust you’re aware that good Questar scopes come up on the used market regularly for $2000 and under. I presume you’d enjoy an ETX for 1/10 the investment.

If you can justify dedicating the funds you’re virtually guaranteed to get every penny back if you sell.
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#3 spereira

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Posted 21 July 2019 - 12:33 PM

I've heard say that the tele Vue TV-85 is very similar in optics.  Obviously, it's a refractor rather than a Maksutov, and f/7 rather than f/13 (13.5?) but I think it's very similar in optical performance.

 

Just my 2 cents worth...

 

smp


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#4 justfred

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Posted 21 July 2019 - 01:29 PM

Hey there, David.

 

I've owned the Q and the ETX90 for a long time and have used and compared them both.

 

Begin with the ETX90. The optics are close - very close. Get the UHC if you have the choice. Also - and I can't believe I'm writing this - get one of the later goto models. The electronics are much more reliable than in the distant past when most of the bad press was printed. (always use a battery - never the a/c adapter)

 

The mount is plastic and it has some flex, but it is plenty functional. The straight through finder is useless, so get a right angle or add a Rigel. In equatorial configuration you need to be a contortionist to see northern objects, so use it in alt/az. The useful magnification is 200X, 250X on an exceptional night. (again similar to the Q).

 

The Meade Plossl EPs are a good match. Everything goes in a little blue bag. Add a Meade 883 tripod and get everything out under the stars.

 

Now - all that said - start saving for the Q. :-)

 

Fred


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#5 bobhen

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Posted 21 July 2019 - 01:33 PM

Questar produces high quality optics AND mechanics. The mechanics on the ETX are pretty poor. And mechanical quality will impact your observing enjoyment as much as optical quality.

 

As far as other scopes with comparable optical quality, have a look at the offerings from the high-end refractor makers like: Takahashi, TEC, Astro-Physics or Televue.

 

Both Televue and Takahashi offer scopes in the 76mm to 100mm range with some mount options (both alt/az and driven) as well.

 

Decide on what is important to your observing program: ultimate portability, aperture, wide field, daytime use, solar observing, deep sky imaging, visual observing etc. and then pick the scope than meets you needs.

 

If you have the budget and purchase a Questar, Televue or Takahashi telescope you will not be disappointed. Just make sure the scope and mount meets your needs.

 

Bob


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#6 Matt Looby

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Posted 21 July 2019 - 02:15 PM

Save up and get a used Questar... or Quantum 4.


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#7 cbwerner

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Posted 21 July 2019 - 05:54 PM

David,

 

You don't buy a Questar for the optics. Don't get me wrong - they're great, especially on my 50th, but if optics is all you're after, you can save a pile of dough with something else. You buy a Questar because of the overall build quality and the ease of use that lies largely in the magic that is the control box.

 

You didn't mention a budget, but as others have mentioned, used ones are far less expensive than new. If you want one, used is a great way to go.

 

Have you used one? If not, check locally - I'm sure someone would give you a look see if you're nearby. My first view through a telescope ever was through a Q3.5 - owned by a middle school Earth Sciences teacher who (god bless him) held a star party for us one October night. I was hooked on astronomy and the Questar forever after that night.


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#8 Matt Looby

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Posted 21 July 2019 - 06:04 PM

It's a wonderful scope, two nights ago, riding through a cloud the spooky Moon in finder mode was a marvel to behold. I Love finder mode, high power and amplified mode.  Switch up keeps the observation interesting.


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#9 BillHarris

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Posted 21 July 2019 - 08:30 PM

I have been into astronomy for over 50 years, and have built a few scopes and used many.
The one thing that impresses me about Questar is how everything works as an integrated package. The optics, the controls, the mount all work together so well. It's not perfect, but no human construct is.
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#10 Gregory Gross

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Posted 22 July 2019 - 02:30 AM

Ditto regarding what others have said about Questar offering a complete package of high-end optics and mechanics. I'd add that owning a little piece of amateur astronomy history also has a strong allure.

 

I'd venture to say that, in the arena of 90mm Maksutov-Cassegrains, no one does it better than Questar. In the arena of 90mm telescopes of any design, I'd say that a high-end refractor of roughly the same aperture (those offered by Takahashi et al) would definitely give Questar a run for its money considering that one is comparing apples to oranges due to fundamental differences in optical design.



#11 terraclarke

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Posted 22 July 2019 - 06:47 AM

My Takahashi FC76 F8 Fluorite apo is very similar in sharpness of image, color fidelity, contrast, star images, and planetary views to my Questar but is capable of providing much wider fields. However, it isn’t nearly as portable as the Questar which is a completely self-contained mini-observatory and it’s not nearly as pretty to look at. I wouldn’t part with either one.


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#12 rcwolpert

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Posted 22 July 2019 - 07:04 PM

My Takahashi FC76 F8 Fluorite apo is very similar in sharpness of image, color fidelity, contrast, star images, and planetary views to my Questar but is capable of providing much wider fields. However, it isn’t nearly as portable as the Questar which is a completely self-contained mini-observatory and it’s not nearly as pretty to look at. I wouldn’t part with either one.

 

I feel the same regarding my 80mm Mayflower 816, which optically beat out my Unitron, my Swift 831, my Royal Astro and a dozen other refractors. The FOV is much wider than the Questar, but nothing is as convenient to use or as nice to look at as is the Questar.


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#13 JimP

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Posted 22 July 2019 - 07:53 PM

A Quantum 4. I just got one several days ago and am in the process of evaluating it. Very impressed so far.

More to come...

Jim
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#14 Kevin Barker

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Posted 22 July 2019 - 09:43 PM

Like the others my 80 mm Zeiss AS80/840 refractor delivers very similar images. Obviously with a wider actual field of view. If anything the wee Zeiss is a wee bit brighter with slightly higher contrast.

 

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#15 Darkskyaz

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Posted 27 July 2019 - 06:01 PM

Some great advice and observations on this thread. One can purchase a used Questar, and if need be, send it back to Questar for refurbishing, and it's like getting a brand new telescope. 

 

Anyone considering the purchase of a Questar would be well served to read this article first:  

https://astromart.co...tar-35-standard

 

I agree with all of this person's observations, conclusions, and recommendations. In particular, while I love my 3.5" Questar, I don't think the Questar is the best choice if it's going to be your only telescope. For beginners on a budget, I recommend the 5" Orion Mak on the Starseeker IV mount. It's a lot easier to find things with a computerized mount, and the 127mm optics of the Orion Mak are EXCELLENT. The optics compare very favorably to the Questar. For someone who can spend a little more, but still can only afford one telescope, I would recommend an 8" SCT. I'm partial to Meade, but others swear by Celestron instruments. The 8" SCT is the "jack of all trades" in the telescope world. 

 

As others have alluded to, what I love about the 3.5" Questar is how quickly I can be observing either astronomical or terrestrial objects (I also use my Questar in the daytime to look at birds and other animals). The blend of mechanical, optical and design excellence produces a user experience that really is unmatched by any other telescope that I'm aware of. Comparing it to an APO refractor to me is a bit like comparing a screw driver to a wrench. Which is a better tool? It depends if you want to turn a screw or a bolt. 

 

Here is another really good review to read for those considering a 3.5" Questar: 

http://scopeviews.co.uk/Questar35.htm


Edited by Darkskyaz, 27 July 2019 - 06:10 PM.

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#16 Matt Looby

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Posted 27 July 2019 - 10:51 PM

Antone can find an object by use of Q 3.5 Setting circles.  If I could own only one telescope, it would have to be the one I use the most, that's the Questar 3.5.


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#17 Kevin Barker

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Posted 28 July 2019 - 02:41 PM

I agree with the assertion that a Q3.5 should not be ones only telescope. I own a dozen or so different scopes.

 

I do not think they should be ones first telescope either. Although the ease of use and quick set up is appealing. They are however quite pricey for a beginner, and the aperture is on the smallish side.

 

Having said that I am sure there are plenty of happy observers who own only one telescope, and it's a Questar.


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#18 Matt Looby

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Posted 28 July 2019 - 03:02 PM

A 6 inch f/6 or f/8 reflector is the recommended first scope and a life long scope, re, Criterion.

 

V/R,

 

Matt



#19 Toxo144

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Posted 29 July 2019 - 01:03 PM

Stargazer/David,

 

To get back to the original subject, you might find Ed Ting's  "comparo" article informative.  Link is here:

 

https://www.scoperev...0mmComparo.html

 

Compares three Mak/Cass scopes including the Questar 3.5, and his insights are trenchant. Hope this helps.

 

Personally, I find that my observational enjoyment in other telescopes doesn't measure up to the Q3.5 until I get to a premium APO 80mm or, a recent lucky find, an older Brandon 94mm bought used for $1200.  In other Cat scopes I find I need A LOT more  aperture to make me smile as much at the Q, and I don't like lugging them around or setting them up. Stellarvue recently launched a line of premium APO refractors that may be worth looking at,  but last I checked the smallest aperture on these was 80 mm.

 

Good luck with whatever you decide.

 

Cheers,

 

Toxo



#20 munirocks

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Posted 01 August 2019 - 06:51 AM

Yesterday evening was cloudy so I briefly compared my Questar with my ETX90 on terrestrial targets with a pair of 19 mm Panoptics (same eyepiece in each scope).

The ETX90 views were excellent, but the Questar was slightly better. The difference was very small but more noticeable on targets with a fine texture, like cloth or bark. The Questar was brighter, too (manufactured in 2015 with Zerodur and Broadband coatings). I would imagine that the difference would also be noticeable on fine lunar textures, at which the Questar excels.

 

The ETX90 actually gives a slightly wider True Field Of View at the low end. With a 24 mm Panoptic the Questar vignettes but the ETX90 doesn't. The extra width on the ETX90 isn't perfect, however, as it shows a slim but rather sharply delineated ring of brightening at the outer edge of the field with this eyepiece.



#21 munirocks

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Posted 01 August 2019 - 07:09 AM

As for the ETX90 mount, yes it's rather a toy made of creaky plastic but I still liked it. I had the basic RA version - it had no goto and had a simple RA motor drive, but it was portable, ran on batteries, and did the job as long as you avoided stressing anything and ignored the incorrect setting circle instructions that came with it. I sort of wish that Questar would return to the simple self-contained battery-and-switches-in-the-base format like the ETX90RA and Questar Powerguide I.

 

I eventually put the ETX90 tube onto a sturdier B&L4000 fork mount, and that's how I still run it today although now I need to plug it in.


Edited by munirocks, 01 August 2019 - 07:10 AM.


#22 Loren Gibson

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Posted 01 August 2019 - 08:51 AM

I too liked the ETX90RA self-contained RA drive and power supply. The only problem is that the tracking rate was way off, which appears to be a well-known problem with some of them. Fortunately, the drive rate was too high, simplifying re-centering: When the object became too close to the edge of the field, I'd switch the drive off and let the object drift back to center. Once re-centered (or maybe biased towards the opposite edge of field) I'd turn the drive back on.

 

Loren


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#23 munirocks

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Posted 01 August 2019 - 10:51 AM

My ETX90 sessions (visual only) weren't long enough to notice if the rate was off, but I definitely liked the two switches. One for On/Off. One for North/South hemisphere rotation direction. Simple.

 

I'm sure it wouldn't have had a long lifespan, though. Not like the Questar that Company Seven left running for years just to show that they could.



#24 Gregory Gross

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Posted 01 August 2019 - 11:57 AM

I agree with the assertion that a Q3.5 should not be ones only telescope. I own a dozen or so different scopes.
 
I do not think they should be ones first telescope either. Although the ease of use and quick set up is appealing. They are however quite pricey for a beginner, and the aperture is on the smallish side.
 
Having said that I am sure there are plenty of happy observers who own only one telescope, and it's a Questar.


Kevin, I see in your signature that you own an 80mm f/10.5 refractor. Considering that I’ve been preoccupied lately with long-focus refractors in the 80-100mm range, I’m very curious to know your specific thoughts on how the optical (not mechanical or ergonomic) performance of your Questar compares with that of your long-focus 80mm. My primary interests are lunar, planetary, and, with a Herschel wedge, white-light solar observing.

#25 Kevin Barker

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Posted 01 August 2019 - 02:19 PM

 

Kevin, I see in your signature that you own an 80mm f/10.5 refractor. Considering that I’ve been preoccupied lately with long-focus refractors in the 80-100mm range, I’m very curious to know your specific thoughts on how the optical (not mechanical or ergonomic) performance of your Questar compares with that of your long-focus 80mm. My primary interests are lunar, planetary, and, with a Herschel wedge, white-light solar observing.

Hi Gregory

The Zeiss AS lenses are pretty good, well the one I have is a GEM. They have an unusual correction designed for CDe rather than the standard CeF. The letters referring to the Fraunhofer Hydrogen absorption/emmission lines as reference wavelengths.

 

This is great for planetary detail. My wee lens which is uncoated has a perfect star test as far as I can ascertain and its splits doubles really well. It took lots of attempts and perfect seeing but I have seen E and F in Orion's trapezium in M42 and also seen Antares B and Sirius B with this scope.

 

My 1989 Q3.5 with BB optics has seen E and F in the trapezium and Sirius B but has not been able to show be a split on Antares yet.

 

My AS80/840 is uncoated but still appears very slightly brighter than the Q. It also renders a tiny bit more detail on Jupiter's belts. The AS80/840 has a correction similar to a an f-15 with normal glass. The shifting of the two points that come to a common focus to C and e.

 

I once compared a views of Jupiter and Saturn with my AS to a view in a so called "apo" triplet at a star party. Both scopes around 140 X. The AS revealed more detail and seemed to have better contrast. I suspected the apo may have had a little spherical aberration. It also required a Barlow which may have been a factor. The AS80/480 was using a 6 mm Zeiss Abbe 1 eyepiece which works well in this scope.

 

I will confess I have had some wonderful views of Jupiter in my Q3.5 in recent weeks. It is so easy to pull out and pull inside. Especially with my Q table. The AS80 requires setting up a mount which takes a while.

 

Re solar, I once used the AS80/840 and another small refractor to show around 400-500 adults and students telescopic views of a partial solar eclipse(up to 92% from memory) about 7 or so years ago. I also used this scope to show 60+ students a Mercury transit in the 2000's. 

 

I did not have the Q3.5 then. I would use this scope if the opportunity arose again.

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Edited by Kevin Barker, 01 August 2019 - 05:21 PM.

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