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Equipment Discussions >> Classic Telescopes

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starman876
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Re: Questar Opinion new [Re: Paul Hyndman]
      #5685618 - 02/17/13 05:46 PM

Let me explain further. That wonderful little scope will cool down faster and provide beautiful images while the monster next door is cooling down. Then the turbelence in the sky will further make that monster useless, while that little questar with the wonderfully figured optics will provide breathtaking images. We are talking about the quality of the optics here which will outperform any other optics of the same size that is not made with the same craftmanship.

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terraclarke
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Re: Questar Opinion new [Re: starman876]
      #5685628 - 02/17/13 05:50 PM

Ed Ting says it all.

http://www.scopereviews.com/90mmComparo.html

Terra


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Glen A W
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Re: Questar Opinion new [Re: rmollise]
      #5685647 - 02/17/13 06:00 PM

Quote:



I'm guessing you eiher haven't used an ETX and a Questar side by side, or your ETX was run over by a truck.




I am surprised you have made this claim that the ETX is equal optically to the Questar. That's a first for me.

Haven't used them side by side. Uncertain about the truck. But I do know dim when I see it, and the ETX is dim. There is something so lame about that - some scopes just seem so bright and perky. The best thing about the ETX I have is the pretty paint. In fact, it makes a better ornament than anything else.

So that's one thing my ETX has on the Questar being auctioned. ETX wins at last! GW


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starman876
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Re: Questar Opinion new [Re: terraclarke]
      #5685650 - 02/17/13 06:01 PM

Note to be fair. Ed did say the C90 was a bargain. Which is what most of the astronomers I know are always looking for.

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azure1961p
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Re: Questar Opinion new [Re: terraclarke]
      #5685659 - 02/17/13 06:05 PM

Quote:

I've seen M42 through both a Questar and a C5. The Questar won hands down. It was a good C5 and an average view of M42. The Questar presented what I could only characterize as superb. The contrast, definition, resolution of the trapezium, was handsdown, head and shoulders above the C5 view. Sure, you might see a few more faint fuzzys with a somewhat a larger aperture but you won't be seeing them through a Questar. Of course you won't be spending as much money either.

Terra




Then that was a lousy c5 and that's the end of it. Maybe it wasn't cooled - who knows - I've looked through both and the dim Q90 view very very obviously had better optics and the C5 was trash. Who knows maybe it was a cool down issue, seeing whatever - but when things are where they should be the Q would be sharp but dim.

You can't say it was a good Celestron and get that result. Sorry.

Pete


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starman876
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Re: Questar Opinion new [Re: azure1961p]
      #5685666 - 02/17/13 06:09 PM

This is really funny. Comparing caviar to eggs from a carp
Next we will be hearing how sharp that Skywatcher was when compared to an Astro Physics.


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rmollise
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Re: Questar Opinion new [Re: terraclarke]
      #5685688 - 02/17/13 06:22 PM

Quote:

Vindicated again
And the C90 has one of the worst reputations of any small scope.




If you like. But the C90, the current C90 doesn't have one of the worst reputations; it has one of the best. You haven't read Ed Ting's review, have you?


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rmollise
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Re: Questar Opinion new [Re: starman876]
      #5685691 - 02/17/13 06:25 PM

Quote:

I have had both the cheap ETX-90, the C5 the C6 and Meade 5" scope and they were all your typical optics from a third rate vendor. I bought an ETX when they first came out thinking oh boy here is a scope that they claim is the equal of a questar. I never laughed so hard after I looked through a couple. Surprised they did not sell a bottle of snake oil with it.
It is kind of like comparing a Telementor to a Meade 60mm refractor.
The larger optics of the C5 might show more fuzzies, but I like to resolve what I am looking at rather then imagine what I am seeing. It sounds like there is a lot of imagination here rather then straight facts about the quality of really good optics versus aperture. brighter object because of increase in aperture does not mean you are resolving the object. I would suspect your brain is doing the resolving rather then the second rate optics.




There is a lot of imagination, beginning with "resolution." The C5 will easily out resolve the Questar, good though the Questar's optics might be. That's optics, and there is no way around it. I'd suggest you're unclear about the definition of "resolution," which is a function of aperture.

Edited by rmollise (02/17/13 06:29 PM)


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rmollise
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Re: Questar Opinion new [Re: Glen A W]
      #5685697 - 02/17/13 06:28 PM

Quote:



I am surprised you have made this claim that the ETX is equal optically to the Questar. That's a first for me.

Haven't used them side by side. Uncertain about the truck. But I do know dim when I see it, and the ETX is dim. There is something so lame about that - some scopes just seem so bright and perky. The best thing about the ETX I have is the pretty paint. In fact, it makes a better ornament than anything else.

So that's one thing my ETX has on the Questar being auctioned. ETX wins at last! GW




I haven't used your ETX. There might be something wrong with it or your setup. The fact is, an ETX is no "dimmer" than a Questar. I know that's unpleasant for folks who want magic out of the Questar, but it's also a good way to avoid being disappointed when it becomes clear that a Questar is a nice telescope--a nice 3.5-inch telescope no different optically from any other well-made 3.5-inch telescope.


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azure1961p
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Re: Questar Opinion new [Re: starman876]
      #5685700 - 02/17/13 06:29 PM

Quote:

Unless you have looked throuhg one for extended periods and have made serious observations with the comparison scope I would suggest you do not make any comments [/qoute]

Ok I qualify. His comments are all valid and strong testament to why the design dead ended into oblivion. A fraction of the cost in a great number of different designs still yields a highly portable telescope and very often one that trounces the Q performance. Moreover, pardon me, but SERIOUS observers often don't bother with 90mm maksutovs. Oh some do - heck I ADORE my 70mm refractor but when I want to make a serious observation - lol - well most folks would consider the Q90 laughable. I'm an advocate of the one arm carry too - especially at the end of a long day - it'll only take a half breath at focus though to realize that you pay for that convenience with a tiny object and contrast levels routinely had through comparably cheap scopes aren't even hinted at with the 90. It's good you are an advocate of extended periods with Q90 - it's going to be a long wait.

I love the little thing but your assessment of the scope and one persons post is hard to take seriously. It's a nice little scope. That's all.

Pete

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terraclarke
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Re: Questar Opinion new [Re: starman876]
      #5685701 - 02/17/13 06:29 PM

Yes, the C90 has improved dramatically, (for one, they got rid,of that stupid circumferential focus ring) and it does give you bang for your buck. The ETX just needs bang! Shoot it and put it out of its misery.



Terra


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rmollise
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Re: Questar Opinion new [Re: terraclarke]
      #5685706 - 02/17/13 06:31 PM

Quote:

Yes, the C90 has improved dramatically, (for one, they got rid,of that stupid circumferential focus ring) and it does give you bang for your buck. The ETX just needs bang! Shoot it and put it out of its misery.



Terra




Who is they? The current C90 has no relationship to the Celestron made model. Have you used the current C90 Terra? As a matter of fact, have you used a Questar 3.5?


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starman876
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Re: Questar Opinion new [Re: rmollise]
      #5685709 - 02/17/13 06:34 PM

Answer not a fool according to his folly, lest you also be like unto him.

American King James Version


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Datapanic
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Re: Questar Opinion new [Re: rmollise]
      #5685712 - 02/17/13 06:36 PM

I think DAVIDG's evaluation deserves repeating:

Quote:

When it comes to the optics quality of Questar and ETX-90 it's difficult to see any difference on a double pass autocollimation test on the my optical bench of ones I have done.




Ed Ting's review states of the ETX and C90 that "Both scopes are slightly out of collimation." Of the Questar, he said "...but the optics appear to be very slightly miscollimated. It wasn't as bad as the ETX or the C90, but you could see it."

So, a visual shoot out of three scopes all out of collimation does not make a good test and doesn't cut the mustard of anything scientific, like the double pass autocollimation test.

The value of Ed Ting's review is more on comparison of the mechanics of the 3 scopes.


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azure1961p
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Re: Questar Opinion new [Re: starman876]
      #5685721 - 02/17/13 06:43 PM

Quote:

This is really funny. Comparing caviar to eggs from a carp
Next we will be hearing how sharp that Skywatcher was when compared to an Astro Physics.




No. Next you are going to hear how Questar was the disappointment of the 70s. They literally ruled the want ads in sky and telescope once people got beyond the great catalog, nature favoring smaller aperture, a ridiculously high price tag and the fact that at star parties even a C5 was putting it to bed. I've been in the hobby for decades and I recall Questar in its glory. It was a ringing disappointment that all but a few could love and everyone wanted their money back. Johnny Carson didn't, and generally millionaires who didn't have to come to terms with their gross waste of money didn't mind the Rolex factor. For anyone else who thought they were getting views as good as its luster and hype - the Questar afterlife was in the want ads. They'll always be around. I do love them but I couldn't think of a more empty investment. If I want to look at my money - Ill buy a Questar. If I'm serious about looking through a telescope - it'll be anything but a Questar.

Pete


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terraclarke
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Re: Questar Opinion new [Re: rmollise]
      #5685739 - 02/17/13 06:54 PM

Please up in the thread, I cited Ed Ting's article.
But apparently you haven't read his article Uncle. I suggest you actually do read it. in particular, if you aren't going to read it in its entirety, then read at least conclusion of the article. The only thing the C90 wins at is value, which is what I also said (above). And perhaps if you read the thread in its entirety you would have read my first comment and you wouldn't have asked if I have used a Questar. But then you have repeatedly overlooked, ignored, or simply not comprehended what I and others have written in this thread, (if it wasn't what you wanted to hear perhaps).

Enough of comparing carp eggs to caviar. And enough casting of pearls before swine.

"Do not give what is holy to dogs, and do not throw pearls before swine, lest they trample them under their feet, and turn and tear you to pieces." (Matthew 7:6)


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starman876
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Re: Questar Opinion new [Re: terraclarke]
      #5685747 - 02/17/13 06:58 PM

http://www.cloudynights.com/item.php?item_id=475

This is a good review of the Questar versus the C5.


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GlennLeDrew
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Re: Questar Opinion new [Re: starman876]
      #5685751 - 02/17/13 06:59 PM

I checked out a friend's Meade 90 in double-pass autocollimation mode and was most impressed by the degree of smoothness and correction. Under the stars it delivered a beautiful diffraction pattern. Very good optical quality. I did not assess system transmission.

Regarding comments of dimness on other such Meade scopes... It would require significantly inefficient coatings on the mirrors to result in a noticeable diminution of the image. (The corrector is well coated, and should transmit at least 95%.) If both mirrors have been given the 'standard' protected aluminum coating, the combined reflectance of the two 89% surfaces is 79%. If we credit the Q90 with 96% enhanced coatings, the combined reflectance is 92%. We can assume similar transmission for the corrector (let's say 95%), and will neglect 'after' accessories at the back end.

Each OTA has total transmission of; .79 * .95 = .75 for the M90, and .92 * .95 = .87 for the Q90.

The Q90 therefore transmits .87 / .75 = 1.16, or 16% more light. Even doing a side-by-side comparison, it would be most difficult to see the difference. It would require at least a 30% difference to become noticeable. And we can discount any difference in secondary obstruction, which area wise cannot amount to subtraction of light differing by more than a couple of percent.

I suspect the noted difference in image brightness has more to do with a difference in exit pupil diameter. And if the comparisons were conducted not side by side, and especially after some lapse of time, *uncertainty* on any perceived differences in brightness is the watchword.


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Ducky62
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Reged: 10/31/10

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Re: Questar Opinion new [Re: terraclarke]
      #5685764 - 02/17/13 07:10 PM

Quote:

Ed Ting says it all.

http://www.scopereviews.com/90mmComparo.html

Terra




The C-90 tops the Questar in brightness and contrast as well as value.

Quote:

The C90 throws up the brightest, most contrasty images, the ETX the dimmest. The Questar is in the middle - just right.




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starman876
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Re: Questar Opinion new [Re: Ducky62]
      #5685832 - 02/17/13 07:50 PM

This part of Ed Tings comparison really says it all about the quality of the Questar optics. To me a scope that provides a quality image accross the whole field of view is what I want. Every Meade and Celestron SCT or Mak has never provided that kind of image. Sharp in the middle and soft off center. Anyone who had evaluated optics knows that it takes a true craftsman to provide those kind of optics. A mass produced scope will never provide that kind of view. So argue what you want about what you viewed, how bright it was or how sharp the view was. Can you honestly say that that view was sharp accross the whole field of view????? Read below what was said and now let us argue that part of the review and the rest of you stop reporting on this subject like you were FOX news

The most interesting part of this test is what you can't see on the images above. The Questar was such a pleasure to use. Not only did it provide the best images, it did so with the least amount of effort. I spent the least amount of time focusing the Questar, by far. Although the C90 had no image shift, sometimes I had to rack the focuser back and forth a little to arrive at the best focus. I got good images out of the ETX, but I had to work at it. Also, watching Registax working its way through the images was fascinating. Overall, the Questar yielded more usable frames, per capture, than either of the other scopes. There were times, even with the quality threshold set at at 95% or higher, that close to 100% of the frames were deemed usable by Registax. No other scope I've ever used has come close to that feat.


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