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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 528
Loc: Haren, The Netherlands, Europe
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Last week I had my Questar 7 tested by master optician Hans Dekker at Opticon. After some fiddling with the OTA to align it wit the artificial star he became silent while focusing the Questar 7 image in my 4 mm Zeiss Abbe (700x) . His jaw dropped. After a while he started smiling and jumping up and down. Then he called out for his colleague Bart to come and see for himself what the noise was all about. He too started smiling after examining the image in the eyepiece. They both urged me to never ever sell this scope and to inform my wife and kids about the unusually fine optics and timeless value of this scope. I guess that is where Heirloom-value supercedes Strehl-value. By the way, the quality of the Questar 7 optics proved to be significantly better then that of my best APO's, which were also tested that day.
Clear and stable skies to all,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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Les
professor emeritus
Reged: 04/22/06
Posts: 730
Loc: Maryland
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Sweet! Did you pay extra to achieve a particular spec? Normally they are produced to deliver "diffraction limited" performance i.e. 1/4 wave. Were you commenting more on the smoothness of the surface?
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Les
Canon 10x42L IS
Oberwerks BT80/45, Helix Hercules mount on Oberwerks Standard Tripod
Swift 8x44ED Ultralite
Questar 50th Anniversary Model, 501 head on Manfrotto 475 tripod
Stellarvue SV90T 90mm Fluorite refractor Bogen 3236/Televue Tele-Pod Head
Questar 7 Astro
Vixen GP-DX on Baader Surveyor Tripod
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 528
Loc: Haren, The Netherlands, Europe
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Quote:
Sweet! Did you pay extra to achieve a particular spec? Normally they are produced to deliver "diffraction limited" performance i.e. 1/4 wave. Were you commenting more on the smoothness of the surface?
Hi Les,
Years ago, I payed a premium price used because of the quality of this Q7. I have reported on this forum before about the stunning performance of the optics. I went to Opticon to have my refractors evaluated. The best of them was the little 55mm fluorite with very smooth optics and around 1/10th wave P-V.
Out of curiosity I couldn"t resist to put the Q7 on the test bench as well. It's diffraction image was visibly quite a bit better then even the 55 fluorite. Mind you, we were using my 4mm Zeiss Abbe. That's ca. 700x! In focus the image was perfect. So were the intra- and extra focal images. With incredible contrast between the light fresnell rings and the dark space inbetween. Smooth and precise optics as fine as the hands of man can make them. Just the reason why I bought it years ago after seeing it next to my 1/10th wave P-V Astro-Physics 130 refractor. The Q7 was quite a bit better then the AP EDF130. The great thing is, that the Q7 test INCLUDES the built-in diagonal, which therefore must also be of superb quality.
So thanks to the wonderful people at Questar, Cumberland and VernonScope for crafting this masterpiece back in 1985. 
Clear skies,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
Edited by Erik Bakker (10/04/09 04:33 AM)
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SATMAN
sage
Reged: 12/02/07
Posts: 276
Loc: NJ 39.7 lat., -74.3 long
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Erik,
This is why Questars are really amazing "the Finest Optics Created by the Hand of Man!"
I wonder how my Brandon 94 would have fared on this test visually it is just as good as the Questar.
In 1985 I don't think anything could have equaled the performance of your Q-7, or today for that matter. Some thing said about hand crafted and assembled optics! 
Hopefullly the weather will clear up here so I can get to observe soon we are back into our Rainy run again 
I purchased my Brandon Eyepieces back in 1986 and they still are my main planetary, general purpose eyepieces inspite of a good collection of Naglers that I have.
I am primarily a visual Observer now And these two telescopes (Questar 3.5, Brandon 94 APO)get the most use, I have just upgraded from a Vixen Porta-Mount to a Quarter Half hitch Mount on a KB1001 tripod for the Brandon.
Clear skys and keep enjoying that splendid optical system.
Gary
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CELESTRON/VIXEN C102 GP REFRACTOR
CELESTRON SUPER C8 PLUS
VIXEN 90 CUSTOM REFRACTOR ALTAZ. MOUNT
QUESTAR 3.5 STANDARD POWER GUIDE II ON TRISTAND
CORONADO PST DOUBLE STACKED
BRANDON 94mm f/7 ON VIXEN POLARIS MOUNT
VIXEN PORTA MOUNT, QUARTER HALF HITCH MOUNT
BRANDON EYEPIECE SET (circa 1986) 8,12,16,24,32, 2.4X DAKIN BARLOW
VARIOUS NAGLERS 3-6 ZOOM,7,9,11,13,16,24PANOPTIC
ETHOS 6mm, 10mm
ZEISS 10X40B/GA T*P* BINOCULARS
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 528
Loc: Haren, The Netherlands, Europe
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Quote:
Clear skys and keep enjoying that splendid optical system.
Gary
Same to you Gary,
The Brandons are superb as is the 94 Brandon. And as always, Questars are a joy to use.
CS,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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dougspeterson
Pooh-Bah
Reged: 09/01/04
Posts: 1040
Loc: Murrieta, CA
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Company 7 had a story about several Q7s tested with decent but not astounding numbers, 1/4 to 1/6 wave, and Peter Ceravolo showed an interferogram of a defective Q7 at an RTMC talk quite a while ago.
But mine from the late 80s has a simply superb star test so that I strongly feel mine exceeds those numbers and may be in the class of Erik's above. Were those Company 7 tests poorly done, or were there eras of superior quality?
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18" Dob
12" SCT
8" TMB F6 + Chromacor
6" F6 APM/LZOS Fluorite triplet, 32", 32lbs
2ea. 6mm singlets, one blind
"--Granted, that's a worse case scenario. The destruction might in fact be ... limited to our own galaxy."
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 528
Loc: Haren, The Netherlands, Europe
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Quote:
Company 7 had a story about several Q7s tested with decent but not astounding numbers, 1/4 to 1/6 wave, and Peter Ceravolo showed an interferogram of a defective Q7 at an RTMC talk quite a while ago.
But mine from the late 80s has a simply superb star test so that I strongly feel mine exceeds those numbers and may be in the class of Erik's above. Were those Company 7 tests poorly done, or were there eras of superior quality?
Don't know. But congrats on your Q7 Doug. I do know that Opticon tested several Q 3 1/2 over the last decades, one being around 1/6 wave, the rest being significantly better. They consider Questar the initiator of consistently delivering very good optics to the end-user. They are very straight and critical testers AND amateur astronomers themselves. Of course, a Questar is somewhat handicapped by it's large central obstruction. A truly dedicated planetary system should have under 18 % CO in my opinion. But the Questar is a superb and extremely enjoyable compromise as far as I am concerned. Love touring the heavens with it.
Clear skies,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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Les
professor emeritus
Reged: 04/22/06
Posts: 730
Loc: Maryland
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Quote:
Company 7 had a story about several Q7s tested with decent but not astounding numbers, 1/4 to 1/6 wave,...
If I remember correctly from my last visit, C7 has the 1/6 wave unit on display in their "museum". Or maybe it was just the test report?? Anyway, the placard said that it was the finest Q7 that had ever been delivered to C7. I do remember someone on this forum commenting that they had contracted with Questar to produce a Q7 to the same spec as the Q50th i.e. 1/10 wave. I also remember Dr. Cohen saying that you could contract with Questar to build to a spec but that "time is money" and you can expect to pay thousands more. Still, it is a tribute to the Questar/Cumberland team that they have the talent and expertise to deliver these systems.
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Les
Canon 10x42L IS
Oberwerks BT80/45, Helix Hercules mount on Oberwerks Standard Tripod
Swift 8x44ED Ultralite
Questar 50th Anniversary Model, 501 head on Manfrotto 475 tripod
Stellarvue SV90T 90mm Fluorite refractor Bogen 3236/Televue Tele-Pod Head
Questar 7 Astro
Vixen GP-DX on Baader Surveyor Tripod
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Les
professor emeritus
Reged: 04/22/06
Posts: 730
Loc: Maryland
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Quote:
Were those Company 7 tests poorly done, or were there eras of superior quality?
Let's remember that test reports that come with Questars are zygo measurements where thousands of points across the the mirror are examined. I believe that if a single point exceeds 1/6 wave then the slot in the report for P-V will show 1/6 wave. Now if there is a single point that high but the rest of the mirror is dead on that will produce a very different image than a mirror with a slow undulating 1/6 wave error across the whole mirror. So the distribution of the error is important. Strehl readings or rms reading provide additional information but ultimately it is the quality of the star image in a star test that can be most revealing. Obviously the opticians saw something in the testing of Erik's Q that they REALLY liked - and Erik is a lucky man to have such a fine scope.
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Les
Canon 10x42L IS
Oberwerks BT80/45, Helix Hercules mount on Oberwerks Standard Tripod
Swift 8x44ED Ultralite
Questar 50th Anniversary Model, 501 head on Manfrotto 475 tripod
Stellarvue SV90T 90mm Fluorite refractor Bogen 3236/Televue Tele-Pod Head
Questar 7 Astro
Vixen GP-DX on Baader Surveyor Tripod
Edited by Les (10/07/09 05:47 PM)
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 528
Loc: Haren, The Netherlands, Europe
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Quote:
Strehl readings or rms reading provide additional information but ultimately it is the quality of the star image in a star test that can be most revealing. Obviously the opticians saw something in the testing of Erik's Q that they REALLY liked - and Erik is a lucky man to have such a fine scope.
I am shure there are some other lucky guys/girls out there. Doug shurely must be one of them. Just felt good to share these results about the Q7 optics since they are so rarely reported. They really are very nice. I have never looked through another Q7 since they are very rare where I live.
Clear skies and many thanks to the great people crafting our Questars,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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Rick Woods
Postmaster
Reged: 01/27/05
Posts: 5648
Loc: Inner Solar System
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Erik, Doug,
Exactly what were the numbers on your tests? Erik, yours was much better than your 1/10 wave APO: but what was it?
Come on, brag! We want to hear and envy!
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- Rick
14" LX200GPS
83% of all statistics are meaningless.
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Erik Bakker
professor emeritus
Reged: 08/10/06
Posts: 528
Loc: Haren, The Netherlands, Europe
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Quote:
Erik, Doug,
Exactly what were the numbers on your tests? Erik, yours was much better than your 1/10 wave APO: but what was it?
Come on, brag! We want to hear and envy!
Sorry Rick,
No bragging here. 
Clear skies,
Erik
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Visual astronomer, main instruments:
Fully mounted Questar 7 P-BB
Celestron C 102F f/8.8 fluorite
Vixen FL 70S f/8 fluorite
Celestron C 55F f/8 fluorite
Sets of Zeiss, TeleVue and Brandon eyepieces
Zeiss 7x50 Marine B/GA
Zeiss TM german equatorial
Gitzo 224 with Manfrotto 501 fluid head
Unitron alt-az mount
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