Interesting topic that hits close to home.
Some 20 or so years ago, a friend that had (and still does have) a Unitron #142 3" f/16 refractor got the bug to give a 3.5 inch Questar a try. He decided that he ultimately would only keep one telescope - either the Questar or his 3" Unitron so challenge #1 was to get a Questar vendor to commit to selling him a Questar with the proviso that should it show no real advantage in a head to head test vs his 3" Unitron it would be returned to the vendor for a full refund. Anyway the first contacted vendor would not agree to these terms even after telling my friend that there would be no way that the Unitron would be able to best the Questar in a head to head challenge. I guess he really did not have faith in the superiority of the Questar.
On to the next vendor, I believe it was Spectra, or a similar name, in California. Now out of business. The owner (Dan Gordon, I think) also believed that the Questar would come out on top and that my friend would be very happy with the Questar. He was a bit hesitant to agree to the terms of the purchase and the test (Questar going back to the vendor if it could not clearly show some advantages over the Unitron) but ultimately he decided that his confidence in the superiority of the Questar made his risk as a vendor minimal.
So Joe eventually got a Questar to compare to his 3" Unitron, which he had purchased from me. I already had another 3" Unitron as well as the 4" and the 2.4", all equatorially mounted. Note that at the time of the test there was no "driven" advantage of one scope over the other in that both had simple right ascension drives.
On the night of the test I went to Joe's and brought my C-90 with me. It would be interesting to compare the C-90 to the Questar, there being approximately an 8 to 10 fold price differential between the two scopes.
Over the course of the evening we looked at the Moon, Saturn and some double stars and indeed the comparison was close. At f/16 the Unitron displayed little if any chromatic aberration, certainly nothing that was objectionable. All targets looked good thru both the Unitron and the Questar. Comparisons were very, very close. Both scopes are classics and both look very nice when set up to be displayed when not in use. The Questar has an advantage in being able to be packed up into a tighter package when not in use. Although the Unitron is not a real problem in this regard. We both felt that the Questar offered no real advantage over the Unitron, to the point at close to a $2000.00 outlay would be justifiable.
The lowly Celestron C-90, while clearly inferior to the Questar was not that far behind in performance. The Questar's performance was not 10 times better, which would have been in line with it's 10 times better price increase.
So the Questar went back, and Dan at Spectra was stunned, but he had agreed to the terms. Joe, some 20 years later, is still happy with his Unitron.
Note - I had a second hand Questar briefly. I quickly learned that the optics needed recoating. With full disclosure I managed to sell it without too much of a loss. I currently have a Questar 7 which I admittedly have only used once, being just a few weeks out from a right hip replacement. The views were quite nice and it is a keeper.
I am posting a photo of the 3.5 Questar that I had briefly. I have to admit that it is a stunning telescope to look at.
Barry Simon
Edited by BarrySimon615, 27 July 2023 - 11:17 AM.
