A-P 130GT 8" EDGE HD AVX AP Wood Tripod
Quote: One thing you can count on: the owner of the Questar is far more likely to see a difference...
Quote:One thing you can count on: the owner of the Questar is far more likely to see a difference...
Cactus Patch Observatory / 14" LX200
"The four points of the compass be logic, knowledge, wisdom, and the unknown. Some do bow in that final direction. Others advance upon it. To bow before the one is to lose sight of the three."
Clear skies, Erik
Visual astronomer since 1978.
Matthias Wirth 16" f/5
Takahashi FS-102 NSV on EM-10
Celestron 1983 C5
Zeiss, TeleVue and Celestron eyepieces
Nikon 18x70 IF-WP Zeiss Victory FL 7x42 Zeiss Victory FL 10x32
Astronomy educator/Sidewalk astronomer
Owner of Astronomy Delight franchise
18 inch f4.42 Dob on eq platform w ST120 f/5 finder
12 inch Zhumell Dob
8 inch f/6.9 home made Dob with Seevers optics
William Optics red 10th Anniversary 80mm FD
C8 XLT on Vixen GPDX
26lb eyepiece box
Cernan Space Center astronomer
Member of Northwest Suburban Astronomers
Quote:Equal? Maybe, maybe not.. But close. Very close if the optical quality is as high as my sample on contrast, and perhaps a bit brighter on deep sky.
LS60THa/B1200 Cerevolo 8" F5 MN Orion 11 SCT Tak EM200, Meade 6" F5 Newt, Starblast 4.5", ETX 90 C6 SCT, Meade 90 mm F9 refractor Meade 10"SN Canon T3, Mallincam Extreme
Quote:Rohr (Astro-foren) tested an EdgeHD 11 and the Strehl was .95, which is in the excellent catagory.
- Jared Willson
Quote:I had the opportunity to look through a Questsr 7 at the Alberta Star Party in 1988. Prior to looking I observed M13 in my 1983 SC8 and I went back after and re-observed it after looking at M13 in the Q7. My C8 had better than average optics (tested by Peter Cerevolo). I used the silver top 17mm Celestron eyepiece but I forgot what eyepiece was in the Q7 - probably a Brandon which gave about the same magnification. Although this was not a controlled test and clouded by the passage of time, the C8 gave a much brighter image but the Q7's stars were finer and the globular seemed better resolved. We also looked at M57 in the Questar and the view was nice but not as bright as I thought it should be. To be sure it was a beautiful instrument to behold. I took a photo of it during the day and if I can find it I will post. One thing I didn't like was the F 15 focal ratio which didn't suit my style of observing at the time.
Quote:Quote:Rohr (Astro-foren) tested an EdgeHD 11 and the Strehl was .95, which is in the excellent catagory. OK, I'd like some clarification. It seems to me that I've recently read, on this forum, that an SCT with a 30% CO can't possibly do better than a Strehl of .80. (IIRC, this was from Jon Isaacs; but I may be wrong about that.) I know I've seen the reference repeatedly as to the impossibility of having a Strehl as high as .95 on an SCT, due to design constraints.Now you're saying a C11 tested out to Strehl of .95; which of these contentions is correct, and where's the proof of one or the other?
Quote: I own a C11HD with virtually identical inside/outside diffraction patterns and it wouldn't surprise me if it has better than 1/30 RMS optics (= 0.96 Strehl), which is what Roddier testing my erstwhile C9.25 showed me. It's "real Strehl" may be 0.80 but then it's an 11" scope and where do I find an unobstructed 11" scope in a compact package?
150mm MCT f/13, 31% CO
"People say I'm in denial. I disagree."
Quote:Maybe it's better said to be nominal or system Strehl. In any case the lower peak intensity is a Strehl-like number defining peak intensity.