Group - in Mar 08 I posted the results of some Roddier tests done on my Celestron (Synta) C6R 150 mm f/8 refractor; see message #26697 and subsequent...
... If this software returns SPHERICAL ABERRATION 0.21 wave at 150mm and 0.025 wave at 140mm, then this software is false at best. SA can't has such unusual ...
I've had my suspicions as well. I tested my 4" APO and got differing results. Mick, at what power did you test your C6R? I tested mine at 136X and 272X and...
... I am not very knowledgeable about digital imaging, but are there issues with taking images that are not in FITS and converting them to FITS format? It...
... The C6R was tested with the camera CCD sensor at prime focus (no eyepiece) so no magnification is definable. Roddier images are produced by defocusing the...
Hi all, I'm new to this group and grinning ear to ear with my new Tak FSQ106ED. I can observe visually with a diagonal. Anyone have a photo of the lineup of...
I have perused D & G's website, and I am intrigued by their 5" f/12 and 6" f/12 offerings, although the sheer length of the optical tubes gives me pause. (I...
... and ... gives ... anyone ... Thanks, Bud. I'm assuming that at f/12, the chromatic abberation will be quite minimal. Would anyone care to comment? How...
... Bill, I think you'll find the answer depends on who you ask. I know that the 5" f/15 Lohmann Brothers achromat I owned showed obvious color, but provided...
Bill, Our club has a used 8" F/12 that I took the lens to Barry Greiner (the G of D&G) for cleaning and also testing and it is 1/7 wave. It gives excellent...
I have been interested in the 6" f12 from this site on eBay. It is Hong Kong but the price is lower. The newer filters that are available today do make the...
The Canon PowerShot E1 is the newest addition to the company's popular PowerShot line, within which it represents the starting point of an entirely new...
... I would be more concerned with optical quality. You could be buying a dog of a lens. Star testing will not tell you the wavefront error, so there is one...
... and ... gives ... Bill, I have a friend who owned an 8" and he was so enthralled with its performance that he ordered an 11" F/15. Interesting story...
Bill, I have the 6" f/15; owned a 5" f/12 in the past (and sold) and have a replacement coming soon; will try again in the near future for the 8" f/12. The 5"...
Hi Mike Be careful and remember that you get what you pay for... A sample bought from "Great Eye" was optically tested on a German site with the following...
... site ... get a ... from ... magnifier for your child's next science project or to start a fire on a sunny day, but not much more than that. Tom Mack...
The various forums at http://www.astro-foren.de/ are found here... http://www.astro-foren.de/forum.php For optical testing of a variety of instruments look in...
... happy ... Unfortunately, in all my years of going to star parties, I have never seen a long-focus refractor. So, trying one out appears to be out of the...
... a ... 8" ... filters ... on ... Real ... apos ... prices ... its ... focuser ... best ... Pat, Can you describe the 6"'s performance on the Moon, planets, ...
... Bill, It can be difficult to find such instruments, although I see them at some of the larger gatherings fairly frequently (Stellafane, WSP, the old...
... In my personal experience I have found that a quality long focus achromat will visually show you 95% of the details on Jupiter and Saturn when compared...
The G11 will be near its limits with the 6" F12 or F15. Remember the longer the tube the lower the load a GEM can handle effectively. The long tube combined...
... Bill - I looked through this scope a couple times in college, you should check your area, a lot of schools have big old achromats available for public...
... From my experience, all EP's perform better when used with longer f ratios. I notice this with my f5.5 TMB 92ss. Eye placement is ultra sensitive vs....
That is an excellent idea, and as soon as I read your suggestion, I began the process of contacting a local university, which has a 9" Brashear refractor,...
Bill - 9 incher, very nice, hopefully they have frequent public nights. I don't know where you are but here in New England there seem to be old refractors...
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