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Samir Kharusi | all galleries >> C14 Hyperstar - Initial Tests > Moon w C14 Hyperstar
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Moon w C14 Hyperstar
1st September 2007 Samir Kharusi

Moon w C14 Hyperstar

Azaiba, Muscat

First light with a C14 Hyperstar. What did I learn? Focusing is possible through the camera's viewfinder! Sort of. Just use Canon's Angle Finder C to keep your head out of the way. Only problem is you need gorilla-sized arms to reach the focus knob :-( Real bummer. Write that off unless you have one of those motorised focusers, basically just a motorised replacement of the focus knob. I had one for a C8 and often wondered what use it had. Manual focusing on the C8 was more pleasant. So I used the focus routine in ImagesPlus. Not as critical as I would have liked but of course it does work. There is a longish excursion when there does not seem to be much happening; the C14 has a very fine focus thread. This could also have been caused by poor seeing (rather hazy) and/or largish star diameters. But basically, focusing is no more difficult than when preparing to image at f7 or f11 with an SCT. I was set up with a Baader 7nm H-alpha filter ready to shoot some nebula, but never did get around to it. Too many things to learn and re-learn (like even the mount's hand paddle after many months away). So I ended up shooting the Moon with the H-alpha and a UV/IR blocker in place. Focused the Moon when in the middle and then slewed to place it in the corners, without refocusing. Checking out orthogonality/collimation at the all-tight factory setting, all collimation screws unused. You be the judge. I think the collimation is pretty good as is. How sharp is the Hyperstar? Definitely sharp enough for 1200 pixel-wide presentations like this one (if you have clicked "original" below right. At a larger presentation size and for prints? As the following images will demonstrate, sharp enough, all over the frame. At the 675mm quoted focal length seeing starts interfering, even with Moon pics, so one has to make an on-site comparison to a premium APO, rather than just examine the frames. Ah, just for completeness, note the potential loss in resolution through the use of just the Red pixels in a Bayer array.

Hutech modded Canon 20D,675mm f/1.9
Baader 7nm H-alpha Filter + Hutech UV/IR Blocker pop-in Front Filter. Exposure 1/1000sec for each image. full exif

other sizes: small medium large original
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Charles Lasnier04-Sep-2007 06:54
Definitely a nice wide field of view!