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Samir Kharusi | all galleries >> Galleries >> C14 Hyperstar - Initial Tests > Full 20D Frame
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05-SEP-2007 Samir Kharusi

Full 20D Frame

Azaiba, Muscat, Oman

For the pixel peepers. Enjoy. This is simply a camera Jpeg, unprocessed, unsharpened. If you click "original" below right (white indicates it is already active and that is what you are viewing), you can scroll all over the frame at 1:1.

I tried collimating the Hyperstar. I expected a hugely daunting task; viewing stars at 1:1 into the corners, twiddling collimation, refocusing, etc. Could take a week! But actually, it was surprisingly easy. Just defocus slightly and you see the typical SCT donut stars all over. Use the stars in the middle and make them nicely round donuts using any focus software for your camera. I used ImagesPlus. The ringing around the bright stars, I suspect, is not Airy discs, but sort of the shadow of my lop-sided DSLR and cables. If you use a camera with a circular cross-section, you should get circular rings, or none.

There is visible vignetting, as to be expected for such a fast focal ratio. Not sure whether this is purely a property of the Hyperstar, or the Hutech pop-in LPS Front Filter combined with the f/1.9 light cone. Investigated further in the next slide. But hey, one should not grumble too much when you can shoot 7 to 8nm narrowband with this hippo using 90sec subs in a DSLR. I think I might have just given up autoguiding...

Canon EOS 20D ,C14 Hyperstar 675mm f/1.9
60s iso200 with Idas LPS-P2 pop-in Front Filter, Unguided full exif

other sizes: small medium large original auto
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