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making of flats; flats are used to remove shadows caused by vignetting and to remove stains in the image; two t-shirts do the trick

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Comment by Arie Nagel on April 20, 2011 at 12:56pm
Hi Charles, thanks for the information. I know the principle and they are also available in Europe. But indeed expensive and i wonder if it really is worth the money if your 'only' aim is to produce nice pictures. One of my friends (Karel Teuwen) is one of the best photographers in the world and he used to make flats at the sky, just around sunset and sunrise.
Comment by Charles Dunlop on April 20, 2011 at 12:11pm
The big boys all use these. refocus, slew to flatman, turns on, flat, then back to target, plate solve to line up perfect, then shoot again. That's how Gendler, Keller, etc all do it.
Comment by Charles Dunlop on April 20, 2011 at 12:11pm
http://alnitakastro.com/products/flat-man-xl/ It's not cheap but they work great, you'll need plate solving software if you want to flat for each filter color, but this thing works great, no question.
Comment by Arie Nagel on April 20, 2011 at 11:41am
Charles, what is a flatman?
Comment by Arie Nagel on April 20, 2011 at 11:40am
no Marc, in fact i close the roof and make exposures up to half of the saturation; this takes usually a few seconds, so i don't need a dark; however i have to subtract a bias
the shirt on the wall is not really needed and has been removed by now
Comment by Marc Basti on April 20, 2011 at 11:16am
Arie, do you wait for the sun to hit the shirt on the wall? 1 t shirt on the scope or is it doubled up? I'm prying for your secrets haha. Thanks Arie Marc
Comment by Charles Dunlop on April 20, 2011 at 8:00am
Why not use a flatman?

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