Quote:
Originally Posted by Placidus
The reflection nebulosity came out really well using your method. Well done!
I understand your need to use short subs to get round differential flexure. Short subs work fine with really bright targets and fast F-ratios. Eventually, you'll want to photograph fainter things and off-axis guiding (or an instrument with no differential flexure) will be the way to go.
Regarding exotic CMOS sensors and electronics, I agree wholeheartedly with Peter, Colin, and Rick.
Consider an extremely faint target, say the outermost super-faint and rarely imaged chevrons in the Helix, or the ultra-faint OIII bubble near NGC 602. I've imaged parts of these where there may not be even one single photon per five minute sub per pixel at 3.5 metres focal length. You need literally tens of hours of exposure with a 20 inch scope. Readout noise is overwhelming. A very quiet chip will help. But even with fancy electronics, you will always do far better with one hour subs than with 5 minute subs.
For more routine objects, not blindingly bright, you can get away with shorter subs, but you will still always do better with a few longer subs than with squillions of short ones.
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Thanks m&t for your comments and thoughts. I take them with high esteem. I have manged to fix all the problems with the oag and am pulling some lovely 10 minute subs. So i will see in the morning once I get some flats applied to my shots.
Once again thanks for your time and thoughts
Scott
