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DSLR Fuji S2: 10 sec. on M42 @800 ISO

Started by Astrovale, 01/02/2004 06:17PM
Posted 01/02/2004 06:17PM Opening Post
I was trying out a Stiletto focuser for my fuji s2 and I was strongly adviced not to use any focal reducer to get accustomed to the Ronchi screen focusing. So, since I was using a DSLR that has a built in 1.5 focal multiplier on my 11" at F10, I was imaging at F15 in altazimuth! At F15 I could not afford more than 10sec exposures at 800 ISO and this is the raw frame unprocessed. I would love some opinion on focus, mostly. This image is 33% of the original. I was not able to capture to many images (I am an absolute beginner and it took some time to test new stuff!) I will try to stack them and see what comes out.



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Astrovale's attachment for post 11953
Solar Imaging Website
Posted 01/03/2004 06:38AM #1
Hello James and Steve and thanks for your interest and advice. I'm sorry if it were unclear in the original post, but this is an alt-az driven picture taken from my backyard in the middle of the city at F15 (F10 of my nexstar 11 GPS and the 1.5 focal multiplier built in the Fuji finepix S2 pro at prime focus). Unfiltered and unprocessed (not even dark frame)
That is the reason why I had to keep my exposures so short and even that short was not enough for an unforgiving F15! In some of the images I was able to test shorter exposure batches (6sec @800 ISO and 4sec @1600 ISO) and the drift effect there is less evident although still present. Next time .63 focal reducer that will bring me still close to F10, but better than F15!
As far as collimation is concerned, you may be right although I check it everytime I start observing or imaging. I have a hard time performing the operation with my scope (mostly due to size). I'm expecting a collimating "help" that's coming in the mail. I do not trust my ability to determine visually if collimation is as good as it could be (the large donut is too misleading and the slightly out of focus star is extremely dependent on the quality of the seeing). If it is not collimated it is only a little bit that I could not judge visually.

Thanks again for the comments.

Solar Imaging Website
Posted 01/03/2004 09:18AM #2
Despite the oblong stars, your focus was good enough to capture E and F in the trapezium. Very nice.


Alan Friedman
Posted 01/04/2004 12:41PM #3

Pretty nice for a first attempt! I will be looking forward to more images from that setup.


Jeff 8O