iceman
20-11-2007, 06:53 PM
Well, it's no Ralf but I was happy to have captured something on video when watching it back afterwards, given my problems described below.
With a favourable ISS pass over my area last night (54deg max altitude, -2.1 mag), I decided to try and capture it with my 12" newt, unfiltered DMK21AF04 + 2x barlow.
I decided that a dob-based approach would give me the most flexibility in trying to manually track the ISS in the finderscope, so I set my 12" newt back in its dob base, instead of on the EQ6.
Conditions were absolutely horrible. A very gusty wind, with thick low clouds, and it wasn't even dark yet (20:16 local time, sunset ~19:50). It meant I couldn't find ANY stars to align my finderscope with the DMK, so I just had to hope it was aligned. It also meant I couldn't find a comparable brightness star to set the exposure, so I just hoped that leaving it on auto-exposure would allow the software to pick the right brightness for the histogram.
I captured at 30fps, and after 5000 frames, I got 4 useful images :) Not a great strike rate :) The ISS made an appearance in probably a hundred+ frames, but they were all overexposed. The ISS wasn't in the FOV long enough for the software to adjust the exposure/shutter :(
So, next time I have to hope for a darker pass, so I can find some stars to align the finderscope and set the exposure. I'll choose a faster shutter to freeze the ISS as it wanders through the frame with bad hand tracking :)
I was actually lucky I had the moon up, so I could focus on the moon - otherwise I wouldn't have even been able to focus before the pass.
Anyway, here's the ISS. The 2nd attachment is an example of the overexposure, and that's a good one. Most times it was a long white streak. The third attachment shows the conditions in a 181sec exposure with my 350D. You can faintly see the ISS streak.
Thanks for looking.
With a favourable ISS pass over my area last night (54deg max altitude, -2.1 mag), I decided to try and capture it with my 12" newt, unfiltered DMK21AF04 + 2x barlow.
I decided that a dob-based approach would give me the most flexibility in trying to manually track the ISS in the finderscope, so I set my 12" newt back in its dob base, instead of on the EQ6.
Conditions were absolutely horrible. A very gusty wind, with thick low clouds, and it wasn't even dark yet (20:16 local time, sunset ~19:50). It meant I couldn't find ANY stars to align my finderscope with the DMK, so I just had to hope it was aligned. It also meant I couldn't find a comparable brightness star to set the exposure, so I just hoped that leaving it on auto-exposure would allow the software to pick the right brightness for the histogram.
I captured at 30fps, and after 5000 frames, I got 4 useful images :) Not a great strike rate :) The ISS made an appearance in probably a hundred+ frames, but they were all overexposed. The ISS wasn't in the FOV long enough for the software to adjust the exposure/shutter :(
So, next time I have to hope for a darker pass, so I can find some stars to align the finderscope and set the exposure. I'll choose a faster shutter to freeze the ISS as it wanders through the frame with bad hand tracking :)
I was actually lucky I had the moon up, so I could focus on the moon - otherwise I wouldn't have even been able to focus before the pass.
Anyway, here's the ISS. The 2nd attachment is an example of the overexposure, and that's a good one. Most times it was a long white streak. The third attachment shows the conditions in a 181sec exposure with my 350D. You can faintly see the ISS streak.
Thanks for looking.