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I am trying to catch up on the time I have lost because my Samyang is at my parent‘s home…. But part of my thoughts is also about beeing as efficient as possible, so here are a few of my ideas, comments welcome: - shooting at f2 to get maximum efficiency for building up SNR The reason I did not do shoot at f2 before was quality of stars, but more on that later - for now, shoot only 2h per field 2h is not enough for our goals at my Bortle 4 skies but the required 4h simply take to long for my taste, so the plan is to reshoot the rest in the next year and to cover more fields per year. - Always shoot on the same side of the meridian in one night Meridian flips take their time, decreasing efficiency. When only shooting 2h it is quite easy to shoot targets high in the sky, and then to switch to another field that is again on the same side of the meridian. Besides beeing more efficient it also makes guiding more stable, in few cases I have lost subs directly after the flip because the mount first needed a while to re-adjust. - Shoot good stars in an extra session Stars can be done at f2.8 or higher as they are bright anyway. Half an hour is also normally good enough for the stars. Still have to find the f-ratio for nicest stars - Play with GAIN With narrowband I have completely switched from doing 10min subs at gain 100 to 5min subs at gain 200. Less frames to drop when something goes wrong… Should in theory also work well for new 1min subs at gain 200, dithering needs to get adjusted to run on every 2nd sub, otherwise the dithering process eats up to much imaging time. Perhaps also dithering every 3rd frame could be an option. Any thoughts on this, especially @James Tickner , could this work with your process, one thing I might have to do is to throw away the f2 stars and replace them with the f2.8 stars for final submission Michael |
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@Michael Ring Thanks for the comments. Here are some thoughts (in no particular order!)
Looking forward to seeing some of your fields come though! |
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Hi @Michael Ring - Great thoughts, and I agree pretty much with @James Tickner responses. I shoot wide-open, try to take as close to the meridean as possible, without crossing. If I do cross [briefly] I don't flip. I shoot 25 x 3min subs with dithering every 3pix dither every 2 subs. I don't shoot separately for the stars. We will end up with more saturated stars, but that is a small disadvantage compared to the increased complexity of processing and QC. Indeed this is where the bottleneck is currently, and I am strongly with @James Tickner on this one - lets gather enough data to get a large enough sample with which to do the QC. Only with a large sample we will be able to establish the relationships between the wide range of variables we have in this survey; geography, equipment, sky brightness, transparency, seeing. I am really looking forwards to James' QC and mosaicing work, which will give us great insight to the data taken so far. The only other observing protocols I follow are 1) Re-focus for every field [1.5hours] 2) Don't observe lower than 45deg above the horizon. [Avoiding light domes - and for me going "below the Pole" on far Southern fields] CS Brian |
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