Quote:
Originally Posted by h0ughy
so what would F2.2 do to the results?
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Quote:
Originally Posted by JA
It (f/2.2) is about 2 photographic stops (EV) faster than f/4 so I'd expect all of the times in any f/2 tables to be one quarter of what they are in the Shiraz's published f/4 table. Just like the published f/4 table has approximately one quarter of the times that are in the published f/8 table, which also differs by 2 stops. It's really no different to equivalent photographic exposures
I'm not sure if the f/2.2 f number takes in to account the central obstruction, but if not that would need to be corrected for if one wanted to know any exact result which took account of the true light collection area. Not sure how much or whether that is already factored in to the f number.
Best
JA
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yep, just did some model runs to make sure there are no hidden gotchas - the subs are about 1/4 as long and the total time is about 1/4 as long at f2 cf f4. The dynamic range remains the about same. There is a minor downside of having very short subs - the download and dither settling times become significant compared to the imaging time and somewhat limit how quickly you can image. However, that is not a bad problem to have. Cheers Ray