What the heck is an f-stop?

Started 7 months ago | Discussions thread
Paul Anderegg
Forum MemberPosts: 73
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Re: What the heck is an f-stop?
In reply to D Cox, 7 months ago

It would be important to point out at this point that for shooting in low light, practically ANY broadcast video camera will be set to 1/30 second shutter speed.  Broadcast cameras also only have THREE gain switch settings, normally 0db, 9db, and 18db, although these can be adjusted for shoot conditions.  Typically you want your 0db, then your aggressive darkness high gain, and a medium to split the difference.

My main confusion here is with similar f10@2000sensitivity ratings, but with the dissimilar maximum f-stop ratings.  Is it as simple as if both the 1/3" and 2/3" are 100IRE at 2000 lux at f11, then the 1/3" sensor will produce a brighter picture at f1.4 than the 2/3" at f1.8 if both are set to their lowest and default 0db gain setting, because it can "open wider"?  My limited understanding of the math involved would seem to indicate that I am confused here.

Noise in the video world is simply accepted at the price level you are able to compete in.   For cameras with a fixed 0-18db gain/ISO range, you've got the lowest setting, the highest value, and a choice in between available in a three position flip switch.  When everyone is shooting a scene at 18db, noise becomes irrelevant, and the main priority is to actually be able to discern detail in the darker areas, with the limited amount of on camera lighting you have available.

Paul

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