brett8883
Well-Known Member
You hadn’t quite fully formed the idea but you were on the right track. It’s not how frame rate effects exposure directly but how it affects shutter speed which affects exposure. A slower frame rate allows you to use a slower shutter since your shutter can never be faster than your frame rate.If the shutter is faster the frame rate then yes it's a moot point. And for most people most of the time that is the case. In my original reply I was talking about how long the sensor was available to collect data. Available is the key word. I misspoke by taking it farther than that. But if you need to maintain your 180 degree shutter angle there is an fact an exposure issue to deal with somehow.
Yet I also mentioned that there are other aspects to conside. One is a consideration of maximum bitrate the equipment is capable of. If there were not other things to consider it would just be a matter of a firmware upgrade to get the m2p to shoot 120fps.
I stick to my guns. Shoot for your intended use rather then maxing out the capability or your equipment. This is sound advice regardless of what fine point is drawn to argue.
If you have 100 ISO 1/30 shutter and 30FPS and your video is properly exposed then switching to 60 FPS would force you to use a shutter of 1/60 making your video under exposed. Especially in low light conditions using a lower frame rate will allow you to use a slower shutter and prevents the necessity for a higher ISO.
I’ve heard people say that you should shoot in the frame rate you intend to output in but I’ve never gotten an explanation for the technical difference between shooting in 30fps and shooting in 60fps and throwing out every other frame. Unless somebody can articulate what that difference is it seems those two are the same thing. However if you wanted to output your clip at 30 FPS and shoot in 60FPS you’d have to account for that when choosing tour frame rate. in that case you’d still need a shutter speed of 1/60 to get 180 degrees of motion blur. Having those extra frames just means you have more latitude in post to do some retiming if needed.