Many folks Know I have a Nikon D7100 (24mp) anyway this camera has built in a crop mode that in effect crops away 1/3 of the outer edge leaving 15mp's, this has a few uses - larger buffer size, faster frame rate, more files on mem card and smaller files on pc, it also changes the effective eqv fov size of a 300mm lens including the crop sensor crop, to a generous 600mm.
My quiry is this - when using this would it change the lens holding situation aka lens legnth vs shutter speed (I have no stabilisation on my lens) to eliminate shake when I want to get some prop blur from helicopters or piston planes, another words in theory with a 300mm on a crop = 450mm requiring a shutter speed of 1/400 - 1/500sec, but with the extra crop mode equaling 600mm eqv, does that mean it now requires 1/600sec min to stop shake?.
I wonder if the camera calculates the extra crop after pressing the shutter or should the extra crop be taken into account with a higher shutter speed from the get go?
Sorry if I havn't made sense - just dont know how else to explain it
Hi, Pag. The shutter speed rule of 1/FL is a very rough one, I mean VERY rough. You might guess this from the fact it just happens to coincide with the focal length of the lens. Other factors, like your ability to hold the lens steady, or supporting on a nearby pole, or lens weight, or your coffee consumption, all play a big role compared to this overly simple rule.
A crop factor of 1.3 (of the native image) is not very much.
So I would suggest to not worry too much about it and go out and shoot.
As far as propeller blur is concerned, whether you use the 1.3 crop mode or not makes no difference. For that matter, shooting in crop mode or in native mode and cropping later on the computer will give exactly the same result.