A reminder for some memebers as to what the F stop is all about.

Started Jan 26, 2014 | Discussions thread
Great Bustard Forum Pro • Posts: 43,009
Let's say...

gsergei wrote:

Someone in Dave Gaines' thread exclaimed:

"convince me, that an Olympus 25mm F/2.8 produces the same light" as a FF lens at F/2.8"

then someone referred to a "guru" , saying" that bigger sensor "gathers" (I totally hate this) more light. This statements prompted me for my essay. That's all. Then the topic was highjacked by other people. I wasn't going to cut circles ad infinitum about DOF and FOV, which topics have already been beaten up to death.

...we take a pic of the same scene from the same position with the same shutter speed at 25mm f/2.8 on 4/3 and 50mm f/2.8 on FF. Then the amount of light per area falling on each sensor is the same (same exposure), but 4x (two stops more) light will fall on the FF sensor, resulting in half the noise for equally efficient sensors and half the DOF (this is the connection between DOF and noise that some did not understand).

best wishes.

Indeed!

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