Effective Aperture

Started Nov 6, 2012 | Discussions thread
speed12 Junior Member • Posts: 26
Re: Effective Aperture

The aperture f number is just a ratio of the diameter of the opening into the lens by the focal length of the lens. Therefore f2.8 is f2.8 is f2.8 no matter what lens you are using. So in that fact they are wrong.

However, m4/3 cameras due to their 1/2(ish) FF size sensor have, for a given aperture size, a depth of field equivalent to twice the aperture ratio of an FF camera. So in terms of depth of field, an f2.8 m4/3 lens will give the same depth of field as an f5.6 FF lens at the same focal length. So in this they are correct.

In terms of the amount of light hitting an m4/3 sensor through an f2.8 aperture compared to the light hitting an FF sensor through an f2.8 aperture, this again is the same for both cameras.

It is purely the depth of field that is affected.

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