Comparing Olympus 4/3lenses to FX "Full Frame" offerings

Started Jan 25, 2014 | Discussions thread
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seho Contributing Member • Posts: 905
Re: remaining "ignorant"

Ian Stuart Forsyth wrote:

Exactly physics, the 50mm F2.8 has a larger front element than the smaller 25mm F2.8 front element now are you going to try and convince me that the same amount of light will pass thru the smaller 25mm F2.8 as a 50mm F2.8. Has the 25mm F2.8 have some special power that allows it to suck more light thru its smaller opening.

You're correct, kinda sorta, but for any significant reason. Which is a good thing, otherwise figuring exposure with a handheld light meter would be enormously more complicated than it is in practice; we don't have to make significant changes for proper exposure for every single different lens you might be using.

The intensity of the light hitting the sensor/film will be the same for both lenses at the same f-stop (modulo whatever slight differences there might be in transmission losses depending on the number/composition of lens elements).

Equivalency rants would be even less interesting and useful than they already are if it weren't that effective depth of field between different formats wasn't obviously visible.

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