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

Started Jan 25, 2014 | Discussions thread
bobn2 Forum Pro • Posts: 54,217
Re: Wrong

JiminDenver wrote:

The only reason full frame delivers more light is because it delivers a larger scene.

Well, yes, but it depends what you mean by a 'larger scene'. It delivers a larger image with the same density of light (for the same f-number and shutter speed) so that is more light.

Put a 25mm on 4/3s instead of a 50mm and the 4/3s sensor will see the same light a full frame does at 50mm

No, not at the same f-number. a 25/1.4 on a Four Thirds sensor will deliver one quarter of the light to the sensor that a 50/1.4 does to a full-frame, because the density of the light is controlled by the f-number. Same f-number, same amount of light per unit area of the sensor. Four times larger area is four times more light.

AND it will require the same f stop to achieve the same shutter speed at a given ISO as the full frame does.

That is a circular argument, since ISO is defined by exposure. Same ISO, same exposure but four times as much light on the FF sensor, four times as many photons, twice the SNR. It's that simple.

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