Sensor size affect on effective aperture

Started Sep 7, 2011 | Discussions thread
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dsjtecserv Veteran Member • Posts: 3,151
Re: Sensor size affect on effective aperture

Everlast66 wrote:

Many thanks for the replies guys, much appreciated!

The reason I thought a smaller sensor would be getting narrower effective aperture is because the smaller sensor (DX) would not be collecting all the light that an FX seonsor would collect with a lens designed for a full frame, obviously due to the smaller size of the sensor. We would not be benefitting from the full opening of the lens, as if we had a smaller opening and that made me assume that we would be getting smaller efective aperture.

You are mixing up total light with light intensity . The f/number (not the absolute size of the aperture) regulates the intensity of the light, which is the light per unit of area. If the f/ number is the same, the light intensity per unit area is the same, regardless of the size of the sensor. But the total amount of light falling on the sensor is greater the larger the sensor, simply because it has more area.

Dave

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