Sigma 18-35mm f/1.8 FX equivalent

Started 9 months ago | Discussions thread
MediaArchivist Veteran Member • Posts: 5,474

SushiEater wrote:

MediaArchivist wrote:

SushiEater wrote:

MediaArchivist wrote:

Not is, but is like. On a crop sensor, f/1.8 is like f/2.8 on a FF sensor. It has to do with both DoF and light gathering capability.


Wrong. I mean right. I mean "wrong" is wrong, thus in fact right.

F1.8 lens gathers over a stop more light than F2.8

All things being equal, of course. But... all things are not equal if the total area of the sensor gathering the light are not equal (or the focal length is not equal, or other things are not equal).

Get a FF and put any F2.8 lens on it. Set the exposure like aperture at F2.8 ISO, shutter speed so the exposure is right. Now take crop camera and do the same thing with F1.8 lens on it. You will notice that at the same ISO, F1.8 your shutter speed will be 2x higher.

Now do the same, but include SNR on your list of things you are matching (or trying to).

Case closed.


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