Focal length 35mm equivalent, but not F-stop?

Started Jul 24, 2014 | Discussions thread
Beachcomber Joe
Beachcomber Joe Senior Member • Posts: 1,256
Re: Focal length 35mm equivalent, but not F-stop?

Chikoo wrote:

Beachcomber Joe wrote:

Chikoo wrote:

If my angle of view changes, so does my exposure.

Your camera's meter may suggest a different exposure because it sees more light or dark areas. The actual exposure required does not change. You need to take a very basic class on exposure. Clearly reading the technobabble spewed forth on these forums has left you confused.

Probably so.

However consider that I was photographing 100 light bulbs of 10w with 160 lumens output each when I was using a 35mm lens on a FF camera.

Now if I switch to a APS-C (1.5x crop) camera with the 35mm lens at the same distance, same focal length, the number of light bulbs in my frame would decrease, which means the light coming in will also decrease.

Yes, no?

The total light will decrease but not the light per square mm of area.  Since the amount of light falling on a specific area of the sensor remains the same the exposure remains the same.  A lot of the technobabble you read hear is about total light.  Total light can be ignored.  What matters from a photographic standpoint is the amount of light per square mm hitting the sensor.

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