The Recent F/stop Controversy

Started 1 month ago | Discussions thread
Pixel Pooper Veteran Member • Posts: 3,117
Re: Really?
  • Michael Fryd wrote:

Actually, at the same angle of view the "equivalent aperture" is the one with the same diameter. In other words it really is the same aperture; no math needed.

You only need to do the math if you normalize everything to light per unit area (which is a great idea when shooting film).

Whether you are shooting film or digital makes no difference. The reason we use the f/stop is that it gives us the same exposure regardless of focal length or angle of view. If we used aperture diameter it would be more complicated because we would need to change the diameter every time we changed our focal length.

While shooting I am much more likely to change my field of view than my sensor size and if I do change my sensor size it is to take advantage of the differences between the two formats, not to take the same picture on both.

The fact that the same aperture diameter gives the same total light at the same field of view is good to know, but it's not as useful when taking pictures. Whatever format you use, the way to maximize total light is to maximize exposure and your total light is limited by the need to avoid overexposure.

Equivalence is a way of comparing formats, and it is a great framework to understand how things work, but it is not a replacement for f/stops and exposure.

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