f stop and crop sensors

Started May 11, 2010 | Discussions thread
Barrie Davis
Barrie Davis Forum Pro • Posts: 21,460
Re: f stop and crop sensors

SilverbirdFLG wrote:

Not that I would ever trust a wiki article, but here is a direct quote from the very article you recommend:

"At the same f-number and subject distance, the same lens provides the same DOF in the original image for all formats. If original images from two different formats are given the same enlargement, both formats have the same DOF. The final images will, of course, have different sizes."

Sorry, but sensor size does not affect aperture.

  • That's right. The size of the sensor does NOT alter the size of the aperture... and, for exposure purposes , f/8 remains f/8 whatever size of lens/sensor/camera is in use.

  • But for Depth of Field purposes , the same aperture number does NOT have the same effect on all formats. Smaller sensors exhibit more Depth of Field when Field of View and final image sizes are matched. As an example, the gain in DoF between Full Frame and APS is close to one stop's worth.... f/8 on APS being DoF equivelant to f/11 on Full Frame.

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Regards,
Baz

Well, I'll see your Cher, and your Streisand... and I'll raise you an Alice Babs!

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