Is a 50mm on my APS-C camera an 80mm for a DoF calculator?

Created by brainwins on Oct. 14, 2013, 5:53 p.m.
  • Hi,

    I'm using a DoF calculator on my phone to quickly find out the focus distance on my 50mm prime lens.

    My camera is a Rebel XT, and as far as I understand, I don't see the same as someone with a full frame camera with the same lens. For DoF effects, what value should I enter?

    Thanks!

  • I Believe it still works out to 50mm On the DOF calculator cause your cropping the 50MM so that depth of field should work off that original calculation. But I could be wrong.

  • Still in the learning phase myself, but found a site that I stumbled upon before that agrees. It should emulate a 80mm depth of focus.

  • @Anominal:  yeah i am not sure if i would call the calculator on that page correct. I would call that more of a lens equiliant calculator. Since a DOF calculator should include a distance field. then an output of closest point of focus, from det distance. farthest point of focus, and hyperfocal point (though some lenses don't posses hyperfocal points in trade for closer focusing distances)
  • @Anominal: @TsunamiJuan: That's a great site with awesome info, thanks. It's not a DoF calculator, but it seems that in one, I should enter 80mm if I'm used a cropped sensor and a 50mm lens.

  • A 50mm lens will give you the same depth of field regardless of the sensor size. The lens is still projecting the same image, the sensor is just capturing a smaller amount of it.

  • There's a subtlety here, which is that by comparing images taken with APS-C vs full frame with the same lens, the APS-C camera will have to be farther away to get the same image. This increased distance to the subject will increase the DOF around the subject. This applies if you're trying to frame the same image with both APS-C and full frame.


  • Sorry I missed this thread.

    I think this site sums it up pretty well.

    http://www.bobatkins.com/photography/technical/digitaldof.html

    • If you use the same lens on a Canon APS-C crop sensor camera and a 35mm full frame body and crop the full frame 35mm image to give the same view as the APS-C crop image, the depth of field is IDENTICAL

    • If you use the same lens on a Canon APS-C crop sensor camera and a 35mm full frame body, then shoot from different distances so that the view is the same, the Canon APS-C crop sensor camera image will have 1.6x MORE DOF then the full frame image.