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depth of field question

jkdlee
Posted 07/01/2014 - 22:56 Link
Hey guys, a question just popped up in my head. Probably a silly one but..

If i took a 50mm prime lens designed for cropped sensor and a 50mm prime lens for full frame. And then take the same picture at f1.8 using both lenses on a crop sensor dslr. Will i get roughly the same amount of depth of field???
just a newbie with a good eye
Edited by jkdlee: 07/01/2014 - 22:58
johnriley
Posted 07/01/2014 - 23:42 Link
Yes and no. A 50mm lens is a 50mm lens regardless of what you put behind it, so the DOF doesn't change.

However, on APS-C you are getting the same depth of field with a moderate telephoto lens as you would with a standard lens on FF. The APS-C camera therefore delivers more DOF.

Looked at in reverse, to get a standard view on FF you use your 50mm lens. But for APS-C you use a 35mm lens and therefore APS-C delivers more DOF.

Bigger formats give less DOF, the smaller the format goes you get more DOF.

At the extreme, a Minox "spy camera" uses a 15mm lens to give the field of view of a 50mm on FF. We know 15mm lenses have immense DOF, so the Minox can be fixed focus and give DOF from about 9" to infinity at open aperture.
Best regards, John
pentaxian450
Posted 08/01/2014 - 00:10 Link
A 50mm 1.8 lens designed for full frame and a 50mm 1.8 lens designed for APS-C sensor would give exactly the same DOF if both are used on an APS-C camera.
Yves (another one of those crazy Canucks)
sterretje
Posted 08/01/2014 - 00:27 Link
As said, you will get exactly the same DOF.
Pentax K10D + Vivitar 55/2.8 macro + Super Takumar 55/1.8 + SuperMultiCoated Takumar 85/1.8 + SuperMultiCoated Takumar 135/3.5 + SuperMultiCoated Takumar 200/4 + Super Takumar 300/4
Pentax K100D + DA18-55ALII + DA55-300
Pentax K5 + FA31Ltd + M50/1.7 + DFA100WR + M120/2.8 (+ DA18-55WR at occasion)
jkdlee
Posted 08/01/2014 - 01:16 Link
thanks! i appreciate the replies
just a newbie with a good eye

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