DOF full frame vs. crop sensor

Hi,


Been wondering much difference in DOF is there between a FF body like say 5Dmkii [ which I use now] and a 1.6 crop body?


Of course lens used for comparison will be the same.


Any "scientific" way on how I can manually compute for DOF?


thanks..

For the same framing, DoF will be 1.6x shallower on FF (at same focal length and f/number). That

FOR THE SAME FRAMING


but for the same DISTANCE FROM THE SUBJECT is the DOF not the same for FF and CROP


(also is there not a factor for the lens to sensor distance)

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Originally Posted by iND

but for the same DISTANCE FROM THE SUBJECT is the DOF not the same for FF and CROP

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No it's not


In the chart John provided you can test these yoruself


The only correlation I see is that if you have a 100mm lens on the 7D and 5D II, and you are 100' away from the subject with the 5D II and 160' from the subject with the 7D, the DOF difference between the two is the 7D is 1.6.


This ratio doesn't really work very well for other scenarios, say a 7D at 100mm and the 5D II at 160mm, both have the same framing but the DOF doesn't match the 1.6 crop.


If your at the same distance, with the same lens your DOF is significantly diffrent from the 7D and the 5D II. The ratio isn't 1.6 on it either.

DOF is a hard one to quantify as it really is subjective. What you consider effective out of focus blur might be different to somebody else.


From real world experience - going from a crop body to a 5D Mark II, the difference is very significant.

so would be easier to achieve OOF blur on a FF or crop sensor body?? with same lens of course....

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Originally Posted by jks_photo

so would be easier to achieve OOF blur on a FF or crop sensor body?? with same lens of course....

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To put it simply, FF gives more OOF blur.

Quote:

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Originally Posted by btaylor

DOF is a hard one to quantify as it really is subjective. What you consider effective out of focus blur might be different to somebody else.

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Isn't DOF just a distance? Like, "4 inches", with a given COC. How is that hard to quantify or subjective? (Though I agree, the question of what is effective is subjective).

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Originally Posted by neuroanatomist

To put it simply, FF gives more OOF blur.

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That sure was simple :)

Though it might seem obvious, I'd like to mention that the OOF blur is the same when DOF is the same. If you stop down with your crop camera, you'll get no DOF advantage shooting full frame (you'll just stop down more).