DOF with FF sensors

[HW]

my question is do FF sensors have a shallower DOF than crop sensors? as in a D4 with a 70-200 f 2.8 and a d3200 with the same lens both at the same fstop would the d3200 have more in focus than the D4 using the same focal length, distance etc?
here is a shot taken with the 70-200 at f 6.3 on the d4 at about 6ft away at a focal length of 175 mm. focus was right on the face between the eyes

 

[Tim]

Good question. ; Glad you posted it.

Roger...? ;

 

[mSummers]

That is a great question. The answer that's always made the most sense to me is that depth of field is a product of the focal length of the lens, the aperture and the distance from the film plane to the subject. So, since crop sensor field of view is narrower, the subject has to be farther away than it would on a full frame sensor at any given focal length, which makes the depth of field appear shallower on crop sensor cameras. ; However, I've read so many answers to that question, I'm not sure if that's the correct answer or not.

 

[Roger]

my question is do FF sensors have a shallower DOF than crop sensors? as in a D4 with a 70-200 f 2.8 and a d3200 with the same lens both at the same fstop would the d3200 have more in focus than the D4 using the same focal length, distance etc?

With that exact scenario, NO

Crop sensor means exactly that. ; It's a crop of a larger sensor. ; However, imagine the same picture but crop out the body. ; You wouldn't be using the exact same focal length in that situation. ; You would use less zoom leading to....more in focus.

Which is why it seems that crop cameras have less DOF than FF.

 

[HW]

I have read more on this and there is a lot of different opinions. yes DOF is mostly a factor of focal length and aperture and distance to subject.
What I am seeing is the FF sensors have a shallower DOF than crop sensors. I read where Med Format have real shallow DOF.
then again this may all be in my head ;
have only used a FF a few times but it always seems that I have to stop down way more to get more DOF than I do with a DX body
thanks anyways guys. not that big of a deal as FF is not in my immediate future anyway. D600 is a no for me

 

[ExploringWDW]

Do a search for dof "calculator". This is the first result on google: http://www.dofmaster.com/dofjs.html The first parameter is camera type. All other variables the same, switching camera types, (sensor sizes) a smaller sensor equals a narrower dof. But, as Roger said, when you go from dx to fx you need to multiply the focal length by 1.5 to get the same composition. When you take that into account, the smaller sensor equals a wider dof.

Fun question. Just wish I didn't start looking into it at 10PM. If you really want to make your head spin, browse around the rest of that web site I linked to. Whew. I'm going to bed now... ;