Comparing Full Frame to APS-C DOF/Separation test

I have come to the conclusion that a modern Full Frame camera doesn’t hold as many advantages over APS-C as they used to. You can read more about that here:

Why Full Frame cameras are becoming redundant (for most)

One reason I do think is perhaps valid for some people is the shallower Depth of Field (DOF) that Full Frame will give you.  However how MUCH of a difference is there really and is it worth someone going Full Frame? I’ll tell you, for me I don’t feel the difference (in real world shooting, not just side by tests) is enough.  However, I have put together this very, very quick test using my son to see the difference between the Canon 1DsIII (a 35mm sensor camera) and the Fuji Xpro2 (an APS-C camera).

I am comparing two of the best 35mm equivalent lenses out there (that don’t cost an arm and a leg), both of which are a similar price.  On the 35mm (Full Frame) camera I am shooting with a Sigma 35 1.4 Art and on the X-Pro2 I’m using the 23mm 1.4.

The purpose of this comparison is to give myself and whoever stumbles across this a sample of the DOF difference you’ll experience going from FF to Fuji or vice versa.

NOTE: DOF is different to bokeh.  Bokeh is the quality of the background blur.  DOF is how much of the subject is in focus.   Bokeh between lenses will differ, so this isn’t really a bokeh test.  However, I’d like to compare the difference in DOF in real life between a 35mm sensor and the Fuji APS-C sensor, and for myself, see if it’s worth keeping my 1DsIII for occasional use.


Here’s the comparison.

Two compared. I did the same settings despite fuji using a slightly different ISO standard. Matched Histograms the best I could

Two compared. I did the same settings despite fuji using a slightly different ISO standard. Matched Histograms the best I could.

At first glance these photos look quite similar. I prefer the 1DsIII one personally because I like my son without forehead distortion (lens or angle problem, nothing to do with the sensor). With closer inspection I can definitely see a difference in the DOF/background blur.   Subject separation looks quite similar though.  The Fuji 23mm seems to have a bit more distortion, that could be the angle, again this isn’t the most scientific of tests. Distortion tests are best done on a tripod etc.

In real life, people are NOT going to look at your shot shot a f/1.4 and say “Oh that’s full frame” or “Oh it’s a pity it wasn’t shot of full frame” (unless you tell them you’re using APS-C and they’re trolling) they just won’t be able to tell without looking side by side.  Is there enough of a difference for you?  Well that’s up to you isn’t it. 🙂

Background Blur

Background blur comparison.

Background blur comparison.

There’s definitely more blurring with the 1DsIII.  Whether this difference is enough to warrant a 35mm camera I don’t know.


Details and falloff

Details and falloff

Details and falloff


Details is an interesting comparison.  The 1DsIII has 22MP and the Xpro2 has 24MP.  So the xpro will have more details on the whole.  A 36MP+ 35mm sensor will of course have a lot more resolution too, so if having the most resolution is important a 35mm sensor can be the best bet.

The 1DsIII seems to have a tad more skin details in there, but if you look at the iris, the blacks on the 1DsIII look quite blotchy.

So I boosted the shadows on the Xpro2 a bit to see if it would have the same problem:

shadow details

Seems the Full frame sensor maintains more details.  Is this my focus being slightly off, the lens or the sensor?

Hopefully it’s noticeable on the web as it is on photoshop.  But the Xpro2 seems to fall off more naturally in the blacks.  This may be a fault of the 1DsIII sensor, not the fault of the sensor size.   I just found this interesting.


NOTE: I’ve since determined this sharpness issue is more of a lens issue.  The Fuji 23mm 1.4 is slightly soft at 1.4 and the Sigma 35 1.4 is incredibly sharp at 1.4.

See this article: http://www.aevansphoto.com/23mm-1-4-soft-wide-open/


Falloff is smooth on both cameras/sensors, but the 35mm (Full Frame) sensor has a quicker fall off obviously, the ear is slightly blurrier.



This test IS NOT very scientific, I didn’t use a tripod, I just set the cameras at the same settings and used lenses that give a 35mm FOV.

It shows that there is some difference in DOF between a 35mm format sensor (called “Full Frame” by many) and a APS-C sensor (x1.5 crop factor of the full frame sensor).  Is it enough to warrant keeping the Full Frame camera?  Well, time will tell.  I still want to do detail tests using a tripod etc.

I’ll leave it up to the reader to judge if the difference in DOF/Blur is enough for them to warrant buying a Full Frame camera or not.