Originally posted by Pål Jensen The lenses giving the same image (angle of view) will have different focal lenghts and different close focusing distances so it is not just a question of stopping down. If you are one of those (I'm not) who insist that the smaller format lens must display the exact same DOF wide open in order to compare them, the smaller formats lens will also have more apertures to choose from (as most lenses in reality display the same minimum aperture), display more maximum DOF and obviously closer minimum focusing distances.
Control over DOF means being able to control DOF over a range (or getting the DOF you want). A larger range give you larger control; it has nothing to do with absolute values except from the fact that enough DOF is an absolute, ie the image is unsucessful if not properly in focus, and the degree of out of focus is a relative and dependent on aestetics and taste. It has nothing to do with absolute thinness. If it had, a 8X10 large format camera would have had great control over DOF; in fact, it hasn't without tilt/shift movement. In fact, every large format photographer will tell you that control over DOF for him (or her) means more of it (ie more DOF).
That some want thinner DOF than what can be achieved with APS is fine by me but having more DOF than can be achieved with FF (at the same angle of view), eg near/far relationships, is also control over DOF and very much so.
Good April fool's joke, for a while I thought you were serious!
Oh. You were.
Ok, I feel like we've explained this so much already, but it just doesn't seem to take...
For the same FOV and aperture and distance to subject, the FF image will have 1.3 stops less DOF than aps-c.
Example:
50mm f/2.8 FF, 35mm f/2.8 aps-c, taken from same position You can stop the FF image down those 1.3 stops to match the aps-c shot if you wish, and you can't always go the other way with aps-c - until they make affordable, good 13mm f/1.8, 33mm 1.0, etc, etc lenses. This is what is meant by 'more DOF control', and it's not theoretical, it's very practical and you notice the capability and flexibility in the field right away.
Example - I wish I had an aps-c example of this at 35,mm f/1.8 to show you, but from this distance 35mm 1.8 on aps-c just doesn't 'float' the subject quite as much:
50mm @ f/1.8 FF == 34mm f/1.1 on aps-c
So to summarize - the FF shot can match the aps-c shot DOF - aps-c can't always go the other way. More DOF contol.
Now, aps-c has other advantages especially at telephoto when you take pixel density, size & cost in with the image-equivalency equation - but for most practical shooting situations and considering existing/possible lenses, FF gives you more DOF control.
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