>>3247786>Depth of Field is constant for a given subject magnification and f-stop, so if the subject size in the frame is the same, the DOF will depend entirely on f-stop.Thanks for your reply. That makes sense.
>The 1.2 lens will give more background blur.I'm interested in how to compare the effect of focal length on background separation, in conjunction with the depth of field achievable from the f-stop alone. In portraiture use, if I understand correctly, the 90mm can compress the background more than the 56mm lens can at the same f-stop, for the same subject framing, by virtue of the focal length alone. So while f/2 is two stops slower than f/1.2, the subject is separated from the background in this other way, which interacts with the depth of field while not being the exact same kind of effect. Maybe illustrated in an exaggerated way by the difference between these two images.
