Hey all.
So I was play around with my DFA 100/2.8 WR when I noticed something rather odd - it would change its focus depending on what aperture I set it to. Note that this isn't a case of the point of focus changing upon stopping down while taking a photo, but just what the setting was - the lens hadn't stopped down at all at this point.
For example, I had it on my tripod pointing at a focus chart (point where there was only one line it could focus on), and set the camera to Av. I have a split screen installed so I could watch for any shifts (in addition to hearing it
). At 2.8 to 4, it remained constant, then at f5.6, it refocused (and was subsequently slightly off). The same happened again at f7.1
Anybody know what this problem is, and any way I can fix it? :/