Focusing Nikon PC-E lens
I'm using a new Nikkor 85mm PC-E lens on an old F4. While the lens is manual focus, the camera's AF sensor still works the same as when you have an AF lens on the body (set to manual focus). So I like using that as a double-check on my manual focusing especially in low light (the small green dot in the viewfinder tells you you're in focus).
However the manual for the lens says you cannot use the camera's AF detector when the lens is tilted or shifted. Clearly that applies to tilt, but I'm not sure why it would apply to shifting (assuming no tilt). In large format, I've never really had focus change on me when only using rise/fall. A modern, slightly long focal length lens like this Nikkor PC-E should have a flat enough field to avoid focus shift when shifting the lens, especially at apertures smaller than wide open.
My assumption is that this is simply a flaw in the lens manual, since these things are gerenally badly written, and vague. When I focus this lens, either before or after shifting, and check the camera's focus indicator either before or after shifting, there appears to be no change.
So what do people think? Is it just a bad sentence in the manual as I suspect?
I use the older 28 and 35 Nikon PC lenses and have noticed that they are hard to focus when shifted because the center of the focus screen starts to black out.
So, maybe it has something to do with a slightly lower light level, or, the angle of the light when it is striking the focus sensors?
I would think that longer lenses such as your 85 would have less of this issue. If the focus assist works, use it.
Thanks, I had not really thought about the light level, or angle. That could indeed be the issue, particularly if you're using maximum shift. And perhaps the manual is also referring to more recent and advanced AF cameras that have AF points closer to the adges of the frame, which would further compound these issues.