I recently bought VIVITAR 100-300mm F5.6-6.7 macro zoom. I use it with Nikon D70S. Here is my problem. When distance between my D70S with VIVITAR and object of photography is 15meters and more, I can not focus on this object of photography. I am in manual mode and in manual focus. Focus is set on infinity - everything less than infinity is more, out of focus. I attach photo of roof, 31meters away from D70S (1/40s, f14, 300mm).
Do you know, what it is going on?
Thank you for answer.
Answer is assuming that a) lens is not adapted, b) camera is in calibration, c) lens isn't so heavy that it warps the lens mount elastically.
This looks like the infinity stop on that lens is simply out of alignment.
Professional repair is likely uneconomical here.
You can attempt to fix that yourself. How to do that is lens dependent, and zoom lenses are absolutely not good starter lenses to learn that on, especially if a service manual is not available (see my comment on vivitar serial numbers).
Typical ways to align infinity on lenses are a) mechanical pegs that can be shifted after loosening a screw, or b) focus rings with an integral end stop that can be loosened and readjusted after loosening a screw, or c) shims that will need to be added or, in your case, much more likely removed. The trouble with zoom lenses is that there is not unlikely to be a combination of either a) or b), and multiple places with c) - all interdependent, and needing to be aligned in concert. Setting things to the wrong balance can compromise image quality in some cases.
Most of the users here that have some experience with lens repair would likely consider it a write-off without a service manual.
If the focus range is off because something got misaligned that is not even intended to define the focusing range, that is worse news.
Other options: Return, discard, use as a closeup/portrait only lens, pass on to someone willing to try and fix it, pass on to a mirrorless user who might in some cases be able to use it with a slightly short adapter (as many are).
Many large zooms focus past infinity, you may need to focus back.
Secondly, this may not be a sharp lens at f14, try rolling back to f8.
Thirdly, 1/40 second is not going to help. Take a test show nearer 1/500-1/1000 of a second and report back.
