davesrose wrote in post #18518824
I don't have personal experience with this lens....it has good reviews on B&H. It looks to be a fully manual lens: there are no contacts for a camera to be able to AF or select aperture (or tell the camera what aperture you've selected to meter while open). You'd have to use the aperture ring to select an aperture....stop down the aperture to see DOF and meter at that aperture.
It gets harder to see through the viewfinder, though, if you have a really small aperture with a small amount of light coming through. Edit: from what I can find....you may not have to stop down meter with Nikon: the Nikon mount has indicators like an old manual Nikon lens. You first setup the lens in the menu by select non-cpu lens, and assign the focal length and max aperture.
Beware, that a manual controlled lens like the Tamron 90mm/2.8 Adaptall may well result in Metering ERROR when used on the Canon dSLR. In the past I have documented error varying by lens, when doing stopped-down metering on Canon dSLRs. I have no experience with Nikon to know if it is prone to such error or not.
One can observe any non-linearity in metering as one stops down the lens while pointed at a uniformly lit wall...every f/stop change by -1EV should be accompanied by a +1EV change in the necessary shutter speed to maintain a fixed density in the resulting shot...any departure from the [-1EV:+1EV] or [+1EV:-1EV] correlation is a flag for metering error when stopped down!
The Adaptall mount is indeed not specific to a brand, but the Adaptall mount ordinarily uses appropriate linkages for use on one brand's lens mechanical linkages like the AI and AIS for Nikon film camera with meters; a Nikon dSLR uses electronic linkages for its dSLR lenses. Ordinarily lens mount adapters now contain electronic chips linked via electronic contacts, that allows the lens to identify its FL and its wide-open aperture, and that permit AF confirmation signals in the viewfinder. So on the used market there can be found some Adaptall mount adapters with chips and contacts for some brands...I have one for my Canon dSLR since it is the same as for the film EF mount lenses.
But, for certain, the Adaptall lens will behave as a 'manual diaphram' aperture control lens...it will always be at the set f/stop, and open fully when the aperture selection ring is set to the largest setting.