Some of these oldies will not meter without a CPU chip, because there might not be an aperture linkage. Or there is no aperture ring in the usual position at the very rear. Put a "G" CPU in any of these and as long as there is an aperture stop-down lever in the lens, it'll be a breeze to use. Even without direct mechanical linkage, i.e. a preset lens, a "G" chip will allow metering at the wide open aperture (to attain maximum accuracy), but you have to flick the preset ring immediately before shooting. Thus in the preset case, put the ring on the lens to the intended shooting aperture, flick it wide open. set camera to that aperture number, meter, then flick the ring to stop down the lens and shoot. You can work this procedure very quickly with some practice.Obviously, only "M" exposure mode will function as intended. If you insist on "A", it *is* possible even with preset or non-coupled lenses*, but then you might have to set an additional exposure correction as well and this is limited to max. 5 stops on most cameras.
* if you can do with reduced metering accuracy and a much dimmer finder, shooting in "A" mode with the lens already stopped down to the intended aperture makes for slightly faster action. However, now focusing might well be the critical limiting factor. This is essentially the situation with third-party lenses on a mirrorless camera, by the way. Doing away with aperture automation is a throwback to the '50s. The EVF sooner or later becomes a noise blur if the aperture is small enough.
