Thanks.
Quick question on the older lenses. I remember reading that some of the lenses from the 35mm film cameras could not be used on the DX sensor cameras, due to the glass movement inside the lens. Something about the lens glass hitting the sensor.
Aside from a few exotic fisheye lenses, which could only be used on cameras which allowed the mirror to be locked up; I think this issue only applies to certain rare lenses that Nikon made for a short-lived line of APS-based SLRs back in the age of film, during that very brief period when anyone thought that APS might ever become a viable alternative to the standard 35mm film format. I believe that some of these lenses did indeed have elements that intruded far enough into the camera body that they could not safely be used on 35mm bodies because the rear elements would be in the path of the mirror.
Certainly no such issue exists mounting any normal 35mm camera or “FX-format” lenses on a DX-format camera, and I don't think Nikon has made any lenses intended for use on any digital cameras that have any such issue. The only issue of compatibility regarding DX vs. FX lenses is that while a DX lens will mount and function on an FX body, it cannot be counted on to fully cover the FX frame, resulting in vignetting and cropping.
It looks to me, if I am correctly understanding what I'm reading in the relevant Wikipedia article, like your F80 uses CPU lenses, and will freely share lenses with any Nikon DSLR body that has a built-in focus motor, such as the D7100. Lower DSLR models, such as the D5?00 and D3?00 series will also share lenses with the F80, but will only autofocus with AF-I and AF-S lenses that have built-in motors; lenses that are fully compatible with the D3?00 and D5?00 models should also be fully compatible with the F80, aside from the above mentioned DX/FX issue which will also apply to the D7?00 models. Buy only AF-I or AF-S FX lenses,and you should be happy using them on your F80 and on whatever DSLR you end up getting.
Your older FG takes non-CPU AI lenses. If you've tried using the lens from it on your F80, then you know what to expect using that same lens on a DSLR; you'll be able to use it manually, but don't expect any metering auto exposure, or autofocus.
I believe some of the higher DSLR models do support the mechanical AI aperture coupling, and can therefore meter and possibly do autoexposure with your old lens from your FG, but I am unclear as to which models this applies to.
You'll want to avoid G-series lenses if you hope to use them on the FG, as these have no manual aperture ring which would limit their usability on the FG.
I should disclaim that nearly all fo what I've written here is a combination of educated guessing and minor research via the Wikipedia. Others may have more solid experience, and be able to correct errors in what I have written.
Not that it's relevant to you, but just because it is something that I can say from solid experience rather an educated guesses and research, I am going to throw in that contrary to what Nikon states on its web site and in the user manual for the D3200, old non-AI lenses (those made before 1977) can, in fact, be used just fine on the D3200, albeit with the obvious limitations of no autofocus, no exposure metering, and no automatic exposure. I have three such lenses, that go with my 1972-vintage F2, and have used all of them on my D3200. I'm given to understand that there are some Nikon bodies that can be damaged by mounting non-AI lenses on them, but I am unclear as to how this happens, or which bodies are thus vulnerable. I gather it has something to do with the mechanical AI aperture ring coupling, with which I am entirely unfamiliar. My D3200 doesn't have any mechanical aperture ring coupling, and my F2 uses a completely different coupling mechanism which the AI method replaced. I've never had occasion to examine a Nikon that uses the AI coupling to see how it works, or what, on it, might conflict with anything on a non-AI lens.
