Originally posted by THoog On the A-series mount, only the aperture range is communicated, as a code via the row of contacts/insulators on the mount. The code indicates the largest and smallest apertures the lens is capable of. The camera sets the aperture by the number of steps it moves from the largest aperture (or smallest, I forget). It's all very 1980s technology. It wasn't until the F-series lenses that the "data" pin was added, which passes actual lens info in a digital stream. There are a handful of modern manual-focus lenses that have the data pin, but most A-series lenses, (especially vintage ones), aren't going to communicate focal length.
Thank you for the additional information. I'm thinking that with zooms, it might be easier to go with F-series and newer then (I think this corresponds with the first version of the KAF (and newer) mount as opposed to just the K mount?) just to have all the data available and not have to take notes as I'm terrible at notes. I'm kind of curious as to how it would work if I left the camera set at 3.5 as I zoomed out to where it has a 4.8 maximum aperture. Assuming the lens would only go to 4.8 but the camera would record it at 3.5? I've already packed it back up so I probably won't test this. Not to mention, I'm not sure how to determine what the lens actually did.
For primes, A series I think would be nice just so the data gets recorded in the EXIF, though I've had a little bit of fun trying to figure out how to work my M-50 and am looking forward to playing with it a bit more. I really need to get faster at focusing, but it'll hopefully come over time. I was skeptical on how much I'd use the all manual prime, but I rather enjoy it.