I was thinking of much more than a passive ‘extension tube’ FD to RF lens adapter.
It’s all predicated on the RF lens/body electrical contact interfaces and their capabilities, which I have no knowledge of. My thoughts might not be possible to implement.
The Canon FD lens mount has 4 mechanical interfaces when mounted to a compatible camera body:
If all these features can be incorporated into a ‘smart’ FD to RF lens adapter, that would make a world of difference when using existing vintage Canon FD lenses.
- A cylindrical ‘boss’ pin which indicates the lens’ maximum aperture and compensates for the small difference between a f-stop and T-stop.
- A ‘tab’ lever which moves in a semi-circular ‘race’ which follows the lens’ aperture selection ring. This moves a small ‘circle’ in the camera viewfinder for ‘match needle’ light metering. (On old mechanical FD lens cameras.) This tab lever could be coupled to a mechanical encoder followed by an analog-to-digital converter to transmit the lens’ aperture setting back to the camera.
- A very small pin which pops up when the lens’ aperture ring is moved past its minimum (smallest) setting by depressing a button on the ring to either a green circle (old) or green ‘A’ (new) index. This was used on the ‘electronic’ FD mount cameras (AE-1 etc.) to allow shutter-priority Automatic Exposure. More on this in (4)
- A much larger tab lever which stops the lens down to its selected aperture when the camera shutter button is pressed. This allows both focusing and light metering with the lens wide open (how quaint!) An electromechanical solenoid could be incorporated into the FD/RF adapter to provide the same function. For shutter priority AE, the position of the stop down lever at shutter release needs to follow what the camera decides is the correct exposure aperture.
Lens correction profiles for vintage Canon FD lenses – a whole different topic!!!
Oh I see. Sorry about that. There'd be no way for any sort of communication with the lens itself. I guess it could be done with the adapter if you could select the lens and the adapter would do the work. There is a company that makes lens adapters that turn manual focus lenses into autofocus. I don't know off the top of my head if they do FD.
Upvote
0