Originally posted by Parallax I'm not sure I understand the question. SR and AF don't have anything to do with each other. Can you describe the situation in detail?
I understand the question. I just don't know the answer.
Here's the scenerio: I have a Tamron AF 90mm f/2.8. I want to use a Tamron 2X teleconverter with it.
The combination of the lens and a TC gives me an AF lens, with focal length of 180mm, and f/5.6 max aperture.
But electrically, the TC is just a pass-thru. The camera sees the combo as a lens with 90mm focal length and the SR will act accordingly. The action of SR is not sufficient for a lens of 180mm focal length.
Since the camera already has the focal length data (even though incorrect), it does not allow me to enter the actual focal length (as when I use a manual lens).
If I block the electrical connections that transfer focal length data (assuming I figure out what pins to block), chances are I will also block the AF connections.
The question is how do I NOT block the AF connections, yet trick the camera into allowing me to enter the focal length of the lens.