I am currently using an AF 300/2.8 with a (mod'd ) TC-20E converter. Because of the degraded image quality by the 2x TC, I am willing to try my TC-16A with the 300mm. I could compensate the lost magnification by trying to get closer to my targets (birds). Now I'm having the following question to those of you more familiar with the TC-16A (like Mr. John Wall) and better mastering the optical formulae: If I drive the internal focusing elements of the TC-16A to one end (the front end?), will the AF 300/2.8 focus closer than it would without the TC-16A? You would imagine that the TC-16A forms a (very short) extension tube. So, my intention is to set the TC-16A to one end, put the body and the 300mm in MF and focus the 300mm manually as close as possible. Since I'm used to manual focus with the TC-20E, using the body in MF is no problem. Thanks, Ilkka