I previously wrote: >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. Now I did some experiments with my AF 300/2.8 and the TC-16A. It was not scientific; I was moving my tripod on the floor and couldn't make accurate measurements. I was wrong, the elements of the TC-16A have to be on the back end (closer to the film plane) for maximum extension and thus shortest minimum focusing distance (MFD). Having the elements of the TC-16A at the front end made no difference to the MFD of my 300mm. Placing the elements of the TC-16A at the back end (by turning the AF shaft with a screw driver) the MFD was reduced by 20 to 25 cm. This is not a big change, but you get it if you use the TC-16A anyway for the magnification. And it can be useful in those cases when I'm literally against the wall. As a comparison, my 12 mm extension tube reduced the MFD of the AF 300/2.8 by ca. 1 m. Regards, Ilkka Fascinating possibility! The TC does add extension. The 300 mm f 2.8 is compatible with the TC 16A according to Nikon so you are ok in that regard. It will focus to 8.5 feet. You will have the effect of closer focusing in any case because the TC 16A will magnify the center of the lens image by 1.6 times. I wish I had a 300 mm f 2.8 to experiment with but my pockets aren't deep enough to add this piece of gear. Try it and let us know what happens. Best, John Wall
