Originally Posted by dcstep
Wow, no wonder that lens gets such mixed reviews.
Unfortunately, I think you're limited to one adjustment for each lens/extender combination. For a zoom you'll need to chose a compromise. In this case, I'd suggest adjusting for the long in, where you'll have the least DOF. Then, when you use the short end of the lens you'll need to stop down much more, or MF. Instead of doing +11 at 400, you might do +8, but remember that focus is real critical out at 400mm and wide open.
Thanks for the tips, Dave. I just re-ran the program in much better lighting. I have to say, I'm much more pleased by the results. It indicated a -2 adjustment for both 100mm and 400mm. A few test shots confirms this adjustment. Images are much sharper, even when shooting handheld, indoors, at 2000 iso. I'm going to do some more testing before tomorrow, but as of now, I'm very pleased with the images.
I think this lens is really dependent on ideal lighting conditions. This may also contribute to the mixed reviews. I'm struggling a bit with the slower performance due to the variable aperture.