I have a 2.8 E and a 3.5 F, both with the Schneider Xenotar lens, which is the same design as the Planar, but made by Schneider. I like the image quality of the 3.5 better, but don't ask me to describe the difference. The F is lighter and at 75mm, 5mm shorter (wider), in addition to the half a stop difference in aperture. The most recent F Planars are multicoated, but I don't miss it. If you have to get it overhauled anyway, or if it is in good shape, then you can go back to the 1950's, the C, D or E, and get a great camera. In my way of thinking you can't go wrong, so long as you're willing to get it fixed up. Tom Perkins