David Klepacki,
Unless you plan on traveling with your rear lens caps off, I can't see why what you describe could be a problem. Definitely one can see into the rear of the lens - same is true into the mirror box, and also true for every camera that has interchangeable lenses. I've traveled all around with my Rollei... death valley, yosemite, etc ... been caught in the rain, and not had problems, but I'm not foolish enough to open up my camera and change my lenses in a sandstorm, and I'll bet most readers of this forum are not either.
Dave,
Regarding the AF sensor size setting in the options setting of the camera that has three area sizes, I have only used the smallest area which is the default setting, and should experiment with the other settings. I too would like to know how much the area changes by.
The offset setting is used to calibrate the focus confirmation indicators in the display seen through the viewfinder. As it does not change the physical placing of the sensor, lens or focus screen I doubt that this setting can do anything other than change where the camera thinks the sensor is and thus where the focus indicators will show focus. It will affect all lenses not just AFD lenses. You mention infinity focus - this is something I've put a lot of time into - not being able to focus to infinity is either a function of the infinity stop on the lens not being set correctly or the spacing of the sensor/film plane not being set correctly. Contact me privately for more info.
btw - My AF 50/2.8 also shows firmware 1.13B and was purchased new just a few months ago.
Geoff,
That's a good tip on storing the lenses, and from my experience 'exercising' them is a good idea.
Eric