Hi; I think you somewhat answered one of your own questions. The faster lens is great IF you need the extra speed. If you don't you can save a lot of money. You may want to look for an "A" lens in manual focus as I think, but am not sure, that the MZ-5 loses a number of metering functions without the "A" lens. However, the F* and FA* 300/4.5 have been both getting raves on the list for being superior optics, and at least here in the States the cost of a M 300/4.0 and an F* 300/4.5 (used) seem to be similar. You would then have the advantage of all the metering options and autofocus.
BUTCH "Each man had only one genuine vocation - to find the way to himself" Hermann Hesse (Demian)
