Hello William I'm not sure what the optical differences are, but I have The M* 4.0/300mm. It is an excellent lens and doesn't really need a tripod mount. It's quite small/compact (I guess that's what the M* stands for) for a 300mm lens. It's perfectly usable for hand held shooting with fast film/or in bright light. An old fashioned Pentax camera is supposed to be strong enough (metal bayonet) to hold the lens, while the camera is on a tripod. However I believe that some companies offer a tripod mount ring put on the lens, if you want one. Others might know more about this, but I think I remember seeing one in a magasine...
Best Regards, Jens - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
