Have had a Pen F for a long time now. Fortunately I have been able to add a selection of the lenses over the years. Some are quite rough though, thats what little money buys. Have a 150mm f4 for $15 with jammed focusing. Got it working after much much travail and a lot of muttering but its still not smooth near the last few degrees of focus travel. I now have a set of the 20 f3.5, 25 f4, 38 f1.8 and 100 f3.5 and also a 50-90 f3.5 zoom. The zoom is a nice lens but too large and heavy for everyday carry, I only use it if I cannot stand in the right place and need an angle of view between the 38 and 100. As noted, adapters for other lens mounts were available but can be well over $100 each now, if you can even find them. I have a OM and M42 (Pentax screw) and the OM was about $100 but amazingly I was the !high bidder on the M42 at only $35 so there are bargains out there. One caution about adapters. There are some clowns on eBay trying to sell 'T' mount adapters as M42 adapters so be careful, they are not near the same.