I recently cut the aperture pin that protrudes out from the mount on one of my old k mount lens so I could change the f stop settings manually (like m42s) to use on K10. Am thinking of modifying all k's so can use like a manual lens in AV mode. Does that hurt the resale value of lens? Also have searched for some method to cut down focus screens from older cameras for DSLR use and no luck--any suggestions from anyone?