Thanks for the info, I think it was the design of the lens that was throwing me. The lens has kinda like a hood over the front element and as you adjust distance the inner barrel moves in and out of the outer. I was trying 52,55, and 58 on the outer barrel, no luck. I got rid of all my 49mm stuff but found an old Pentax cap, uv filter, rubber lens hood and metal lens hood in 49mm and by putting the uv on the inner barrel protrudes out enough to use the lens cap