Bought this cute little lens from fengwei and a Pentax K to EOS adaptor from Tagotech. Mounted the lens but could not work as the aperture lever protuding out from the back of the lens got block and aperture could not stop down. Tried removing the lever, but 2 of the 5 screws attaching the mount got stuck and refused to unwind. Tried cutting the lever, but my plyer went blunt. Anyway, remounted the lens to my 40D, then suddenly it works. My first shot of a beautiful Ixora at wide open. Love it and now enjoying the lens. Thanks fengwei.