Nice lens with clean glass. Aperture is sluggish.

Glass is clean and clear of scratches, fungus, haze or separation. Focus is smooth. Please note aperture is sluggish on opening. However, if you're using this adapted it won't matter because when the pin is depressed, the aperture will both open and close using the aperture ring. If you use it on an actual M42 mount camera, the lens will probably take a while to open back up after an exposure.