Originally posted by elliott Same reason many M42 lenses said "Auto", automatic diaphragm, not necessarily automatic exposure. The aperture would stay open until you release the shutter, making focusing easier.
Thanks. That one never sticks in my head.
Originally posted by ieabu My Image 28mm looks just like yours, with 49mm filter size, and I would definitely quarrel with anyone who calls it horrible. It has lovely colours, smooth bokeh, low CA, soft but useable at f2.8, very sharp at f8, needs a hood to reduce flare, and it has auto aperture, which is a nice feature. All in all, well worth the $35 I paid for it.
Sell your lens, buy a K-mount 28mm. I would venture to say none are horrible, most are quite good and very affordable. I love 28mm focal length. In addition to the Image, I have a Kiron f/2 and Pentax FA 28mm. I cannibalized the Kalimar for parts, but it's still useable in reverse mode for macros.