Hi everyone!
Although this is my first post here, i'm not a complete Pentax novice, as i've been using a nice Spotmatic F for quite some time now. However, i 've always considered it more of a "M42" rather than a "Pentax" camera (looks like it's the mount that defines a camera, isn't it?).
Recently, to get advantage of the small size and the nice lenses i got myself a nice ME Super and ordered a Pentax-M 1.7/50 and a Sigma mini-wide 2.8/28 to go along with it. (with a Pentax DSLR down the road maybe?) The Sigma arrived yesterday in mint condition, complete with hood, caps and case.
However there seems to be a problem from the beginning, as after fitting the lens onto the camera, the aperture ring refused to go wider than 4.0, even though off-camera the aperture ring turned all the way from 22 to 2.8. Removing and re-fitting the lens corrected that (sigh of relief).
The problems remained however, as there seems to be a breakdown of communications between the lens and the camera. More specifically, the camera seems to constantly underexpose (2.8 straight at the sun, ASA 400, the speed is 1/250 and 2s indoors) and the shutter speeds do not change despite changing the aperture.
I am not familiar with the Pentax bayonet, but it seems to me the small lever in the groove (green arrow) should be the one telling the camera what the aperture is, and extent of its movement should be according to the aperture when the other lever (magenta) is moved as the shutter fires. With the tall (magenta) lever held down, changing aperture should cause the small lever in the groove to move to an extent dictated by the chosen f value. Problem is the small lever just moves one click (from 2.8 to 4.0?) and then stops, despite continuing to turn the aperture ring. When the tall lever is to its resting position, using a toothpick i can move the small lever freely along its groove without any changes to the aperture or any resistance. If i abruptly tap the large lever, the small lever travels a little further along its groove, but for distances that are not always constant, aperture value being the same. Is any of this normal? I'm pretty sure it's a lens problem and i'll probably have to send it back. If you recognize the problem, it would be great if someone could explain it to me so that i can claim a refund for the lens.