Need help with a 28 2.8 M

[meremonkey]

I picked up an ME Super with 50 2.0M, 28 2.8M and a 135 2.8M with a pentax flash for $35.00 from a neighbor. The 28 and 135 are Image brand? Never heard of it but the 135 works and is very sharp. The issue is the 28. I give me the same photo no matter what f stop I set. I have enabled the allow aperture ring function on my K10D but it still doesn't seem to work. It works fine on the 135. By the way the pentax flash doesn't work, too bad it was a nice small one. Any advice?

[Adam]

Check the diaphragm lever on the 28mm-it might be stuck or broken.

[blende8]

Is the aperture closing when you use the DoF preview (ON/OFF button to the right)?

[borno]

Like mo said the lever in the back should open the iris easily from the minimum f22 or whatever and when released it should snap closed to where the ring is set. If it doesn't look for oil on the iris,the grease used to lubricate the focus can migrate into the lens from being in a hot place. They can be cleaned but it's a delicate operation.hope this helps.
tom

[meremonkey]

Originally Posted by blende8

Is the aperture closing when you use the DoF preview (ON/OFF button to the right)?

I'm using that button for digital preview.

Check the diaphragm lever on the 28mm-it might be stuck or broken.

It does move but the iris doesn't seem to do anything.

I'll keep trying.

[roy]

as stated, ck it off camera and see what it does.