With the lenses being so old and being manual for both focus and apature, they are probably not worth repairing... if they can be.

Does anyone have one of these lenses that works OK ?

I was wondering if this is just speed that these lenses work at normally

I think the important thing is the speed the apature returns to it's stopped down position from the fully open position,

Yes, sorry, brain fade...

on minimum apature the photo was over exposed untill the 2 sec delay was initiated then the exposure was correct again.

I've just done a quick test. Took a picture of the garden with my vivitar set at full apature - perfect
stopped down to minimum, pressed green button, shot again, - under exposed
switched 2 sec delay on, everything else same - perfect again

I think this proves it's an apature fault, but at least I have a work around now by using the delay function.

I have examined the iris on each lens and can't see any sign of oil. Operating the iris by the lever in the mount shows the action to be sluggish. I don't know if this is normal for these lenses or not

The vivitar lens stops down OK when the green button is pressed and also when the preview lever is actuated. I believe the iris is slow in stepping down and does not achieve the correct position before the shutter fires. My Vivitar lenses are the 28 - 90 series 1, and the 70 -210 series 1.

Anyone else had similar problems ?

Thanks Pete,

could be, but I've never had the lenses in bits. As far as I know they are working the same as they have ever done. Having said that, they haven't been used for a few years !!!
I have been 'flicking' the iris to see if Icould loosen it up a bit...

Thanks Martin,

I've read the other posts about the metering system not working very well as the lens is stopped down, but my fault is a greater error than that and I believe the vivitar lenses arn't stopping down in time ans are still in the process of stopping when the camer is taking the shot.

ie what I think I have is a lens fault, not a camera fault... sort of... well, I don't think the camera and lens are singing from the same hymn sheet !!

I recently bought a K10. One reason for this was to use my lenses I bought for my mesuper.
The problem I have is that the pictures are always over exposed when using my vivitar zoom lenses. My pentax lenses seem to work fine. The lenses are manual ones.

I have noticed that the lever on the K mount that operates the iris appears to be 'damped' on the vivitars, but work much quicker for example on my pentax-m 1:1.7 50mm.

I suspect my K10 is taking the picture whilst my vivitar lenses are still stopping down. Anyone having the same problem ? Any solution besides only using the lense fully open, which of course works fine.