Lens and exposure question.

Can anyone answer this question for me?
I have a Vivitar 28mm 1:2.8 manual lens that I use in my istD but it always over exposes so I have to remember to nip the EV to -0.5 to use it. Sometimes I forget but this is now getting less often. I can't understand why it should need this compensation in the first place - anyone got any clues?
Incidentally my Pentax FA 28-200 exposes spot on.

Ta

Rob

You don't mention whether or not it is a KA-mount or not, that is, with an A setting on the aperture ring.

If it is, maybe the link isn't accurate, or maybe it's slightly faster than marked.

If it's a K mount lens it uses a different metering pattern by default, so that might account for the discrepancy.

I had exactly the same issue with a Pentax SMC-F 50mm/f1.7
When I upgraded to firmware 1.12 it is perfect
(Might be worth a try anyway!)
Let us know what happens!
Matt

It is a KA mount (all my manual lenses are - that sounds like i have loads!!!) I havent tried the other lenses as I dont tend to use them on the istD but will try and see.
FYI the oter two lenses are Sigma 70-210 F4-5.6 and the standard SMC 50mm F2. All I will say is I have never noticed a problem when the viv was used on my MX.
HMMMM its just a bit weird

Rob