Originally posted by Jonathan Mac M42 lenses that reach the electrical contacts on the mount work properly in Av mode. Lenses that don't are around 2 stops off on my K200D, unless I use foil to make the connection. If the lens reaches the contacts but has paint over the metal, removing the paint in the right area will provide a connection and make Av work ok.
Thanks, I will look into that. I previously tried using foil taped to the body, which was unreliable, so just used +1.3EV which seemed about right on most lenses.
I looked today, 24 hours later, and the 135/2.5 is big enough it covers those pins. The other Taks seem a bit smaller.