Originally posted by pschlute The light meter needs to know the aperture set on the lens to function. M42 and pre A-series lenses do not transmit this information. The green button method or DOF preview physically stops the lens down and meters with the aperture stopped down when using a K or M- series lens..
With M42 lenses you should be able to use Av mode also as the lens stops down when you turn the aperture ring.
Brilliant. Thanks
I use both methods, I think I prefer the Av route then I can lock the exposure, although, green button and exposure compensation works nicely too. On the K3, using the dof preview also gives you the exposure which is nice. For some reason I thought I had seen the meter lol. Mystery solved. Thanks