[Not a Number]

but the metering w/ a M42 lens and a (pre A) K lens should be the same-

Non-A K mount lenses will always shoot wide open regardless of the aperture ring setting in Av mode. Unless you either remove the auto stop-down lever or not completely twist the lens into the mount. M42 lenses can be manually stopped down via the aperture ring.

[dms]

Right, what I meant (implied) was:
-- closing a M42 lens down and then getting a reading (as in AV mode)
-- versus closing a K lens down when in M mode and using the green burtton,
would likely lead to the same e.v. error, which is related to the screen design (used/optimized for slower AF lenses).

[stevebrot]

Someone else can say if I am wrong--but the metering w/ a M42 lens and a (pre A) K lens should be the same--and thus you need to come up with a e.v. correction vs f/stop either way--as both are metering at the taking f/stop--unlike an A lens.

You would think, but that is not the case. Neither M nor Av mode uses the straight meter output. Both use mathematical "splines" to correct for the behavior of the focus screen at various maximum apertures. M mode when no A contacts are detected is supposed to be closer to raw meter output and is generally preferable except that on the K-30 and K-50 the camera requires a conductive base for green button metering to work.


Steve

[Dlanor Sekao]

My solution to the frustration with the particular lens/K30 problem ??
I sold the M42 Takumar on Ebay and bought the SMC-K 35mm f3.5......Now it works perfect and matches the other two SMC-K lenses I have !
I will see if this lens lives up to its reported expectations and post that seperate.

[strangeboy]

Once I added a bit of aluminium foil, I fell in love with this lens. A Super Takumar 50 f/1.4... green button method.
This is a link to my G+ album, hopefully it will work.
https://plus.google.com/photos/101916914139406466829/albums/6082783779149334321