Jyrki,
I have a Pentax 100-300 4.5-5.6 (The Powerzoom version), I might consider selling it, let me know if interested (It's in Espoo).

Can you please give me your view on the value of this lot, which I found for sale:

Pentax *istDS
Takumar-A 28mm f/2.8
SMC Pentax-M 50mm f/1.4
SMC Pentax-M 100mm f/4 MACRO
SMC Pentax-K 135mm f/2.5
Pentax extension tube set
Manfrotto 190DB tripod and 486RC2 head

Thanks!

(sorry for the spelling mistake in the title....)

Kris,
I fully agree with you.

Thanks Kris! Yes I was, now I tested with center weighted average and it seems to work fine. Problem solved.

Reading on KatzEye's site I also found the explanation of the difference between lenses:

Spot Metering Mode: Our testing showed spot metering mode to be within factory tolerance for all AF lenses having a maximum aperture of f2.0 or larger (lower f number). Lenses having a maximum aperture smaller than f2.0 (lager f number) will show a significant shift toward increased exposure, with the shift increasing for lenses with smaller maximum apertures. Spot metering mode is NOT RECOMMENDED when using a split prism focusing screen with lenses slower than f2.0.

Thanks Stefan.
But is it normal that the problem exists only with certain lenses and not with others?

I recently bought a new split image focusing screen for my K20D from Focusingscreen.com (K3 model). I find it very good and I am very happy with it.

Today I put a Pentax FA 100-300 on the camera and found out that it overexposes by some 3 stops with the new focusing screen. The same happens with the FA 28-105 zoom.

After some testing I found out that the focusing screen works fine with some lenses, but not with others. The only commonality I found is that it works fine with fast lenses (for instance the DA* 50-135, but I have not tried all lenses).

Do you have any ideas and recommendations? I have read many reviews about Focusingscreen.com and this particular focusing screen, and no one reported similar problems.

Thanks to anyone who can help....

Yes. Just had my MX serviced and bought a Spotmatic II. I bought some XP2 film and decided I will shoot some B&W as I used to do in my youth. And realized how hard (and instructive) it is after getting used to digital...

Most of the time centre point and re-compose. Increasingly MF and now that I have bought a Focusingscreen.com split image screen MF will increase further.

I'm curious: which focusing screen did you buy?

No, it become the very next thread only because Carlosg replied.