Hello!
I've searched this forum without success about this topic, so I'll share my experience here with you (sorry if this sounds like réchauffé to you!)... I've hesitated putting this in the lens section, but this is more related to the body, IMO.
Following these sites (
robertstech and
kmp.bdimitrov), I've found that it's indeed possible to activate P-TTL flash and matrix metering with old m42 and PK lenses, contrary to what is said in these sites ("This modification will not work for Pentax Digital cameras because they use the digital data pin on the lens to get aperture information, not the multi-contact array discussed here.")...
The trick is to short the Data pin too, and this works! Guess they did a little step back in their algorithms...
And good news, it's surprisingly easy to use!
For m42 lenses:
- short
all the contacts (the A contact is a little bit hard to short due to its recessed position),
including the Data pin.
- the body then display an aperture (f/1.2 if all the pins are shorted), the value is not important.
- select the smallest value available (f/1.2 if available).
- Tadaaa! Now you can use PTTL and matrix metering...
- Want to change the aperture? Just use your aperture ring, without changing anything on the body...
For PK lenses:
- short the contacts following the tables available on the sites above (the A contact is a little bit hard to short due to its recessed position),
including the Data pin.
- select the same aperture on lens
and body...
- Tadaaa! Now you can use PTTL and matrix metering...
- Want to change the aperture? Use your aperture ring, and synchronize Av value on the body.
This is possible due to the shorter course of the PK actuator compared to the PKA actuator, for a given aperture...
The other modes are then available with a PK lens... Just sync the lens with whatever aperture is given by the K10...
I've not done extensive tests to check the accuracy of the matrix mode yet (and the meaning of an accurate aperture with m42 lenses), but PTTL works just fine at all apertures (given you've installed a LL60 focus screen beforehand, or you'll fall back on the non-linear exposure problem
).
But now that I think about it, this is a great solution for PK-owners having exposure problems : this method simply removes altogether the need of the Green Button, at the same time as enabling PTTL and matrix metering!!!
Damn, there must be something rotten lying somewhere, this is too good to be true...
Last edited by dlacouture; 10-31-2008 at 01:13 AM.