Need technical info on modern Pentax lenses

[sbc]

Anyone has any info on Pentax FA, DA and Sigma DG lenses? What I mean is, is there any electronics parts in the lenses? Ignore the DA*, OS and HSM lenses. Obviously they have 'tons' of those stuff in there.

Reason why I am asking; The old lenses are fully mechanical. There is nothing much to 'die' on you. Therefore we can have 20 year old lenses that still works fine today.

I hv read in forums that the SDM in the DA* lenses can fail and have failed before. I want my lenses to last a long long time. If there are NO IC chips in the DA and DG lenses, I would avoid DA* lenses and instead concentrate on DA and Sigma DG lenses. If there are, then I will drop my plan, because then they have an equal chance of failing.

I can live with noisy AF, as when an F-16 flies overhead, you can't even hear your own voice. Anyway I have used Pentax AF SLRs since the SFXn and have never been bothered about AF noise.

[fengwei]

I'm sure there are some electric parts inside most modern lenses, including F/FA lenses too. Otherwise how the camera could get infos like focal length, focus distance and etc?

I don't know about lenses before A era, but all lense since F series have digital chip inside the lens body Here is a good reading if interested:
http://www.bdimitrov.de/kmp/technolo...unt/index.html

[sbc]

OK thks! Forgot about that web site.
Those A lenses do not have chips inside. They communicate with the body by the rows of contacts at the mount. If you observe, every lens has a different pattern of contacts. It works like a binary system of on/off to tell the body the max Av, etc.
I think F lenses don't tell the body the distance, only the FA do. So I guess the F don't have chips in them.