Pentax K-M

I think there's been a trend away from using K and M lenses, most of us preferring to use A series onwards.

Of course there are some lenses that are useful anyway, and mirror lenses may well be one type that is worth the extra process needed.

Not here

My entry to the last fortnightly competition was with the K 85mm 2.2 soft. A very strange beast of a lens: http://kmp.bdimitrov.de/lenses/primes/short-tele/K85f2.2-Soft.html

And that's another specialist lens that is an exception! There are a few odds and ends like that which have no current equivalents at all.

and of course with the mirror lens having a fixed aperture the lack of communication actually makes no difference to how it works. Even if Pentax were to produce a DA mirror lens with electric contacts the only functional difference would be that it would read F8 in the viewfinder, and you wouldn't have to set the custom function to use it.

SORRY, I was mistaken about the K20D being different from the other models in the way I mentioned. An obscure thing fooled me:

A modification I made to my M and K lenses allows the camera to fire the shutter regardless of the "Allow aperture ring setting". It also allows Av mode to work with any aperture. I suspect this would work with all Pentax digital cameras.

The "modification" is simply a piece of Selotape stuck over the part of the lens mount (on the lens) where the electrical contacts would be if there were any.

By the way, Av mode with this modification is only useful when you can add enough EV compensation to correct for the metering error. It just enables you to stop down a stop or three if you're lucky, with Av mode.