[zekewhipper]

I'm lost as to what you guys are calling a "M" and "A" lens. An "A" mount lens (A-mount) is the Minolta/Sony Alpha mount.

As for what Pete above said, that matches what I said earlier. In Aperture Priority mode the camera will automatically shift the shutter speed (and even the ISO if in Auto) with just a half-press of the shutter release. This will obviously be the same for any lens used that has an aperture ring whether M42, M39, Nikon F, or K-mount. There is no need to use the Green Button at all.

[ramseybuckeye]

I'm lost as to what you guys are calling a "M" and "A" lens. An "A" mount lens (A-mount) is the Minolta/Sony Alpha mount.

As for what Pete above said, that matches what I said earlier. In Aperture Priority mode the camera will automatically shift the shutter speed (and even the ISO if in Auto) with just a half-press of the shutter release. This will obviously be the same for any lens used that has an aperture ring whether M42, M39, Nikon F, or K-mount. There is no need to use the Green Button at all.

The Pentax-A lens has the letter A on the aperture ring next to the smallest aperture. The A series lens were produced after the M series and before the F series (first autofocus).. You set the aperture to A and then you can use aperture priority on your DSLR and the camera will meter. There is a whole sticky thread about using the green button.

[sterretje]

I have to disagree. I checked with my M42 Lentar 135mm this morning, Av does work with it.

You disagree with who? If it's with me, just read my post again because I can't remember saying that M42 does not work in Av

I'm lost as to what you guys are calling a "M" and "A" lens. An "A" mount lens (A-mount) is the Minolta/Sony Alpha mount.

We're refering to lens series, not mounts. Check the lens database for a list; Pentax Lenses - Pentax Lens Reviews & Lens Database

[Paleo Pete]

OK I tried it, couldn't remember. Av will work with K and M lenses, but it will only shoot wide open. Set the aperture ring wherever you want to, it shoots wide open. But it does work...if you call that working...I thought maybe it just might take an exposure while stopping down to shoot a picture, but it does not, it stays wide open and uses that for metering. So it works, but only if you want to shoot a the largest aperture available. So it had to be with an M42 lens that I used it, I Knew I had but it's been a while and I couldn't remember for sure. So I tried both. M42 works great, K and M wide open only.

[Bonavista]

Thanks for the effort Pete so I guess I can use M42 lenses on the K-30 with full functionality