[Benz3ne]

I've some M lenses I use on the K-1 and they perform well. It doesn't take much effort to get into the habit of tapping the green button for metering. The metering seems to be pretty accurate too, which is nice.

[Jean Poitiers]

I use a lot of manual lenses ... because I really like them and have plenty to play with ... M, K, A, M42 Taks plus other brand M42, etc.

[Lowell Goudge]

I guess I was thinking initially of the functionality aspect, what the experience of using K and M lenses on the K-1 is actually like. I'm pretty familiar with the look of vintage glass on FF digital in the general sense and like how it works out.

The biggest issue, for me is the lack of flash support. Unless you shoot with A series or later, you give up on through the lens metering (TTL). Since the *istD series Pentax has dropped dual flash support and shifted to only P-TTL that requires to know the native and stop down aperture values for a lens. The Pentax system , like both Nokia and canon, use a pre flash With the lens wide open, to measure the flash vs ambient ratio and then with then calculates the flash needed for the exposure settings based upon the flash GN and set iso, shutter and aperture. While this stops the issue of overexposure in some blended lighting situations, I find the preflash drains the flash batteries much faster, and disturbed wild life much more than classical ttl metering. I wish the flagship lines offered both systems.

[HDpotato]

Big fan of old glass here.
K 28mm 3.5

By far one of my favorite Takumars (mine is an M42) - I'm waiting for the 30120 adapter to come in the mail, can't wait to try it out on the K-1 Mk2, which is my first FF camera, and Pentax camera.

I've been shooting it on Fuji bodies and love the close focus distance and the possibility to create images with short DoF and plenty of environment due to the wide angle.