Yes it is P Auto with diamond grip. So, there is no "K" mark? And K version is the auto compensating aperture or not? Please excuse my ignorance with this lens.
"Mechanical compensation, cams. "Auto" means auto diaphragm, it stops down when you take the picture and opens back to max. aperture for viewing and focussing, they all said "auto", standards, wideangles, etc. Yours, if it is indeed the 'K' version, does not have a compensating diaphragm and does not focus to 1:1 without an extension tube. I have the identical lens, there are two ratio scales - one from infinity to 1/2 lifesize, and one from 1/2 lifesize to 1/1 lifesize for use with the tube. "
As I mentioned, all (and more) of this information is available at the Mir site I linked you to.
There is no 'K' mark on the lens.
OK. But do you have to compensate when at 1:2? and if yes then how much?
Um, er, ah, ignoring complexities due to pupillary magnification not equal to 1.0, the magic formula for exposure compensation given magnification is effective aperture = aperture set (f/ number) * magnification + 1
At 1:2, magnification = 0.5 so you'll need approximately 1 stop more light or exposure time or to open up one stop from whatever the meter says. At 1:1, magnification = 1.0, 2 stops more light or exposure time or open up two stops from whatever the meter says. If your camera has TTL autoexposure it will take care of this for you, whether you want it to or not.
Yes, Thank you very much. I am enlightened now.