I'm sure that a lot of other people already know this, but I didn't until a couple of days ago. This post is meant for people, like me, that may have been confused about the compatibility of my DSLR and m series lenses.
For months now, I was under the impression that if I got an M series lens, I would only be able to use it in manual mode. You can imagine my joy and delight when I got my first m lens and accidentally put the camera in AV mode only to discover that it does work. I think what confused me was reading this:
-Screwmount lenses may also be used in Av mode since they are always stopped down to the aperture you will be shooting at (unlike M&K lenses, which are stopped down only when the shutter is released or when you meter as described above).
from this article:
https://www.pentaxforums.com/forums/pentax-lens-articles/110657-how-use-meter...-x-k-7-a.html?
I'm not really sure if that quote is misleading, or if my limited understanding just didn't really allow me to understand. I'm pretty sure I misunderstood.
I should mention that you do have to manually set the aperture using the aperture ring on the lens, but the camera does set the shutter speed for you once you've done this. Another thing to note is that the camera will not automatically compensate when using flash (or I haven't figured out how to do it) so all of the shots are extremely over exposed when using flash (I'm sure this can be corrected with manual flash settings, but I'm trying to point out the lack of automatic function).
Again, I'm sure that this is not a revelation for most people, but if this helps one confused soul it was worth the time writing it up.