I just got a Pentax 50mm f.1.4 the smc-m version.
I also ordered this adapter ( http://www.amazon.com/gp/product/B005JV06QI/ref=oh_details_o03_s00_i00 ) to use it on my canon 60d.
When the lens is on the camera I can't change apertures!
But I can change aperture on the lens with the adapter attached while its not connected to the camera.
Am I doing something wrong?