About the lens settings

On Super Takumar f1.8/55mm, there is A-M swicth on the lens front.
When you use this lens attached to Pentax SV, set it to "A".
By this, whatever the aperture selected is, the aperture blades opens at full aperture at any time except when the shutter is released.
This makes it convenient to see the subject through the viewfinder.