Quote Originally Posted by PentaxBronica View Post
The genuine Pentax M42-K adapters aren't hard to remove. You just use a fingernail to pull the little tab toward the centre of the mount, then turn the adapter to remove it.
And get the genuine ones only. I once bought a Chinese clone of the genuine Pentax adapters and it refused to release no matter how hard I tried. I ended up carefully cutting it with diagonal cutters to remove it.