Originally posted by UncleVanya Correct - but it only fits on using a Bayonet if you mean the Pentax one. It won't fit any 3rd party lens and doesn't use the filter threads to attach.
The 3rd party one you picked should work otherwise. I am not certain of the length of that vs. what is needed to avoid vignetting.
Well, that's what I was getting at. Judging by the size of the 50-200mm hood, the one I picked should be just fine. We'll find out. If it vignettes on the 50, I'll use it with the K 55 and maybe even with the A 135 2.8, because that lens really needs something bigger than the built-in hood, it flares very badly...