[trikosis]

Hi lads,
I need some advice. I found to oxfarm these two lens. I have a couple o question:
1 - what do you think about helios m44-2? I already have helios 44m. Which is the best one?
- pentacon prakticar 2.8-135 mc. How is? Is it possible to attach it on a pentax?



Thank you very much

[Skodadriver]

I find that both the 44-2 and the 44M have differing images, the 44-2 having the more unique bokeh and the 44M a tiny bit sharper. Might be my copies though. Worth using both. The Pentacon 135mm F2.8 pre-set (M42 mount) is also a nice lens, not razor sharp but with lots of Iris blades for interesting bokeh and I suspect good for portraits, I assume you are looking at a Practika bayonet lens, not sure if there is an adapter to use it on Pentax and it may only have 6 blades.

[sys3175]

There's no easy way to use Prakticar lenses with the Praktica B bayonet on a Pentax body because the flange distance is smaller than that of the Pentax.
An adapter would either lose infinity focus or need a corrective optical system, and afaics, due to the relative rarity of the B mount, neither type exists.
People have machined off​ parts inside the Praktica lenses to accommodate a Pentax mount, but for a common lens like the 135 this would probably be way too much work.
Hartmut

[trikosis]

perfect, I checked and unfortunately it's a bayonet. Thanks for your help.

[BigMackCam]

I can't comment on the Prakticar, I'm afraid, as I've never used that model.

As for the Helios 44-2... Optically, it should perform very much like your 44M. In fact, subject to sample variation, it could perform just the same, very slightly worse or even very slightly better. I have several copies of both the 44-2 and 44M, and whilst I haven't scientifically tested them, my perception has been that the 44M may be just a little better in the borders, though resolution specifications are the same for both models. As for the amount of "swirl", there really shouldn't be any difference between the two. See this earlier post of mine, comparing the 44-2, 44M and 44M-4.

One downside to the 44-2 when used on a Pentax body with flush-fitting, non-flanged M42 adapter, is that the rear part of the lens body (just up from the mounting threads) is too narrow to cover the "cut-out" areas of the adapter. As a result, you need to cover those gaps somehow to avoid light leaks and dust ingress. You can use bits of tape, a hair band, a rubber O-ring or any other method.