[rdeloe]

I need a light weight, short tele lens and am looking at the Pentax 645 135mm f/4 LS and the 150mm f/3.5 (A version). I'm only interested in how these compare optically; I won't be using the leaf shutter of the 135mm lens if that's the one I choose.


The user reviews suggest the 135mm LS is an optically excellent lens, and I've used the 150/3.5 A lens as a shift lens on a full frame camera (where it worked quite well). But I've never had them both in hand at the same time to compare their qualities.


Any thoughts? I'm leaning to the 135mm but would appreciate hearing from people who have used both.

[texandrews]

So, I have both. I *think* the 135 is sharper---my copy is dead sharp. Of course it is only manual. The LS bit can be handy. Note: these LS lenses may eventually give out. I think the mechanisms have a lifespan. Unclear if they can be repaired. OTOH, they are a bit rare, so if you have a line on one I'd get it.


The 150FA and A versions are both very good, but you might as well get the FA. Quite sharp, and fine bokeh. This is a favorite lens of all who have it. So, if you don't have a line on the 135, don't hesitate to get the 150, but I think spring for the FA.

[RICHARD L.]

I have a 645 A 150 mm f/3.5. Light, built-in sunshade, crazy-sharp and dirt cheap. Just my 2 cents ...

[rdeloe]

Thanks for the advice folks. When I had the 150/3.5 A lens on a full frame sensor I was quite pleased with it. I've never used the FA version, but it's good to hear that it's also a very strong performer.


I do like the manual A lenses in P645 so I wouldn't use the autofocus capabilities of the 150/2.8. Do those of you who have used both 150s think the FA version is sharper overall? How about flatness of field? I'm going to be using it on a tilt-shift setup so I need it to not have noticeable field curvature.