So I finally managed to get a (half) lunch walk with the M 50 1.4 and K10D. I say half because my K10D battery now falls off the cliff in a few shots, it goes from full to completely empty really quickly... I only managed something like 20 shots total. On a lunch walk my average is more like 60-70... so less than half, really.
The first thing is that the M 50 1.4, like the previous version I have that had iris problems, is a bit soft wide open. There's purple fringing in this picture as well - something that my similar "magic light" picture from last page didn't show at all and I was a bit surprised to see in this picture (but shouldn't have been... I should have been surprised NOT to see it in the K 50 1.2 picture and that only emphasizes how good the 1.2 lens is!) And before you ask - I did have a proper "metal tele hood" on it, the same one I've been using on the M 50 1.7 for a long time (though that lens probably doesn't really need it...)
The next couple shots show a bit of the bokeh wide open again, and it's a nice bokeh, and I think the sharpness wide open is quite a bit better than the previous copy I had (which had issues but I didn't think was optically flawed). I think this is quite good actually - the problem is that I keep thinking, the K 50 1.2 would have done this better.
Another thing that surprised me is how rich the colors are - if you are not pointing to a light source. Then the old optical design rears its ugly head. Compare these two shots - on the lake shot I used my usual "sunny day landscape" style (preset) that I built on Darktable but had to turn back the saturation quite a lot because it really was too much! On the other one, not so much, but you can see how sharp this thing is. Both at f8.
Finally a shot at f2.8 (I think) taken the previous day that shows how nice and sharp and rich in colors the M 50 1.4 is... just not quite as nice as the K 50 1.2.... and I'm not sure yet how it compares to the M 50 1.7.
So there it is, my summary of the M 50 1.4 on the K10D so far, for my CCD loving friends. Less words and more pictures
In short: a very nice lens.
But this "review" comes with a warning... don't get a 50 1.2 Pentax lens because it might ruin other lenses for you