Originally posted by Pentaxor hmmmm...interesting. I'm not sure if the 55/1.8 Taks are the same with the K counterparts. from what I noticed, the K55/1.8 is sharp and the 1.7 slightly sharper. and the 55 has a consistently smooth bokeh to that of the 1.7 which on some instances have far less desirable busy bokeh. also the difference in color temp.
Exactly my experience. The 55 isn't really a master of anything, but it makes a great little portrait lens due to it's smoother bokeh. I find the lack of insane sharpness acceptable in portrait settings (and it actually gives the photos a bit of a natural vibe to combat digital perfection... does that make sense)?
The 50 1.7 was one of the best low-light lenses I have used because it was so very sharp wide open (I took my best concert photos with that lens). However, the look of it is rather... boring.
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RE: the 43 vs 50 shots. Interesting. Noticed:
1) Can clearly see increased DOF for the 43 due to focal length. I think that plays a role in sharpness determination.
2) Can see increased contrast in 43 photo. Flare resistance or perhaps something else?
3) I think the 50's shot is misfocused... there is no point of critical sharpness on the elephant. My K20d required a +8 calibration... perhaps this has skewed the results.
Also, was the 50 used with a hood? I find this lens pretty much needs one to even look half-decent (large, exposed element = flare).
In general it looks about right though - the 43 is much sharper in the f2-f4 range when compared with the 50, while the 50 has the creamier bokeh.