Originally posted by sophie100 I have a K-5 II, bought about two years ago. In the interests of carrying as little about with me as possible, I also bought a SMC Pentax-DA 18-135 Zoom.In terms of convenience (and price) brilliant! In terms of picture quality, something about it always seems to disappoint.
This was thrown into sharp focus (pun sort of intended) when I recently resurrected my Pentax-M 85mm f2 portrait lens, left over from my pre-digital days. I've always thought this a wonderful lens, and it doesn't disappoint today. Wonderfully clear. The down side comes when stopping down. Being totally manual, in bright sunlight (particularly) it can be a pig to see properly in order to focus.
First - have you tried manual focus on the 18-135? Is it possible that the Autofocus is front or back focusing it? Second is the difference in the shots you like more from the 85 f/2 based on sharpness, color, contrast, Depth of Field? Maybe post a few 18-135 blah and a few 85 f/2 wow shots to get some feedback. Have you tried setting the 18-135 on 85mm and just doing some A/B comparison shots also?
Originally posted by sophie100 So two (linked) questions come to mind:
If I were to buy an up-to-date lens today, with all the bells and whistles useable on my current K5, is there a single zoom lens which will give me the convenience of the 18-135, together with the clarity of my old portrait lens?
First the 18-135 is pretty up to date. Not sure what you mean. The 16-85 lens is a bit higher in terms of quality of image in some head to head comparisons but not enough to abandon one for the other unless you never need 86-135 in my opinion. The 17-70 is an older lens with similar minor improvements in IQ that again I would not jump to unless the constant f/4 speed is needed or the extra 1mm width is required or the 71-135 range is never used.
Originally posted by sophie100 Alternatively, given the sort of clarity I'm looking for overall, what are people's views on the following:
Pentax-DA* 50-135mm F2.8
Pentax Telephoto SMCP-FA 77mm f/1.8.
The main questions for me are:
Will the 50-135 be an improvement over my 18-135?
In terms of the 77mm can I expect the same level of clarity as I get on my old manual portrait lens, or is there a trade-off in clarity to be made against the convenience of a fully automatic lens?
Yes the 50-135 is an improvement over the 18-135. I have owned both simultaneously and the 50-135 is sharper and has greater edge to edge performance. It's also faster optically speaking at f/2.8. It is however slower to focus sometimes and larger and covers a more limited range (short tele to mid tele vs. wide to mid tele).
The 77 supposedly holds its own against the best portrait lenses ever made for Pentax. I own the A* 85 f/1.4 and find it to be supremely sharp and yummy but I typically preferred shooting the 50-135 over that lens due to simplicity. The results of the f/2.8 vs. f/1.4 depth of field were about the only real delta between the two lenses at 85mm. Put another way the 50-135 is a stellar lens for portraits and other photography where the 50-135 focal length fits. But for an all around lens? You would give up 18-49mm... not great if you need an all around lens.
The 77 also is NOT an all around lens by most definitions. In a fixed prime the Pentax FA Limited 31 or the DA 35 Limited Macro would make a good all around lens since it is close to the normal lens focal length. Personally the 18-135, the various 17-50/70 lenses, or the 16-85 are the best choices for all around shooting.