...here's a comparison of three 50mm lenses, Olympus OM 50/1.8 MC (2366xxx), SMC Pentax-A 50/1.7 (1218xxx), and SMC Pentax-A 50/2 3474xxx).
I'll post a total of three sets of four images.
1. all lenses wide open
2. all lenses at f/2.8
3. all lenses at f/8
Each image is a four-panel screen capture of PS CS6 windows; three are 100% crops from each of the three lenses, and the fourth is the Navigator window, with a red square to show where the crops are located in the full images. The 100% image crop panels are arranged as follows.
top left: Olympus OM 50/1.8 MC
top right: SMC Pentax-A 50/1.7
bottom left: SMC Pentax-A 50/2
bottom right: Navigator window
Method: 5DII CR2 RAW files (no PP), ISO 100, tripod, MLU, 2 sec self-timer. Three images were taken at each aperture, for each lens, with focus/defocus between each image, using LiveView manual focus. The first step was to select the best image from each set of three, and then use that particular image for all 100% crop views. IOW, the 100% crops for a given aperture are all from the same image, not (for example) the best top-right image from one photo with the best bottom-left edge from another photo, and etc.
Summary: Oly wins this particular test at infinity focus.
Caution: I only tested copy one of each lens, variation between copies for a particular lens can be significant. OTOH, the results are very consistent.
The Oly was on a Fotodiox Pro and the Pentax lenses shared an old adapter that I got on a 'famous' 24mm Sigma lens that I bought about five years ago from Mark Hubsand, at 16-9.net. The adapter worked very well on that lens, and on many Pentax lenses that I've had since then.
Wow, this isn't even a remotely close competition. I wonder if the Pentaxen will pick up at closer distances, or if they're always this stupendously outclassed.
Frankly, I'm surprised. This particular SMCP-A 50/1.7 served me very well with Pentax film cameras, even for fairly large prints. It really doesn't look too good on my 5DII. The Oly is quite new, photo of it below.
I might do some more comparison photos with closer subjects and 'bokeh' content.
I'll be comparing my SMCP-A 50/1.4 with a recently acquired Fuji EBC 50/1.4 that's also very nice.
I would expect the 50/1.7 to improve significantly at closer focus distances, it's reputation for excellent is to some extent particular to close focus performance.
Overall this does confirm my expectations, having owned all three lenses. The 50/2 is adequate, cheap and tiny, the late Oly 50/1.8 is outstanding and the 50/1.7 is in between.
Is that the last version of the 50f1.8 ? If I remember correctly there are 6 or 7 different optical formulae over the years.
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Hum this link suggest it is not the last version: http://forums.dpreview.com/forums/post/23998062
Second last as far as I can tell. However, reportedly no difference in optical construction to the last one according to olypedia
Just noticed that your link says that the aperture ring on this one is made of plastic. Can anyone confirm that this is also the case for the last version ("Made in Japan" on the front ring)? A metal one would be nicer
I'm 99% sure the aperture ring on the last one is also plastic. The lens is not the best in over all construct (I had a couple) as it was sold as a very cheap 'kit' lens near the end of the OM cycle. After olympus dumped the OM line you could pick them up new for less than $50 (which is when I acquired a pair). I liked the optical results.
Definitely 5 major flavors with the MIJ usually thought of as the best. John Hermanson
confirmed this and he has worked on all of them. Found this quickly on the OM list archive: http://lists.tako.de/Olympus-OM/2011-09/msg00048.html
That be said I like my Z. 50/1.4 better than my type 3 50/1.8. The Z. 50/2 macro when used as a normal non macro lens has a nice rendition as well.
Basing on filenames you confused the last 2 images from the f/8 set - they are for max apertures, not f/8. Also some of the f/2.8 set images are at max aperture.
