I'm curoius as to your evaluation of the Vivitar 28mm. I haven't even tried my Minolta 28mm f2.8 since I assumed legacy wide angles would not be that good and the Minolta 28mm f2.8 was never considered a stellar performer (I have the Panasonic 14-45mm for that focal length anyway). Of course, your Vivitar is f2 which is a plus, but I'd really like to know how well it performs at the minimum focus distance and f5.6. I do a lot of work close up so I'm always looking for alternatives...
Can't give you much of a personal evaluation at this point since I have yet to get an adapter as well as an m43 camera to go with it. ;-) I did try to see if it would fit provisionally on my current Pentax, but the K-mount is so much wider than the MD mount that it would not even hold the lens in place.
In fact, since I don't have an m43 camera yet, this was something of an accidental purchase. I was just browsing the legacy lens market a little to get an idea of what was available at what prices when I came across an intriguing offer for two MD mount lenses. One was clearly labeled as a Minolta MD 50 mm 1:1.7 but the other was sold as a "Hoya HMC Skylight 49 mm 1:2.0". ;-)
While this "lens designation" made it obvious that the seller had rather limited photographic experience, it did not tell me a whole lot about the lens except that it would take 49 mm filters and possibly had a max aperture of 2.0 (since filters are rarely labeled "1:2.0" ;-)). Nor could I make much out of the picture accompanying the ad since the lens was shown from pretty much the same angle as in the guessing game of this thread.
Since this sparked my curiosity and the price seemed promising (300 SEK, which translates to about 45 USD, for the pair), I called the guy and asked him to read the text on the front ring. After a brief Google session, I called him back and closed the deal. I think I was fortunate that the ad was so cryptic, particularly since it had already been out for a couple of weeks when I ran across it. Had the lens been appropriately described, I am pretty sure it would have been gone before I found it.
What I have since learnt is that this lens is a bit of cult object in certain circles. While there are quite a few Vivitar 28 mm lenses out there, as you see from "The Great Vivitar 28 mm Bestiary" available here
http://photografica.robinparmar.com/vivitar.html
the "close focus" versions (f/2.0 and f/2.8), both made by Komine, appear to be the most desirable, not only because of their close focus ability but also because of their general optical quality and good build. There is also a bunch of Vivitar 28 mm lenses built by Kiron (owned by Kino) and Cosina but none of these seem to have quite the reputation of the Komine versions, especially the Komine 28/2 that I was fortunate enough to stumble upon.
The Kirons seem to have systematic problems with oil on the aperture blades, do not appear to be quite on a par optically, and lack the close focus ability. The Cosinas, which appeared at a later stage are reported to be rather cheap and mundane constructions. The only other Vivitar 28 that might give the Komine 28/2 a run for the money is the 28/1.9 Series 1 built by Tokina. But the Tokina is bigger and heavier, does not focus quite as close, and the Komine bests it for optical quality (resolution/contrast as well as distortion), at least according to my eyes in the test provided here (where it also beats, among others, a Kiron 28/2, probably identical to the Kiron-made Vivitar 28/2, and a Zuiko 28/2):
http://translate.google.se/translate?hl=sv&sl=ja&tl=en&u=http%3A%2F%2Fhomepage3.nifty.com%2F3rdpartylens-om%2FLens%2520Test%2F28mm%2F28mmLensTest2.htm
You find an example of how it does at close focus at 5.6 here:
http://www.flickr.com/photos/anktonio/4022511428/sizes/o/in/photostream/
Further examples here, where the first one (to which I link directly) is probably a crop from a picture later in the same series
http://www.flickr.com/photos/anktonio/4021916523/in/photostream/
You'll find more examples if you search a bit on the net.
As you can see, the lens is unusually compact (only 50 mm long, with a diameter of 64 mm) and light (260 grams) for what it is: A fast, retrofocus 28 mm with a floating elements design (8 elements altogether) and a minimum focusing distance of 23 cm. Maximum magnification is 1:5, which implies that an 18 cm wide object would fill the frame on FF and a 9 cm wide one do the same on m43. Due to the short focal length (and possibly, to some extent, the floating elements), the lens extends only 5 mm when you go from infinity to 23 cm. For the same reason, even a short extension ring (about 10 mm) would give you significantly greater magnification if you want.
I still feel a little sorry for this lens, which was obviously a really hot wide angle on the cameras for which it was originally designed but on m43 is reduced to a mere "standard lens", and no longer particularly fast, light or small for that category.
I also wonder why they started to give wide angles close focus abilities. Was it only because it was relatively easy to do without making the lens particularly expensive, large or heavy or what? Personally, I do not see much reason to use a wide angle for close-ups (except for intentional distortion of perspective) and would normally prefer the tele range (for greater working distance) but ... I would welcome any thoughts on this.
