I have the 85-250mm and am quite pleased with it. Nice sharp contrasty images. Typical Olympus. I compare it to my 35-70mm f3.6 which is an excellent value for the $$$'s.
It is not a small zoom even though it is an Olympus OM lens. It is rather heavy - probably because of it's all metal construction. The good thing is it comes with a tripod foot and built in lens hood. For the price, this is one sweet lens.
The 50-250 is a very late lens, and partly made of polycarbonate.
It is a fine lens, I used it with my OM's, but normally too pricy. Both zooms cannot be combined with the OM 1.4TC.
The 85-250 is a very good lens optically and has the tripod mount, which the more compact 50-250 does not have. Maitani said he always had the 50-250 with him while travelling, that says something (he also had the 40/2 with him!)
I don't have these film images scanned, so no help from that perspective.
The 300 f4.5 is the one to get for price/performance however. a very fine lens and still rather "compact", and can be combined with the OM 1.4 TC!
On film, the 85-250 is the clear winner over the 50-250. The latter one was actually designed for "being compact in size and low in price" (from the US patent). When the 85-250 was discontinued in 1985 and the 50-250 introduced at the begin of 1986, the latter one was about 25% cheaper. The reason that the 50-250 nowadays is usually more expensive is that only around 20% as many as of the 85-250 have been produced. On the net, there are anecdotal reports that meanwhile a lens group of the 50-250 is slowly disintegrrating/getting cloudy; a problem shared with the 65-200/4 zoom.
The 50-250 was recommended for use with the 2x-A converter (===> f/10!), but the 1.4x-A doesn't fit as that would require a larger inner diameter of the lens to accommodate the protruding front group of the converter.
The best OM Zuiko lens in that range is probably the 250/2 which I had never in my hands due to $$$.
edit: I actually think that Olympus' strength during the OM time was in the wide angle range. The tele range was handicapped as the major self imposed restrictions to the designers (up to ca. 1983) was to keep everything as small and compact (for its time) as possible. This does not go well for tele and zoom lens when keeping image quality at the top.
My own choices in the range you are looking at are (mainly based on a restricted budget):
Voigtlander Apo Lanthar 125/2.5
Tamron SP 180/2.5
Tamron 80-200/2.8
I've just gotten my first Zuiko 24mm 2.8. I really like the colors that come out of it much better than anything else I've ever shot with. I've only been shooting RAW, but these colors are good enough that I'm considering shooting JPG's (at least testing them) with it. I was hoping to find something similar in the longer ranges.
Budgetary constraints also have me thinking about the AF Tamron 70-200 2.8 Macro & a 300 or 400 prime manual focus ... if the xx-250 & 1.4x aren't an option.
I'm still wondering about the 85-250 ... hmmm. I've got a CZ C/Y 80-200, but the 200 leaves me a little short. I had been shooting a Sigma 100-300 f4 (nice lens) till I switched from Nikon D70s to Canon 1D MK II. I usually pulled it back to around 275 to keep image sharpness from going soft @ 300 when shooting wide open.
I was hoping that the Oly xx-250 would have better color, sharper wide open and I wouldn't miss the 25mm all that much. Since I also used my 1.4x with my 100-300 it gave me a 140-385 (pulled back to 275) @ 5.6. I had been planning on replacing it in the Canon mount ... but the Oly has made me take some time to re-think things.
Will any other 1.4x's work with the 85-250? I think a 120-350 would be a good range for me, and I could probably live with the f7 when I needed to (ISO bump with clean glass)
Zuiko 65-200 f4 that is very subject to the cloudy rear element--? oil etching it? I have never heard of a consistent issue with the Z. 50-250. Prices have been quite variable--almost 800 USD a couple years ago at KEH though saw one go for 200 a few months back. It is small and light for the length but is F5 of course. (has built in hood)
I use it as a back up long lens if I need a light kit. Stopped down at hyperfocal distance--works like a charm. It has a macro setting, but it is a well earned reputation for bokeh being a bit busy. Perhaps the the well performing Tam SP 80-200/2.8 can be had for cheap these days---it works well with the Tam SP 2X TC--perhaps the optics are well matched. It is quite large and heavy of course. There is a Tam 60-300 SP that does OK for macro (I think on the short end though)
For an excellent 300/4.5 get a Nikon (pre-ED). I have a late one and it delivers excellent performance, even with a Canon 1.4x TC. Some believe they are ED, but were never marketed as such.
I would also highly recommend the Tamron 80-200/2.8 adaptall lens. Really high quality build and excellent IQ.
I would not write off the Zuiko 50-250, however. Nice sharpeness across the frame at all focal lengths. CH Ling a wonderful Photog on the OM list uses it on his 5DII.
I trust he won't mind the link as long as it is appropriately credited.
On the long end with background that is not too busy the bokeh improves.
The range of the 50-250 was very inticing, as well as the macro capability, but having heard a few negs about the 50-250 ... COMBINED with my belief that a 3x zoom SHOULD be able to be designed to outperform a 5X zoom.
Now I'll just have to see how its native IQ is, then try to find a good 1.4x (Kenko Pro / Canon / ??) that can be used with it. The OM 1.4x has the protruding element that would have an interference with the rear elements of the 85-250. While my preference is for a 1.4x, I might wind up with a 2x since the wider converter provides enough space that the converter elements don't interfere with the 85-250 rear element.
I should be getting my 85-250 around Thursday. I'll definitely be doing a shootout with it vs. my CZ C/Y 80-200. I suspect there will be room for only one in my bag
I'm hoping the 85-250 brings the Oly colors and some crisp detail to the party. If not, then ?? ?? ??
(he also had the 40/2 with him!)