Like this maybe? Are you using the extension tube?I'd say go for the orange version.
As far as I know both these versions have the same optical design; it seems the optical design has never been changed from the very first to the last model. Differences in image quality might well be caused by sample variation; I have three of these, an early MC Rokkor-QF, an MC Celtic (budget version, somewhat younger than the Rokkor-QF) and a plain MD with the blue writing. The latter two are wonderfully sharp, the Rokkor-QF is somewhat behind in corner performance. I prefer the Celtic because I like its handling better, even though it has a tiny fungus spot in it. Its white balance is also a bit different from the Rokkors, but colours are beautiful from this lens.These are Minolta MD lenses, ie fully manual. Two versions were made, the first one has orange markings on the front around the front element. The second one has the same markings in blue.
I have seen test shots where the orange version was sharper at wide aperture settings and also had better border sharpness throughout. It wasn't a huge difference, but if you have the choice of both, I'd say go for the orange version.
Too true. Concerning the 135/2.8, I have all MD models (4/4 and 5/5) and they are all excellent from f/4 onwards; CA is virtually absent in all of them. My guess is that your worse sample has had a knock or something, CA seems to be one of the traits that is fairly constant across samples of a certain model, as I have noted after testing my lenses.Evaluating old lenses is difficult due to the number of variables. For instance, I have two MD 135/2.8 [4/4] that are fairly close in serial numbers. One has no visible CA the other one, in nicer cosmetic condition, has heavy green and purple CA. Is it mishandling, quality control, change in manufacture? We can't know.
We simply have to look at the tests, form an opinion and cross our fingers as we place our bids.