58mm f1.2 Minolta Rokkor-PG with Yellow tint

[GeorgeDexter]

I've recently come across a 58mm f1.2 Minolta Rokkor-PG in the MC that has a yellow tint in the glass. I am familiar with the Takumars that used rare earth, and yellow over time, but the yellowing in the Rokkor seems to be uneven -- it's more pronounced in the middle than at the edges. These are nice lenses, and command quite a premium, so I'd like to resolve this issue if possible. When looking through the viewfinder (SRT 101) I found it to be quite dark, also. It doesn't seem any brighter than my 50mm f1.7. Has anyone had any experience with this lens?
Thanks,
George

 

[EdSawyer]

UV flashlight pointing into the lens will cure the yellowing. It will take several days. It's a great lens, probably the best Rokkor ever, possibly. Certainly the best in the 50mm-ish range, by Minolta.

 

[davela]

The colors one sees in complex groups of optical glass have little to do with what the film will sense (which is predominately blue sensitive). These colors are due to interference effects of thin coating films, multiple reflections, etc. and depend not only on the details of the coating process, but also on viewing angle, and other factors (too numerous for a discussion thread to elaborate on). None of this has anything to do with radioactive rare glass material. I predict that if the lens is otherwise free of haze, free of fungus, or other alien contaminations (and no separation) it will deliver spectacular results.

 

[Ralph Javins]

Good morning, George;

I have three (3) samples of this lens. One of them I keep around to show why you should not leave such a nice lens in a damp basement or unheated garage for several years. The fungal growth in that lens is spectacular.

My other two lenses in that group are working lenses. They are not as sharp as some of my other Minolta "normal" ROKKOR lenses in the 50 to 58mm range, but I cannot deny that the f/1.2 capability does help in getting the focus right in low light levels. For me, that is the main advantage for this lens; the ability to reduce my focusing errors in low light. I think that helps more with getting a good printable negative than worrying about the number of line pairs per millimeter that it will resolve.

For several years now, I have been suggesting the Minolta MC ROKKOR 1:1.4 f=58mm as the preferred "normal" lens. It has a nice combination of low price, good low level light performance to help with focusing, good lens resolution, some of the later lens coatings to help with flare and contrast if you do not like to use a lens hood, and it has the 58mm focal length which to me provides a true "normal" perspective on 35mm film.

For me, the 1.2/58 is a special purpose lens and not just a "normal" lens to hang on the front of a camera you carry around all the time. If you have the lens already, try taking some photographs under some standard repeatable lighting condition, perhaps of a white target also, and see just how much yellow -- if any -- you get on your prints. You may see that this is not a problem. It could be a point of discussion for getting a lower price for the lens if you are still considering the possible purchase.

And, yes, in looking at mine, they also do have a slight yellowish tinge of color when I look through the lens at a white surface. Mine have an even overall slight yellowish tinge over the entire lens aperture. As was mentioned earlier, this may be an effect of the reflected light from the lens surface coatings, and not a major factor in what colors are transmitted through to the film. I do not find this to be a major problem, even with my older Minolta AUTO ROKKOR-PF 1:1.4 f=58mm lenses from around 1960 with the known Thorium additive glass in the lens. Try yours and see what you get.

One thing I do recommend is storing Minolta ROKKOR lenses with the lenses off the camera, with the lens caps on, and set to the smallest aperture or the highest aperture number setting -- f/16, et cetera. This helps to relax the springs that drive the lens aperture leaves to the selected lens opening at the moment you take the photograph. Over several years, it could help prevent the springs from taking a set in their compressed or loaded condition.

 

[Christiaan Phleger]

Sorry Davela, those traits indicate that thorium was used in the glass melt. A few Nikkors, Takumars and most famously the Kodak Aero Ektar have it, and the decay of the isotope is what causes it. Do a google and read up on it. My impression is that at the time the lenses were released nobody knew for sure if they had that glass, but now as these lens start to hit multiple decades on the yellow glass is a sure giveaway.

 

[fmajor]

The yellowing is no real problem. It's a well-known "condition" with some of the early Rokkor lenses and is easily "cured" by exposing the lens to direct sunlight. Simply point the lens toward sunlight and allow it to rest there a week or two depending on the severity of the yellowing and it should clear right up. This is a well-known condition of some early MC Rokkor lenses and is easily remedied.

 

[dynachrome]

58/1.8 Rokkor Yellow

I have a 28/2.5 MC Rokkor whihc is in nice condition but which has a severe yellow-green tint. I think the radioactive element is somewhere in the center. The glass on either side will probably filter out most of the UV light so clearing it might take some time. I did manage to clear my 35/2 Canon FD SSC with the concave front element after many months of keeping it under a CFL bulb so I can use it with slide film now too. Before I did that I accumulated several examples of the 35/2 New FD which is also an excellent lens.

The newer 50/1.2 Rokkor is supposed to be a much better lens in technical terms but without the same personality as the 58/1.2. I have two early 57/1.2 Konica Hexanons and one 55/1.2 Canon FL. I am interested in eventually getting a 58/1.2 Noct Nikkor, a 55/1.2 Canon Aspherical and maybe a 50/1.2 Rokkor. Years ago I bought a 55/1.2 Chinon Tomioka M42 lens as a gift for someone. Now that lens goes for a lot more money.

 

[Christiaan Phleger]

Dynachrome, I'd throw in a 50mm 1.4 Super Takumar radioactive into your mix, a gem of the time period.

 

[Pumalite]

The best!