Question about Mamiya lenses

[newton]

I have two Mamiya 55 mm f/1.4 manual lenses. One is an SX; the other non-SX. The non-SX Auto has a yellowish tint to the glass. The SX is crystal clear. Is the yellowish tint part of the coating, if there is one? Why is there a yellowish tint? Is the lens damaged from sun as some one posted online or is it naturally the coat color? What is the difference between the two lenses? Is white balancing needed?

[Andrew G.]

If you look through the lens and see a yellow tint, it probably isn't the coating.. it's far more likely that the lens has [radioactive] Thorium glass, which turns yellow over time. This can be treated and reversed with UV light.

[William]

Bearing in mind that you have two, I'd use the yellowed one when you want that golden cast on your images, as long as it's not too heavy it can be a pleasing effect. If you use it very heavily in the sun the cast should go away over time, assuming that this lens is thoriated.

[LucisPictor]

I would bet that the AWB will delete any golden cast in your images.

[newton]

Thank you. What is the difference between the SX series and the non-SX? Do the latter lenses have a multi-coat, understanding that the yellow is due to the sulfur in thorium? If I leave it out in the sun, it should turn clear again? The yellow does have a very pleasing antiquated look, but the subtle white balance distortion does mess with the normal eye and it's senses.

[Pancolart]

Try UV lamp rather. Sun will warm-up lens too much and you might damage it. One of the best M42 Mamiya for me.

[ramiller500]

I think there is still a lot of confusion between yellowed glass and yellowish coatings.

Any lens model suspected of radioactivity should be properly metered by a competent professional to establish how much if any radiation it emits vs. background level. I'm fed up with the blog rumor mill even if its allegations are sometimes correct.

[newton]

Wait, there are actually radioactive lenses? Damn, those Japanese sure were clever. .

[mo]

I have the 1.8/55 mamiya non SX,It has the yellow cast to it but it produces lovely images.Check out/compare both mounts I am sure the SX mount may have a little extra on it that could cause problems on a pentax camera.

[newton]

Yep. I have to return the SX 55 mm 1.4 bc of that extra non circumcision. My non SX is the one with the yellow 'coat'.

[estudleon]

1- The SX version is the last serie of M42 mamiya's lenses. In some lenses the sx have a different schame (F,e. in the 2,8/135 or in the case of the 200 mm lens too).

In the 1,4/55 lens, both have the same formula. They are the same lens. The difference is the coating.

2- If you see the yellowing cast looking the lens at reflection, the yellow is the coating (at the time the coating seems to be reflecting yellow and purple, to benefict the transmission of the blue and green waves).

3- And if the yellow cast is transmitted to the image (looking thru the lens the white things that there are behind the lens are seeing yellowish too), it's a radiactive lens.

4- Theoretically, the SX is the best of both and with great resale value.

Rino.

[newton]

Oh GREAT! Thanks this is exactly the clarification I was seeking.

My SX 1.4 has a lip that needs to be shaved off, because it jams the f-stop. It is crystal clear both on view and for white tables in pictures, for example. The non-SX fits right but is producing the yellow tinting, as you say due to radioactivity. It does have a yellowish coat but I think it goes beyond that.

All Mamiya's do have a unique quality about them.