[Fixcinater]

Had found these laying in a pawn shop's case about 6 months ago, and have been beating the owner down in price. The 135 included the correct hood, and a Takumar rear cap. The 55 had nothing for accessories. Both have a small amount of paint wear on the fluted focus ring, but the glass is clean throughout, and I paid $70 with tax, in California.


I figure it's an OK deal, not great, but OK. My question is: Was the Super Tak 55mm f/1.8 ever similar to the 50mm f/1.4 with the yellowing elements? Mine sure looks yellow compared to the S-M-C 35mm f/3.5 and Super Tak 135mm f/3.5 that I have.

[jamesk8752]

(snip) My question is: Was the Super Tak 55mm f/1.8 ever similar to the 50mm f/1.4 with the yellowing elements? Mine sure looks yellow compared to the S-M-C 35mm f/3.5 and Super Tak 135mm f/3.5 that I have.

I'm pretty sure that the S-T and SMC-T 55/1.8 lenses did not use the thorium-contailing rear element (which was subject to yellowing on aging) that the 50/1.4 lenses did. What you are interpreting as yellowing may just be a reflection from the coating. Try holding the lens over a piece of white paper and look at the paper through the lens - the paper should appear to be the same color seen through the lens as seen outside it.

Regards, Jim

[raymeedc]

The 55 did not have the "radioactive" yellowing element of the 50. The coatings on the Super can appear slightly golden when compared to the "bluish" coatings of the later Super-Multi-Coated versions though.

[séamuis]

are you sure? my SMC 55 sure seems to have a little yellowing. in fact all of my 55's seem to have some yellowing. I can actually see the colour shift in the viewfinder of my istD.

[raymeedc]

are you sure? my SMC 55 sure seems to have a little yellowing. in fact all of my 55's seem to have some yellowing. I can actually see the colour shift in the viewfinder of my istD.

I'd always heard that it was only the 50 that had the "radioactive" element. I could be wrong, of course. Maybe someone with better absolute evidence one way or the other will chime in with the definitive answer.

[Fixcinater]

My GF just picked up a Spottie with S-T 50mm f/1.4, so I'll compare that to the S-T 55mm f/1.8 I also just picked up.

There was also a 135mm f/3.5 Auto Tak in the set (along with a surprise S-T 85mm f/1.9 that snuck it's way in there somehow) so I'll do a comparo with the S-T 135mm f/3.5 that I have as well.

Now I just could use a 20-24-28mm for a bit wider angle on life and I'm done collecting Taks. I'm thinking AF would be nice for the next thing I'd need (300+mm).

[raymeedc]

(along with a surprise S-T 85mm f/1.9 that snuck it's way in there somehow)

Quite a fortuitous bit of luck, as that's a relatively expensive, much coveted, great lens..... nice unexpected surprise!

[Fixcinater]

Quite a fortuitous bit of luck, as that's a relatively expensive, much coveted, great lens..... nice unexpected surprise!

It actually was in the name of the listing, it'd be hard to have such a big case/lens be a surprise. I'll be putting some results up in the Tak club thread once I've shot with it a bit and hopefully can do it justice.

[MattGunn]

I have the Super Tack versions of the 50mm f/1.4 and a 55mm f/1.8. They were both yellow when I got them, the 1.4 was a bit worse but they both have about the same level of radioactivity as measured with my cheep geiger counter. It appears that it is the rear lens element that is radioactive so if you intend to leave one in the sun for UV treatment then it should have the back end facing up.
The thorium was added to the glass to raise the refractive index and lower the dispersion of the glass so these lenses used the LD glass of their day. The radioactice decay slowly turns the glass yellow but UV treatment anneals the yellowing out of the glass turning it clear again. The type and level of the radioactivity from these lenses is not really dangerout but it's best not to keep one in you pocket for long periods...
I also have the 135mm f/3.5 and the 300mm f/4 and neither of these are radioactive.

[séamuis]

so then I wonder how many lenses Asahi optical manufactured with thorium? and why only the 50 1.4 is known today to have included it? I knew I wasn't seeing things with my 55's and that they indeed have some yellowing. very interesting info. I wish I had some more information oh Asahi Optical's use of this element in its lenses.

so then I wonder how many lenses Asahi optical manufactured with thorium? and why only the 50 1.4 is known today to have included it? I knew I wasn't seeing things with my 55's and that they indeed have some yellowing. very interesting info. I wish I had some more information oh Asahi Optical's use of this element in its lenses.

For sure my M42 35mm F2 is another design with radioactive glass and it was quite yellow when I bought it. Of course the vendor "forgot" that detail and the tint in the demo pictures they send me was mistaken by me for a bad WB in difficult conditions.

Radu

[Fixcinater]

RaduA, so you consider it a bad thing?


I'm considering leaving it as-is on both/all the lenses. AWB on digital takes care of it if I don't want to see the tint, and I've made comparisons to "correct" lenses and if anything, I like the tint it adds. I would be interested in getting back any lost light throughput though...I want f/1.4 to be f/1.4.

[séamuis]

RaduA, so you consider it a bad thing?


I'm considering leaving it as-is on both/all the lenses. AWB on digital takes care of it if I don't want to see the tint, and I've made comparisons to "correct" lenses and if anything, I like the tint it adds. I would be interested in getting back any lost light throughput though...I want f/1.4 to be f/1.4.

I haven't really noticed any downside. personally, I think it adds a bit of character (can a lens have character?) I imagine there will be some light loss due to the yellowing.. but light loss will occur from lack of a proper multi-coating so no big deal there... at least for me. I haven't attempted to bleach any of my yellowed lenses. and I don't imagine I will at any point in the future.

does anyone know when Asahi Optical started using the element? like in which lenses they first appeared in? I really wish I could get my hands on that 'Ultimate Screw Mount Guide'.....

RaduA, so you consider it a bad thing?


I'm considering leaving it as-is on both/all the lenses. AWB on digital takes care of it if I don't want to see the tint, and I've made comparisons to "correct" lenses and if anything, I like the tint it adds. I would be interested in getting back any lost light throughput though...I want f/1.4 to be f/1.4.

Anthony, I wanted removed because although fixable by custom WB it was both pretty heavy and IMO cut a part of the light that reach the sensor. A friend of mine (electrical engineer) built me an industrial UV source and it was crystal clear about 1 day latter (10-12 hours of exposure to the UV). The advantage besides short time is that the lens wasn't heat up too much (could leak the lube from the aperture blades) neither exposed to dust and elements.

The irony is that I bought the DA35Ltd soon afterward and the old Tak never seen too much action anymore. I think I'll try to find it a better home soon ...

Radu

[richard64]

are you sure? my SMC 55 sure seems to have a little yellowing. in fact all of my 55's seem to have some yellowing. I can actually see the colour shift in the viewfinder of my istD.

I have an early version of the Super Takumar 55/1.8 (the aperture ring is 1.8 to 16 and in the 'wrong' direction, that is turn it away from the A/M switch to open up the aperture as opposed to all later pentax lenses where you turn the aperture ring towards the A/M switch to open up the aperture). It must be more than 45 years old. Looking through it at white paper, I can hardly see a difference, the paper is white. Looking obliquely at the front element I see a slight straw colour.

Richard