5cm Summicron 1023xxx serial number coating color.

[kknox]

I have three 50 Summicrom lens from the late 50's & early 60's. I just received a 5cm LTM Summicron serial # 10231xx that has a slight yellow cast to the glass. I have seen this before is it the coating or the type of glass they used? The coating is not damaged.

[ferider]

An early version with radioactive glass.

[kknox]

So I need to call the haz-mat crew to come over and take it from me. No not really, will my color pics take on a yellow cast?

[Brian Sweeney]

The early Summicrons used Thorium Glass, including in the front element. You can "bleach it out" with a UV light, or direct sunlight. You need to set it in light for a few days. Sunlight will make the lens hot, and bake the grease. Make sure the exit of the glass is covered in foil to prevent the suns rays from setting something on fire. I had a friend that set some optics in the basement window and started a fire. He put it out before it got out of hand.

The pictures will take on that yellow cast. Great for B&W. If you are not interested in it as a collectible, you might consider trading it or selling it and buying a later one.

[kknox]

Is it a collectable lens? I know its a early Summicron

[Brian Sweeney]

Early Collapsible Summicron on Left, later Collapsible on right.

http://farm4.static.flickr.com/3064/2641110604_a1526288d3_o.jpg

And yes- collectible. It's the first generation Summicron, used RADIOACTIVE glass, and uses Commas instead of decimal points in the F-Stop numbers...

It usually carries a ~$100 premium over a similar condition lens. You might want to see if someone wants to trade a mint glass Summicron for it. Or: do what I did, bleach the Yellow out and shoot with it. I received my lens after someone bleached it, but had to relube it.

[benmacphoto]

So I need to call the haz-mat crew to come over and take it from me. No not really, will my color pics take on a yellow cast?

I have one, and did some work with Velvia 50 and the results were very pleasing. A bit of a color cast but it was a nice warm glow. Try it out for yourself to see if you like the way it looks.

BTW the lens is great for black and white work.

[kknox]

Thank's everyone it should be fun to try.

[John Shriver]

Yeah, that almost certainly is an early radioactive one. Mine is 10241xx, and it definitely excites my Geiger counter, and the glass is tea-colored. I tried to bleach it with a UV light, but it was a UV C light, and I think the glass is opaque to that wavelength.

The glass is radioactive because it's 30% or more thorium. Well, some elements are (the flint glass).

It turns brown because that's what ionizing radiation does to glass. They can't use fiber optics in the tunnels at CERN due to this.