Thread: FS: Leica 5cm f2 Summicron in LTM, First Version

For sale is an early Leica Collapsible Summicron 5cm F2 in Leica in Thread Mount. This is a “Hot-Glass” lens that uses thoriated glass. This lens was “sun bleached” to reduce the amount of yellowing in the glass. It was then cleaned and relubed after this process. The optics are very clean for a Summicron of this vintage, see close-ups of the front element. My other Summicron was like wax paper before going to Focalpoint. Cosmetically it is in EX+ condition.

This lens would be perfect for black and white film, or for the new M9 monochrome. On a color camera, it will produce a slight yellow cast which can be corrected using color-balance. Thoriated glass was used for its low-dispersion properties: the Infrared Focus index for this lens is within the F2 DOF marks. Not an “APO-Summicron”, but it does not get much better than that.

Price: $540 shipped within the United States, $565 anywhere else via International Priority Mail. Paypal, Personal Check, Money Order. I reserve the right to hold shipment until check/MO clears. Return policy: returns must be made within 10 days, refund for the price of the item will be given after receipt. Postage cost is not refundable. Front cap and plastic rear cap included. If you need an IR cut filter for use on an M8, I will include one for an extra $30.

Beauty!!

I've read somewhere something about "hot" glass. What makes it "hot"?

"Hot Glass", as in --- Radioactive ---

This lens, and others such as the Pentax 50/1.4 and Canon 58/1.2, use "thoriated glass"- Thorium Oxide. It is slightly radioactive, an Alpha emitter. If you leave it Face down on photo-sensitive paper, it can darken it after a day or so. Not dangerous, just do not smash it into dust and breathe it in.

Thoriated glass has very low dispersion, and this lens is highly color corrected. Well enough that the Infrared focus index is within the F2 depth of field marks. That is exceptional for an "achromat", the new APO is better- bit at 12 times the cost of this lens.

Radioactive!! That's quite interesting!! Thanks for the explanation.

The radioactivity will cause the glass to yellow over the decades. This yellowing can be bleached out with UV light, or sunlight. This lens was sun-cured. My other Thorium Summicron was dard-yellow before going to Focalpoint.

NEVER do anything like this:

Brian Ayling's photographic repair tips

The only way this glass can be harmful is if you ingest it. Don;t eat it, do not smash it into fine dust where you can breathe it in.

I think he means Lanthanum glass. It appears to be radioactive too.

Originally Posted by Brian

The radioactivity will cause the glass to yellow over the decades. This yellowing can be bleached out with UV light, or sunlight. This lens was sun-cured. My other Thorium Summicron was dard-yellow before going to Focalpoint.

NEVER do anything like this:

Brian Ayling's photographic repair tips

The only way this glass can be harmful is if you ingest it. Don;t eat it, do not smash it into fine dust where you can breathe it in.

What a sad end to a fantastic lens, shame!!! and kinda awkwardly funny too.

Someone buy this glass! Brian only has the best in equip.

Lanthanum glass will not yellow, or at least not within our lifetime.

I do have a lot of camera equipment- been collecting it since I was a teenager. Of course, some of the stuff that I bought when just introduced is now "antique".

Does that make you an antique too Brian? :D

I would love to try this lens but alas I will look on it from afar as I enjoy most works of art.