Zeiss Tessar

I have a 16.5, f4.5 Zeiss Jena Tessar lens that had a small amount of edge

separation. I read a few articles about separating the elements and re-gluing

them. It was actually very easy to do, I set my oven to 350 and put the lens in

it. About 15min after it reached 350 I used a pair of tongs and was able to

just life one of the elements off the other.

 

After a little cleaning in acetone they came out looking perfect. Using type 61

UV glue and a v-block holder I made I was able to center the elements and glue

them together. It only takes a small drop in the center of the concave surface,

capillary action causes the glue to migrate to the edges. Short time in the sun

and it was set.

 

My question comes from putting the element back into it's brass ring. The edge

of the element looses it's black coating and the brass that holds it in was also

painted black. How important is it to repaint the edge of the lens and the

brass that holds it in?

 

I'm also trying to date the lens, it's a Zeiss Jena Tessar 16.5mm f4.5. Serial

number 623241. Thanks for any tips,

 

Michael

Since the black paint was used to avoid reflecting surfaces inside the lens you should repaint the edge of the lens as well as the brass.

McKeown's camera guide has a table of Zeiss lens serial numbers by year of manufacture. According to this table your lens was manufactured between 1923 and 1924.

 

Ron Gratz

I have used a felt-tipped Sanford Sharpie brand permanent black marker pen to reblacken

the edges of lens elements. It may take several applications to get the edges really black,

but the pen is very easy to control, and the ink should last and not flake off.

hmmm.... I think a Sharpie marker may employ acetone or something similar as a carrier, and

depending on what you've used to glue the elements back together, there may be a problem

with this de-gluing the elements - so maybe be careful using this on the element edges.

Testors makes a nice flat-black paint, available in hobby-shops in small bottles. I've used it

in many of my earlier camera building projects, but not to blacken element edges. Maybe do

a little more research into compatibility issues.

For re-blacking lens element edges and the like, I use a cotton swab (Q-tip) and india ink. Hey, it works...

 

The 16.5cm, f/4.5 Tessar is a nice lens, as you've probably discovered. :)

Thanks everyone, it came out looking great. Edge separation is gone and it looks brand new. I used the type 61 UV optical cement from Edmunds optical.

The black paint on the lens is to seal the glue and to avoid reflections.

The paint on the tubus is to avoid reflections.

The paint was in the early days of lens production (1850 to 1900) a mixture of carbon black (pure carbon) and a animal-

orrigine varnish (annimal skin can be used to produce glue and varnish).

The German company Dick can still deliver the basic products. The varnish is still used in musical instruments.

I probably will find the formula for the lens paint if I look hard in my archive.

By the way, regular black paint will also do.

Succes!