yellowing lens

[rob spence]

Hi

I've been given a cooke kinetal 50mm prime. Unfortunately the lens has yellowed, I've been told that this is due to some sort of radiation action within the glass. Does this means that the lens is now scrap or can it be rectified?

Thanks Rob Spence.

[Freya Black]

Hi

I've been given a cooke kinetal 50mm prime. Unfortunately the lens has yellowed, I've been told that this is due to some sort of radiation action within the glass. Does this means that the lens is now scrap or can it be rectified?

Thanks  Rob Spence.

<{POST_SNAPBACK}>

 

How bad is the yellowing? Maybe any colour casting could be timed out in post?

I'm sure it could be used to some creative end either way!

 

love

 

Freya

[Robert Hughes]

I've heard similar reports of Som Berthiot Pan Cinor lenses yellowing from radioactive decay also. I have a Pan Cinor zoom, it's got a yellow cast, and it's not too sharp either, but that may just be the primitive zoom optics. Other than replacing all the glass elements, you're probably out of luck. Shoot a test and let us know your results.

[Dirk DeJonghe]

Probabaly the Canada balsam used to glue glass element together yellowing. Quite common in older lenses. I don't know if the glue can be unglued and redone.

 

You need to talk to a qualified lens technician.

[Stephen Williams]

Hi

I've been given a cooke kinetal 50mm prime. Unfortunately the lens has yellowed, I've been told that this is due to some sort of radiation action within the glass. Does this means that the lens is now scrap or can it be rectified?

Thanks  Rob Spence.

<{POST_SNAPBACK}>

 

Rob,

 

I have used a very yellow Cooke Speed Pancro 75mm lens! Its still a great lens and you don't need to use an 85 filter! You should test the lens, However I am sure that you will be able grade out the yellow by printing or in telecine.

 

Good Luck

 

Stephen Williams DP

Zurich

 

www.stephenw.com

[Jack Honeycutt]

Hi

I've been given a cooke kinetal 50mm prime. Unfortunately the lens has yellowed, I've been told that this is due to some sort of radiation action within the glass. Does this means that the lens is now scrap or can it be rectified?

Thanks  Rob Spence.

<{POST_SNAPBACK}>

Here is a fix:

 

http://www.hermes.net.au/bayling/repair.html

 

jack

[Guest Ian Marks]

I have an older Nikkor lens which, as I understand, employed special "radioactive" glass in some of its elements to achieve its high speed. When I got it it had the same kind of yellowing you describe. I did some research and found out that this was fairly common for high speed lenses of its era - it doesn't effect anything except color rendition. The best advice I got was to leave the lens in a bright, sunny place. After a few days, I saw a noticeable reduction in the yellow cast. You might give it a try - it's free!

[Robert Hughes]

Jack's link to the Brian Ayling site demonstrates the modern precision adjustment options available to the serious lens enthusiast. By the way, it also looks appropriate for varying the width of older anamorphic lenses.

 

But no adjustment may be necessary. If the only problem with the lens is color cast, shoot a grey scale at the head of your roll and your post house will work around the yellow cast, just as it would any other filter.

Edited April 14, 2005 by Robert Hughes

[rob spence]

Thanks chaps,

I think I'll try Ian Marks idea of leaving it in a sunny place.

I'll post it to the Bahamas and see what happens!