Schneideritis?

[Nathan Potter]

Nathan, my Boyer lenses with severe boyeritis have brass barrels, not aluminum.

Dan, what does boyeritis look like from brass? I wouldn't think it would be whitish like "schneideritis". Of course you can't have "schneideritis" on a brass lens plus I've never heard of "boyeritis".

Has anyone ever had "rodenstockitis" of "fujiitis"?

Nate Potter, Austin TX.

[Dan Fromm]

Nathan, boyeritis looks exactly like schneideritis. It is the same thing. What's wrong is your theory that it is due to corroded aluminum barrels.

I'm sorry that you've never seen boyeritis. Have you ever seen a Boyer LF lens?

[Leigh]

Has anyone ever had "rodenstockitis" of "fujiitis"?

Yes for Fujinon, though not nearly as common as for Schneider lenses.

I've never heard of nor encountered a similar problem with Rodenstock lenses.

- Leigh

[Leigh]

Nathan, boyeritis looks exactly like schneideritis.

How can a cosmetic defect on a brass barrel look exactly like a cosmetic defect on an aluminum barrel?

Or are we talking solely about black&white photos of the defect?

- Leigh

[Nathan Potter]

Yes Leigh, I'm still trying to understand why the appearance would be the same when the base metals are entirely different. Unless the effect is solely from the paint or the anodic film if that is used. The oxides of copper are usually reddish to blackish. Of course the chemistry could be more complex than just an oxide.

But looking at the schneideritis under a microscope the tiny blooms appear to pop up from the base metal, although admittedly I can't be wholly certain of that. Just trying to understand the histology of the mess I have with one lens.

Maybe I'll be forced to do a microprobe analysis of a bloom using Auger, on my own dime. I think the lens will survive a high vacuum environment.

Nate Potter, Austin TX.

[Leigh]

Hi Nate,

I wonder if we're talking about the same problem.

The Schneider lenses I've seen with Schneideritis have bright patches of varying size, from quite small to much larger than a pin head.

- Leigh

[hoffner]

Yes Leigh, I'm still trying to understand why the appearance would be the same when the base metals are entirely different. Unless the effect is solely from the paint or the anodic film if that is used. The oxides of copper are usually reddish to blackish. Of course the chemistry could be more complex than just an oxide.

But looking at the schneideritis under a microscope the tiny blooms appear to pop up from the base metal, although admittedly I can't be wholly certain of that. Just trying to understand the histology of the mess I have with one lens.

Maybe I'll be forced to do a microprobe analysis of a bloom using Auger, on my own dime. I think the lens will survive a high vacuum environment.

Nate Potter, Austin TX.

One must know that what you see when looking at "Schneideritis" is the reflection of light between the glass and the air surface who takes place of the detached paint. It is there that the reflection of light takes place. Why the paint detaches from the glass surface is then another question. The outside material, behind this glass/paint layer is not so important. The reflection takes mostly place before the light hits the barrel material.

[Leigh]

One must know that what you see when looking at "Schneideritis" is the reflection of light between the glass and the air surface who takes place of the detached paint.

Absolutely not true in any of the cases I observed.

These were blemishes in the coating of the aluminum, definitely not related to any element edge.

- Leigh

[Dan Fromm]

Leigh, Nathan, if the edge blacking adheres to the glass, as it should, then it will pass no light and corrosion on the inside of the barrel won't be visible from the front (or rear) of the lens.

Nathan, have you removed an affected lens' elements from the barrel and examined them directly or are you looking at the effect through the front of the cell?

[BrianShaw]

... Nathan, have you removed an affected lens' elements from the barrel and examined them directly or are you looking at the effect through the front of the cell?

Good question. I was going to ask both you and Leigh the same thing. As for me... I've only looked at Schneideritis from the front of my lenses when setting the shutter so my theories are extremely limited.