Hoya Pro1 UV, CPL, and 8X ND SAMPLE IMAGES

Lester Wareham wrote in post #2575848
I understand B+W claim the brass they use solves this issue. I have never quite understood why they say that, as having two dissimilar metals in contact is not generally a good idea from the corrosion perspective. I am sure there is logic.

Corrosion needs an electrolyte, like salt water. If you want a really corroded camera, drop it in salt water and sent it in to the repair shop with the salt water in it...no surprise if it cannot be salvaged at all.

If you want a camera that can be salvaged, drop it in salt water, then dunk it thoroughly in fresh water rinses, then send it in after thoroughly rinsed!

Wilt wrote in post #2579026
Corrosion needs an electrolyte, like salt water. If you want a really corroded camera, drop it in salt water and sent it in to the repair shop with the salt water in it...no surprise if it cannot be salvaged at all.

If you want a camera that can be salvaged, drop it in salt water, then dunk it thoroughly in fresh water rinses, then send it in after thoroughly rinsed!

Yes that's right, of course there is some water in the air all the time in most parts of the world. I have not looked up the data for brass and aluminium; it may be their relative potentials are fairly close.

What I was wondering was the rational that brass was less likely to stick than aluminium or whatever. Have you got any idea what that is?

Lester Wareham wrote in post #2579519
Yes that's right, of course there is some water in the air all the time in most parts of the world. I have not looked up the data for brass and aluminium; it may be their relative potentials are fairly close.

What I was wondering was the rational that brass was less likely to stick than aluminium or whatever. Have you got any idea what that is?

Lester, water itself is not an electrolyte. Water in the air is not the issue. I borrowed this from wikipedia...

"Electrolytes are normally formed when a salt is placed into a solvent such as water and the individual atomic components are separated by the force applied upon the solute molecule, in a process called chemical dissociation in which the solution applies force to hold the ions apart. Salts are compounds that are linked by weak ionic bonds, and will separate into charged ions in the presence of a solution containing stronger covalent bonds.
An electrolyte may be described as concentrated if it has a high concentration of ions, or dilute if it has a low concentration. If a high proportion of the solute dissociates to form free ions, the solution is strong; if most of the solute does not dissociate, the solution is weak. The properties of electrolytes may be exploited using electrolysis to extract constituent elements and compounds contained within the solution."

The brass vs. aluminum filter ring issue is that a aluminum left alone will bind to itself a bit better than a dissimilar material like brass. I do have some older lenses whose aluminum filters have gotten somewhat stuck over time (in spite of my deliberate effort not to tighten them down too firmly!)

Wilt wrote in post #2580734
Lester, water itself is not an electrolyte. Water in the air is not the issue.

No but there will be enough trace elements to create free ions enough, if nothing else salt from the owners fingerer tips, but lets not argue about high school physics. It may or may not be an issue.

Wilt wrote in post #2580734
The brass vs. aluminum filter ring issue is that a aluminum left alone will bind to itself a bit better than a dissimilar material like brass. I do have some older lenses whose aluminum filters have gotten somewhat stuck over time (in spite of my deliberate effort not to tighten them down too firmly!)

I am just curious why this should be in terms of the physics.

I am guessing that perhaps it is due to the thin oxide that forms instantaneously on aluminium in air. But as this has the same volume (unlike rust and iron) I don’t see why it should stick.

I guess if you have had aluminium ones stick that is enough. I was always rather doubtful, re the brass, as this never happened to me. My FD stuff has had filters on for nearly 30 years and still comes loose easily.

Lester Wareham wrote in post #2575848
I understand B+W claim the brass they use solves this issue. I have never quite understood why they say that, as having two dissimilar metals in contact is not generally a good idea from the corrosion perspective. I am sure there is logic.

A good trick with a stuck filter is to just put a rubber band around it. You will find the increased grip will get the thing off very easily.

I must say I have never had a single Hoya UV filter on a lens get stuck in over 25 years. It may only be an issue with low profile polarizers where there is very little edge to get a grip.

Lester, let me start by saying I am way over my head on this topic, as I never have studied anything relative to material science. The web is magic, though, and Google 'adhesion' and 'aluminum' found this information in this abstract on a paper found at

http://adsabs.harvard.​edu/abs/2000APS..MAR.B​9006S

(the boldface emphasis in mine, in response to your question)

"One of the most common wear problems is adhesion and related adhesive metal transfer, in which one material transfers to the surface of another material along a heavily loaded interface. It is especially prevalent in the aluminum industry, for example, where thick ingots are subjected to massive loads in numerous hot and cold rolling processes that form the ingot into strip and plate products. One means through which adhesive metal transfer can be reduced is through the application of a ceramic tool coating that protects the tool surface for an extended period of time. "

Wilt wrote in post #2581597
Lester, let me start by saying I am way over my head on this topic, as I never have studied anything relative to material science. The web is magic, though, and Google 'adhesion' and 'aluminum' found this information in this abstract on a paper found at

http://adsabs.harvard.​edu/abs/2000APS..MAR.B​9006S

(the boldface emphasis in mine, in response to your question)

"One of the most common wear problems is adhesion and related adhesive metal transfer, in which one material transfers to the surface of another material along a heavily loaded interface. It is especially prevalent in the aluminum industry, for example, where thick ingots are subjected to massive loads in numerous hot and cold rolling processes that form the ingot into strip and plate products. One means through which adhesive metal transfer can be reduced is through the application of a ceramic tool coating that protects the tool surface for an extended period of time. "

I did get involved in some materials science when I worked on comms satellites many years ago but it’s not my speciality either.

I would think the issues of hot and cold rolling are involving many tones per square inch so I am doubtful about this being the direct explanation. In any event most metals cold weld under sufficient pressure including gold.

I have looked in the past at B+W literature to see if they explained themselves and never found anything. This gave me the impression it may just be hype.

But as so many B+W users are convinced of the benefit I thought they might know the justification.

Thanks for trying but, where is a metallurgist when you need one!

Lester, I know the first time I tried a B+W filter and compared it with an aluminumed ring filter on the same medium format lens, and the ease of removal was instantly apparent with the B+W. I didn't worry about the materials science, I simply knew it worked, and it remains my choice for polarizing filters because of that one experience.

Wilt wrote in post #2587852
Lester, I know the first time I tried a B+W filter and compared it with an aluminumed ring filter on the same medium format lens, and the ease of removal was instantly apparent with the B+W. I didn't worry about the materials science, I simply knew it worked, and it remains my choice for polarizing filters because of that one experience.

As I say I have six lenses nearly 30 years old with Hoya UV filters on all come off very easily. As far as I can see the only problem with the polarizers is the rotating part.

Perhaps the advantage with the B+W's is with some aspect of the mechanical design making it eaier to grip rather than the actual brass construction?