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Material of Lens Body / Anodizing possible?
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PostPosted: Mon Nov 24, 2008 1:06 am    Post subject: Material of Lens Body / Anodizing possible? Reply with quote

What is the material that is used for the MF lens bodies?

I have access to anodizing facilities, and i need to strip 1-2 lenses.
Is the lens outer body suitable for anodizing?


PostPosted: Mon Nov 24, 2008 5:51 am    Post subject: Reply with quote

As the metal in barrels are usually very soft, and manufacturers often have to give corrosion a thought when designing and planning a lens body I'd guess its plain low carbon construction bar steel with a higher content of Zn and/or Sn. To stop the exposed surfaces from "breathing" the softer metals and surfacing a high-friction film onto the exposed parts, a few percents of chrome and/or vanadin might be in the mix too, to stabilize it a bit. Most outer barrels that I've seen up close are casts with surfaces with low dimensional tolerances reamercut or milled afterwards.

And do consider that this is just an informed guesstimate...!

For dye anodization... nah. Maybe. You might get a very uneven dye coverage depending on the quality of the cast. But just try, you won't break anything... Smile
For plating anodisation, no problem. Just don't build the surface to far, you might get refitting problems or "freezing stick" in cold weather due to the small tolerances normally involved in lens-making... Glass-blast the visible surfaces, and don't polish before treating.

Please repost to this thread if you manage to get it to work Very Happy


PostPosted: Mon Nov 24, 2008 10:21 am    Post subject: Reply with quote

I do not own a single steel or iron lens. Most lenses are from brass or aluminium alloys. Pure, hardened aluminium did not get mass-produced until the thirties, and was restricted to aircraft for quite some time. All earlier aluminium lenses and much that was made from scrap metal in Germany and Japan throughout the earlier fifties contain a considerable amount of magnesium.

Brass lenses can't be anodized, but quite safely chrome or nickel plated if the original plating has worn off. Only reasonably pure aluminium ("Duraluminum") can be (and usually already is) anodized, while many AlMg alloys are damaged or destroyed in the process, so be careful and try with replaceable parts first...

Sevo


PostPosted: Mon Nov 24, 2008 10:08 pm    Post subject: Reply with quote

Sevo wrote:
.....contain a considerable amount of magnesium.

Sevo


Presumably that explains why so many of the early "silver" lenses are often obtained in a badly corroded condition.


PostPosted: Mon Nov 24, 2008 10:17 pm    Post subject: Reply with quote

Are we talking about anodization deposition powder laquer or chemical transfer or plating btw?

Regarding materials: Thanks for the heads-up regarding Mg having problems with anodization. I find it kind of surprising though, quite a lot of my downhill MTB parts are anodized DurAl with 1.4-1.6% Mg content according to the manufacturer.

Zeiss / Cosina use anodized Dural in their newer lenses according to spec. Some Contarex's were pure brass/chrome. Other manufacturers are quite tight-lipped about the materials they choose...
At least a few of the lenses that I've done drilling or abrasive surgery on has had magnetic filings. None has had brass coloured filings (in the outer tube - many have pure brass secondary helicoids). No outer tube has shown destructive reactions to cleaning in ultrasonic alkalid baths, which I use for cleaning "bodies" when I clean/relube a lens.


PostPosted: Mon Nov 24, 2008 10:54 pm    Post subject: Reply with quote

Minor amounts (around 1-2%) of magnesium or copper are present as structural modifiers in just about any common aluminium alloy.

Old lenses however may have as much 20-60% Mg contents, for several reasons - early on (between 1900 and 1930) aluminium was expensive and early hard alloys could not be handled with tools set up for brass or cast zinc. After that, better aluminium alloys became more common (at any rate on Zeiss lenses), only to disappear again in and post WWII, when high magnesium alloys again became popular.


PostPosted: Mon Nov 24, 2008 11:11 pm    Post subject: Reply with quote

the_Suede wrote:

At least a few of the lenses that I've done drilling or abrasive surgery on has had magnetic filings.


Mamiya use steel as the front ring material on their MF lenses, and so will probably many others - threaded brass and aluminium don't mix well, while neither brass nor aluminium filters will freeze onto steel threads. And it is all over the place in couplers, pins, washers and the like, but I've yet to encounter steel lens body tubing.

And dimension critical components (like helicoids, aperture actuator rings etc.) may be made of low thermal coefficient alloys - which can be magnetic thanks to a high nickel content.


PostPosted: Tue Nov 25, 2008 4:35 am    Post subject: Reply with quote

I'm not doubting anything you say, I'm just a bit surprised... ANYTHING based on high-copper alloys or Al-based alloys has a tendency to go imitating a "cheese-cracker" in physical stature when confronted with high-concentration soda, heat and ultrasonic "massage"... Even if the crackelation of the protective surface treatments is microscopic. And this hasn't happened to me once, yet (with lensbarrels, that is...). I've ruined a few other small mechanical parts not connected to photography, but... All in a days work. Very Happy

Hopefully hk300 is talking about EM powder coating and baking, so this discussion will be moot, but interesting anyway... Smile

Did you say 60% Mg???!!! that's almost combustible Shocked


PostPosted: Tue Nov 25, 2008 12:44 pm    Post subject: Reply with quote

the_Suede wrote:


Did you say 60% Mg???!!! that's almost combustible Shocked


LOL ...
My lens will be gone after baking it ...


PostPosted: Tue Nov 25, 2008 1:01 pm    Post subject: Reply with quote

the_Suede wrote:

Did you say 60% Mg???!!! that's almost combustible Shocked


Right. The material on the non-brass Voigtländer Heliars in the 1910-1920 range would better be called a magnesium alloy. And it won't be a Ersatz phenomenon, as the earliest Heliar of that composition which I own dates back to 1911 by serial - I guess they chose it because of weight considerations (the new brood of large aperture lenses like the 4.5 Heliars were taxing the stability of the then common press strut folders that were their main market) and because they could not machine the then available aluminium rich alloys.

Sevo


PostPosted: Thu Nov 27, 2008 7:27 pm    Post subject: Reply with quote

Alu and brass blackening is possible with guns blueing and blackening products containing selenium dioxid (very poisonous) i.e. from birchwood casey products line . It actually works .... I'd never tested it on lens mounts , but on non-iron gun parts (brass, alu alloys of gun sights)


PostPosted: Tue Jun 01, 2010 12:03 pm    Post subject: Re: Material of Lens Body / Anodizing possible? Reply with quote

hk300 wrote:
I have access to anodizing facilities, and i need to strip 1-2 lenses.
Is the lens outer body suitable for anodizing?


This is an old thread, but did you ever try anodizing any of your lenses? I'm curious to see how they turned out if you did. Very Happy