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Konica Hexanon 40/1.8 weird color
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PostPosted: Sat Jan 13, 2024 6:43 am    Post subject: Reply with quote
It might have been left under a powerful UV lamp too long, but I've seen this with anodized aluminium and I have a lens or two kicking around with a similar purple tinge.


PostPosted: Sat Jan 13, 2024 7:30 am    Post subject: Reply with quote
Still strange:
Paint wear all around (and inside) the lens. I’ve never seen wear to this extent (or even close) on a hexanon before. If this was a typical thing to happen to Hexanon lenses, you’d expect to see it more often. To me, this looks like some deliberate action from a previous owner, maybe with the use of sun- or other uv light.


PostPosted: Sat Jan 13, 2024 9:51 am    Post subject: Reply with quote
BrianSVP wrote:
The black chrome was only ever used on the camera bodies, not on the lenses themselves, which by the time the black nickel chrome was introduced were all anodized aluminum.

RokkorDoctor wrote:
E.g. from memory I read somewhere that Leica also shared their black chromium finish procedure with Minolta).


Yes I knew it was only used on the camera bodies. What I meant was that since Leica shared their procedure for the black chrome finish with Minolta, they may also have shared their formulation for the black dye _they_ used in anodising. The later Minolta lenses seem to be less prone to dye fading than the older ones from before the Leica collaboration. This may well be just a coincidence, but I have plenty samples to have noticed a difference.

BrianSVP wrote:
...
Most people don't realize that all black dyes have a base color undertone. You might have noticed this if you ever have accidentally gotten chlorine bleach on a black garment, leaving bleach spots that aren't gray or white, but some other color. In the case of the 40mm, the undertone of the black anodizing is bronze, which is revealed as the black fades. In the 50mm f/1.4 below, the base color is blue.
...


It is still worth noting that the black anodised finish is a very durable one compared to black paint. Many 50+ year old anodised lenses still look like new, whereas painted lenses of that vintage often show scuff marks and paint chips.

The one caveat is salt water damage. Leave sea water to dry on the lens and the salt residue will wreak havoc on the anodised finish and aluminium underneath; paint offers a better protection there.


PostPosted: Sat Jan 13, 2024 10:07 am    Post subject: Reply with quote
BrianSVP wrote:
The dyes used to anodize aluminum are not substantially different from the ones used to dye clothing. The freshly anodized surface is porous and absorbs the dye, and then the pores are sealed either through heating (boiling/steaming), which closes the pores, or with a nickel acetate or similar sealant. While chemical sealants provide some degree of protection to the color, even they don't block 100% of the UV in sunlight, which will bleach out the color in exactly the same manner it does your bedroom curtains.

Color loss can also be caused by alkaline environments, which gradually break down the oxide anodized layer, allowing the pores to reopen and the colored dye to physically wear away. This is essentially a slo-mo version of the lye dip typically used to strip an existing anodized layer prior to re-finishing.

These Konica 40mm lenses contain a substantial amount of plastic, not just the aperture and name rings, but also portions of the helical. In order to bake it and not melt them, you'd have to strip it down to individual components, and bake them individually, in which case, you wouldn't see the two-tone fading as you do on the front barrel.

You're barking up the wrong tree here. Occam's razor says it's almost certainly the simpler solution - environmental factors caused this fading, either UV/sun light (more likely) or exposure to alkalinity (less likely, since there isn't evidence of other corrosion).

kiddo wrote:
Few years ago I've seen a guy baking some black anodized flashlights, same color result and changing , depending on the temperature and time exposed
https://www.reddit.com/r/flashlight/comments/ccsgdu
https://www.reddit.com/r/flashlight/comments/ccsgdu/before_and_after_heat_treated_s2/
I can believe sun light heat can change colors in many items , but regarding anodized aluminum it requires lot of heat as far as I've read
https://budgetlightforum.com/t/fw3a-mod-thread-post-yours/56663/9


I've seen the same procedure applied to get this results with spots of original black anodized ,like zebra type etc, the thing is to protect the part you want to avoid changing colors , and it will get that result.


PostPosted: Sat Jan 13, 2024 2:36 pm    Post subject: Reply with quote
kiddo wrote:
I've seen the same procedure applied to get this results with spots of original black anodized ,like zebra type etc, the thing is to protect the part you want to avoid changing colors , and it will get that result.


So maybe that guy has applied heat by means of IR (=infrared light)? In any case - even with infrared light - it would be pretty difficult (if not impossible) to heat a selected area without affecting the remaining area of a single metal part.

I'll make some experiments and report the results.

S


PostPosted: Sat Jan 13, 2024 3:24 pm    Post subject: Reply with quote
In fact he covered part of it, to change color only on specific area (I don't remember what did he use to cover it up) but I do remember the procedure itself was very easy to do and he has only used the oven no infrared light ,he's been doing customized flashlight and to be honest, they were pretty different than standard black or grey anodized (multiple colors possible depending on the heat applied) , but also on stainless steel to get the rainbow color (also titanium if I remember correctly)
Some people did mention the strength of the anodizing wouldn't be the same, but I don't think anyone ever did test to check it out neither
Covering up part of that ring, would allow a certain transition from black to final color, and that transition color might not be neither black neither final color , it depends ( I don't think there was a 100% science knowledge he was applying just try different stuff, probably because different sell better lol)


PostPosted: Sat Jan 13, 2024 4:00 pm    Post subject: Reply with quote
I remember seeing a Xenon 50mm f1.9 like that. And some others.


PostPosted: Sat Jan 13, 2024 6:12 pm    Post subject: Reply with quote
kiddo wrote:
... he has only used the oven no infrared light ,he's been doing customized flashlight and to be honest, they were pretty different than standard black or grey anodized (multiple colors possible depending on the heat applied) , but also on stainless steel to get the rainbow color (also titanium if I remember correctly)


OK - I made a short experiment:

1) Nikon 52mm UV filter with black anodized aluminum parts.
2) Glass removed
3) Put it on a 1.5kw heating (cooking) plate (IR LED) and turn it on
4) after roughly 30 s the parts directly irradiated areas quickly start to loose the black color:



5) Applying intense heat / IR radiation for another maybe 30 s results in futher bleaching:



Not surprisingly, the originally white color in the enravings now has turned black, as a result of the head (probably some organic stuff turned black).
So it's clear that heat treatment / IR radiation can bleach the black anodized aluminum really easily if high temperatures are applied (well above 100°C, probably more like 250°C).
We still don't know how it was possible to have the exposed part of the 1.8/40mm front ring to be blached while the hidden/protected part remained black. After my trials I'm still leaning towards radiation (IR? VIS? UV?) as the cause of the bleaching of the above AR 1.8/40mm ...

S

EDIT: the color change from silver => dark yellow => brown => dark brown => black is typical for coloring anodized surfaces by addition of tin(II) sulfate (=> embedding of tin(II) sulfate into the oxide layer).

Pure tin(II) sulfate (SnSO4) is oidizing/decaying rapidly at about 360°C, resulting in tin(IV)oxide (SnO2) while loosing SO2 ... this would also explain the loss of color while heating a colored sample. Of course when embedded in the oxide layer of aluminum the decay temperature may be lower.

Mystery at least partly solved ...


PostPosted: Sat Jan 13, 2024 7:49 pm    Post subject: Reply with quote
stevemark wrote:
OK - I made a short experiment:

1) Nikon 52mm UV filter with black anodized aluminum parts.


Somewhat costly experiment~ especially if one intends to replace with new in box. Retail on these is a bit on the stiff side. I've resorted to getting almost all of mine used, or on used lenses.

-D.S.


PostPosted: Sat Jan 13, 2024 8:19 pm    Post subject: Reply with quote
Doc Sharptail wrote:
stevemark wrote:
OK - I made a short experiment:

1) Nikon 52mm UV filter with black anodized aluminum parts.


Somewhat costly experiment~ especially if one intends to replace with new in box. Retail on these is a bit on the stiff side. I've resorted to getting almost all of mine used, or on used lenses.

-D.S.


OOPS ... didn't know that Wink - which means I now have to extend the experiment and re-anodize the metal parts (nothing was destroyed; the filter has been re-assempleed already).

S


PostPosted: Sat Jan 13, 2024 10:36 pm    Post subject: Reply with quote
that was tokina's attempt to support 2nd wave of feminism and introduce empowerment for female photographers by secretly coloring (anodizing) some of those 40mm lenses.


PostPosted: Sat Jan 13, 2024 10:59 pm    Post subject: Reply with quote
There have been "anniversary " and award editions...


PostPosted: Sat Jan 13, 2024 11:18 pm    Post subject: Reply with quote
why don´t you try 2 filter rings screwed inside each other, to check if the thread would get colored or not?
what about using aluminum foil tp cover part of it?


PostPosted: Sun Jan 14, 2024 12:20 am    Post subject: Reply with quote
kiddo wrote:
why don´t you try 2 filter rings screwed inside each other, to check if the thread would get colored or not?
what about using aluminum foil tp cover part of it?


Simply because the dual-color front ring shown in the image of hte AR 1.8/49mm is ONE peace of metal, not two.
Now it's up to you to prove your assumptions - you can put an AR 1.8/40mm in your oven and show us how it works Wink

S
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