Bloomed lenses

FallisPhoto

FallisPhoto

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Today is the second time I have run across a thread here asking how to clean off the oil-slick-like deposit on a lens. DON'T! That "oil slick" is called "bloom" and it is desirable. It is a type of tarnish or oxidation that develops on some lenses; it takes years. Bloomed lenses are what inspired people to develop modern lens coatings. Bloomed lenses have increased light transmission and contrast and, prior to the development of artificial coatings, were in seriously extreme demand. It used to be that a bloomed lens could sell for 100 or more times the price of a plain glass lens. These days it still at least doubles the value, and yet occasionally I'll run across a thread somewhere recommending everything from acetone to metal polish for getting it off of glass. Anyway, if anyone here is wondering what the heck to do about that irridescent stuff on their glass, the answer is: defend it to the death.
 
This phenomenon has been discovered by astromers during the XIXth century. They wanted to know why brand new XIXth century telecopes could not match the perfection from very older ones, like XVII or XVIIIth century. And then they saw this thin layer of oxydation on the glass that has appeard on the older ones, that gave better optics.
 
What people are using metal polish and acetone to remove is fungus, which is harmful. I've never heard of blooming, is that something that only happens to uncoated lenses?
 
I have an Isolette with this "blooming" - it does look like a faint oil slick, makes the glass look dull or un-polished (but it's smooth when the light catches it). It didn't come off with Eclipse fluid and a lens cloth, so I left it. I thought it was deposits from evaporated lube or something, I shall have to re-investigate the possibilities of that camera :)
 
Chriscrawfordphoto said:
What people are using metal polish and acetone to remove is fungus, which is harmful. I've never heard of blooming, is that something that only happens to uncoated lenses?
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No, what I am talking about is something that looks like a faint oil slick, multicolored and kind of irridescent. It is absolutely not fungus (which looks nothing like that) and it is what the people I am talking about have described removing from their lenses. As Mael says, it was originally discovered in the early 19th century, when some astronomers noticed that their older telescopes outperformed the new ones -- by a lot. Then they noticed the bloom.

Here is an article about a series of cameras sold with bloomed lenses. http://www.photomemorabilia.co.uk/Ilford/Advocate.html

Here is a photo of a bloomed projection lens:
ross45inul6.jpg


You and I are talking about two entirely different things here. Oh, and yes, it only happens to uncoated lenses.
 
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Fallis, I knew you weren't talking about fungus, just saying fungus is the only thing i've heard people doing strange things (like using metal polish) to remove. I've never seen blooming on a lens. Does it only happen on uncoated lenses?
 
I have seen blooming and once seen it is not easily missed. It kinda has a metallic sheen to it and looks quite unlike anything else (such as fungus, oil stains etc.)
 
i've seen it on some large format lenses. i must say i never knew they would sell lenses as such though (the one you pictured) where it is actually labeled "bloomed". crazy!
 
enochRoot said:
i've seen it on some large format lenses. i must say i never knew they would sell lenses as such though (the one you pictured) where it is actually labeled "bloomed". crazy!
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Not as crazy as it may seem - the discovery of blooming may have been accidental, but by the twenties, several manufacturers had developed chemical or polishing processes which could create controlled blooming. That was a rather short-lived phase, though - after WWII, the German strategic patents were put into the public domain, and everybody had access to the cheaper, more controllable and more efficient Zeiss vacuum process, and "coating" rapidly beame the new term for that.
 
interesting! things of this nature never cease to amaze me.


sevo said:
Not as crazy as it may seem - the discovery of blooming may have been accidental, but by the twenties, several manufacturers had developed chemical or polishing processes which could create controlled blooming. That was a rather short-lived phase, though - after WWII, the German strategic patents were put into the public domain, and everybody had access to the cheaper, more controllable and more efficient Zeiss vacuum process, and "coating" rapidly beame the new term for that.
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Chriscrawfordphoto said:
Fallis, I knew you weren't talking about fungus, just saying fungus is the only thing i've heard people doing strange things (like using metal polish) to remove. I've never seen blooming on a lens. Does it only happen on uncoated lenses?
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Yes, I know about those. One ignorant college professor made a post years ago calling fungus infested lenses bloomed and people have been picking up on that ever since. The posts I was talking about were ones where they described the irridescent sheen they were trying to remove though. As peterm1 says, once you've seen it, you are not going to mistake it for anything else. Yes, it only happens on uncoated lenses -- and not on all of them.
 
Interesting topic.

I bought a Super Ikonta C (531/2) about six months ago (I think the camera dates from the mid-1930s) and noticed some faint multi-colored patches and spots on the lens as I examined it carefully under a light. I wonder if this lens has bloomed.

Rob
 
Melvin said:
Are uncoated Leica lenses ever bloomed?
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I'd say yes, although I have not seen it personally. I have heard of it happening on old uncoated Summars and Elmars though. Not all lenses can do it. There have to be certain metallic salts present in the glass.
 
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michalski said:
Interesting topic.

I bought a Super Ikonta C (531/2) about six months ago (I think the camera dates from the mid-1930s) and noticed some faint multi-colored patches and spots on the lens as I examined it carefully under a light. I wonder if this lens has bloomed.

Rob
Click to expand...

Could very well be.
 
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