Uncoated lens bloom

[f16sunshine]

Recently I have brought in a trio of Rolleiflex cameras in order to choose one to overhaul and make my daily user.
I've "settled" on an f2.8D in fantastic shelf queen condition.... It's now in for overhaul.

One of the cameras I have is an automat v3 with Uncoated Lenses.
The tech commented that both lenses have developed what he considers to be perfect bloom.

I've read this term before. It is oxidation of the glass surface and is said to help increase contrast as well as having inspired more modern coatings.
What experience do folks have with this?
Does it really improve a lens? How careful must one be with cleaning ?
Do you have a picture of a blooming lens to share?

I've run a test roll and the lens does indeed have excellent contrast considering it's uncoated.

Here is a pic of the "bloom". The blue/green/bronze reflection.
Rolleiflex uncoated Tessar f3.5/7.5cm lens bloom by Adnan, on Flickr

Here is a scan from a wide open test pic upon receiving the camera.
Tmax400 Rodinal 1:50 #5 by Adnan, on Flickr

 

[Larry H-L]

A few of my older view camera lenses have bloom, especially a 300mm f6.8 DAGOR. They seem to work just fine, though I only shoot B&W with them. Someone told me that bloom is somewhat protective, but I don't know why that would be the case?

 

[mpaniagua]

I suppose it means that it works to protect the lens against further oxidations? A layer o oxide will prevent oxidation of the glass below?

Regards


Marcelo

 

[peterm1]

Recently I have brought in a trio of Rolleiflex cameras in order to choose one to overhaul and make my daily user.
I've "settled" on an f2.8D in fantastic shelf queen condition.... It's now in for overhaul.

One of the cameras I have is an automat v3 with Uncoated Lenses.
The tech commented that both lenses have developed what he considers to be perfect bloom.

I've read this term before. It is oxidation of the glass surface and is said to help increase contrast as well as having inspired more modern coatings.
What experience do folks have with this?
Does it really improve a lens? How careful must one be with cleaning ?
Do you have a picture of a blooming lens to share?

I've run a test roll and the lens does indeed have excellent contrast considering it's uncoated.

Yes, naturally occurring lens bloom caused by oxidization was what first gave rise to the idea of artificial lens coating. It was first observed and studied (I think) by German optical engineers before the war when it was realized that older lenses frequently made better images than newly made ones of the same design and people came to understand this was due to the presence of bloom on the older lenses. This led ultimately to the idea that if natural lens bloom could improve image making ability of lenses, applying an artificial coating could as well by improving the transmission of light waves through the lens. This also allowed much more complex lens designs to be implemented improving lens speed and correction of aberrations. This is why early lens designs tended to be limited to a few elements - too many uncoated internal elements meant too much flare etc with consequential image degradation. It was not until after WW2 that coating of lenses became common although I believe some were made before and during the war.

 

[Steve M.]

Some of the sharpest lenses I ever owned were on a 1937 Zeiss Ikonta 6x4.5 folder with an uncoated Tessar, and on a Voigtlander Brillant of about the same year w/ an uncoated Heliar. The uncoated Tessar on my early Rolleiflex was a great lens as well. All these lenses had bloom. Actually, the 5 element Heliar and several other lens designs with more than 3 elements go back to 1900. That's 117 years ago. The 4 element Tessar goes back to around 1900, and the 6 and 7 element Zeiss Sonnar lenses date back to the early 1930's. These are all excellent lenses, and all coatings did for them was increase the contrast (usually too much in my opinion). The main optical advances were higher quality optical glass, and correcting the lenses for spherical aberrations. See link below for info on the development of one of my favorite lenses, the Heliar.

http://www.antiquecameras.net/heliarlenses.html

 

[David Hughes]

Hi,

It was noticed in 1892 by Harold Dennis Taylor* and I hope everyone recognises that famous name; here's a hint Cooke Triplet, Tessar and so on.

It was tarnish that he noticed and it happened naturally as the lenses aged but couldn't be done commercially until the mid 1930's when several people were working on it for different firms. According to the internet (Wow!) it was a state secret until after WW2 but I have seen 1930's magazines with articles about it. (Edit) I've a heap of elderly photographic magazines from 1913 onwards but the heap is about 3 ft. high so I doubt if I could find the article quickly...

Regards, David

* Some sources call him Harold Taylor others call him H Dennis Taylor and the Patents call him H D Taylor; I just hope they are all the same man...

 

[sevo]

One of the cameras I have is an automat v3 with Uncoated Lenses.
The tech commented that both lenses have developed what he considers to be perfect bloom.

Too perfect, if you ask me. Given that the finder and taking lenses have different makers and will not share the glass formula it is surprising that they should develop the same bloom. Chances are that that is a after-market coating upgrade. These were quite popular and accessible in the 1950s.

 

[x-ray]

I owned a Series III 12" Dagor from the 1920's - 30's that had a very nice bloom. I shot thousands of sheets of 8x10 Ektachrome with it for catalogs and It produced beautiful color. It was actually one of my favorite lenses.

There were no issues cleaning it so I wouldn't be concerned.

 

[Novembersierra]

Everything said in the thread is correct, I also have a 1939 Triotar from a Rolleicord that I love and that exhibits nice green/purple concentric circles of blooming.

That said, It was the first ever lens I bought when starting protography (as a student, I could only afford a beat up prewar rolleicord) and as such, moreso than the horrors of ww2, saw what I tried to do to it:
I tested everything on it, from alcohol to acetone to metal polish (blame my young inexperienced mind) but still looks pristine, the scratches I bought it with are still there and - surprisingly - the blooming never came off the front element, so I'm positive it has something to do with glass at a molecular level, given that even my tour de force wasn't able to get rid of it.

I still laugh when thinking about how stupid I was, but the lens is sure clean now.🙂

 

[Erik van Straten]

It is simply great to have uncoated lenses that are blooming. It is, like others have said, a natural coating that protects the lens and improves the optical quality. It looks very nice too.

Erik.

 

[jamin-b]

RFF at its best.. a lot of interesting info and perspective regarding something otherwise completely unknown to me...

 

[wes loder]

flare and element numbers

flare and element numbers

The amount of flare that a lens transmits is usually related to the number of air-glass surfaces, not the number of elements. For example, the Protar series VIIa from 1912 had eight elements (!) but only four air-glass surfaces. The first Protar from 1907-08 had only four elements but the same number of air-glass surfaces. The optical designers at that time kept adding elements in order to improve optical corrections, but did everything they could to avoid adding more air-glass surfaces. One of the reasons the pre-war Sonnars generally gave superior results over double-Gauss designs is that they had only six air-glass surfaces while as a DG design such as a Biotar had at least eight.
Zeiss patented its version of lens coating in 1935, but it was deemed a state secret until the outbreak of the war. Kodak was internally coating lenses by then. Both the Ektra's lenses and the Ektar on the Bantam Special were internally coated. Nippon Kogaku was coating the optics in its periscopes by 1943. So it was a technology that quickly caught on.

 

[Erik van Straten]

One of my Leica I cameras has a blooming Elmar. Superb performer.

Erik.

 

[x-ray]

The amount of flare that a lens transmits is usually related to the number of air-glass surfaces, not the number of elements. For example, the Protar series VIIa from 1912 had eight elements (!) but only four air-glass surfaces. The first Protar from 1907-08 had only four elements but the same number of air-glass surfaces. The optical designers at that time kept adding elements in order to improve optical corrections, but did everything they could to avoid adding more air-glass surfaces. One of the reasons the pre-war Sonnars generally gave superior results over double-Gauss designs is that they had only six air-glass surfaces while as a DG design such as a Biotar had at least eight.
Zeiss patented its version of lens coating in 1935, but it was deemed a state secret until the outbreak of the war. Kodak was internally coating lenses by then. Both the Ektra's lenses and the Ektar on the Bantam Special were internally coated. Nippon Kogaku was coating the optics in its periscopes by 1943. So it was a technology that quickly caught on.

I owned a Protar VIIa and loved the lens. It was a much better performer than any of the Turner Reich convertibles that I've owned. There was a considerable amount of variability in the Turner Reichs and I never got one I thought was as good as the Protat VIIa I had.

 

[wes loder]

The Turner Reich anastigmat was a ten element symmetrical lens in two groups that mirrored each other. The British patent dated to 1895. Four air-glass surfaces.

 

[sevo]

Zeiss patented its version of lens coating in 1935, but it was deemed a state secret until the outbreak of the war.

That has often been claimed, but it is wrong. The application was regularly published on November 1st 1935 - the patent was granted four years later, the then regular grace period (for claiming prior art), that the war happened shortly before the latter is a coincidence. And in the short period between mass production in late 1938 and the begin of the war, there was no export restriction for the lenses themselves.

The patent did not describe enough to allow for direct reproduction - Zeiss kept some parts a trade (not national) secret. This is evident in that German competitors did not get access to it either, not even after Germany began losing the war. It took the German makers even longer to develop something similar but patent free than US and UK makers, as the latter could at least fall back on the published patent documents. Leitz were limited to using a drip coating process (stolen from Oude Delft) in the war period. And Schneider did not fare much better - Zeiss (supposedly grudgingly) erected a Zeiss-staffed on-site black-box coating facility at their subsidiary ISCO when the latter won the bulk contract for aerial lenses from the Luftwaffe, but Schneider/ISCO did not get direct access to coating technology until they reverse engineered it by themselves. The odd wartime coatings made by Schneider themselves were experimental and much below the standards set by Zeiss - I owned one period lens, with the external coating gone and the internal peeling off in golden flakes.

 

[rfaspen]

Is there something we can do to encourage bloom? I have uncoated lenses I kind of like, but maybe I would like them more with bloom?

Gives new meaning to the phrase "a late bloomer".

 

[Erik van Straten]

Is there something we can do to encourage bloom? I have uncoated lenses I kind of like, but maybe I would like them more with bloom?

Gives new meaning to the phrase "a late bloomer".

Maybe there is someone on this forum who knows what causes this blooming. Some lenses have it and others - the same type and the same age - do not.

Erik.

 

[Novembersierra]

How it develops it's a mystery to me. But a word of advice to anyone wondering, not lucky enough to have a bloomed lens: take a good look the Leica lens another gentleman posted above: its still an uncoated lens.

I lined up what I had on the table, the aforementioned Zeiss 75mm bloomed, a 1953 80mm xenotar single coated, a '60 single coated Telexenar, and a modern multicoated 50mm Rolleiflex FW viewing lens (I know don't ask how)

The blooming is faint at most, the difference even with the single coated lenses was pretty big.

I guess its something more about the perceived 'magic' properties that we associate with particular tools than something scientifically measurable. They sure may perform better in few situations than plain uncoated lenses, but I would't lose sleep about it, like reading some posts here might suggest. Don't point uncoated lenses to bright light sources, blooming or not 🙄

 

[Huss]

Here is a scan from a wide open test pic upon receiving the camera.
Tmax400 Rodinal 1:50 #5 by Adnan, on Flickr

Lovely shot. Dang that lens is working well!