Coated Lenses

[seawolf66]

How is one sure a lens has been coated, was there a specific period of time where all lenses became coated, I have just gotten a bunch of old barrel/brass lenses some glass is very clear and some have a coating like color film to them : example I have a congo F/4.5 210mm K.Yamasaki Tokyo 87398 it has a film like color on it, like when you spill gasoline on water that type of sheen: Thanks for any information

[Robert A. Zeichner]

Coating of photographic lenses pretty much became a standard procedure after WWII. Various manufacturers had their own techniques and so depending on whose lens you look at, there may be a bluish, greenish or amber color color cast to the surfaces. Kodak engraved an L inside a circle indicating the lens was Lumenized. Other manufacturers had different ways of identifying coated optics. Pre-WWII lenses might appear to have such a cast although more likely than not it appears as more of a odd rainbow of colors. This is due to the natural oxidation process that is often referred to as "blooming". It was a comparison of the performance of lenses exhibiting this blooming phenomenon with pristine new examples that got optical scientists interested in coatings in the first place. One way to determine if a lens is coated is by comparison to a piece of glass that you know is not coated. Take an uncoated clear or UV filter from Tiffen or a scrap of window glass and hold it in such a way that it reflects a light source such as an incandescent bulb. Now hold the lens in question in a similar position and compare the brightness of the reflection. A coated optic will reflect far less and almost always impart a color tint to the light source. You will no doubt see a multiple of reflections from within the lens and if these are different bright colors like violet or green, you may be looking at a multi-coated lens.

[Dan Fromm]

Lauren, wishful thinking is a killer. As Robert said, pre-WWII lenses weren't coated.

There are coating services and some ancient lenses were coated after WWII so old age isn't a guarantee that a lens isn't coated. But with old lenses the odds strongly favor uncoated.

I don't know how old your 210/4.5 Congo is. You might ask Yamasaki and while you're at it ask them if it was sold coated.

[E. von Hoegh]

Well, some pre war lenses were coated. Not many, and the coatings were not always durable.

A coated lens will display a uniform cast on the outer surfaces. It will be bluish, straw or purplish in color, depending on the substance used. Some early coated lenses have lost (or never had) the coating on the external surfaces due to the lack of durability of some early coatings.

An uncoated lens can be very good - I read of a test comparing an uncoated Dagor (4 surfaces, 2 internal) with a single coated Symmar (8 surfaces, 6 internal) The Dagor was about the same as regards flare.

A "Bloomed" lens will have a mottled purple/blue cast.

Don't be afraid of uncoated lenses; the cemented doublets (Protar, Dagor, Collinear & etc) can be very good. I use a compendium shade religiously; it makes a big difference with ANY lens, as bellows flare can be an issue with lenses that have large image circles.

[seawolf66]

Dan: You have me lost on this one:][Lauren, wishful thinking is a killer[] I am just try-ing to understand if I have a coated lens or not or do I have another type of problem: If its a none coated lenses them I have no problem of use-ing orange cleaner on the lenses :
do you have web address for Yamasaki Optical company, I found one but no email address on it:

[Peter K]

Lauren, lensmakers have observed that lenses with a thin coating can improve the transmission of the lens long times before Smakula at Zeiss invented the T-coating. So don't "clean" the "natural" coating ancient lensmakers tried by artifical aging the lenses.

[seawolf66]

E.von Hoegh: A "Bloomed" lens will have a mottled purple/blue cast. but you still see thru the lenses except when held at an angle then you will see the BLOOM ?

[E. von Hoegh]

E.von Hoegh: A "Bloomed" lens will have a mottled purple/blue cast. but you still see thru the lenses except when held at an angle then you will see the BLOOM ?

Yes that sounds about right.
I can't tell much from your images; I can tell if I see the lens. Sorry!.

If you have doubts, look at the inner surfaces; they will likely have well preserved coating.

[E. von Hoegh]

Lauren, lensmakers have observed that lenses with a thin coating can improve the transmission of the lens long times before Smakula at Zeiss invented the T-coating. So don't "clean" the "natural" coating ancient lensmakers tried by artifical aging the lenses.

The "bloom" is rather durable. The early coatings often were not. Look up the work Kathleen Blodgett (sp) did, for info on early coatings. Way before Smakula. (wink)

[Peter K]

E.von Hoegh: A "Bloomed" lens will have a mottled purple/blue cast. but you still see thru the lenses except when held at an angle then you will see the BLOOM ?
This is a with MgF coated lens. Be careful with cleaning, this coating could be an older and softer coating.

Peter K

[E. von Hoegh]

This is a with MgF coated lens. Be careful with cleaning, this coating could be an older and softer coating.

Peter K

Peter, A "bloomed" lens is one that has had natural aging of the surfaces exposed to the atmosphere. HD Taylor tried to duplicate this process by exposing the glass to various "energetic" substances.

Magnesium flouride is a different beast, it is and was deposited by vapor deposition.

[Peter K]

Peter, A "bloomed" lens is one that has had natural aging of the surfaces exposed to the atmosphere. HD Taylor tried to duplicate this process by exposing the glass to various "energetic" substances.

Magnesium flouride is a different beast, it is and was deposited by vapor deposition.
Thanks for the lesson "E. von Hoegh", I've vacuum-coated glass and other materials. :p

[E. von Hoegh]

Thanks for the lesson "E. von Hoegh", I've vacuum-coated glass and other materials. :p

Well that's good! So have I! And I made some of the apparatus.


I made a comment. I did not intend it to be a "lesson"

By the way, I'm Bill.

[Peter K]

Well that's good! So have I! And I made some of the apparatus.


I made a comment. I did not intend it to be a "lesson"

By the way, I'm Bill.
Nice to meet you Bill.

Peter

[seawolf66]

To All of you folks , I thank you for your time and Information, But have come to the concluesion this is one of those things you ask when you have lens with you and are talking to others who have more knoewledge or time around lenses: I guess I will have to use it to see if the discoloration or bloom effects the Shot:

[Neil Purling]

I was shooting some stuff last week and wondered if coating increased contrast or the optical design of the lens was the deciding factor.

If you had two examples of the same optic, but one was coated:
Could you tell difference in image contrast? I am talking about a lighting situation where the sun was diffuse, but coming over the photographer's shoulder. Therefore perhaps we can discount the chance of flare?

[Ole Tjugen]

I have two old 135mm Rodenstock Eurynars, one of which has been coated at some later date. The difference in contrast is staggering!

[IanG]

Having just received a pair of 1950's coated 150mm Tessar cells and tried them alongside my 1932 uncoated Tessar I have to agree with Ole about the differences.

I'd never have believed just how significant the improvement in clarity and contrast would be until I saw it for myself. I also made comparisons to a modern multicoated Caltar (Symmar) and while there was a further increase in clarity and contrast is was less obvious and not such a marked step change.

In the next few days I'll make some test exposures and compare the images.

Ian

[Gene McCluney]

Some of the most beautiful still photos in large format, and some of the most beautifully photographed movies were shot long before lens coatings were invented. Photographers used to know how to "use" their lenses, and how to shield them from flare. Even today, cinematographers use large mat box type lens shades to completely eliminate any extraneous light from their well-coated lenses. With careful shielding, there is no reason "classic" pre WW-2 lenses can't produce top-quality images. Modern lens coatings have, to some extent, caused us to get sloppy in our techniques.

[Ole Tjugen]

I have several pictures that I just wouldn't have got with a coated lens. Including one (in the LF book) which I shot twice - once with an uncoated Amatar and once with a coated Tessar. The difference in shadow detail surprised even me - the Tessar shot was unuseable, the Amatar a clear winner.

[IanG]

With careful shielding, there is no reason "classic" pre WW-2 lenses can't produce top-quality images. Modern lens coatings have, to some extent, caused us to get sloppy in our techniques.
The quality is different, coated lenses and particularly multi-coated lenses now allow photographers to make images that just weren't feasible with uncoated lenses.

It also has to be remembered that alongside improvements with lens coating manufacturers also made very significant improvements in lens designs, and also film emulsions. When you combine modern films with modern multi-coated optics the resulting images are very substantially different to images made by pre war photographers - assuming similar formats etc.

Sure we've lost some of the rounded tonality you find in images by photographers like Kertesz and early Cartier Bresson etc which came from the combination of lenses & films in use in the 30's & 40's.

The aesthetics change, it's progress. It doesn't mean that older lenses are unusable, rather that they should be used for their own distinct characteristics.

Ian

[Neil Purling]

I assume that my Bausch & Lomb R.R. lens, being from a Kodak Autographic is a cheap n cheerful lens, wheras my Beck was made with more care. It will be interesting to burn a few more sheets of film to shoot the above two lenses & my Dagor on the same subject in the same conditions. I expect these uncoated lenses to have some differences.

[Dan Fromm]

Neil, B&L made good lenses and y'r Autographic was approximately the top of the line. Its a far cry from a B&L RR taken from an Kodak Autographic to a nameless Goerz dialyte taken from who-knows-what.

[Ernest Purdum]

Before coating, many photographers preferred lenses with only four air-to-glass surfaces so as to minimize contrast loss. This was a significant factor in the popularity of the Dagor and the Ser.VIIa Protar.

Detailed lens design makes a huge difference. I have an old (1930's. I think) report on actual lens transmission, showing over a stop difference between lenses of the same nominal aperture. In general, the more elements. the more loss.

Now, with coating, and particularly multi-coating, much more of the light that comes in the lens winds up on the film. Contrast is higher and transmission loss less significant. Very many modern lenses have eight air-to-glass surfaces and some even more.

[Bjorn Nilsson]

I have several pictures that I just wouldn't have got with a coated lens. Including one (in the LF book) which I shot twice - once with an uncoated Amatar and once with a coated Tessar. The difference in shadow detail surprised even me - the Tessar shot was unuseable, the Amatar a clear winner.

Ole, for once you seem to have made a funny statement.
The lack of shadow detail when using a coated lens is due to...
...
... underexposure!

In very short, what happens is exactly the same as when preflashing paper in the darkroom to get more highlight detail in a print. It's just done during the exposure rather than before. (... and of course affecting the shadows as we are talking negs, not prints.)

Part of the calibration process is to know the limitations and abilities of every lens. (I for one admit that I havn't got that far with my relatively few lenses yet. Now Ole, how many lenses do you have that you need to test? ;) )

The difference in exposure varies with the amount of flare in the situation, but it can easily vary by a stop or more. (The situation can be a deep forrest with almost no flare and thus no difference in exposure. Or it can be a hazy backlit beach where the uncoated lens will be stops faster, if not almost useless due to the flare. All of this can be handled to a great part by proper use of a compendium shade.

A proper test would be a black hole shot various occations (like the examples given above). I think Phil Davies gives the long version of this test in one of his books. The very short version is: Make a black hole out of a one foot (30cm)cube paper box. Make a 6" (15cm) hole in one side. Dress the inside with some deep matte black cloth to make it the deepest black you can get (i.e. a zone 0 exposure). Now go out and shoot this black hole in the various conditions that you can think of. Position the hole so that it takes up enough of the neg so that you can measure it with e.g. a densitometer (or some kind of trick with your enlarger...). When developed you can see and measure the difference in between the blank undeveloped film and the black hole, and you should now have an idea of how much you need to compensate for the flare with your old uncoated gem. This should be done with every lens in your arsenal, as part of getting to know the lens. (Ole, get a roll film back! ;))

Else I do have the deepest respect for your knowledge and I learn something from you almost every day.

For myself, I own both modern multicoated state of the art lenses and quite a few older barrel and even brass mounted lenses. While I know what I get with the modern glass, the older lenses have "personality and carisma", something I get to appreciate more and more. It seem like I pick up e.g. a Symmar S to make a "reference shot" while really working with the shot using some old brass lens or an uncoated Heliar used wide open.

Cheers
Björn

[Ole Tjugen]

Well of course the shot with the coated lens was underexposed - but any more exposure would have blown the highlights completely! Since I shot on slide film, the only way to get good highlight tones and acceptable shadow detail was with an uncoated lens - giving a similar result to preflashing.

How many lenses do I own that I have yet to test... Several. More than most photographers have lenses in total. Among them are most of my modern multicoated lenses. I know what I get with the old singlecoated lenses I started out with, and I like the "personality" of the older uncoated lenses. I seem to trust that when I need a modern MC lens, it will perform to specification. ;)

My "super test pair" is a pair of rodenstock Eurynar 135mm's: One is original and uncoated, the other has been coated at a later date. With eight glass/air surfaces the difference is astonishing: With the coated one the shadows of my "standard test scene) gets two stops less exposure, and the highlights a stop more. The loss from reflection in the uncoated one amounts to almost a full stop, and this "lost light" lifts the shadows up like a zone II preflash.