evolution of leica lens coating

[tobias_mennle]

As far as I understand some Leitz/leica R-lenses have not changed in

their optical formula over the years, eg. 50/2, 60 macro. I´ve just

bought a Leica bellows 100mm/4 macro elmar which has a magenta

coloured coating which is obviously not modern standard. How has

Leica lens coating evolved over the years? Would Erwin Put´s book be

helpful in connecting serial numbers with the type of coating ?

Thanks very much.

[jay_.]

The only really major coating change in Leica lenses in the past 30 years has been in the past 5 years or so the front coatings have been made more abrasion-resistant. They changed the model designations in their binocular line when they switched to the new coating, but remain secretive regarding the camera lenses. There is really no way to tell from looking at the lens. But to put it in perspective, the new coating is still not invulnerable, and given the cost of replacing a Leica front element (sometimes a multi-element group must be replaced) and the superb anti-reflection properties of the B+W MRC filters, I'd still keep one of those on permanently.

[george_l._doolittle]

Zeiss had the patented process for a modern coating method using

vacuum deposited coating during the 1940's and early '50's. I

understand that Leitz used a dipping process at this time which was

much less durable than the Zeiss approach. Whether Leitz bought into

the Zeiss process or developed something else, I don't know. What I

can tell you is the bottom line...modern Leica lenses are much more

resistant to abrasion than the early lenses. I've never had a problem

by rarely cleaning my lenses. I don't use filters but feel protection

is achieved by always using a sunshade. When I do clean a lens, I use

a camel's hair blower brush to remove any particles, the moisture from

a breath and gentle wiping with a microfiber cloth.

[jay_.]

<<I don't use filters but feel protection is achieved by always using a sunshade.When I do clean a lens, I use a camel's hair blower brush to remove any particles, the moisture from a breath and gentle wiping with a microfiber cloth>>

 

Someone always repeats this same lame lament. It's such a simple concept: lens shades and filters offer completely different kinds of protection. Filters protect the lens from grit particles which can still elude all the blowing and brushing in the world and get picked up in that nice soft clean microfiber cloth and while wiping with that breath get dragged across the coating leaving multple spiral wipe marks that lower contrast and increase flare a lot more than a good multicoated filter. I ruined the front 2-element group of a 180/3.4 APO-Telyt-R ($800 for the parts only) being just as fastidious with my cleaning technique. And the fact that Leica lenses are on sale every day with "slt mks frnt" or some other designation for cleaning scratches indicates it's not an isolated occurance.

 

Lens shades OTOH *may* protect the lens from damage in a knock or drop situation but *only* if the shade is soft enough to deform or break off to dissipate the force of impact. Otherwise it will cause as much or more damage to the lens as if there had been no shade attached.

[al_kaplan1]

There is a big difference in performance between 1930's vintage uncoated lenses and post WW-II single coated lenses. This shows up in two ways. The first is the greater contrast and better color fidelity from flare suppresion. The second, often forgotton today, is that lens design was often dictated by the flare problem; a design giving a sharper image, or better coverage across the field, might have too much flare. Coating freed up lens designers from this problem.

 

Going from single coating to multi-coating in the late 1960's and early 1970's was an improvement, and perhaps opened up avenues of design previously overlooked, but the improvement was really minor compared to the improvement of coated vs. uncoated that took place a quarter century earlier.

 

We should remember that Honeywell Pentax built an entire advertising campaign on "Super Multi-Coated Takumars" back in the 1970's. Leitz had been multi coating for several years at that point. Probably Nikon, Canon, Minolta and others too. Lens designers and engineers looked at it as normal improvements that were to be expected from their research. The Pentax advertising department saw a way to grab headlines and promote the name of a well made but second tier camera. Soon everybody knew the name Takumar, and with it, Pentax. They started selling like hotcakes. Amateurs bugged dealers for multi coated lenses. This board has MC crazed folks, to this day, fretting over which brand of filter has the best multi coating.

 

Because the problem with internal reflections has to do with angles, the relationship of spacing and the curvature of the elements determines whether or not a particular light ray gets through to the next surface. Many lenses have been made that are not multi coated on every surface. The designer decides where it makes a major difference and where it becomes a waste of effort and money.

 

Also not usually mentioned on this board is the changes in optical glasses that have taken place over the past half century and more. Designs have been tweaked to take advantage of newer glasses as well as coatings. You really can't tell much by looking at the "color" of the lens. You still have to compare side by side prints or transparencies. At that point, whether it's color or bokeh or smoothness of skin in a portrait or luminosity of shadows the newest isn't always the best choice.

[tobias_mennle]

To Jay and Al: If I look at a modern Nikon or Canon lens I can see a lot of different colours in the reflections off the front lens: red, green, blue etc. and I guess it´s the same with modern Leica lenses. With the Leitz 100/4 I only see two kinds of red. I remember I talked to a technician some time ago about lens coatings, he claimed the green/blue reflections show that it´s a modern coating but maybe he´s wrong...

[roger_michel]

the smc takumar campaign was much more than ad hype. many of those pentax lenses from the 70s were stunning performers. to this day, my of the wides hold up to the best competition.

[al_kaplan1]

Tobias, the 100mm/4 Leica lens has only 3 groups. There are 4 internal air to glass surfaces where multi coating might help, and 2 external surfaces where it would have next to no effect. The Elmar formula (Leitz's version of the Zeiss Tessar) has always been considered a contrasty and flare resistant design. You really can't compare the coating requirements of this lens to a design with twice that number of surfaces, like some retrofocus wide angle designs, or a zoom with a dozen or more surfaces to worry about, surfaces that move in relation to one another resulting in constantly changing angles of the reflecting surfaces. Most lens designers would probably say that the coatings are "modern standard" but not overkill. Stop fretting about it! If you keep obsessing you'll have to trade in all your lenses every few years just in case Leica upgraded (which they do) without faxing you a press release or making a public announcement. I doubt that you'd see enough difference between the oldest and the newest 100/4 Macro Elmars to be able to pick out which one was used in a random selection of photographs.

[steve_barnett2]

Its a daft idea trying to judge the colour of the coating with what you see. It may be the colour of the glass as much as the coating, and the glass can be different formulas for different elements. The point is that only when the light strikes the film can the lens can be judged on the overall quality, not on one loan factor. So going back to Tobias's orginal question, the magenta colour of his 100mm Elmar may only be a response in the lens design to the glass used, and not an 'old' standard in coating.

[david11]

The newer coatings are superior, but I have a 1961 90mm Elmarit that doesn't seem to suffer in comparison to the latest offerings. It may not be quite as contrasty as the newer editions (I also use the 90 SAA), but truly, the 1st version Elmarit is sufficient for most all of my 90 focal length photographs, F2 notwithstanding. I don't view photographs made with the Elmarit and lament the lack of contrast, and it is very "sharp".

[andrew_hall1]

"This board has MC crazed folks, to this day, fretting over which brand of filter has the best multi coating."

 

There are also a sizeable group of people (you know who you are) to whom all flare, ghosting and loss of contrast are ALWAYS caused by a filter (and vice versa), regardless of the coating quality. ;)

[karl_georg_wolf]

I would like to thank AL KAPLAN for his splendid historical outlook on lens-coating here.

 

It is always enlightened to go through his answers ...

 

Best regards

[tobias_mennle]

Thanks, Al, for your competent answers. I´m in no way obsessed by lens coating evolution... the background for this question was basically that I have a 90mm macro (Kilfitt, Munich) which is a spectacular design with respect to bokeh, but it´s hardly usable for 35mm because the coating has, well, dissolved or something (but I still love to use it for 16mm with a sunshade which blocks the biggest part of the image circle). Moreover, I was wondering why the Leica coating looks so different from other lenses I have and if the Elmars really differ because some are very cheap on ebay, some not.

[tobias_mennle]

To Steve/on magenta-coloured coatings: My Zeiss luminar 64mm has the same magenta colour, and I found descriptions of old Canon coatings called "magenta-type".