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Colors of lens coating?
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PostPosted: Mon Jun 15, 2009 4:01 pm    Post subject: Colors of lens coating? Reply with quote
When I was puting my lenses in order this afternoon. I found the coating color of lens is so fantastic. CZJ/Pentacon are mostly purple or blue color while Nikkor is green or light-blue and SMC Taks is yellow or light-orange. Could anyone teach me what is the effectiveness fomr different coating? And what is the coating material? And......... anything about coating? Thanks. Mike


PostPosted: Mon Jun 15, 2009 4:12 pm    Post subject: Reply with quote
1- The strong reflections, high contrast lens (see this among the same schame lenses only).

2- The color of the reflection favors the pass of the complementary color. (orange reflection, pass better the blue and green waves).

3- The last is true for the filters too.

Rino.


PostPosted: Mon Jun 15, 2009 6:18 pm    Post subject: Reply with quote
more than you want to know: http://www.zen20934.zen.co.uk/photography/optical%20coatings/index.htm


PostPosted: Tue Jun 16, 2009 1:18 am    Post subject: Reply with quote
siriusdogstar wrote:
more than you want to know: http://www.zen20934.zen.co.uk/photography/optical%20coatings/index.htm


Thanks for the link. I am bookmarking it. Very informative but unfortunately at the moment too much for me to digest.


PostPosted: Tue Jun 16, 2009 3:13 am    Post subject: Reply with quote
Try this one then:

http://rick_oleson.tripod.com/index-166.html

Just one starting point to get you interested enough to read on: lens coating has no color.


PostPosted: Tue Jun 16, 2009 4:51 am    Post subject: Reply with quote
siriusdogstar wrote:
more than you want to know: http://www.zen20934.zen.co.uk/photography/optical%20coatings/index.htm


rick_oleson wrote:
Try this one then:
http://rick_oleson.tripod.com/index-166.html
Just one starting point to get you interested enough to read on: lens coating has no color.


Siriusdogstar/Rick, thanks for the link. Good articles.
Is there any "exceptional lens" which is great but uncoated or single-coated?


PostPosted: Tue Jun 16, 2009 10:47 am    Post subject: Reply with quote
There are tons of great uncoated or single-coated lenses. Carl Zeiss (the people who introduced lens coating, later on), in particular, placed great emphasis on designing to minimize internal reflections before antireflective coating was available. Some of the greatest lenses were the result of this effort, including the 50/2.0 Sonnar, 50/1.5 Sonnar, 85/2.0 Sonnar, 135/4.0 Sonnar, and one of the most famous of all, the 180/2.8 Olympia Sonnar of 1936. The "Sonnar" name indicated that the lens had only 6 air/glass reflecting surfaces, even though it might have as many as 7 elements in it. They did this by cementing elements together in groups ... a very challenging restriction to place on a lens designer, but it paid off in increased contrast. After WWII, lens coating made this design less valuable and they stopped designing this way - "Sonnar" today is just another name, it no longer signifies any particular design approach.

Another exceptional uncoated lens is the Zeiss Tessar; images from the 75/3.5 Tessars in prewar Rolleiflexes and Zeiss Ikontas can be almost startlingly sharp in black & white, and are equally sharp but with slightly subdued colors on color film. Cooke Triplets also, while they might not be thought of as great lenses, retain high contrast in uncoated form and are probably the single greatest achievement in photographic optics.

Single coating permitted good contrast in more complex lenses with more air/glass reflective surfaces - this allowed lenses like the Leitz Summicron, the rangefinder Nikkors that created Nikon's reputation in the 1950s, and fast SLR lenses like the 50/1.4 normal lenses from Nikon, Canon and all of the other major makers to become practical. Like the Sonnars, the Summicron and Nikkor have to be considered great lenses. Other single coated lenses that I would consider to be great include the 55/3.5 Micro Nikkor, the 105/2.5 Nikkor and all of the postwar rangefinder Sonnars, which are even better with coating than without.

Multi-coating has advantages with any lens (although of course it does nothing for sharpness), but it only becomes a major factor with the introduction of extremely complex formulas for retrofocus wide angles and, especially, zoom lenses, where there may be as many as 20 reflective surfaces or even more. The performance of many modern zooms would be seriously degraded by loss of contrast if they were only single coated, and without coating they would be virtually unusable.


PostPosted: Tue Jun 16, 2009 11:05 am    Post subject: Reply with quote
In 35mm camera lenses, Pentax introduced multi coating with the SMC Takumars, soon followed by Fuji etc. This was around 1971. Pretty much anything before then was single coated. Even after the SMC, other makes took longer to introduce, sometimes gradually, the multi coated lenses during the 70s. Nikon, Canon, Olympus, Konica - googling any of these reveals some things about when and which models received the multi coatings...


PostPosted: Tue Jun 16, 2009 11:22 am    Post subject: Reply with quote
A peculiar situation was considered in the Literature from the end of the 70's to middle of the 80's.

That was the fact that some manufacturers of lenses showed that many lenses did not improve with the MC, but that in fact lost something of his resolution power, but the market required that sold them with the MC.

They adduced that the MC modified the route of waves (refraction, reflection, incidence, etc) and thus changed design of the lens, that had not been modified for the MC.

Rino.


PostPosted: Tue Jun 16, 2009 11:37 am    Post subject: Reply with quote
rick_oleson wrote:
There are tons of great uncoated or single-coated lenses. Carl Zeiss (the people who introduced lens coating, later on), in particular, placed great emphasis on designing to minimize internal reflections before antireflective coating was available...................


Rick, thanks for great advice. Any reason why CZJ/Pentacon's look purple , Tak SMC's yellowish, Nikkor's blue-green? Becasue of different coating materials?


PostPosted: Tue Jun 16, 2009 3:20 pm    Post subject: Reply with quote
No, not different materials. Please read the link I posted earlier, it explains why you see colors.


PostPosted: Tue Jun 16, 2009 3:25 pm    Post subject: Reply with quote
more on various coating materials: http://www.edmundoptics.com/techsupport/DisplayArticle.cfm?articleid=247


PostPosted: Tue Jun 16, 2009 3:31 pm    Post subject: Reply with quote
Siriusdogstar/Rick, thanks again.


PostPosted: Tue Jun 16, 2009 3:34 pm    Post subject: Reply with quote
Wink the other aspect of that peculiar situation in the 70s and early 80s - the manufacturers trying to find ways around patents and licensing fees for multi coating naturally were inclined to be of the opinion that MC was not necessarily a Good Thing. The issue died as soon as the technology became free of restrictions...
http://digilander.libero.it/aohc/selart07e.htm


PostPosted: Tue Jun 16, 2009 3:36 pm    Post subject: Reply with quote
thanks for all great infos!


PostPosted: Tue Jun 16, 2009 4:03 pm    Post subject: Reply with quote
My opinion is, that the fact, that some MC lens version are less sharp, than older single-coated lenses, isn't related to the coating, but to worse manufacturing precision, less strict tolerances and worse final inspection. I think that's the case of Sonnar-based lenses, which are not easy to manufacture. Old Jupiter-9 is better than the new one (MC), old Sonnar 135/3.5 (zebra) is sometimes sharper than newer (black MC), the same for 180/2.8 Sonnar. Another example can be Helios 44-2 and MC Helios 44M-4. Older version is more constant in quality, than the newer (MCed) one...


PostPosted: Tue Jun 16, 2009 9:27 pm    Post subject: Reply with quote
what a great, educational thread!
thank you all!


PostPosted: Tue Jun 16, 2009 10:49 pm    Post subject: Reply with quote
I have no special inside information, but I tend to agree with no-x on this. There are surely many lenses that get no particular benefit from multi-coating, including most normal and tele formulas of modest aperture ... but I can't think of any reason why multi-coating would make a lens' performance worse. This might have been an argument that was made by companies whose coating technology was not on the cutting edge.

But I don't know, there might be something to it....


PostPosted: Wed Jun 17, 2009 2:35 pm    Post subject: Reply with quote
I see. But it's that true MC version willl have better color contrast than uncoated, right?


PostPosted: Wed Jun 17, 2009 4:07 pm    Post subject: Reply with quote
Generally, yes. But in a lens with a small number of reflecting surfaces, such as a Triplet, Tessar or Sonnar, the difference between single and multicoating may not be noticeable on film. Where the number of surfaces gets very large (the 15mm Nikkor has 24, some zooms will exceed that), the difference in coating becomes very important.


PostPosted: Wed Jun 17, 2009 7:36 pm    Post subject: Reply with quote
I think the same. Less elements, less MC is necesary.

But Koji showed that with his tessars and prakticars, a few elements lenses are beneficiaries with MC.

See

http://forum.mflenses.com/biotar-t-or-not-to-t-that-is-the-question-t14763,start,30,highlight,tessar.html#125223.

Do you like the tessar SC not MC? Well, but the differences there are.

Rino.


PostPosted: Fri Jul 03, 2009 6:07 pm    Post subject: Reply with quote
this message is outdated and deleted!

Last edited by Aykman on Mon Oct 11, 2010 6:49 pm; edited 2 times in total


PostPosted: Fri Jul 03, 2009 6:14 pm    Post subject: Reply with quote
estudleon wrote:
2- The color of the reflection favors the pass of the complementary color. (orange reflection, pass better the blue and green waves).

3- The last is true for the filters too.


Actually, it is only true for filters. It would be true for coating if you could see the colour of the coating when you look directly through the lens. And this you can't.


PostPosted: Fri Jul 03, 2009 8:02 pm    Post subject: Reply with quote
LucisPictor wrote:
estudleon wrote:
2- The color of the reflection favors the pass of the complementary color. (orange reflection, pass better the blue and green waves).

3- The last is true for the filters too.


Actually, it is only true for filters. It would be true for coating if you could see the colour of the coating when you look directly through the lens. And this you can't.


It can be true that you say, but only if you see thru the lens. If you do it thru each element, you can see by reflection which is the color that has the MC in this element and which has the favor pass. The imposibility to see any color thru the complete lens is due to the sum of all the colors reflected by all the elements the lens. But if you look at the first frontal element (at the last rear elemnt it's true too), you can see the reflection of the color which complementary is favor to pass.

Rino.
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