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Zeiss T* vs. Pentax SMC coatings
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PostPosted: Fri Dec 21, 2012 8:54 pm    Post subject: Reply with quote
Secondly, using a planar 50mm is a terrible example and shows your misunderstanding of coatings. Its the many element lenses like complex wide angles or zooms where multicoating makes the biggest differences. Hell, a single coated planar would probably perform well as its a relatively simple optical design. I stand by my contention that Pentax's super multicoatings of the 70's was superior to zeiss t* at the time and any other mfgr. too. As I stated earlier, not all multicoatings perform equally.


PostPosted: Fri Dec 21, 2012 8:56 pm    Post subject: Reply with quote
I'm sorry but the example is valid, here is some info on coatings, maybe this will make things clearer:

Quote:
Coating - Before coating, each transmission surface resulted in about a 4% to 8% loss of light to reflection depending on the refractive index of the glass. So an uncoated Dagor or Protar with four transmission surfaces looses 15% to 29% of the light to flare. An uncoated Tessar looses 22% to 40% of the light to flare. An uncoated Planar with eight surfaces looses 28% to 49% of light to flare. The flare would exhibit itself on the film as unfocused non-image forming light which reduced the contrast of the picture.
Single Coating - After single coating, this dropped to about 2% to 4% loss of light per transmission surface. Applying the coating at quarter wavelength thickness could greatly increase the effectiveness of the coat, but it could completely block some wavelengths of light and partially block others. Typically blue-green wavelengths were suppressed with an amber coat, or green wavelengths with a purple coat.
Multi-coating - Multicoating was first done as two separate coats at different wavelength thickness on different transmission surfaces to balance the color of the light transmitted to the film. Later, multi-coating as we know it, one coat stacked on another (first used on a production lens by Leitz) reduced the light lost to diffraction further to about 1/2% to 1% per transmission surface. The classic second coat was bismuth oxide again applied at quarter wavelength thickness for a different wavelength, typically orange-yellow for the second coat and green-blue for the first coat giving a faint green reflection. A multi-coated Planar could now only loose about 4% to 8% of the light to flare, quite a difference.
Coating and multicoating allowed designers to use more complex designs with more air spaces which allowed easier design for correction of spherical aberrations. The difference between uncoated lenses and coated lenses are great, the difference between single coating and multi-coating is visible, but not nearly as great as the first leap from uncoated to coated. Coating and multicoating opened the way for many otherwise unfeasible modern lens designs, such as complex wide-angle lenses, big multi-element zooms, and lots of marketing hype. Coating still won't save you from nasty flare in certain lighting conditions, such as shooting into the sun, so make sure to use those lens shades!


Last edited by iangreenhalgh1 on Fri Dec 21, 2012 10:05 pm; edited 1 time in total


PostPosted: Fri Dec 21, 2012 9:53 pm    Post subject: Reply with quote
OK, the thread has been split. But please keep your language respectable, both of you.


PostPosted: Fri Dec 21, 2012 9:56 pm    Post subject: Reply with quote
Thank you Peter!


PostPosted: Fri Dec 21, 2012 9:58 pm    Post subject: Reply with quote
Attila wrote:
Thank you Peter!


+1


PostPosted: Fri Dec 21, 2012 10:21 pm    Post subject: Reply with quote
Thanks.

I think perhaps we can easily settle the dispute about the beginnings of multi-coated lenses, with or without the "Super" prefix. Pentax was already marketing S-M-C Takumars in 1971, before the co-operation deal with Zeiss was struck. The SMC 1.8/55 K lens you pictured Ian is the third version of SMC lenses, from 1975. Before that came the S-M-C and SMC Takumars.


PostPosted: Fri Dec 21, 2012 10:24 pm    Post subject: Reply with quote
I picked that lens as it was contemporaneous to the Planar which was introduced in 1975 with the Contax RTS.

I'm not bothered who was the first with multicoatings, we just need to counter this propaganda about the inferiority of all other multicoatings to SMC and the claim that Zeiss didn't use multicoatings until the 1980s. It really doesn't matter who was first, but the latter two points have the potential to confuse and mislead people and I think it's important to try to avoid such things as it helps no-one.

Last edited by iangreenhalgh1 on Fri Dec 21, 2012 10:32 pm; edited 1 time in total


PostPosted: Fri Dec 21, 2012 10:29 pm    Post subject: Reply with quote
hifisapi wrote:
Secondly, using a planar 50mm is a terrible example and shows your misunderstanding of coatings. Its the many element lenses like complex wide angles or zooms where multicoating makes the biggest differences. Hell, a single coated planar would probably perform well as its a relatively simple optical design.


Ok, I normally try to stay out of petty disputes but what is said here really needs a punctualization.
Firstly, the fast Planar or double Gauss optics have plenty of large glass-air surfaces. That is a crucial factor in causing loss of contrast and (at extreme angles) visible flaring, and indeed it was exactly because
coating technology became available only in the late 30s that the big launch on the market of Planar optics was delayed until WWII.
So, Planar lenses are very sensitive to flaring issues, even if they have less elements than a zoom lens.
Secondly, I happen to own a single coated Planar lens (the Contarex Planar 2/50) and I own the 1.7/50 Contax as well (and the 1.4/50 and the 1.8/50 for Rollei SL), and *no*,
the Contarex 2/50 Planar does *not* perform as well as the Contax SLR Planars as far as flaring is concerned. The lens flares visibly when not used at a favourable angle,
which limits it's contrast visibly at many angles, and causes a bad flare problem in critical positions, whereas the Contax SLR Planars always perform great except when pointing directly to the light source.

Brand wars are always a stupid thing to do in photography, but when you choose to do it, at least please try to have first-hand experience of the things you are talking about.
This forum is frequented by many knowledgeable persons, and trust me, if you claim untrue facts about things that you don't know well, it won't take much before someone else will make you stand publicly corrected.


PostPosted: Fri Dec 21, 2012 10:36 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
I picked that lens as it was contemporaneous to the Planar which was introduced in 1975 with the Contax RTS.

I'm not bothered who was the first with multicoatings, we just need to counter this propaganda about the inferiority of all other multicoatings to SMC and the claim that Zeiss didn't use multicoatings, it really doesn't matter who was first, but the latter two points have the potential to confuse and mislead people and I think it's important to try to avoid such things as it helps no-one.


OK, that's settled then. Pentax introduced them. I hadn't heard the story about buying the technology from NASA, but I can well believe it. This was 2 years after Armstrong set foot on the moon, and many years after the start of the Apollo project!

As for which coating system is better, does it really matter? I bet each has its own different merits when you examine them closely. As coatings make only a marginal difference to the quality of the pictures, and any difference between Z & P is going to be marginal too, I think you two are really arguing over something rather insignificant. BTW, how do you measure the quality of the coatings? Light transmittance, durability, pretty colours? Smile


PostPosted: Fri Dec 21, 2012 10:38 pm    Post subject: Reply with quote
Thankyou for the info Orio.

As you say, the Planar was not feasible due to having 8 air-glass interfaces until the advent of coatings in the late 1930s. This is why Zeiss designed the Sonnar as their premium 'normal' lens - it only has 6 air-glass interfaces.

I'm not bothered at all about brands, not in the slightest. I just like to try to keep things accurate, if that's petty than I'm sorry, I thought I was trying to do something helpful to people.


PostPosted: Fri Dec 21, 2012 10:42 pm    Post subject: Reply with quote
peterqd wrote:
iangreenhalgh1 wrote:
I picked that lens as it was contemporaneous to the Planar which was introduced in 1975 with the Contax RTS.

I'm not bothered who was the first with multicoatings, we just need to counter this propaganda about the inferiority of all other multicoatings to SMC and the claim that Zeiss didn't use multicoatings, it really doesn't matter who was first, but the latter two points have the potential to confuse and mislead people and I think it's important to try to avoid such things as it helps no-one.


OK, that's settled then. Pentax introduced them. I hadn't heard the story about buying the technology from NASA, but I can well believe it. This was 2 years after Armstrong set foot on the moon, and many years after the start of the Apollo project!

As for which coating system is better, does it really matter? I bet each has its own different merits when you examine them closely. As coatings make only a marginal difference to the quality of the pictures, and any difference between Z & P is going to be marginal too, I think you two are really arguing over something rather insignificant. BTW, how do you measure the quality of the coatings? Light transmittance, durability, pretty colours? Smile


Nope, multicoatings existed before SMC, but that's fairly irrelevant.

I'm not bothered which coating system is better, it's also fairly irrelevant.

I just want to keep facts straight, to correct claims such as all coatings being inferior to SMC, that Zeiss didn't used multi-coatings until the 1980s, things like that.

It's a complex subject, the effect of coatings, Erwin Putts and Marco Cavina both have websites with lots of material worth studying.


PostPosted: Fri Dec 21, 2012 10:45 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
Thankyou for the info Orio.

As you say, the Planar was not feasible due to having 8 air-glass interfaces until the advent of coatings in the late 1930s. This is why Zeiss designed the Sonnar as their premium 'normal' lens - it only has 6 air-glass interfaces.

I'm not bothered at all about brands, not in the slightest. I just like to try to keep things accurate, if that's petty than I'm sorry, I thought I was trying to do something helpful to people.


Ian, I didn't mean the word to be personally addressed, it's just that every now and then someone appears with a new (or old) brand war to fight
and to "feed" them with replies ends up in endless debates that really take nowhere, because such people typically are not interested in exchange of information
but are just searching for someone they can flame with.


PostPosted: Fri Dec 21, 2012 10:50 pm    Post subject: Reply with quote
iangreenhalgh1 wrote:
peterqd wrote:
iangreenhalgh1 wrote:
I picked that lens as it was contemporaneous to the Planar which was introduced in 1975 with the Contax RTS.

I'm not bothered who was the first with multicoatings, we just need to counter this propaganda about the inferiority of all other multicoatings to SMC and the claim that Zeiss didn't use multicoatings, it really doesn't matter who was first, but the latter two points have the potential to confuse and mislead people and I think it's important to try to avoid such things as it helps no-one.


OK, that's settled then. Pentax introduced them. I hadn't heard the story about buying the technology from NASA, but I can well believe it. This was 2 years after Armstrong set foot on the moon, and many years after the start of the Apollo project!

As for which coating system is better, does it really matter? I bet each has its own different merits when you examine them closely. As coatings make only a marginal difference to the quality of the pictures, and any difference between Z & P is going to be marginal too, I think you two are really arguing over something rather insignificant. BTW, how do you measure the quality of the coatings? Light transmittance, durability, pretty colours? Smile


Nope, multicoatings existed before SMC, but that's fairly irrelevant.

Ian, you can be very argumentative. I am trying to calm things down, so please try to be more agreeable. I didn't say Pentax invented SMC, I said they introduced it to the mass market. Can't you agree with that?

Quote:
I'm not bothered which coating system is better, it's also fairly irrelevant.

I just want to keep facts straight, to correct claims such as all coatings being inferior to SMC, that Zeiss didn't used multi-coatings until the 1980s, things like that.

It's a complex subject, the effect of coatings, Erwin Putts and Marco Cavina both have websites with lots of material worth studying.

Frankly, I'm not a*sed how you measure it either. You didn't get the point I was trying to make in a polite way. I'll say it more plainly - this argument is silly.


PostPosted: Fri Dec 21, 2012 11:10 pm    Post subject: Reply with quote
peterqd wrote:
I didn't say Pentax invented SMC, I said they introduced it to the mass market. Can't you agree with that?


There are only two things that are pretty much sure on the subject:

1) Pentax and Zeiss were collaborating at the time. The collaboration was requested by Zeiss, which was looking for a reliable Japanese partner
to produce a cost-concerned camera system for their lenses after the commercial disaster of the pricey Contarex line and the bankrupcy of Zeiss Ikon Stuttgart.
But Pentax turned out to be too much of a competitor than a partner for Zeiss, so the collaboration was interrupted and Zeiss turned their attention to Yashica;

2) Pentax lenses with SMC appeared on the market before Zeiss lenses marked with T*.

The second fact does not mean much per se: let's not forget that also the Distagon 3.5/15 lens first appeared on the market with a Pentax suit; and yet, it was entirely, since even before it's beginning, a 100% Zeiss project.

Whether the SMC and T* coating systems are the same or not, and if yes, who did invent it first, remains something that probably only some of the people of the two companies really know.


PostPosted: Fri Dec 21, 2012 11:28 pm    Post subject: Reply with quote
hifisapi wrote:
Besides the 15mm in question, I dont know of any other zeiss and pentax lenses with the same exact optical design.


Distagon 2/28 "Hollywood", created by Erhard Glatzel (like the 3.5/15)
Both lenses were created in the same period, between the end of the Contarex project (two prototypes of the 3.5/15 in Contarex mount exist) and the launch of the Contax SLR line four years later.
Because of this temporal circumstance, both of these magnificent (and for some aspects revolutionary) lenses appeared in Rollei and Pentax versions before they appeared as native Zeiss Contax lenses.


PostPosted: Fri Dec 21, 2012 11:42 pm    Post subject: Reply with quote
Orio wrote:
iangreenhalgh1 wrote:
Thankyou for the info Orio.

As you say, the Planar was not feasible due to having 8 air-glass interfaces until the advent of coatings in the late 1930s. This is why Zeiss designed the Sonnar as their premium 'normal' lens - it only has 6 air-glass interfaces.

I'm not bothered at all about brands, not in the slightest. I just like to try to keep things accurate, if that's petty than I'm sorry, I thought I was trying to do something helpful to people.


Ian, I didn't mean the word to be personally addressed, it's just that every now and then someone appears with a new (or old) brand war to fight
and to "feed" them with replies ends up in endless debates that really take nowhere, because such people typically are not interested in exchange of information
but are just searching for someone they can flame with.


Thanks Orio, I will try to remember this. I really wasn't trying to argue and certainly not flame, I am completely disinterested in brands, for me, it doesn't matter who made something, only it's capabilities. I should have stopped earlier, I realise that now after you explained it this way. I'm not fond of arguing, but I love to debate as I find it one of the best ways of learning, in a debate, both parties bring to the table what info they have and then we discuss it and where the info matches up or where it contradicts is usually where new understanding is found.

Orio wrote:
peterqd wrote:
I didn't say Pentax invented SMC, I said they introduced it to the mass market. Can't you agree with that?


There are only two things that are pretty much sure on the subject:

1) Pentax and Zeiss were collaborating at the time. The collaboration was requested by Zeiss, which was looking for a reliable Japanese partner
to produce a cost-concerned camera system for their lenses after the commercial disaster of the pricey Contarex line and the bankrupcy of Zeiss Ikon Stuttgart.
But Pentax turned out to be too much of a competitor than a partner for Zeiss, so the collaboration was interrupted and Zeiss turned their attention to Yashica;

2) Pentax lenses with SMC appeared on the market before Zeiss lenses marked with T*.

The second fact does not mean much per se: let's not forget that also the Distagon 3.5/15 lens first appeared on the market with a Pentax suit; and yet, it was entirely, since even before it's beginning, a 100% Zeiss project.

Whether the SMC and T* coating systems are the same or not, and if yes, who did invent it first, remains something that probably only some of the people of the two companies really know.


Yes, I fully agree with this and I was trying to make both of these points in my earlier postings.

SMC and T* are both surely very effective, and both have evolved over time so blanket statements are problematic in this regard. I don't think there's much point in debating which is superior and it is fine to just say they are both very good and roughly equivalent.


PostPosted: Fri Dec 21, 2012 11:44 pm    Post subject: Reply with quote
Orio wrote:
hifisapi wrote:
Besides the 15mm in question, I dont know of any other zeiss and pentax lenses with the same exact optical design.


Distagon 2/28 "Hollywood", created by Erhard Glatzel (like the 3.5/15)
Both lenses were created in the same period, between the end of the Contarex project (two prototypes of the 3.5/15 in Contarex mount exist) and the launch of the Contax SLR line four years later.
Because of this temporal circumstance, both of these magnificent (and for some aspects revolutionary) lenses appeared in Rollei and Pentax versions before they appeared as native Zeiss Contax lenses.


Yes, Marco Cavina covers this very well, I just wish it was in English as well as Italian, I have read it all through Google Translate but it leaves something to be desired in many passages.


PostPosted: Sat Dec 22, 2012 1:18 am    Post subject: Reply with quote
I dont want to repeat myself but if Pentax and OCLI ( Optical Coatings Labratory Inc who worked for nasa on some earlier projects ) co-developed the SUPER multi coating process and it was PATENTED and exclusive to Pentax which it was in the early 70's, then all other company's hands were tied as far as being able to use this process in their lenses. Now, I dont have a copy of the patent and I dont know if Pentax licensed the technology but I doubt they would unless it was very profitable. Is the early zeiss T* the exact same coatings as SMC? It would have to be licensed if it was. If its not, and zeiss somehow did their version of multicoating on their own, I honestly doubt that its as good as SMC just as much as the other poster claims that it is as good or better. As far as determining how to determine which coatings are better, things could be measured such as light transmission percentage, broadband wavelength transmission uniformity, color accuracy, and durability, etc.


PostPosted: Sat Dec 22, 2012 1:51 am    Post subject: Reply with quote
Well, the Glatzel lens designs were patented but Pentax got those. It happens all the time - companies license technology to others. What I expect happened with Pentax and Zeiss is that they shared various elements of technology that were needed to produce multi-coatings. For instance, perhaps Zeiss had some vacuum deposition technology that was better than what Pentax had and maybe Pentax had some chemical engineering technology required for the production of some exotic oxide that Zeiss didn't and they shared. Quite possibly some Zeiss technology went into SMC and some Pentax technology went into T*. But this is just speculation; point being, a patent is rarely a barrier to the use of technology, it usually just means a license fee is paid to the patent holder.

We don't have to rely on claims about Zeiss T* coatings, we can test the lenses. Just take a look around this forum at some T* sample images or look around the net at some of the comments users make about T* lenses. As Attila said, they are usually superior to most others in many aspects.

There are other companies that had their own excellent coating technologies too, Fujinon surpassed Pentax's 7-layer SMC with their more advanced 11 layer EBC (Electron Beam Coating), Canon developed first Spectra Coating then Super Spectra Coating, Nikon had their own multi layered coatings too.

It's fine to acknowledge the excellence of SMC and that Pentax were first to market, but wrong to denigrate other companies due to brand loyalty.


PostPosted: Sat Dec 22, 2012 2:04 am    Post subject: Reply with quote
This isnt about "brand loyalty" this is about technology, My contention is that PENTAX had superior multicoating
technology in the '70's and thats that. Until someone can produce some hard evidence to the contrary, which
no one has, then I have to stick to my position on the matter. Now you can claim that the early Zeiss T* coatings
were just as good even though Pentax held the patent if you want, but Im not going to change my positon just
based on your undocumented contention. Patented is more "proof" than no proof other than subjective t* user
experiences. As for the original thread that started this discussion, I own two different (M42 and KA) copies of the
SMC 15/3.5 and considering the huge exposed front element and the very high number of lens elements in the
design, the contrast, saturation, and general flare resistance is excellent for its class of lens, a testiment to SMC
and the lens probably wasnt even possible to produce until the smc era which it wasnt.


PostPosted: Sat Dec 22, 2012 2:12 am    Post subject: Reply with quote
Here's something I find very odd. If Pentax coatings were so good, how come Pentax lost their market position completely in the 70's, precisely when coatings became the big thing.


PostPosted: Sat Dec 22, 2012 2:25 am    Post subject: Reply with quote
fermy wrote:
Here's something I find very odd. If Pentax coatings were so good, how come Pentax lost their market position completely in the 70's, precisely when coatings became the big thing.

Lost their market position in the 1970's? You are mistaken, by the late 70's they were VERY popular with their small size
line of cameras and lenses MV,ME Super, MX, M lenses, etc. Big mass marker sellers. One of their cameras the K1000 was so popular that
it was made for over 20 years. Pentax fell out of popularity later, in the 80's, once P&S cameras replaced the SLR market
for 35mm cameras. As I stated in the other thread, at least Pentax and Nikon have brand new DSLRS that support their legacy
MF lenses, something that zeiss doesnt have. That makes them more popular than Zeiss, no?


PostPosted: Sat Dec 22, 2012 2:30 am    Post subject: Reply with quote
fermy wrote:
Here's something I find very odd. If Pentax coatings were so good, how come Pentax lost their market position completely in the 70's, precisely when coatings became the big thing.

Well, Canon, Nikon, Olympus, Minolta etc had caught them up in the SLR market. But they still had a strong market share when I bought my ME Super in 1982. I think the point they really started losing out was in 1984, when they went downmarket with the A and then the P & F ranges. The plastic cameras and even cheaper Takumar non-SMC lenses were a disaster.


PostPosted: Sat Dec 22, 2012 2:48 am    Post subject: Reply with quote
iangreenhalgh1 wrote:
What I expect happened with Pentax and Zeiss is that they shared various elements of technology that were needed to produce multi-coatings. For instance, perhaps Zeiss had some vacuum deposition technology that was better than what Pentax had and maybe Pentax had some chemical engineering technology required for the production of some exotic oxide that Zeiss didn't and they shared. Quite possibly some Zeiss technology went into SMC and some Pentax technology went into T*.

But haven't we just agreed that Pentax were marketing their SMC lenses before there was ever any collaboration with Zeiss? Confused

Quote:
It's fine to acknowledge the excellence of SMC and that Pentax were first to market, but wrong to denigrate other companies due to brand loyalty.

Absolutely right. We should all be thankful for the benefits that the competition for best quality has given us. It could have easily have been a price war, with quality going downhill.


PostPosted: Sat Dec 22, 2012 3:15 am    Post subject: Reply with quote
Peter, I'm not clear on the Pentax-Zeiss co-operation, I have yet to see any info on the dates of this co-operation, just vague info about it being around the time of the end of Contarex production, which was sometime in 1971. The first Zeiss lesnes with T* coatings were released in the autumn of 1972, so sometime between the end of Contarex lens production and autumn 1972 is when Zeiss developed T*.

hifisapi wrote:
This isnt about "brand loyalty" this is about technology, My contention is that PENTAX had superior multicoating
technology in the '70's and thats that. Until someone can produce some hard evidence to the contrary, which
no one has, then I have to stick to my position on the matter. Now you can claim that the early Zeiss T* coatings
were just as good even though Pentax held the patent if you want, but Im not going to change my positon just
based on your undocumented contention. Patented is more "proof" than no proof other than subjective t* user
experiences. As for the original thread that started this discussion, I own two different (M42 and KA) copies of the
SMC 15/3.5 and considering the huge exposed front element and the very high number of lens elements in the
design, the contrast, saturation, and general flare resistance is excellent for its class of lens, a testiment to SMC
and the lens probably wasnt even possible to produce until the smc era which it wasnt.


Again, you are ignoring a huge body of evidence, I keep telling you how many people here have T* lenses and the vast number of sample pictures and reports. That is a massively strong counterargument to your contention that Pentax had better coatings. So it's far from an undocumented claim. Look at some sites that have MTF information for Hasselblad Zeiss T* lenses and Pentax 67 SMC lenses, then tell me the Zeiss coating is inferior, or look at MTF information for Contax Zeiss T* lenses and Pentax SMC lenses, again, there is a very large amount of information available that contradicts your viewpoint. You just have to be prepared to accept it, which you don't seem to be.

Your point about the necessity of SMC to enable the production of an ultrawide lens is incorrect. I own a 2.8/18mm lens made in 1961 by LOMO in Leningrad, it has the typical purple/magenta Russian coating and it has excellent contrast and saturation, flare resistance is also good as long as there isn't a bright light source in the frame such as the sun. Certainly comparable in those regards to the much later multicoating Tokina AT-X 3.5/17. The front element is much bigger than the Pentax 3.5/15. There are other examples of very complex wide angle lenses that perform very well without having sophisticated multicoatings. There are other factors to consider such as the internal mechanical design - light baffles, anti-reflective paint surfaces, glass types, number of air-glass interfaces, size of entrance and exit pupil. As Attila said, there are plenty of single coated lenses that are superb performers and can match later multi-coated optics.
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