CZJ T3M (1 Viewer)

[Ignatius]

Zeiss West, Swarovski and Leica have continually improved their coatings with iterations of Swarotop, T, P and presumably the Leica equivalents too.
But what about the Carl Zeiss Jena T3M multi-coating introduced in 1978? Was that ever updated until CZJ's demise in 1991?

 

[Patudo]

I have a feeling only someone like Gijs, who has tested transmission in binoculars of different dates of manufacture, would really know. I wonder whether better anti-reflection coatings were used in the Nobilem/Octarem series compared to the traditional Dekarem/Jenoptem models.

Incidentally, I have never come across anything that mentioned the improvement of phase coatings - I would imagine current phase coatings have been improved compared to those from the very late 80s/early 90s, but am completely in the dark as to how they might have been improved, or what improvements might have been achieved.

 

[Ignatius]

As far as my statement about steadily improved coatings goes: I have that information partly from stuff John A. Roberts has uploaded here. For example in a pdf entitled 'Swarovski Traditional Binoculars - Introduction of Optical and Mechanical Features' he lists
DV (2 layer) mid-1948
EV (1 layer) 1956
Transmax 1982? (NB. I have never heard of this coating before reading this in Mr. Robert's pdf)
Swarotop (3 layer) from ca. 1980
Swarodur 1996
Swarotop v2 early 1997
Swarotop v3 start 2009

My own research about Zeiss and Leica brought forth:

Type​	Zeiss​	Year​	Leica​	Year​
Transmission	T	1935/1954
Transmission MC	T*	1979	HDC, lens	2003
Phase corrective	P	1986	P40	1989
Phase correction + MC	P*	1988	HLS, dielectric prism	2002
Hydrophobic	LotuTec	2007	AquaDura	2007

I do not know about others, but I see a steady progression in coatings, the number of their layers and presumably also in the technology behind their application, and I was wondering whether anything is known about the Zeiss Jena coatings, especially whether from 1978 (T3M) on they were on a par with western coatings, and whether CZJ worked on keeping up with the western cousins.

 

[jan van daalen]

Just to be complete, from1987 it is marked T*P.

 

[Patudo]

My impression was that Zeiss West's T* multicoating was superior to Carl Zeiss Jena's T3M - but I cannot in any way prove this. It's also possible that different qualities/grades coatings were used in the different ranges of CZJ porro and roof prism binoculars (Nobilem/Notarem/Jenoptem).

I sometimes wonder whether the same anti-reflective coatings are used in camera lenses and binoculars, and if there are differences (as I suspect they are) what they are and what the reasons for those differences might be (lens curvature, different requirements for colour balance, etc). Does anyone know what photography buffs think about CZJ camera lenses, and specifically their coatings, versus Zeiss West?

 

[Ignatius]

I, too, have been wondering, whether the coatings of 'aus JENA', 'Q1' and 'Jenoptem' models were in any way different or better because those models were for export. Let us not forget, that the East German Mark was not freely convertible and exports always had to be paid in foreign currency to bolster the DDR coffers.
But this is what this thread is meant to be about - accumulating knowldge about CZJ coatings. Thanks for playing, gentlemen. Any former CZJ employees out there who might add the odd Pfennig or three's worth?

 

[Binastro]

Camera lenses have to cover much wider fields than binoculars, at least with standard and wide angle lenses.

The TTH patent 3 layer coatings were tunable depending on application.

I am surprised to see a Zeiss 1935 coating on a binocular, although some lenses had internal coats in 1933, but this was kept secret.

Kodak were hard coating at the end of the 1930s at least with military lenses.

More important than the type of coating is, how many surfaces are coated?
All air to glass surfaces, only lenses, not prisms or only two external surfaces, or every surface except the rear surface.

Also, how accurate are the coatings.

Additionally, top end professional lenses have all cemented surfaces coated as well.

Few if any binocular seem to have cemented surfaces coated, although some Pentax eyepieces have this.

I am very happy to use a binocular with single surface coating on all air to glass surfaces.
With clear 'white' glass, not grey glass.

Regards,
B.

 

[henry link]

From 1985 to 1988 I bought five pairs of CZJ binoculars with T3M multi-coating, one aus Jena 8x50 Nobilem "super", three 8x50 Octarems, two of which were aus Jena GA versions and one was a CZJ from the UK. The last pair was an CZJ 8x30 Deltrintem from the UK.

I found all of those binoculars to be very similar in terms of light transmission and color accuracy, except the Nobilem which was dimmer than the rest, maybe because of four more surfaces and very large prisms. All of them had a green bias. I considered the T3M coatings to be inferior in both transmission and color accuracy to the Nikon and Fujinon multi-coatings of the same period as well as the early Swarotop multi-coatings and Optolyth Ceralin. I don't remember comparing T3M to Zeiss T*, but the only T* coated binoculars I bought in the 80s had un-phase corrected roof prisms (one with silver prism coatings), which would not have been good representations of the true quality of T*.

BTW, the strongest color bias I ever experienced from any of those 1980s multi-coatings was from Swarovski Transmax, which was like looking through a yellow filter.

 

[Ignatius]

Carl Zeiss Jena binocular coatings 1948-1991

Paul Ahnert wrote in 1961 (Beobachtungsobjekte für Liebhaberastronomen, JAB-Verlag Leipzig), that the surfaces of the lenses of Zeiss Jena amateur telescopes had a very thin reflex reducing coating. No idea whether that even had a name. I assume it was a single coating.

Altogether this makes my table look like this now:

Type​	Zeiss​	Year​	Leica​	Year​	Swaro​	Year​	CZJ​	Year​
Transmission	T​	1935/1954​		​	EV	1956​		1961​
Transmission MC	T*​	1979​	HDC, lens	2003​	DV	1948​	T3M​	1978​
Phase correction	P​	1986​	P40	1989​	SwaroTop	1980​		​
Phase correction + MC	T*P​	1987​	HLS, dielectric	2002​	SwaroTop v2	1997​		​
	​	​		​	SwaroTop v3	2009​		​
Hydrophobic	LotuTec​	2007​	AquaDura	2007​	SwaroDur	1996​		​

 

[John A Roberts]

Anti-Reflective Lens Coatings

For an historical overview see: Development of Anti-Reflective Lens Coatings

In brief . . .
There was awareness by some going back to at least the early 19th century (Fraunhofer) and again late in that century (Taylor),
that modifying the reflectivity of a lens surface could increase light transmission.

In 1935 Zeiss lodged a patent for a process to apply a single layer lens coating (based on the work of Smakula and others at Zeiss).
The patent was kept secret by the Nazi regime due to its military implications.

Unsurprisingly, Smakula and his collegues also explored the concept of additional layers. With the Schott company succeeding in applying
a dual layer coating on a lens in 1939, and a triple layer one (what we commonly refer to as multicoating) in 1943!


There's also info in the post as to when various coatings were first commercially used (verses earlier government and industrial uses).


John

 

[tenex]

Altogether this makes my table look like this now:

Not sure why you list "Phase correction" separately from "Phase correction +MC", as if there were phase-corrected models without MC, or what all that has to do with dielectric?

 

[Tringa45]

I don't remember comparing T3M to Zeiss T*, but the only T* coated binoculars I bought in the 80s had un-phase corrected roof prisms (one with silver prism coatings), which would not have been good representations of the true quality of T*.

And if they had silver-coated the roof surfaces, would not that have improved contrast and obviated the need for phase coatings, albeit with a small loss in transmission?

Regards,
John

 

[Hermann]

And if they had silver-coated the roof surfaces, would not that have improved contrast and obviated the need for phase coatings, albeit with a small loss in transmission?

Phase correction does a lot more than improve contrast, cf. Weyrauch/Dörband 1988. Good summary in Holger's book.

Hermann

 

[Tringa45]

Phase correction does a lot more than improve contrast, cf. Weyrauch/Dörband 1988. Good summary in Holger's book.

Hermann

Please elaborate. If you mean resolution, then a lack of contrast naturally results in impairment of resolution.
As Holger states, modern phase coatings bring binoculars with S-P prisms close to the best Porros and the difference with A-K prisms is just about indistinguishable.
AFAIK metallized surfaces don't polarise, so if roof prism binoculars had had metallized roof surfaces prior to the awareness of phase cancellation effects and the discovery of phase coatings, they would probably have performed better.
Even today Baader Planetarium use a silver coating on their 90° prism diagonals, where total internal reflection would otherwise occur.

John

 

[Patudo]

if roof prism binoculars had had metallized roof surfaces prior to the awareness of phase cancellation effects and the discovery of phase coatings,

... but they did, didn't they? Before the introduction of dielectric coatings, mirrored surfaces on Schmidt-Pechan prisms had to have been metallized - either aluminium (some Leitz) or silver.

 

[Tringa45]

... but they did, didn't they? Before the introduction of dielectric coatings, mirrored surfaces on Schmidt-Pechan prisms had to have been metallized - either aluminium (some Leitz) or silver.

No, the metallized surface was where the angle of incidence was too acute for total internal reflection.

Schmidt–Pechan prism - Wikipedia

en.wikipedia.org

I'm not aware that roof surfaces were ever metallized.

John

 

[Patudo]

No, the metallized surface was where the angle of incidence was too acute for total internal reflection.

Gotcha. But what would be the benefit of metallizing those other surfaces, given that total internal reflection would have taken place there?

 

[Tringa45]

Gotcha. But what would be the benefit of metallizing those other surfaces, given that total internal reflection would have taken place there?

No benefit today as we have effective phase coatings.
However, if the manufacturers of roof prism binoculars had been aware of the reason for image degradation it might have made sense to apply a metallized coating to the roof surfaces prior to the 1980s.
Where there is total internal reflection there is polarisation and in the roof prism, which corrects the image left/right,. there are interference (cancellation) effects when light rays off both roof surfaces are combined. A metallized surface does not polarise light.
There would, of course, have been additional transmission losses as the reflectance of silver is at best around 96% and only about 85% at 400 nm, and aluminium averages around 92%.

John

 

[Gijs van Ginkel]

To my knowledge only one prism surface of Schmidt-Pechan prisms has to be supplied with a metal mirror, since the light rays do not enter under an angle of perfect reflection on that surface leading to light losses. Abbe-König prisms do not have that problem, so no silver- or dielectric layers in these prisms.
Gijs van Ginkel

 

[tenex]

And if they had silver-coated the roof surfaces, would not that have improved contrast and obviated the need for phase coatings, albeit with a small loss in transmission?

I do think this is an interesting idea for understanding the thought process back then. Why did it not happen: did they suppose users would notice a loss of brightness more easily than contrast/resolution? Or once they understood the nature of the problem, did they just expect to develop an effective correction faster than turned out to be the case? Was this seen as not a high priority, since the product was selling? (And were "they" only at Zeiss, or also Leitz?)