[ToW 2 is a Sniper War?]

http://www2.avs.org/historybook/links/tfexh96.htm

SINGLE LAYERS

1935 Zeiss (Smakula), German Patent No.605761 claimed on 1/11/1935 vapor

deposition of CaF2;

1936 Strong CaF2 and formula nfilm=nsubstrate0.5 specified. Article submitted 25/9/1935: The reflection will be reduced using this layer from 4.2% to 0.6%;

1938 Cartwright and Turner published a whole class of usable materials including MgF2 and Cryolite;

The vapor deposition of MgF2 on hot glass surfaces is still state-of-the-art today. This procedure was unknown in Germany during the last war. Therefore they primarily used Cryolite which lowers the reflection, but is not as hard.

DOUBLE LAYERS

For a single layer, one only has a few choices of materials. With a double layer, there are more choices using high and low reflective indexes. The three reflections at the three interfaces can always add to zero by varying film thicknesses. This is true for at least one wavelength. The milestone developments were:

1938 Research Corporation, New York announced without mentioning any inventor, the principal of solving the three vector calculations and mentioned materials

that can be used (Swiss Patent No.221992, issued June 30, 1942);

1939 Cartwright and Turner - a short publication, describing the principle of using Al2O3/SiO2, which was not practical;

1940- 1941

Zeiss (Smakula) and Schott (Geffcken) and Steinkeil (Schneider) experimented

with double and triple layers; double layers never got into production in

Germany or the U.S.;

1949 Balzers (Auwaerter) introduced the double layer "Transmar" (MgF2 plus rare earth oxide) and for many years had a leading position with this method.

Further developments are well known. Today large volumes of anti-reflection coatings up to six layers are produced. Not only optical instruments but consumer goods like binoculars and cameras use anti-reflection coatings (modern camera lenses have the label “Imulti-coated”).

The biggest use (in dollar value) of thin films from 1950 to 1970 was certainly anti-reflection coatings.

[ToW 2 is a Sniper War?]

Well, I'm tired so shyte (typo) happens. Yeah, I meant periscopic M38, but the M39 is the illuminator for the 38, so I mixed up numbers. The M39A2 sight was only used in US heavy tanks.

Well, Zaloga isn't very specific there, and I doubt that a new gun sight development for US tanks, which had landed in North Africa in November 1942, was put in as upgrade in the field, as optics were usually only replaced when the tanks in question were handed back to ordnance depots, as this wasn't a job that could be done in the field, especially since the US troops even lacked the infrastructure to support a large operation. Also, the campaign was basically already won in March 1943, when Rommel left the theater, since the Germans didn't have many assets left they could use against the Allies, until they surrendered on the 15th of May, so I doubt that the upgrade was seen as priority on that theater, nor do I believe that the M70 made it to Africa in substantial numbers (if at all).

Well, I was rather asking whether historical facts are depicted in the game or not.

Even If we'd assume that M70 optics made it to the theater, US optics were really inferior, crews often complained about blurred views. So my question is whether US Shermans are way less accurate than the German counterparts or not. Since you read Zaloga, you will know that Sherman gun sights had ballistic reticles where the gunner had to estimate the range. German gunners had rather accurate range finders in their sights.

The reason for the ALLIED optics being inferior was that the more lenses (that had been produced in the old fashioned way) they put into a telescope (to receive a higher magnification), the more clarity got lost (10% with each lense). I've read that a 40% loss of clarity definetly impacts usability, so a US 4-lenses-system wouldn't have been too helpful for a tank gunner. The Germans, in turn, were using 4-lenses in their systems without any problems.

Also: the more lenses the more restricted the field of view (12° FOV for many US gun optics only, while German optics had 25°).

So, if you look at the numbers, generally, German tanks in Africa had better magnification, the same or even better clarity, and twice the field of view compared to Allied systems.

Zeiss used a special technique developed in 1938 which involved an Argon gas coating over the lenses, reducing the loss (of clarity) per lense to 3-4%, which allowed for the production of sighting systems with 4 lenses and more, while maintaining the clarity of a Western gun sight that carried 1 or 2 lenses only. The Germans transferred that technology to Japan (during or at the end of the war in Europe), and you might know that Japan produced excellent lenses for cameras after the war, as they were then using that knowledge too. The Allies didn't know about that production method until after the war.

So, is that particular German superiority depicted in the game?

Means, are Allied tanks less accurate at medium/long ranges or not?

Completely Nonesense.

In WWII, German used MGF2, and allied used CaF2 to reduce reflection, both were single coating, AFTER WWII,a Swiss company developed PRACTICAL multi-coating lense.

Do you know the famous US film <<Gone with the wind>> in 1939?

They were coating anti-reflection films for ‘Gone With the Wind,’ for their projection lenses.