Christian VII. wrote:Yeah I read it, but again there was apparently a great difference in the effectiveness of the coatings and how they were applied, esp. when combined with special made lenses. Also far from as many Allied optical devices were applied with anti reflective coatings as were German devices.
The Germans deposited CaF2 & MgF2 anti reflective coatings on their lenses as well using a method to achieve a stronger & better coating. The result was an increase in light transmission of over 80% pr. lens, and since most optical devices used five or more lenses this quickly added up. Coatings were deposited in either one, two or even three layers by Zeiss in 1938.
The Germans were well ahead in lens manufacture as well, being the only ones to add Lanthanum to their lenses to drastically improve clarity for example, as well as using plasma cleaning of lenses.
In the end this resulted in a marked advantage in the clarity & brightness of image in German optics, something which allowed them to make bigger and better optical equipment. This can also be witnessed by reading allied troop accounts where the amazement of German optical equipment was very pronounced, esp. in terms of binoculars and telescopic sights.
Finally if we look at the range finders on the German, British & US capital ships there also seems to be a marked difference in the availability of magnifications and FoV, with the German RF'ers providing steps in magnification up to 50x in comparison to the 25x of the US & British RF'ers for example. This was most likely only possible due to the use of more lenses with better clarity and light gatherning qualities.
The table that I posted at 0952PM shows the effect of coating optics, and the effect per lens is shown.
The difference in performance between a lens with basic single surface coatings and one with the best possible modern coatings is almost undetectable except when measured carefully with test equipment.
The US NDRC tested a German 4M RF side by side with the equivalent US 3.5M unit and found the German unit to be overall very similar but slightly inferior, while similar testing showed little difference betwen US and UK RFs,
by 1939, there was no way to "drastically" improve military optics because the performance needed for combat effectiveness was much less than that needed for high quality photography or astronomy, for example. Side by side testing of Allied and German optics didn't show any huge advantage for German optics, which is no surprise, because the basic physics of light and optics place limits on ultimate performance.
The effects are not identical though, some coatings and layering techniques work better than others.
The German AR coatings for example provided an improvement pr. lens of over 80%, where'as the best Allied coatings achieved 60%. But the Allies didn't coat their military optics to anywhere near the same extend as the Germans, infact most of the Allied optical equipment such as binoculars & telescopes weren't coated at all.
But also as mentioned coatings wasn't the only thing, the Germans were also well ahead in the manufacture of the lenses themselves, adding Lanthanum to their lenses to drastically improve clarity and making use of plasma lens cleaning.
The below are a few quotes from a report to the Allied supreme commander (Roosevelt) in March 1945:
"Our sight reticule is okay, but our sights are not nearly powerful enough.
These new telescopic sights are an improvement over the old periscope sight,
but are still not powerful enough. The Germans seem to have better glass in theirs."
- Coulter M. Montgomery, 1st Lt. 66th AR
"I took from a German officer a pair of field glasses 10 x 50, the best glasses I have ever seen. On two occasions, I was able to pick up an anti tank position and a mortar position at a range of about one mile, when these same two targets could not be seen using a pair of GI glasses, 7 x 50"
- Sgt. George A. Barden, 2nd AD Scout Section, 1945.
"The German sight is far better than anything we are using today. It takes a bright light in order to se them - and we do not have that. The same thing goes for our field glasses; if we could spot them, we could fire on them ourselves, or get artillery to fire on that spot. I know that we have the facilities to build better optical equipment - why don't we?"
-Donald Morgan, T/4, 67th AR.
"The German telescopic sights mounted in their tanks are far superior to ours. In particular, it is more powerful. Infact all their optical equipment is superior to ours"
- Sgt. Lewis A Taylor, US Army 2nd AD, 1945
"The matter of tank gun sights has caused us much concern. I have looked through and worked with sights in German Mark V and Mark VI tanks as well as our own. I find that the German sight has more magnifying power and clearness that our own, which is a big advantage to a gunner"
- Lt. Colonel Wilson M. Hawkins, US Army 3rd Bn 67th AR, 1944
The magnification of the German sight is greater than ours, on the Mark V & Mark VI, and has an adjustable reticle for the type of ammunition being fired. The lens seems to be made of better glass than ours. They also seem to have better light transmission capabilities."
- Phillip C. Calhoun, Major, 3rd Battalion, 66th AR
In other words the German reputation for making superior optics didn't just arrive from out of thin air :)