Worrying tank spotting results

[JonS]

Testing a Tiger 1 88mm in UK trials showed at 1200 yards [1100metres] a 5 shot grouping of 16" by 18" so we can take it that the gunnery sights were pretty darn good.

Not really.

From that you can take it that the gunnery system - of which the sights formed a part - was pretty darned good.

[wokelly]

The sources I have seen say:

Sherman M70 F telescopic sight:

* 1.8 magnification

* 12° FOV

Not sure about 1.8x. The Early Shermans had the periscope M38 sights with 1.44x optics. The M70F was a 3x scope:

"To correct the problem with the M4 periscope-type sight gun, later production units of the M4 series tank received a new three-powered direct-sight telescope in the fall of 1942. During the winter of 1942-43, several new telescopes with better optical characteristics were developed, and in July 1943, the army standardized the telescope M70F for the M4 Series."

"The three-power M70F telescope was tubular in shape, measured 22 inches in length, and was illuminated by an instrument light..."

Source M4 Sherman at war. You can find a preview on google:

books.google.ca/books?id=SOTDzoncMroC&pg=PA85&lpg=PA85&dq=Sherman+gunsight&source=bl&ots=xeLZY0b6EO&sig=bKi5i4E53GCz2B6DRUOSrrGhEfU&hl=en&sa=X&ei=A6lWT8vwHuLl0gGQwJifCg&ved=0CFkQ6AEwBg#v=onepage&q&f=false

[Vanir Ausf B]

Looks like you're right about the 3x. The 12° FOV appears to be correct.

[stikkypixie]

This was written a few years back by a guy who used to post here years ago. I don't know where he got his numbers from, but he is very knowledgeable on the subject:

***

Up until the late 1930s the standard way to make lenses employed a series of concave and convex mirrors usually two back to back pairs.Each lens lost ~ 10% clarity with the limit being around 40% reduction before clarity became seriously impinged. Also the more lenses the more restricted the field of view. In 1938 the Ziess company pioneered a technique for introducing Argon gass coating over the lenses that cut this per less loss to about 3-4%. What that meant was that german sighting systems with 4 lenses were as clear as western sights with 1-2 lenses. You can see it in the comparison between maginfication and field of view. For the same magnification they achieved twice the field of view...thus making it much easier to detect and acquire the targets in the first place.

No other country did this until after the war. The germans shared this technology with the Japanese who turned around after the war to make such bloody good camaras

-- Paul Lakowski

I just checked around a bit (wikipedia if you must know ), it seems AR coatings were secret until about 1940s. Still it makes more sense now, thanks for the info

[aka_tom_w]

This was written a few years back by a guy who used to post here years ago. I don't know where he got his numbers from, but he is very knowledgeable on the subject:

***

Up until the late 1930s the standard way to make lenses employed a series of concave and convex mirrors usually two back to back pairs.Each lens lost ~ 10% clarity with the limit being around 40% reduction before clarity became seriously impinged. Also the more lenses the more restricted the field of view. In 1938 the Ziess company pioneered a technique for introducing Argon gass coating over the lenses that cut this per less loss to about 3-4%. What that meant was that german sighting systems with 4 lenses were as clear as western sights with 1-2 lenses. You can see it in the comparison between maginfication and field of view. For the same magnification they achieved twice the field of view...thus making it much easier to detect and acquire the targets in the first place.

No other country did this until after the war. The germans shared this technology with the Japanese who turned around after the war to make such bloody good camaras

-- Paul Lakowski

Excellent, thanks for sharing. Great information.