Long range optics

[rexford]

The German 50mm Pak 38 is said to have significantly lengthened the range at which could take place due in part to the optics. Here's a few thoughts on the role of the optics behind that statement.

1. 50mm Pak 38 had 3.0x magnification with excellent light gathering qualities, 2 pdr guns had 1.9x magnification.

So,

A.

If you're aiming at a target at a range where the observed target size is small, higher magnification means it is easier to put the 50mm Pak 38 cross-hairs on the center of mass, which increases the accuracy.

A 2m x 2m target at 1200m range appears to be 0.066 inches high (1.68mm) on each side to the naked eye (measurements taken one foot from the eyeball, or 30.5cm.

With 3.0x magnifying power the observed image is 0.20 inches (5.0mm), with 1.9x is it 0.12 inches (3.2mm).

B.

Better light gathering means that if the target is fading out of sight at range due to camouflage, dust, fog, glare or dusk/dawn conditions, the 50mm Pak 38 has the edge.

As noted in a previous post this thread, better optics make the biggest difference in extreme conditions.

There is a story where a Tiger in fog was able to spot and knock out a group of T34 that were organizing for an attack, and the Russians never figured out where the shots were coming from cause they couldn't see very far into the mist.

In NWE, the Americans had a difficult time fighting in limited light conditions (dusk/dawn/overcast) compared to the Germans, due to the light gathering disparity of the optics.

2. 2 pdr guns had range markings up to 1800 or so yard, 50mm Pak 38 was not as limited.

[JonS]

Originally posted by Mark Gallear:

... I came across an account of 25pdrs been used to stop a German tank attack in Normandy!

Really?! I'd love to hear more about that if you have the details handy. I was underthe impression that the 25-prs never had to face armour again after about August '42.

Regards

JonS

[rexford]

The early Shermans used a hull top scope for the gun aim which was linked to the gun sight on the inside of the tank, and there was a tendency for the linkage to go out of adjustment.

[Mark Gallear]

Originally posted by rexford:

The German 50mm Pak 38 is said to have significantly lengthened the range at which could take place due in part to the optics. Here's a few thoughts on the role of the optics behind that statement.

1. 50mm Pak 38 had 3.0x magnification with excellent light gathering qualities, 2 pdr guns had 1.9x magnification.

So,

A.

If you're aiming at a target at a range where the observed target size is small, higher magnification means it is easier to put the 50mm Pak 38 cross-hairs on the center of mass, which increases the accuracy.

A 2m x 2m target at 1200m range appears to be 0.066 inches high (1.68mm) on each side to the naked eye (measurements taken one foot from the eyeball, or 30.5cm.

With 3.0x magnifying power the observed image is 0.20 inches (5.0mm), with 1.9x is it 0.12 inches (3.2mm).

2. 2 pdr guns had range markings up to 1800 or so yard, 50mm Pak 38 was not as limited.

I think the point about the low light is a good one.

I think the 2pdr is ranged out to 1800m because that’s the maximum distance anybody believed the round would go with any power left to penetrate anything! Hitting something at this range would take a whole stack of ammo and luck. As has been said before the "belief" amongst British crews was that you had to get within 600m before the gun was effective against the German Armour of this period. This distance is not short for WW2.

I think the point about the crosses hairs is a bit misleading for long range fire as the round at these ranges will not travel directly to the target, but follow a curve - meaning that you will have to point the gun below or above it. (Even more so with more exotic rounds such as APDS.) The Germans tankers have a device to help them decide how much below or above to put the cross hairs but it’s not a "battle computer".

The good optics will only give them a rough guide to how far away the target it is from how big it is in their sights. The better optics may allow them to see the puff of dust from the round and then adjust it, where as tankers with simpler gun sights would be unable to do this.

At shorter ranges, the better optics may allow them to target an exact point of tank - allowing them to blow the tracks of tanks that they could not otherwise pentrate. There is some evidence that KVs and Grants when they where first introduced were dealt with in this way. The better optics may enable them to identify the opposing tanks types much earlier.

Periscopes and gun sights sophistication for all nations increases dramatically as the war goes on. I think the CM should model these effects but at normal battle, ranges and light conditions the effects of them are "only a small part of the equation".

Featherstone says, “In 1939 Sighting and Fire Control gear consisted of little more than a telescope of which the graticules could be moved to put on the range. As the war progressed it increased enormously in complication. The first demand brought on by extremely long ranges used in the Desert, was for greater magnification and as a high magnification was not suitable for all purposes, this led to dual magnification. Then to secure better protection and wide angle vision the sighting was combined with the gunner’s observation into a periscope combination and a remarkable all-round improvement was obtained. A good gunner looked after his periscope lens as he might his eyes – each morning tenderly wiping the dew off the periscope in the armoured sponson bulging in front of the turret.”

I think a missed opportunity is that CMAK treats each tank variant separately – compared to other paper and computer wargames, which bundles them together. But then fails to model the minor differences. I admit these are often minor differences such as better periscopes and sights, which are hard to detect and quantify. Hunnicutt does go some way however to list the different marks of periscope in the Sherman. Differences between petrol and diesel engines are also not modelled but again period tests showed that ammo storage was a more critical difference.

For JohnS – I came across the 25pdrs stopping a German armoured attack whilst doing the research for my Polar Bears CMBO op, it is described in Polar Bears by Patrick Delaforce. From memory, a British armoured attack was stopped dead and the Germans then launched their own armoured thrust. 25pdrs supporting Infantry were rapidly brought up and stopped Panthers at very short ranges.

[c3k]

Gents,

An interesting discussion. An important element of a any optics system is the TARGETING element. To clarify that statement, it does you almost no good just to see the enemy unless you can tie that into where you point your gun.

This is where the reticle, focus, and ranging adjustment methods are CRUCIAL.

The typical allied optic had a simple reticle. Imagine a ladder standing upright visible when you view through the sight. The sight itself is fixed to the barrel of the weapon. Each rung of the ladder corresponds to a certain range. It's a very simple sight, requiring some skill to use effectively. If you judge or guesstimate the enemy to be at 800 meters range, you simply elevate the gun barrel until the rung corresponding to 800 meters is on the target. You adjust elevation after that based on where your rounds are landing.

The difficulty is that the ranges rarely lie exactly along a rung and the target is rarely motionless. Now you need to interpolate. That's where the skill comes in.

German sights chose a different path. The sight is complex requiring less operator skill. As you adjust the range knob on the sight the internal reticle (a triangle, not a ladder) moves. THE AIMPOINT IS ALWAYS THE TIP OF THE TRIANGLE. That's kind of important. The reticle moves, the sight moves. You elevate gun to match reticle to target, fire.

The differing magnifications, light sensitivity, reflectivity, viewing angles, etc., are part of the equation, but it's more important to realize how the sighting system is tied into the weapons system and how they're used together. The advantage is clearly in favor of the approach used by the Germans. (In fact, every modern weapon system uses the same technique: the operator puts the pipper on the target. The weapon system adjusts for range and lead, not the operator.)

It is my opinion that BF.C has consistently under-modelled the effectiveness of the advantage of the German optics systems.

Thanks,

Ken

[aka_tom_w]

we have been down this road a few times around here

"The differing magnifications, light sensitivity, reflectivity, viewing angles, etc., are part of the equation, but it's more important to realize how the sighting system is tied into the weapons system and how they're used together. The advantage is clearly in favor of the approach used by the Germans. (In fact, every modern weapon system uses the same technique: the operator puts the pipper on the target. The weapon system adjusts for range and lead, not the operator.)"

for more on this see this web page:

http://www.panzerelite.com/zeiss/zeiss.html

it has pics like this:

and compares the two optics systems with descriptions and images! (it should be noted the game Panzer Elite was out before CMBO and it was made in Germany so it is not new or ground breaking and the designers may have spend more effort modeling German optics and targeting systems) I have played the game and it is fun for a little while (like a couple of weeks) It is like CMBO with Franko's Ironman rules in that you ARE the TC and you can only see the battle from view level one or level 2 BUT you get to see it through the gunner's sight (if you want) and you can BE the gunner and do all the gunner targeting your self and THAT is fun for ME! (for change) you have to be REAL good to get a hit on a moving tank. And you can FORGET firing while on the move because it is IMPOSSIBLE to hit ANYTHING with AP when attempting to target while moving!!!)

While there is NOW actually an attempt by BFC to simulate and model higher quality German optics and targeting systems, in the game (its BETTER than CMBO which did not account for that factor), I would agree that perhaps a better chance to hit could be afforded the German optics systems in some tanks. (but that is only my uninformed opinion)

"It is my opinion that BF.C has consistently under-modelled the effectiveness of the advantage of the German optics systems"

I would have to agree.

-tom w

[ January 05, 2004, 12:29 PM: Message edited by: aka_tom_w ]

[Determinant]

Optics are an important element for long-range spotting - if you can't see them you can't hit them. But effective range-finding is an aspect of optics that is critical for accuracy.

Completely anecdotally I have seen pictures of German troops with rangefinders (either the six foot (?) long tubes or the 'bunny ear' periscopes - both of which I assume are stereoscopic range-finders) but I can't recall seeing a single picture of allied troops using range-finders.

Does any know how range-finders were used and at what scale they were issued to in the various armies? Thinking of the CM 'has binoculars' label there should also be one for 'has rangefinder'.

Perhaps the allied experience is best summarised by the story in that old classic 'Is Paris Burning?' about the British Sherman crew who got a first round disabling hit on Panther on the Champs Elysee in Paris because the commander had only just read in his Michelin Guide that it was 1100 yards long. Splendid if true.

[Redwolf]

I have seen photos of and read about German AFV crews using rangefinder, either the long straight type or the Scherenfernrohre (which are probably pretty lousy because they are not very wide).

Nothing I have seen supports that these have been used in an actual hot battle. The only exception is the Jagdtiger which seemed to have one mounted for regular use from inside the vehicle.

All I can see is use before the enemy arrives to pre-memoize landmarks.

Which brings back the point that pre-registration for the defender is far too rare in CM. Only the bunkers get this bonus by default and the TRPs are far too small to be useful for the cost.