'Superior' German & Japanese Optics & Rangefinders

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GiZi
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'Superior' German & Japanese Optics & Rangefinders

Post by GiZi » Mon Oct 01, 2018 3:14 am

Hello all,

I have a somewhat general question, so I apologize for that, but time and time again I've seen people refer to superior German/Japanese optics and thus superior rangefinders. I'm curious as to why this is.

I know some tend to default to the position of Stereoscopic > Coincidence (which as far as I know is very situational?), which would explain perceived superiority towards British types (who stuck with Coincidence Rangefinders in WWII), but the Americans, Italians, and French all used Stereoscopic rangefinders as well. So that begs me to ask; what made German and Japanese versions superior?

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Re: 'Superior' German & Japanese Optics & Rangefinders

Post by dunmunro » Mon Oct 01, 2018 8:28 pm

GiZi wrote:
Mon Oct 01, 2018 3:14 am
Hello all,

I have a somewhat general question, so I apologize for that, but time and time again I've seen people refer to superior German/Japanese optics and thus superior rangefinders. I'm curious as to why this is.

I know some tend to default to the position of Stereoscopic > Coincidence (which as far as I know is very situational?), which would explain perceived superiority towards British types (who stuck with Coincidence Rangefinders in WWII), but the Americans, Italians, and French all used Stereoscopic rangefinders as well. So that begs me to ask; what made German and Japanese versions superior?
Germany had a very well developed optical industry and the IJN, by disregarding treaty limits could place very large, long base RFs into the Yamato class. However testing of German naval optics by the Allies didn't show any clear superiority for Axis RFs, and only modest areas of superiority in things like binoculars. I'm pretty sure the same was true for the IJN.

The only IJN battleship that used stereo RFs for surface engagements was the Yamato class (1 stereo and two coincidence RFs built into a triplex unit), AFAIK. All their cruisers used Coincidence RFs for surface engagements as well. The RM used a combination of stereo and coincidence RFs, IIRC, as did the USN, but both favoured stereo.

GiZi
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Re: 'Superior' German & Japanese Optics & Rangefinders

Post by GiZi » Thu Oct 04, 2018 2:36 am

dunmunro wrote:
Mon Oct 01, 2018 8:28 pm

Germany had a very well developed optical industry and the IJN, by disregarding treaty limits could place very large, long base RFs into the Yamato class. However testing of German naval optics by the Allies didn't show any clear superiority for Axis RFs, and only modest areas of superiority in things like binoculars. I'm pretty sure the same was true for the IJN.

The only IJN battleship that used stereo RFs for surface engagements was the Yamato class (1 stereo and two coincidence RFs built into a triplex unit), AFAIK. All their cruisers used Coincidence RFs for surface engagements as well. The RM used a combination of stereo and coincidence RFs, IIRC, as did the USN, but both favoured stereo.
So would I be correct in understanding there is no effective advantage held by Japanese and German optics compared to other powers?

While I hate to bring up the page; http://www.combinedfleet.com/b_fire.htm
It seems to make a big deal of their optics being of a greater capability, particular those of Japan in regards to night-fighting.

I recall comments from Italian night exercises in 1941 remarking that the battleship Littorio, while able to target the Caio Duilio with her rangefinders previously, this became impossible when the other battleship turned on her searchlights and blinded the Littorio. However, use of 'Zeiss-Septar' polarizing filters made it possible to target the other battleship with no interference from the light. However, given how backward the Regia Marina was in regards to night-fighting with major-caliber guns at this point, I'm not sure if this is more reflective of Italian unpreparedness for night combat, or an actual advantage that German optics had over those of other navies - and by extension, something that might be expected of the Japanese, who were the 'masters' of optical nightfighting.

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Re: 'Superior' German & Japanese Optics & Rangefinders

Post by dunmunro » Thu Oct 04, 2018 6:18 am

It was superior doctrine not optics that gave one side an advantage over the other at night.

The RN learned from the Germans (the hard way during WW1) how to fight effectively at night and perfected their techniques between the wars, and they taught the IJN what they learned.

The IJN used flashless powder (which had less but not zero flash) and salvo fire at night. A warning bell told observers when a salvo was about to be fired, so they could close their eyes. The time between salvos was used for spotting and the correcting the point of aim.

The USN didn't use flashless powder and used continuous fire; consequently their observers were being constantly blinded by the flash of their own guns.

The USN couldn't use the optics that they had effectively because of their doctrine, and the same was true for the RM.

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Re: 'Superior' German & Japanese Optics & Rangefinders

Post by GiZi » Sun Oct 07, 2018 5:29 pm

dunmunro wrote:
Thu Oct 04, 2018 6:18 am
It was superior doctrine not optics that gave one side an advantage over the other at night.

The RN learned from the Germans (the hard way during WW1) how to fight effectively at night and perfected their techniques between the wars, and they taught the IJN what they learned.

The IJN used flashless powder (which had less but not zero flash) and salvo fire at night. A warning bell told observers when a salvo was about to be fired, so they could close their eyes. The time between salvos was used for spotting and the correcting the point of aim.

The USN didn't use flashless powder and used continuous fire; consequently their observers were being constantly blinded by the flash of their own guns.

The USN couldn't use the optics that they had effectively because of their doctrine, and the same was true for the RM.
Alright, I think I understand now. Thanks a lot for your help!

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Re: 'Superior' German & Japanese Optics & Rangefinders

Post by Dave Saxton » Mon Oct 08, 2018 2:05 pm

It should be understood that the Germans used a completely different set of night optics for fighting at night or low light conditions from the their standard day optical equipment sets.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: 'Superior' German & Japanese Optics & Rangefinders

Post by Frej » Wed Nov 07, 2018 7:40 pm

"the battleship Littorio, while able to target the Caio Duilio with her rangefinders previously, this became impossible when the other battleship turned on her searchlights and blinded the Littorio. However, use of 'Zeiss-Septar' polarizing filters made it possible to target the other battleship with no interference from the light."
This touches on a topic I've been trying to learn more about. Some games, e.g., Battle Stations, claim that you can't fire on a ship that is illuminating your ship with a searchlight, you get blinded. However, it seems to me that it ought to be possible to use a filter to avoid getting blinded, and then the effect of being illuminated by a searchlight would be to make the illuminating ship much more visible. On the other hand I would expect that spotting the fall of shell would then be impossible. You could see the searchlight very well but nothing else. Have I got that right? And if so, how much would being unable to spot the fall of shell degrade the number of hits you could expect to get? I expect that would depend strongly on the range, Does anybody have even a rough idea?

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Re: 'Superior' German & Japanese Optics & Rangefinders

Post by dunmunro » Thu Nov 08, 2018 7:35 am

Frej wrote:
Wed Nov 07, 2018 7:40 pm
"the battleship Littorio, while able to target the Caio Duilio with her rangefinders previously, this became impossible when the other battleship turned on her searchlights and blinded the Littorio. However, use of 'Zeiss-Septar' polarizing filters made it possible to target the other battleship with no interference from the light."
This touches on a topic I've been trying to learn more about. Some games, e.g., Battle Stations, claim that you can't fire on a ship that is illuminating your ship with a searchlight, you get blinded. However, it seems to me that it ought to be possible to use a filter to avoid getting blinded, and then the effect of being illuminated by a searchlight would be to make the illuminating ship much more visible. On the other hand I would expect that spotting the fall of shell would then be impossible. You could see the searchlight very well but nothing else. Have I got that right? And if so, how much would being unable to spot the fall of shell degrade the number of hits you could expect to get? I expect that would depend strongly on the range, Does anybody have even a rough idea?
The RN used an astigmatizing filter to range on enemy spotlights; This filter caused the searchlight to appear as two stretched lines when the range was incorrect, but a single line when the range was correct. Typically searchlights were used a ranges of less than 12k yds so not being able to spot the fall of shot was not a complete handicap, except for correcting errors in target speed and course.

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Re: 'Superior' German & Japanese Optics & Rangefinders

Post by Byron Angel » Thu Nov 08, 2018 6:21 pm

Frej wrote:
Wed Nov 07, 2018 7:40 pm
"the battleship Littorio, while able to target the Caio Duilio with her rangefinders previously, this became impossible when the other battleship turned on her searchlights and blinded the Littorio. However, use of 'Zeiss-Septar' polarizing filters made it possible to target the other battleship with no interference from the light."
This touches on a topic I've been trying to learn more about. Some games, e.g., Battle Stations, claim that you can't fire on a ship that is illuminating your ship with a searchlight, you get blinded. However, it seems to me that it ought to be possible to use a filter to avoid getting blinded, and then the effect of being illuminated by a searchlight would be to make the illuminating ship much more visible. On the other hand I would expect that spotting the fall of shell would then be impossible. You could see the searchlight very well but nothing else. Have I got that right? And if so, how much would being unable to spot the fall of shell degrade the number of hits you could expect to get? I expect that would depend strongly on the range, Does anybody have even a rough idea?
1 - In Japanese practice (and likely other services), one ship might illuminate the target with her S/Ls, enabling other ships to engage without using their own S/Ls.
2 - The historical record strongly suggests that a ship illuminated by large S/Ls would be optically hindered to a large degree: polarizing filters were certainly useful, but it is likely that only a select few observers aboard had them available. It is also my belief/understanding that they were a reactive solution. Since their use effectively reduces the amount of light admitted to the eye, their use at times when the ship was not under intense S/L illumination would presumably hinder normal optical vision by restricting passage of ambient light.

Perhaps a more optically informed member can "shed some light" on this issue.

B

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