U-Boot Periscope Telemeters

[Nikdunaev]

Hi Everyone!

I noticed that in Silent Hunter the telemeters on German periscopes seem to be marked in degrees just like the American ones.
At least, the scale seems to match the Stadimeter reading in degrees, and a manual calculation, assuming the ticks are degrees, gives good range.

At the same time, some other sims, like, say, Wolfpack, seem to have those scales in centiradians. That means, on low magnification, number 10 corresponds to 5.7 degrees.
This actually makes a lot of sense for metric units, as then the calculation of range in hectometers becomes super easy indeed.

Further, historical things, like RAOBF, seem to function in centiradians.

So, my question is, which scale is historically accurate?
Are there any mods producing the correct scale in Silent Hunter?

Also, what are the correct magnification powers for the periscopes?
I thought they should both be 1.5X and 6X. Yet in Silent Hunter the observation scope shows 1 and 4. Is this actually the case? Or is it just a typo on the indicator?

[derstosstrupp]

Hi Everyone!

I noticed that in Silent Hunter the telemeters on German periscopes seem to be marked in degrees just like the American ones.
At least, the scale seems to match the Stadimeter reading in degrees, and a manual calculation, assuming the ticks are degrees, gives good range.

At the same time, some other sims, like, say, Wolfpack, seem to have those scales in centiradians. That means, on low magnification, number 10 corresponds to 5.7 degrees.
This actually makes a lot of sense for metric units, as then the calculation of range in hectometers becomes super easy indeed.

Further, historical things, like RAOBF, seem to function in centiradians.

So, my question is, which scale is historically accurate?
Are there any mods producing the correct scale in Silent Hunter?

Also, what are the correct magnification powers for the periscopes?
I thought they should both be 1.5X and 6X. Yet in Silent Hunter the observation scope shows 1 and 4. Is this actually the case? Or is it just a typo on the indicator?


Real ones were in milliradians on the vertical, degrees on the horizontal. Both attack scope (at least the C/2 Stand-Sehrohr, the one you sit at and operate with pedals in the tower) and the control room “observation” scope were 1.5x and 6x. The sight picture through the attack scope can be seen here, drawing 17:

http://www.tvre.org/en/aiming-with-the-periscope

Hitman’s optics are imo the best representation of historical scopes.

Additionally, that scope model (C/2) did not have a stadimeter or RAOBF, 2 features present in earlier attack scope models but which were dropped in favor of better optical quality. Mostly data was gathered on the surface (by matching or rough plotting), and range was largely irrelevant due to the fact they shot at low gyro angles.

[Nikdunaev]

Real ones were in milliradians on the vertical, degrees on the horizontal. Both attack scope (at least the C/2 Stand-Sehrohr, the one you sit at and operate with pedals in the tower) and the control room “observation” scope were 1.5x and 6x. The sight picture through the attack scope can be seen here, drawing 17:

http://www.tvre.org/en/aiming-with-the-periscope

Hitman’s optics are imo the best representation of historical scopes.

Additionally, that scope model (C/2) did not have a stadimeter or RAOBF, 2 features present in earlier attack scope models but which were dropped in favor of better optical quality. Mostly data was gathered on the surface (by matching or rough plotting), and range was largely irrelevant due to the fact they shot at low gyro angles.

Thank you for your reply! That is a lot of interesting information!

What is the use of having the horizontal scale in degrees?

Also I kinda understand the case against the stadimeter... But the RAOBF ring was just sitting around the eyepiece, right? What does that have to do with optical quality?

I remember seeing the kinds of scopes, like the ones shown in the article, in one of the mod packs, for Silent Hunter V.
Just curious, is there an actual photo showing the view?

Though I was originally referring to the ones that look more like what we have in stock Silent Hunter and Wolfpack, this kind:

https://i.pinimg.com/originals/0d/16/33/0d1633214eb46cb010c4dda12f5ff03e.jpg

Is that a different model or manufacturer? Perhaps, an earlier-war or pre-war version?

Do those scales look like centiradians? I am not too sure... Notice the lack of degree signes next to the numbers. Unlike what was shown in the drawings.

Hitman's mod, from what screenshots I found, uses both types. The night scope is similar to the article drawings, and, at the same time, the attack scope is similar to the photo.

https://i.imgur.com/WOF6qxb_d.jpg?maxwidth=640&shape=thumb&fidelity=medium

https://i.imgur.com/biEXHnH_d.jpg?maxwidth=640&shape=thumb&fidelity=medium

[derstosstrupp]

The degrees in the horizontal were to be able to eyeball spread angles quickly.

Earlier attack scope models had the RAOBF rings around the ocular, but if you look at pictures of the fixed-eye attack scope (C/2), those rings don’t exist. What you have to understand about the RAOBF when it was implemented in the earlier scopes is that it was integrated with the stadimeter, such that when you turned the prisms, the rings turned automatically. So it was all one unit. After measuring the range vertically, the prisms were turned 90° and the same thing was done with the target length, and you had range and angle on bow as outputs on the rings. Both however being dependent on accurate target height and length, both of which cannot be (and weren’t) relied on in wartime.

Those scales with the tens are indeed in centiradians. Now, that’s a good question, that may in fact be a reticle of an early scope model. As for the attack scope one that I mentioned (C/2, the most common wartime one), I know that one for sure since I have access to the service manual for that periscope. The only doohickey it had on it was a true bearing counter. But overall, the tactical advantage of being able to raise and lower the scope by way of a lever while sitting in one spot was huge, because the skipper could keep the head of the scope right at the waterline at all times. So it was definitely a trade off, in more ways than just optical quality, I can’t quite remember all of the others.

The hitman optics I’m referring to though are the ones in his GUI, not his plain optics mod, which is what the above I think is from.

[Nikdunaev]

The degrees in the horizontal were to be able to eyeball spread angles quickly.

Earlier attack scope models had the RAOBF rings around the ocular, but if you look at pictures of the fixed-eye attack scope (C/2), those rings don’t exist. What you have to understand about the RAOBF when it was implemented in the earlier scopes is that it was integrated with the stadimeter, such that when you turned the prisms, the rings turned automatically. So it was all one unit. After measuring the range vertically, the prisms were turned 90° and the same thing was done with the target length, and you had range and angle on bow as outputs on the rings. Both however being dependent on accurate target height and length, both of which cannot be (and weren’t) relied on in wartime.

Those scales with the tens are indeed in centiradians. Now, that’s a good question, that may in fact be a reticle of an early scope model. As for the attack scope one that I mentioned (C/2, the most common wartime one), I know that one for sure since I have access to the service manual for that periscope. The only doohickey it had on it was a true bearing counter. But overall, the tactical advantage of being able to raise and lower the scope by way of a lever while sitting in one spot was huge, because the skipper could keep the head of the scope right at the waterline at all times. So it was definitely a trade off, in more ways than just optical quality, I can’t quite remember all of the others.

The hitman optics I’m referring to though are the ones in his GUI, not his plain optics mod, which is what the above I think is from.

So RAOBF was a mechanically integral part of the stadimeter? Wow.
I never knew that bit. Always thought it was just a calculator, akin to the American calculators, such as the Omnimeter, the hand held slide ruler.
Now, that I am looking closely at the real life pictures, the thing does not even have the Optische Länge scale that all the mods in the sim have. So no way to use it manually...

Does that mean features like speed computation are entirely fictitious?

And it took me a while to realize the original German name was not RAOBF...
Stupid me :k_confused:

ASR C/6 has it:

http://www.tvre.org/images/02_fot_08.jpg

This is actually very confusing. Is C/6 not a Later-war model? The first article mentioned it was meant for the Typ XXIII.
At the same time it is clearly not a stand-scope.
By the way, why the two separate eyepieces?

The C/2, what year was it introduced?
Did the early-war boats have something else as their turm scope?
Was there some other mod of the StaSR? Logic suggests there should be a C/1 somewhere. :)

[derstosstrupp]

I agree yeah seems odd, the numbering. My understanding was it was always early war scopes that had that integrated system. That system was developed after World War I. The C/2 I want to say came around in early 1940, at least that’s the earliest I see it being referred to in the KTBs. The type 21 had the C/2, as well, not sure about any of the other late war boats. Early war attack scopes looked like the one you have pictured. That scope can be seen today in the Vesikko submarine in Finland, a prototype of the Type II.

Speed calculations were typically by matching on the surface, or rough plotting. If they did not have the opportunity to follow the target on the surface, and had to dive quickly upon sighting, they fell back on either eyeball estimation or the fixed wire method, which we are familiar with, timing the target from bow to stern, but based on an estimate of the target length, since they never quite knew this exactly.

These guys simply just got very close, 500 to 1000 m. They were very skilled at eyeballing angle on bow, and range was mostly irrelevant because they shot at low gyro angles, so that whole unit was really redundant in practice.

[Pisces]

...

Does that mean features like speed computation are entirely fictitious?...This particular statement: Yes, the speed computation is fictitious. I just came up with the idea of abusing the scales for that computation while OneLifeCrissis was making his GUI. I worked out the magic number for getting the calculation to work on the scales. And asked him to include a scratch mark on it as if it was carved in by the commander with a knife. Since then this was copied in pretty much every mod, and for different games, that included the RAOBF function.

As for centi- or mili-radians, this is not limited to the metric system! This applies equally well to the imperial system. It is just that in the imperial system height is usually measured in feet, and length or distance in yards. So you need to include a conversion factor of 3 in it. Or start measuring height in yards as well. Considering 2000 yards is close to 1 nautical mile (good enough for government work) this is not such a bad idea.

Essentially, centi-radians (or milliradians) means you are talking about a slope of 1 over 100 distance (respectively 1 over 1000 distance). So if something is 3 milliradians then it is 3 yards (or 9 feet) high at 1000 yards distance. Similarly, if it is actually 27 yards high, you are 9000 yards distant from it.
The same can be done in metric as long as you maintain the same system for both height and distance. 30 meters high over 2000 yards does not result in 15 milliradians. (though you will be close to within 10% error. ballpark quality)

[John Pancoast]

The degrees in the horizontal were to be able to eyeball spread angles quickly.

Earlier attack scope models had the RAOBF rings around the ocular, but if you look at pictures of the fixed-eye attack scope (C/2), those rings don’t exist. What you have to understand about the RAOBF when it was implemented in the earlier scopes is that it was integrated with the stadimeter, such that when you turned the prisms, the rings turned automatically. So it was all one unit. After measuring the range vertically, the prisms were turned 90° and the same thing was done with the target length, and you had range and angle on bow as outputs on the rings. Both however being dependent on accurate target height and length, both of which cannot be (and weren’t) relied on in wartime.

Those scales with the tens are indeed in centiradians. Now, that’s a good question, that may in fact be a reticle of an early scope model. As for the attack scope one that I mentioned (C/2, the most common wartime one), I know that one for sure since I have access to the service manual for that periscope. The only doohickey it had on it was a true bearing counter. But overall, the tactical advantage of being able to raise and lower the scope by way of a lever while sitting in one spot was huge, because the skipper could keep the head of the scope right at the waterline at all times. So it was definitely a trade off, in more ways than just optical quality, I can’t quite remember all of the others.

The hitman optics I’m referring to though are the ones in his GUI, not his plain optics mod, which is what the above I think is from.

I believe the word was actually "doohickeyachnachsingzig" :D

[derstosstrupp]

I believe the word was actually "doohickeyachnachsingzig" :D

Haha indeed!

Truth is stranger than fiction in this case, in the manual it’s even wilder:
Zählwerk für rechtweisende Peilung

[John Pancoast]

Haha indeed!

Truth is stranger than fiction in this case, in the manual it’s even wilder:
Zählwerk für rechtweisende Peilung

The real reason the Germans lost the war; by the time they got emergency orders typed up for the radio it was to late. :D
Same reason the Roman Empire fell; Rome was asked to repeat the message of how many Barbarians were at the gates ?
"Octavious you lout, I said CVIIXVCIIIIICCCCVVVXXXCVVVVIII ! No sorry, I meant VXXXIIIICICIVVVIIIIXXCEEVXCCVVXXCIIICCCIIXXCXCXCXI III ! Send help quick ! By the time they computed how many that was, to late.

[Pisces]

Didn't know there were E in Roman numerals. ;)

[John Pancoast]

Didn't know there were E in Roman numerals. ;)

Fat fingers. :)

[Nikdunaev]

The real reason the Germans lost the war; by the time they got emergency orders typed up for the radio it was to late. :D
Same reason the Roman Empire fell; Rome was asked to repeat the message of how many Barbarians were at the gates ?
"Octavious you lout, I said CVIIXVCIIIIICCCCVVVXXXCVVVVIII ! No sorry, I meant VXXXIIIICICIVVVIIIIXXCEEVXCCVVXXCIIICCCIIXXCXCXCXI III ! Send help quick ! By the time they computed how many that was, to late.

:haha::har::Kaleun_Applaud:

[Nikdunaev]

I agree yeah seems odd, the numbering. My understanding was it was always early war scopes that had that integrated system. That system was developed after World War I. The C/2 I want to say came around in early 1940, at least that’s the earliest I see it being referred to in the KTBs. The type 21 had the C/2, as well, not sure about any of the other late war boats. Early war attack scopes looked like the one you have pictured. That scope can be seen today in the Vesikko submarine in Finland, a prototype of the Type II.

Sorry, what exactly are the KTBs?
You are saying that the stadimeter and the adjustable stand scope never actually coexisted in one unit, is that right?

I am curious, why could they not, say, take the boat one or two meters deeper, and use the normal, full length scope, with the same effect of it sitting low? Especially in quiet weather, when scope is most visible, but depth control is also easier and more precise...

Speed calculations were typically by matching on the surface, or rough plotting. If they did not have the opportunity to follow the target on the surface, and had to dive quickly upon sighting, they fell back on either eyeball estimation or the fixed wire method, which we are familiar with, timing the target from bow to stern, but based on an estimate of the target length, since they never quite knew this exactly.

These guys simply just got very close, 500 to 1000 m. They were very skilled at eyeballing angle on bow, and range was mostly irrelevant because they shot at low gyro angles, so that whole unit was really redundant in practice.

Did they plot on the map? Maneuvering board? I assume they did not have a device similar in function to the allied dead reckoning tracer?

But plotting itself requires reasonably accurate ranges, right?
Did they get those from telemeter tables? Or was there some other way still?

And for the fixed wire, they did use U-Jagd, right?

I remember reading somewhere that they had tables, listing the linear, rather than angular, torpedo parallax, which allowed shooting at any angle without knowing range to the target, using the target length as a rough yardstick.

This particular statement: Yes, the speed computation is fictitious. I just came up with the idea of abusing the scales for that computation while OneLifeCrissis was making his GUI. I worked out the magic number for getting the calculation to work on the scales. And asked him to include a scratch mark on it as if it was carved in by the commander with a knife. Since then this was copied in pretty much every mod, and for different games, that included the RAOBF function.

Oh, so you are the one who invented it?
Very interesting indeed. I think a lot of people now believe it is historical. :Kaleun_Cheers:

Do you know why the whole device was simulated in Silent Hunter the way it was then?
Why the tick counting, instead of linking it to the stadimeter, which is simulated already anyway?
Why are the two marks and the Kurswinkel ring fixed?

How did the real thing function in terms of scope magnification?
Did you have to divide everything by four in low power, like with the American stadimeter?

As you said yourself, this version was reproduced pretty much everywhere.
No pressure, of course, just wandering. :)

As for centi- or mili-radians, this is not limited to the metric system! This applies equally well to the imperial system. It is just that in the imperial system height is usually measured in feet, and length or distance in yards. So you need to include a conversion factor of 3 in it. Or start measuring height in yards as well. Considering 2000 yards is close to 1 nautical mile (good enough for government work) this is not such a bad idea.

Essentially, centi-radians (or milliradians) means you are talking about a slope of 1 over 100 distance (respectively 1 over 1000 distance). So if something is 3 milliradians then it is 3 yards (or 9 feet) high at 1000 yards distance. Similarly, if it is actually 27 yards high, you are 9000 yards distant from it.
The same can be done in metric as long as you maintain the same system for both height and distance. 30 meters high over 2000 yards does not result in 15 milliradians. (though you will be close to within 10% error. ballpark quality)

Yeah, I understand that mils work in any units, as long as those units are consistent. But because of the foot vs yard thing, it is just not as convenient, I suppose.
According to the American Fleet Submarine Torpedo Fire Control manual, those scopes are marked in degrees, not mils, as one degree is 50 feet at 1000 yards. A rough approximation, sure, but something you can compute in your head.

I guess it is a matter of whether you prefer to multiply by two or divide by three. :)

[derstosstrupp]

Sorry, what exactly are the KTBs?
You are saying that the stadimeter and the adjustable stand scope never actually coexisted in one unit, is that right?

I am curious, why could they not, say, take the boat one or two meters deeper, and use the normal, full length scope, with the same effect of it sitting low? Especially in quiet weather, when scope is most visible, but depth control is also easier and more precise...

KTBs are the logbooks maintained on patrol. Correct, stadimeter did not exist on StaSr. To your second question, head of the attack scope was smaller, significantly so, and depth control is still difficult even at a slightly different depth. I’m not sure what the difference in heights was, if any at all. But depthkeeping was certainly difficult even a couple of meters deeper in rougher weather, and they would not have forgone the advantage of an adjustable fixed eye scope just for that anyway.

Did they plot on the map? Maneuvering board? I assume they did not have a device similar in function to the allied dead reckoning tracer?

But plotting itself requires reasonably accurate ranges, right?
Did they get those from telemeter tables? Or was there some other way still?

Plotting was done on what was called millimeter paper, which is like graph paper on steroids. Very tiny squares that allow for accuracy. Now, there was no rangefinding device reliable on the surface, because the UZOjust was a bearing transmitter, but what they did to plot was they used the mast tips on the horizon as a reference. They knew if just a little bit of mast was showing, that might be 16 nautical miles or so, and they based their plot on whether those mast tips grew or shrank. Over time you can develop a very accurate plot. Note that this was only on the surface and only during the day; submerged, plotting like this was generally not done. The preferable method however on the surface was simply adjusting own course and speed until it appeared they were paralleling the target, that is the simplest way to get the target data (“Ausdampfen”). But no DRT or anything like that like the US. All done by the navigator, with information supplied either by the skipper or a watch officer.

And for the fixed wire, they did use U-Jagd, right?

Probably not. U-Jagd means the hunting of subs, ASW. That watch was actually used by German ASW to plan depth charge approaches. Now, it just so happens that it is handy to use for this method, because the principles are the same, distance traveled over time. They had tables to help with this, but may have also used some form of stopwatch, there is reference made to that in at least one source.

I remember reading somewhere that they had tables, listing the linear, rather than angular, torpedo parallax, which allowed shooting at any angle without knowing range to the target, using the target length as a rough yardstick.

Absolutely correct.

How did the real thing function in terms of scope magnification?
Did you have to divide everything by four in low power, like with the American stadimeter?

The reticle was designed for 1.5x. In game you can multiply by 4 in 6x but IRL this was more complicated due to nuances in the optics. Rangefinding at 1.5x only was recommended.

[Pisces]

...
Oh, so you are the one who invented it?
Very interesting indeed. I think a lot of people now believe it is historical. :Kaleun_Cheers:
I am the one that invented the speed trick.
(from the old days: https://www.subsim.com/radioroom/showpost.php?p=678212&postcount=135) And the other scratch mark just under 15 degrees, for magnification adjustment. If I was unclear, I am not the person that made the RAOBF mod. That was a collective effort of Hitman, JoeGrundman and OneLifeCrissis. They don't seem to be around here much. Unless they visit subfora that I don't visit.


Do you know why the whole device was simulated in Silent Hunter the way it was then?
Why the tick counting, instead of linking it to the stadimeter, which is simulated already anyway?
Why are the two marks and the Kurswinkel ring fixed? I have no clue what modding difficulties they encountered while trying to make this. My knowledge is skin deep. But I'm sure this was motivated by that. Lack of available resources in modifying the GUI to move the way he wanted it/work like the historical device. It must have been the best way to replicate it.



How did the real thing function in terms of scope magnification?
Did you have to divide everything by four in low power, like with the American stadimeter?Much of how it works can be learned on the following site. It is a gold mine if you want to know more about everything connected to target acquisition, tracking and torpedo guidance (from both sides of the war): http://tvre.org/en/ They have an English and a Polish language version.

Did you have to divide everything by four in low power, like with the American stadimeter?As mentioned in my above first quote. The magnification trick uses the mark at 14.5-ish degrees. If you calculate the sine of that angle, you get 0.25. In other words, one quarter. If you line up the low-zoom size to the mark, you get the high-zoom size at the index at the top. For correction of the AOB width in low zoom it is a bit more complicated, and I actually forgot. Maybe you can find it in the archives if you search for my name in OLC's threads. The top link should be a start in the right direction. ;)

:Kaleun_Periskop: https://www.subsim.com/radioroom/showpost.php?p=683604&postcount=222
And finally: https://www.subsim.com/radioroom/showpost.php?p=684984&postcount=263

!!! Be aware though, the precise values and steps relied on that older mod. For use in current RAOBF/GUI mods make sure to consult the documentation of the mod. It's scales may differ.

[Nikdunaev]

Sorry for the late reply :oops:


Plotting was done on what was called millimeter paper, which is like graph paper on steroids.


Simple millimeter paper and no proper rangefinding device? Sounds like a big "ouch" to me. :)
:k_confused::Kaleun_Crying:


Probably not. U-Jagd means the hunting of subs, ASW. That watch was actually used by German ASW to plan depth charge approaches. Now, it just so happens that it is handy to use for this method, because the principles are the same, distance traveled over time. They had tables to help with this, but may have also used some form of stopwatch, there is reference made to that in at least one source.


U-Jagd is not a purpose made tool? Oh...
I honestly thought it was designed for this specific purpose. Those scales look very much like reasonable ship lengths and speeds...

What is the use for depth charging purposes? What do the scales represent in that case?

I am no expert in German, but the name, does it not stand for "unterwasser jagd" or "unterseeboot jagd"? Submarine hunting. Does it actually say if the hunting in question is for or by the submarine itself? I am curious. :)

By this point I am afraid to ask further. :) Does the Silent Hunter community actually use any historical tool correctly? :)

The reticle was designed for 1.5x. In game you can multiply by 4 in 6x but IRL this was more complicated due to nuances in the optics. Rangefinding at 1.5x only was recommended.

Was it any different from the US optics?
Cause for the latter, as far as I know, multiply or divide by four was the "officially endorsed" method in real life. Both for the stadimeter and the telemeter scales.

The optical zoom, does it not change the angular field of view by that factor? 4 times in our specific case?

[Nikdunaev]

I am the one that invented the speed trick.
(from the old days: https://www.subsim.com/radioroom/showpost.php?p=678212&postcount=135) And the other scratch mark just under 15 degrees, for magnification adjustment. If I was unclear, I am not the person that made the RAOBF mod. That was a collective effort of Hitman, JoeGrundman and OneLifeCrissis. They don't seem to be around here much. Unless they visit subfora that I don't visit.

I have no clue what modding difficulties they encountered while trying to make this. My knowledge is skin deep. But I'm sure this was motivated by that. Lack of available resources in modifying the GUI to move the way he wanted it/work like the historical device. It must have been the best way to replicate it.


Much of how it works can be learned on the following site. It is a gold mine if you want to know more about everything connected to target acquisition, tracking and torpedo guidance (from both sides of the war): http://tvre.org/en/ They have an English and a Polish language version.

As mentioned in my above first quote. The magnification trick uses the mark at 14.5-ish degrees. If you calculate the sine of that angle, you get 0.25. In other words, one quarter. If you line up the low-zoom size to the mark, you get the high-zoom size at the index at the top. For correction of the AOB width in low zoom it is a bit more complicated, and I actually forgot. Maybe you can find it in the archives if you search for my name in OLC's threads. The top link should be a start in the right direction. ;)

:Kaleun_Periskop: https://www.subsim.com/radioroom/showpost.php?p=683604&postcount=222
And finally: https://www.subsim.com/radioroom/showpost.php?p=684984&postcount=263

!!! Be aware though, the precise values and steps relied on that older mod. For use in current RAOBF/GUI mods make sure to consult the documentation of the mod. It's scales may differ.

Thanks for all the links! :up:

Actually, http://tvre.org/en/ is where I got most of my questions from. :yep:

The scope and ring pictures above are theirs.
That article mentions that the device could be used for either magnification in real life, but does not give any detail.
So, given that there is no Optische Länge scale on the thing, and the two pointers work differently as well, in real life... I started wondering how it was supposed to work.

Why the two different eyepieces on the scope?
Does this have anything to do with magnification?
Apparently the ring could be mounted on either:
http://www.tvre.org/images/02_fot_07.jpg

Also what is the purpose of the big knob in the lower left corner of the ring? I can not find any references to that one in the text of the articles, even though it is numbered in one of the photos.

[derstosstrupp]

Sorry for the late reply :oops:



Simple millimeter paper and no proper rangefinding device? Sounds like a big "ouch" to me. :)
:k_confused::Kaleun_Crying:




U-Jagd is not a purpose made tool? Oh...
I honestly thought it was designed for this specific purpose. Those scales look very much like reasonable ship lengths and speeds...

What is the use for depth charging purposes? What do the scales represent in that case?

I am no expert in German, but the name, does it not stand for "unterwasser jagd" or "unterseeboot jagd"? Submarine hunting. Does it actually say if the hunting in question is for or by the submarine itself? I am curious. :)

By this point I am afraid to ask further. :) Does the Silent Hunter community actually use any historical tool correctly? :)



Was it any different from the US optics?
Cause for the latter, as far as I know, multiply or divide by four was the "officially endorsed" method in real life. Both for the stadimeter and the telemeter scales.

The optical zoom, does it not change the angular field of view by that factor? 4 times in our specific case?

Correct, U-Jagd was the term used for hunting of subs, not by. We have the service manual for German ASW as part of the Crush Depth project (in my sig). The word “Annäherung” means “closure” - it’s for timing closure rate most likely, probably to assist in depth charge pursuits. The concept is the same though, distance in m converted to knots.

To your question about there being anything realistic used by the community, yes, these concepts are all historical, it’s just sometimes the devices that are used to get there are a little different than what they actually used. The recognition manual is overused though, that didn’t have that kind of data that these games have, so that’s probably the biggest diversion. And using the manual assumes that the very good vision we have out of the periscopes in game was how it was, and it certainly was not. Viewing a target with the head of a periscope just at the waterline, with fogging, and waves etc. was apparently very difficult. Hence the emphasis on gathering data on the surface while overtaking.

Multiplied by four is correct for 6x, however, there was something with the optics that made that not so straightforward. To the extent that the commander’s handbook recommends rangefinding only at low power.

I can answer the second part of your question to Pisces, only because I know the answer at the ready about the multiple oculars. So the one on the left, with the wire going out of it, inside of that one there was apparently a depiction of the torpedo triangle in colors. This allowed the user to visualize the lead angle. It was linked, at least by my understanding, to the AOB finder, since AOB is an angle in the torpedo triangle (gamma). The only other critical pieces of information are target and torpedo speed, and I’m not clear on how those were entered exactly. The ocular on the top inside of the RAOBF I believe was how the prisms were viewed for the stadimeter.

These sound like great features, and they are very innovative, but with the TDC it’s easy to see how they are somewhat superfluous.

[diego_gut]

"Multiplied by four is correct for 6x, however, there was something with the optics that made that not so straightforward. To the extent that the commander’s handbook recommends rangefinding only at low power."


The zoom and field of view had different ratios, perhaps that made it impossible to calibrate the graticle for both.

[Hitman]

Ignore the film footage, those were overlays added on post-production to the film. When you looked through teh scope the reticles were noting like what you see in Youtube or Das Boot.

[John Pancoast]

Ignore the film footage, those were overlays added on post-production to the film. When you looked through teh scope the reticles were noting like what you see in Youtube or Das Boot.

I was wondering if you'd chime in. :) Hope all is well.

[Hitman]

Yes John all is OK thanks God :Kaleun_Cheers:

I check daily here but I don't usually have much time to read or reply.

[John Pancoast]

Yes John all is OK thanks God :Kaleun_Cheers:

I check daily here but I don't usually have much time to read or reply.

:up:

[derstosstrupp]

Hitman is the reason I ventured down the path of wanting to learn more - his research back 10 years ago or so was what got me initially curious. Thanks Hitman!

[Nikdunaev]

The zoom and field of view had different ratios, perhaps that made it impossible to calibrate the graticle for both.

Sorry, I am not sure I understand what you are saying

The optical magnification in telescopes is increasing the apparent angular size of an object by a certain factor, compared to what would be seen by the naked eye.
The decrease in field of view, looking through the same eyepiece, is a direct consequence of that, right?

So, it seems that zoom and field of view are proportionally linked to each other by definition.
If not, than the magnification power number is just meaningless.

[Nikdunaev]

Crush Depth project (in my sig).


That one looks really amazing... :Kaleun_Salute:

A highly detailed and accurate, historically and physically, submarine simulation, representing the actual particulars of the boat, as they functioned in real life?
Yes, please!

I can answer the second part of your question to Pisces, only because I know the answer at the ready about the multiple oculars. So the one on the left, with the wire going out of it, inside of that one there was apparently a depiction of the torpedo triangle in colors. This allowed the user to visualize the lead angle. It was linked, at least by my understanding, to the AOB finder, since AOB is an angle in the torpedo triangle (gamma). The only other critical pieces of information are target and torpedo speed, and I’m not clear on how those were entered exactly. The ocular on the top inside of the RAOBF I believe was how the prisms were viewed for the stadimeter.

Visualize the lead angle? How was it different from setting the lead angle on top of the bearing ring on the scope tube? The one visible in the "bubble" when looking through the scope?

Or was it automated, with TDC-like functionality?

So, the stadimeter prisms were only visible through one eyepiece, but not through the other, is that right?

Why not just align the ghost image, or move it all the way out of sight, when not being used?

In the scope photo on the first page, the ring sits on the bottom ocular, whereas on the photo above, it sits on the top. Otherwise they seem to be pretty much identical. Is there any significance to that, in terms of functionality?


http://www.tvre.org/images/02_fot_08.jpghttp://www.tvre.org/images/02_fot_07.jpg

[Pisces]

@derstosstrupp and Nikdunaev:

You are both talking about this image?
http://www.tvre.org/images/02_fot_07.jpg

[Nikdunaev]

@derstosstrupp and Nikundeav:

You are both talking about this image?
http://www.tvre.org/images/02_fot_07.jpg

Yes, exactly

[derstosstrupp]

That whole unit rotated, so you could simply rotate the ocular with the RAOBF down.

As to the eyepiece with the lead angle inside of it, I don’t know much more than that unfortunately. I only have documentation of StaSr but not the older scopes.

[Nikdunaev]

That whole unit rotated, so you could simply rotate the ocular with the RAOBF down.


Rotated, as in, could be assembled either way, or rotatable by the actual user in operation?

[derstosstrupp]

Rotated, as in, could be assembled either way, or rotatable by the actual user in operation?

Rotated in operation. I think that’s what that little tab handle is at the bottom left. In the picture with RAOBF at the bottom

[Nikdunaev]

Rotated in operation. I think that’s what that little tab handle is at the bottom left. In the picture with RAOBF at the bottom

Right... I see the little tab now. Did not notice it before.

Why would you want that though?
Is it something to do with preferring to look with your left or right eye?

[Nikdunaev]

Ignore the film footage, those were overlays added on post-production to the film. When you looked through teh scope the reticles were noting like what you see in Youtube or Das Boot.

Hi Hitman!
We were referencing your mods, so, perhaps, you are the person who can clarify this a bit more! :Kaleun_Salute:

It is quite obvious that films can, and often do, get these kinds of things very wrong.
Still, I believe the photo on the first page to be genuine. Is it not an actual shot from the time?

Anyway, even if this particular picture is not real, it does show the seemingly ubiquitous centiradian reticle.
Seriously, all the film people use it, there must be some source where they got it, right? :yeah:

Further, I trust that this exact reticle is replicated in your mods. A similar one in mods for Silent Hunter V.

So, can you say, whether there is a specific periscope, or some other optical instrument, that this centiradian scale is based on?

[diego_gut]

Sorry, I am not sure I understand what you are saying

The optical magnification in telescopes is increasing the apparent angular size of an object by a certain factor, compared to what would be seen by the naked eye.
The decrease in field of view, looking through the same eyepiece, is a direct consequence of that, right?

So, it seems that zoom and field of view are proportionally linked to each other by definition.
If not, than the magnification power number is just meaningless.




In Sh3 it works like you say, there is a direct and inverse relationship between zoom and field of view. However, it is not like that in real life, it depends on the construction of the optical device.


In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.


To give more examples, the field of view for the 7x50 binoculars was 7.1 but some 10x80 binoculars had a field of view of 7.25 even though they had 10x zoom. The field of view was different even between different models of the 10x80 binoculars.


What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.


Regards

[derstosstrupp]

In Sh3 it works like you say, there is a direct and inverse relationship between zoom and field of view. However, it is not like that in real life, it depends on the construction of the optical device.


In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.


To give more examples, the field of view for the 7x50 binoculars was 7.1 but some 10x80 binoculars had a field of view of 7.25 even though they had 10x zoom. The field of view was different even between different models of the 10x80 binoculars.


What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.


Regards

This makes sense. To be sure I rechecked the C/2 manual I have and it indeed only recommends using the graticle at 1.5x.

[John Pancoast]

In Sh3 it works like you say, there is a direct and inverse relationship between zoom and field of view. However, it is not like that in real life, it depends on the construction of the optical device.


In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.


To give more examples, the field of view for the 7x50 binoculars was 7.1 but some 10x80 binoculars had a field of view of 7.25 even though they had 10x zoom. The field of view was different even between different models of the 10x80 binoculars.


What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.


Regards

:salute: Many times, adding the "historical" figures into a game for most anything causes more problems than it solves.

[Efshapo]

In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.

Hi, sorry to dig up the past but I'm doing some research about periscope fidelity in games.

If the magnification ratio is exactly 4 indeed, I think it's actually possible to get a graticle calibrated for both zoom levels. The field of view wouldn't interfere with the graticle use (it would just mask some ticks that are on the border).

The ratio between fields of view can be different from the ratio between magnification factors. It just means the vignette effect will be different.

Here is an illustration of what I think the observer would see:
https://i.postimg.cc/Sx05jJy2/Vignette.png
Notice that the image disc diameter is smaller at 6x.

What do you guys think?

EDIT:

What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.
What you say is that you used the 6x 2D layout for the 1.5x mode? That would mean the in-game vignette is exaggerated for the 1.5x mode. Did I get this right?

[Efshapo]

Here are my findings so far:

https://i.postimg.cc/SsWvpHZP/Table.png

[John Pancoast]

Here are my findings so far:




Interesting info. to be sure. But I'm not sure a "wrong" this or that is strictly correct.
Real world vs. computer screen, etc.
I'm more of a fan of does something work in the game to simulate it's subject vs. strictly historical specs, etc.
To often, plugging in historical performance specs of equipment, weapons, etc. (which many times are inaccurate anyway, being based on lab specs vs. real world use) causes more problems than it solves in a computer simulation of such. Many times, putting in historical specs for x, breaks function y of some other system, weapon, etc. in a game that was designed to work with the original specs of x.
What is more important is how does it perform in the sim, especially in the "big picture" of the entire sim.
I.e., iirc, GWX's attack scope had a mag of 10x. Historically correct ? No. But a good idea for the limited view of a computer game ? I think so.
Another example is the "pinpoint accuracy" of depth charges originally found in SH3. Historically correct ? No. But it helps make up for the dumb as bricks AI escorts and poor damage modeling. I like it myself, even with the sensor/damage model work since done to the original game, and it's actually not difficult to escape from anyway.

[Efshapo]

Here's how Wolfpack could be corrected to get a historically accurate field of view (current game state on the left, my correction on the right):

https://i.postimg.cc/3xRLk1R1/fov.png

[Efshapo]

And here's how I would correct the reticle (images on the right):
https://i.postimg.cc/s2jcq130/fov2.png

I added a row to my table to check that all fidelity criteria were met:
https://i.postimg.cc/J4j5hjn2/Table.png

[propbeanie]

I don't see SH4's Fall of the Rising Sun Ultimate (FotRSU) listed there... :har: - Sure, they're US submarines, but the periscopes were done by CapnScurvy, based upon his "optical" investigations, and are basically what he did for his Optical Targeting Correction mod for SH4, but without the "Centered" conning tower. He did quite a bit of research work on his mod... :timeout: and posted it all in a thread... :hmmm: which I cannot find. If I can find the thread, I'll link you to it. It is full of all of his findings, and how he tested... :salute:

[ybar]

Real world vs. computer screen, etc.
I'm more of a fan of does something work in the game to simulate it's subject vs. strictly historical specs, etc.
It's a shame if we have to move away from reality to adapt a simulator to a computer game ...
Out of curiosity, I can't wait to see how "Crush Depth" will handle this.

I don't know which eyepieces were placed on the Uboote.
But I am almost convinced that the engineers of ZEISS, have placed "wide angle".
I use a terrestrial telescope to watch the birds, and I use an eyepiece of this type (for the same zoom level, the panorama can be seen better)
On our French forum, a member with a refracting telescope has also just confirmed his change from the inexpensive eyepiece to a wide-angle eyepiece.

[Efshapo]

I'm not sure a "wrong" this or that is strictly correct.
Real world vs. computer screen, etc.
I'm more of a fan of does something work in the game to simulate it's subject vs. strictly historical specs, etc.
To often, plugging in historical performance specs of equipment, weapons, etc. (which many times are inaccurate anyway, being based on lab specs vs. real world use) causes more problems than it solves in a computer simulation of such. Many times, putting in historical specs for x, breaks function y of some other system, weapon, etc. in a game that was designed to work with the original specs of x.
What is more important is how does it perform in the sim, especially in the "big picture" of the entire sim.
I.e., iirc, GWX's attack scope had a mag of 10x. Historically correct ? No. But a good idea for the limited view of a computer game ? I think so.
Another example is the "pinpoint accuracy" of depth charges originally found in SH3. Historically correct ? No. But it helps make up for the dumb as bricks AI escorts and poor damage modeling. I like it myself, even with the sensor/damage model work since done to the original game, and it's actually not difficult to escape from anyway.

Well, "wrong" is not subjective here since we're talking about a game of the simulation genre. The game is either "right" (historically accurate), or it is not.

The magnification I'm talking about in my table is only related to the field of view (the one restricted by the vignette effect, not the in-game FOV), it is not related to the player screen size. There is no way for the devs to control that (unless they add a slider in the setting screen for a kind of "magnifying glass" effect). About that 10x magnification in GWX, I don't see how it could have been computed given what I just said, but I agree that the bigger the ship on screen the better the gameplay: I did the math and found out that for the magnification to be optically accurate, I had to stand as close as 38 cm from my 27" display! And Wolfpack devs actually did an amazing job at that by having chosen to ditch the upper and lower parts of the image circle so it can appear bigger.

Considering your expressed concerns, I haven't found how those modifications would break any current gameplay mechanics. Did you have something specific in mind?

[diego_gut]

Hello,


Sorry for the late response.


What I did was to make the graticle for 1.5x zoom as in real life but it is calibrated for 6x too. That is, if a ship measures 2 degrees using 1.5x, it will measure 8 degrees using 6x zoom. The same applies for the vertical scale.


The graticle in DGUI uses milliradians but the graticle in DGUI Hardcore uses angular radians (16 per degree instead of 17.45) as in real life. I even included real life tables that you can use to convert to distance.


Regards,
Diego

[Efshapo]

What I did was to make the graticle for 1.5x zoom as in real life but it is calibrated for 6x too. That is, if a ship measures 2 degrees using 1.5x, it will measure 8 degrees using 6x zoom. The same applies for the vertical scale.

Of course the magnification ratio should be exactly 4, that's the minimum required! :)
As you can see in my table, the only game that does not respect that is Uboat.


The graticle in DGUI uses milliradians but the graticle in DGUI Hardcore uses angular radians (16 per degree instead of 17.45) as in real life. I even included real life tables that you can use to convert to distance.

Sure, but my question was about the vignette (the dark circle around the image). If you use the same image displayed at the same scale on screen for the graticle (as you should), a 9° and 36° FOV means you also used the same vignette. To correct for the 1.5x one and make it 38°, you just have to make a dedicated vignette with a slightly bigger diameter. That's what I meant.

[diego_gut]

I don't take into account the vignette and there is no way to change the vignette when you change the zoom. I use it to make the attack periscope darker than the observation periscope and both of them darker than the UZO.

[Efshapo]

there is no way to change the vignette when you change the zoom
Then the historical field of view cannot be implemented (38° at 1.5x and 9° at 6x).
The next best thing to do is then to make a vignette that fits at least in one zoom level, without getting too far away from the second (36° at 1.5x and 9° at 6x).

[John Pancoast]

It's a shame if we have to move away from reality to adapt a simulator to a computer game ...
Out of curiosity, I can't wait to see how "Crush Depth" will handle this.

I don't know which eyepieces were placed on the Uboote.
But I am almost convinced that the engineers of ZEISS, have placed "wide angle".
I use a terrestrial telescope to watch the birds, and I use an eyepiece of this type (for the same zoom level, the panorama can be seen better)
On our French forum, a member with a refracting telescope has also just confirmed his change from the inexpensive eyepiece to a wide-angle eyepiece.


A shame ? Not at all. It's on a pc; by it's very nature it's not realistic.

[John Pancoast]

Well, "wrong" is not subjective here since we're talking about a game of the simulation genre. The game is either "right" (historically accurate), or it is not.

The magnification I'm talking about in my table is only related to the field of view (the one restricted by the vignette effect, not the in-game FOV), it is not related to the player screen size. There is no way for the devs to control that (unless they add a slider in the setting screen for a kind of "magnifying glass" effect). About that 10x magnification in GWX, I don't see how it could have been computed given what I just said, but I agree that the bigger the ship on screen the better the gameplay: I did the math and found out that for the magnification to be optically accurate, I had to stand as close as 38 cm from my 27" display! And Wolfpack devs actually did an amazing job at that by having chosen to ditch the upper and lower parts of the image circle so it can appear bigger.

Considering your expressed concerns, I haven't found how those modifications would break any current gameplay mechanics. Did you have something specific in mind?


My comments were general nature, not at your examples. I'm of the opinion that "historically accurate" does not necessarily need, demand, nor require verbatim "historically accurate" figures, specs, etc. to be used, for "historically accurate" and "right" results to occur.

Your mileage may differ. :)

[Efshapo]

My comments were general nature, not at your examples. I'm of the opinion that "historically accurate" does not necessarily need, demand, nor require verbatim "historically accurate" figures, specs, etc. to be used, for "historically accurate" and "right" results to occur.

Your mileage may differ. :)
In any simulation, a wrong model can yield right results in almost all studied cases, that does not make the model right, just "good enough" at best. I don't think that should make us stop striving for the best. But let's agree to disagree I guess. :]

[John Pancoast]

In any simulation, a wrong model can yield right results in almost all studied cases, that does not make the model right, just "good enough" at best. I don't think that should make us stop striving for the best. But let's agree to disagree I guess. :]


Well, if a model produces "right" results, by that very action it is then "right".
After all, that's the end result desired or should be. I.e., better to have that vs. a "right" model that produces "wrong" results.
But I understand what you're saying. Interesting work and effort you've done, thanks ! :salute:

[Efshapo]

Well, if a model produces "right" results, by that very action it is then "right".
After all, that's the end result desired or should be. I.e., better to have that vs. a "right" model that produces "wrong" results.
But I understand what you're saying. Interesting work and effort you've done, thanks ! :salute:
A model is right if it produces right results in all studied cases, not if it's "only" almost all cases.
Also, a model that produces wrong results cannot, by definition, be a right model.
But well... Thanks for your support. ;]

[Efshapo]

In Sh3 it works like you say, there is a direct and inverse relationship between zoom and field of view. However, it is not like that in real life, it depends on the construction of the optical device.

In this particular case, the zoom ratio was 4 ( 1.5 to 6 ) but the field of view ratio was 4.22 ( 38 to 9 ). Since the graticle is just a 2d overlay it can't be accurate for both.

To give more examples, the field of view for the 7x50 binoculars was 7.1 but some 10x80 binoculars had a field of view of 7.25 even though they had 10x zoom. The field of view was different even between different models of the 10x80 binoculars.

What I did for DGUI was to use a 36 degree field of view for the low power, this way the periscopes can be calibrated at both magnifications. This is not historically accurate but I think it is more useful.

Regards

Kudos to you sir, you win the contest so far:
https://i.postimg.cc/MHj2vsWX/Table.png

[John Pancoast]

"This is not historically accurate but I think it is more useful."


:up::salute:

[diego_gut]

Thank you!!

[Efshapo]

Here's the updated table with the new Wolfpack 0.25n reticle:
https://i.postimg.cc/7ZtGCY1s/Table-v3.png

[u crank]

Reported^^^.

[Jimbuna]

Sent packing to Lucknow.