[release] IJN periscope v 1.0

[keltos01]

Originally Posted by Hitman

Keltos!

This last one is excellent And it seems to confirm a good part of my previous comments:

First of all, the gradation is in 5 unit increments (1 big mark per 5 units) and not each 4 as in the US scopes

Second, the horizontal reticle is divided in degrees, as you can see the proper symbol above the "5". However, the vertical reticle is in my opinion divided in radians, and that was a common practice in military periscopes/telescopes for rangefinding when no stadimeter was available. German U-Boat periscopes also used that pattern. The horizontal is in turn divided in degrees because its use is for "lead aiming" and not for rangefinding, hence you go back to degrees because that's the unit you also use in the firing solution computation

The only details I don't see now completely logic in the video are:

-Lack of any numbering.
-Exact same division for horizontal and vertical.

Both details are different in the periscope view you posted, but are not essential in any case.

If I were you I would however model the reticle you can positively point at as coming from japanese submarine

I will do the one from the Kaiten type 10 scope.

btw who said it wasn't a very good scope ? the captain of I-47 ! he said those scopes were useless to attack at night and were of poor quality, you have then to imagine that the type 88 periscope had much better optics .

I think that in the video they mimicked the real scope, as filming through a periscope is very difficult as you can see in Gochin.

keltos

but I still need better pictures taken through that scope Rubenandthejets ! and.. I know you are dying to put your eye to the eyepiece of that scope !

I know I am...

[joegrundman]

I agree that the video image is likely a mock-up and go for the kaiten image

I think the image is probably good enough to model the ingame one. Ask Hitman to draw you a mathematically precise template and he'll love the job!

[keltos01]

By keltos01 at 2009-03-09



I already redrew the markings from the pthotograph using Autocad.

There is also a circle visible in the lower left quadrant of the image.

and maybe another one, larger, in the upper right corner.

keltos

[Hitman]

I had noticed that circle also, but the size of it makes no sense for calculations at 11º unless it's the maximum lead angle for japanese torpedoes, a rough indicator of the proximity of very close targets, or something similar.

It could very well be a image distortion due to a worn out layer in the external lense on a unprotected part of it or similar.

In this thread here: http://www.subsim.com/radioroom/showthread.php?t=148975 I uploaded for Vanjast the reticles I did for the german periscopes in SH4. The one in the observation scope has already the divisions you need, calculated for the game when using an aperture angle of 47 in cameras.dat IIRC. That will put the german reticle out of the scope view, and also give you exact readings from the reticle, at the cost of losing 5º FOV at each side (Unfortunately no alternative is possible since the reticle is hardcoded).

Hope that works for you

[keltos01]

Originally Posted by Hitman

I had noticed that circle also, but the size of it makes no sense for calculations at 11º unless it's the maximum lead angle for japanese torpedoes, a rough indicator of the proximity of very close targets, or something similar.

It could very well be a image distortion due to a worn out layer in the external lense on a unprotected part of it or similar.

In this thread here: http://www.subsim.com/radioroom/showthread.php?t=148975 I uploaded for Vanjast the reticles I did for the german periscopes in SH4. The one in the observation scope has already the divisions you need, calculated for the game when using an aperture angle of 47 in cameras.dat IIRC. That will put the german reticle out of the scope view, and also give you exact readings from the reticle, at the cost of losing 5º FOV at each side (Unfortunately no alternative is possible since the reticle is hardcoded).

Hope that works for you

some of what you just wrote is greek to me !

I thought : I redraw what I see in the RL picture, create a mask in photoshop, change the periscope.dds, done !

too easy ?

about the circles :

the inner one is definitely there. the outer one I'm not so sure, but it goes straight to the 25 mark on the vertical scale.

keltos

[joegrundman]

I think in the original images, there is a very fine vertical line also present that goes through the gradations on the vertical scale.

[Hitman]

I thought : I redraw what I see in the RL picture, create a mask in photoshop, change the periscope.dds, done !

too easy ?

LOL yes too easy

It won't work that way as intended...

You need to be precise for the scale to work as conceived.

The vertical scale is a means of easily getting distance thanks to simple calculations. Each small mark is not one degree, but approximately 0.6 degrees. Why? Because that is close enough to a radian and allows stadiametric rangefinding if you know or can estimate the target's heigth.

A quick example: Looking through the periscope of the Kaiten you see a destroyer whose mast reaches the "10" mark in low power magnification. How far is she?

Asuming a 25 metres mast (A good average for destroyers) you do following maths:

25 metres (mast ) x 100 (The scale "constant" value)= 2500

2500 / 10 (heigth the mast reaches in the scope scale) = 250 metres

The destroyer is 250 metres away.

The same example, but the destroyer is reaching only the "5" in the scale:

25 metres (mast ) x 100 (The scale "constant" value) = 2500

25000 / 5 (heigth the mast reaches in the scope scale) = 500 metres

Got it now?

I created my german periscope reticles for SH3 and SH4 using that same principle, adjusting the marks to the proper size, so I could use them to calculate distance as they were intended. It would be a crime to do all the research job you have completed, and now leave the scale inaccurate.

I will send you a finished scale in a moment, stay tuned. I will just modify my current german one and you are ready to go.

[keltos01]

I don't see a vertical line when I zoom (and I can go pretty far in Raster Design...)

keltos





In this archived document they state that Nippon Optical Co made periscopes,
Rubenandthejets : can you get few pictures of the outside of the scope too : labels etc... ?


http://www.fischer-tropsch.org/prima...ort%20X-05.pdf

[keltos01]

LOL yes too easy

It won't work that way as intended...

You need to be precise for the scale to work as conceived.

The vertical scale is a means of easily getting distance thanks to simple calculations. Each small mark is not one degree, but approximately 0.6 degrees. Why? Because that is close enough to a radian and allows stadiametric rangefinding if you know or can estimate the target's heigth.

A quick example: Looking through the periscope of the Kaiten you see a destroyer whose mast reaches the "10" mark in low power magnification. How far is she?

Asuming a 25 metres mast (A good average for destroyers) you do following maths:

25 metres (mast ) x 100 (The scale "constant" value)= 2500

2500 / 10 (heigth the mast reaches in the scope scale) = 250 metres

The destroyer is 250 metres away.

The same example, but the destroyer is reaching only the "5" in the scale:

25 metres (mast ) x 100 (The scale "constant" value) = 2500

25000 / 5 (heigth the mast reaches in the scope scale) = 500 metres

Got it now?

I created my german periscope reticles for SH3 and SH4 using that same principle, adjusting the marks to the proper size, so I could use them to calculate distance as they were intended. It would be a crime to do all the research job you have completed, and now leave the scale inaccurate.
I agree completely
I will send you a finished scale in a moment, stay tuned. I will just modify my current german one and you are ready to go.

do you mean you are actually gonna make that reticle for us at the Japanese Campaign mod ?


As I told the guys at RFB, our aim is to be as precise as possible in what we do, so far all our models and changes have paved the way to a Real I-Boat mod.

I would truly appreciate if you could help in that way then.

do you need the stuff I drew in autocad or are the here posted pictures good enough ?

keltos




additionnal intel :

iii) Periscopes and Lens Coatings

Added to the company's accomplishments in rangefinder production were similar successes made in the field of periscope manufacturing. Nippon Kogaku's first periscope was produced in 1918, and had an overall length of seven metres.49Following the First World War, the company began to produce periscopes based upon German designs, manufacturing between 50 and 60 units between 1920 and 1922.50By the mid 1920s, German technicians were hired by the company to aid in the development of new models, and records indicate that by the beginning of the Showa period, large numbers of 9-metre and 10-metre periscopes were being produced.51Added to these models, which were featured aboard most first and second-class IJN submarines, was a series of smaller periscopes for use aboard the navy's controversial midget submarines. The questionable effectiveness of these one to five-man submersibles notwithstanding, Nippon Kogaku was called upon to make working periscopes for the over 300 units that were produced across their various classes.52






Added to the optical engineering of the periscopes themselves was an ongoing effort made by Nippon Kogaku to increase the transparency of their glass surfaces. The standard 10-metre periscope produced by the company featured 33 individual optical elements and its complexity resulted in dramatic light losses.53In the interest of maintaining their strategic advantage, Japanese submarine commanders wished to use their periscopes at dawn and in the low light of early evening, but the initial inferiority of the optics prevented them from doing so without difficulty. These commanders placed great pressure on the navy and on Nippon Kogaku to improve the performance of their periscopes under low light conditions, and the company responded by initiating research into new lens coating techniques aimed at increasing their transparency. According to the investigators in the U.S. Navy technical mission:

…two methods were found for 'coating' glass surfaces:

1. The chemical method, in which the glass was treated with nitric acid.
2. The evaporation method, in which cryolite is evaporated and deposited upon the glass surface, in vacuum. After treatment, the glass is baked at 150°C for one hour for durability.54

These procedures were evidently conducted at the Nippon Kogaku's optical factory at Yokosuka, in coordination with the navy's submarine base at Nagaura Harbour. During their analysis of the plant, the U.S. Navy investigators noted: 'Evidence was found that lens coatings had been carried on' and recorded that 'a few samples of apparently experimental coatings and coating material were obtained.'55Such experimental work demonstrated the kinds of subsidiary technologies generated by the company's efforts to deliver on IJN optical contracts. As engineers sought new ways to solve these kinds of design problems, a host of secondary investigations was inevitably added to their ongoing studies in the field of glass production. These new tasks included: experimental methods of glass annealing, the four-stage grinding and polishing of both lenses and prisms, and a variety of efforts to enhance night viewing with the aid of lens coatings and filters.56The company's efforts in the field of experimental periscope lens coatings would be of particular importance in the postwar period as such coatings were later found to have a variety of optical applications. Periscope production too continued after the war, and Nikon manufactured instruments for construction surveying, as well as a series of 10 metre periscopes for use in the railcar maintenance bays of the shinkansen, or bullet-train railway line.57

periscopes diagrams :

type 3 periscope :


By keltos01 at 2009-03-09



Kaiten periscope :


By keltos01 at 2009-03-09


http://www.fischer-tropsch.org/prima...ort%20X-05.pdf

[keltos01]

By keltos01 at 2009-03-09

this is a quick one using what I had redrawn..

keltos

[Hitman]

do you mean you are actually gonna make that reticle for us at the Japanese Campaign mod ?

Yes, it's not a huge job for me now that most research is done

Here is a Beta for you to try: http://www.mediafire.com/download.php?jnzn4cenyja

I wanted to upload it earlier, but the server has been down

I would truly appreciate if you could help in that way then.

do you need the stuff I drew in autocad or are the here posted pictures good enough ?

Any description of the characteristics of the optics (Available zooms, etc) would help narrowing down their true performance, so we can recreate them accurately. I sent you long ago the link to the document in Fischer Tropp web, but I can't find it any longer

I'll study what you are posting and will make the proper updates.

[keltos01]

Originally Posted by Hitman

Yes, it's not a huge job for me now that most research is done

Here is a Beta for you to try: http://www.mediafire.com/download.php?jnzn4cenyja

I wanted to upload it earlier, but the server has been down

Any description of the characteristics of the optics (Available zooms, etc) would help narrowing down their true performance, so we can recreate them accurately. I sent you long ago the link to the document in Fischer Tropp web, but I can't find it any longer

I'll study what you are posting and will make the proper updates.

http://www.fischer-tropsch.org/prima...ort%20X-05.pdf

it was in one of my posts here...

why doesn't the reticle go to 15° like the picture ?

where do I slip the files in ?

keltos

[Hitman]

The reticle doesn't go more than 15 upwards/downwards because for that I would need to allow the standard full field of view, and that would show the old german reticle....

The file cameras.dat goes into data/library (make back up first)

The scope mask must be renamed to whatever name the german scope mask has and placed where the original one is, substituting it, which I currently can't tell because I don't have UBoat Missions installed.

I thought you would know already where the scope mask goes, since you have tweaked it...

[Hitman]

That document was not teh one I meant, but never mind I got to the index and there are a lot more than when I first found it WOW

Interesting....

night periscope has 1,5 and 10x zoom

attack periscope has 1,5 and 6x zoom

Lookout binoculars are 20x

Must go now, will go on with this later

[keltos01]

yeah I kindo knew where it was..









now the periscope head isn't the same as in the japanese movie from 1941...

but the reticle is real !

the view doesn't change yet when you zoom.

keltos

can we have the circle in ? or leave it out till we figure if it was really there ?

btw I changed the file in .dds otherwise it doesn't show.

keltos