Yes I know, the TBT had a FOV of 7.25 degrees and a 7x magnification.

I can't quote where I got it, but I will look for it. In any case, bear in mind that there were some unofficial TBTs handmade by the crew using a pair of standard B&Lomb 7x Navy binoculars and a pelorous and installed on the bridge like f.e. USS Tang had, and also the later "official" Mare Island TBT which was equipped to all submarines twice (Front and rear of bridge). This last one had a simple crosshair that I replicated in an earlier mod of mine:

http://www.subsim.com/radioroom/showthread.php?t=150785

As for the german UZO, it was the same, 7.1x and 7.25 degrees.

In this one I can quote the source: http://www.uboatarchive.net/U-570BritishReport.htm

EDIT:

I forgot to add that 7x was not chosen randomly. There was a good reason to use this magnification, read more here: http://www.opticsplanet.net/binmarine.html

Thanks Hitman for the information.

I'm just wondering out loud, did the WWII vintage TBT look the same as what's on the USS Bowfin now? I had read your post before (regarding the modification you made), and since the Bowfin was decommissioned in 1947, recommissioned in 1951 (probably due to the Korean Conflict) then decommissioned again in 1954. I'm wondering if a change in the TBT was made when it was refitted? Or, maybe a newer TBT was installed just for the museum?

Guess I'm asking, What did the view through the WWII vintage TBT look like? Did it have Telemeter marks as the game view, OR did it have the simple "cross hairs" that the Bowfin's TBT has now?

Well the USS Cod has exactly the same one and it is claimed by the curators as WW2 original :DL, so I think it's safe to asume that this is the Mare Island official one. Look through it is like shown in my other thread, and I have never heard of any model with graticle. But as with many other things, crews "customized" this, so probably there were some (I have a list of several different B&L binoculars handed to the marine and many of them had milliradian markings for range finding).

Thanks again Hitman for the information, there just isn't much information on the TBT when you start to look. Bits and pieces from here and there.

When I read your thread regarding the TBT I noticed you had the same problem I've had regarding the mask not completely blocking the background. I've been able to overcome this by making sure the Alpha image is saved at 32 bit. I know we all have our favorite way of working with images and alpha channels. I will "export" the alpha to a .bmp image and make my changes, then save it at 32 bit. I'll then "import" it back into the .dds image file and the opaque is heavy enough to prevent a bleed through. Having the alpha saved at 8 or 16 bit allows too much transparency (least for the scope views when using the camera image as the background). Just thought I'd pass it on.

Oh cool :up:

Had certainly not thought about it, many thanks for sharing :yeah:

I've been working on having all the stock ships placed at an approximately 1000 yards distance and at a 90 degree abeam angle in my test missions. I finished this last week, and have been creating the Recognition Manual to support the added ship length dimensions. I've followed some of my previous work in creating ship reference points other than the mast head for the height dimension. There are just some ships that lend themselves better to this approach than a nonexistent mast head (many of the capital American warships use the center mast for their flag placement. There is no mast visible at 1000 yards to judge the distance, the flag has to be attached to something, so the top of the flag will be used for the reference point). All Recognition Manual pictures will have the height reference point marked with either a red line or a national flag.

Turning the ships to a full 90 degree abeam angle will allow a correct measurement of the ships length at 1000 yards distance. I thought I'd give you a bit of a preview of what and how I'm doing.

The first image is of the Bogue CVE showing the computer found range at 1000 yards. Notice I have put the ships length dimension along the top of the RM page. The "Divided By:" figure is something I'll get to later.

http://i175.photobucket.com/albums/w...foundrange.jpg


This image is with the game running at the 1024x768 resolution. The dimensions and image ratio will be the same for all other resolutions except for the 1280x1024 (I'll need a whole different set of dimensions for this particular resolution).

The next image shows the Stadimeter at work using the 68.2 feet height dimension for the top of the bridge superstructure as the reference point.

http://i175.photobucket.com/albums/w...foundrange.jpg

I had already checked the range with the Stadimeter and found the distance to be 1000 yards using this 68.2 ft measurement. That's good, the stadimeter is right on (In my opinion, the reading could be as much as 10 yards off, one way or the other, and still be very accurate at a 1000 yard range distance).

Next, I'm using the Telemeter marks to judge distance with the Omnimeter. We know the Bogue is at a 1000 yard distance so lets see how close are we when using the Omnimeter and Telemeter marks as we should. The image has the High Power magnification in use. The first thing to do is to move the Omnimeters magnification scale slider to point to the height of the Bogue found in the RM, 68.2 ft. Next, place a Telemeter line on the target's waterline and read the distance to the reference point. Then check the Omnimeter for the approximately 5 1/4 marks at High Power to the range scale in the center of the device. The red lines are just to point out the Telemeter marks which are a light green in color. The green color will help in night estimates.

http://i175.photobucket.com/albums/w...hpowerOmni.jpg


The range is found to be about 1000 yards which is correct for this particular ship test.

The following image shows the periscopes magnification at low power. The only thing that changes is where you read the Telemeter Power Scale, this time on the Low Power setting. Which is at about 1 1/4 marks.


http://i175.photobucket.com/albums/w...wpowerOmni.jpg

This should give you a taste of how the device will work and it's accuracy when used.

I mentioned something about the "Divided By:" figure on the RM page. When you use ship lengths to find Angle on Bow determinations you will need to divide the total overall ship length by a number that will allow the Omnimeter to be used (the Omnimeter only has the length dimension to a maximum of 200 feet). In the case of the Bogue, its length is 494 ft. A divisible number of 3 will be used to give you a working ratio of 165 ft (494 divided by 3=164.6; close enough to 165). You will simply use the 165ft length figure to calculate with the range; then remember to multiply 3 back into the figure to get the correct finding. This was how the real life Omnimeter was used, so keep the calculators handy. Just think how lucky we are to have a calculator, the crews had to use slide rules or just paper and pencil to figure this. The "Divided By:" figure is just an aid in getting you started toward the final Omnimeter result.

My next job is to finish the ship length calculations for the 100 plus stock ships. This will take time but the game isn't going anywhere. I think the next post will contain the "what and how" to finding AoB with the Omnimeter.

As promised, I want to explain how you will use the Omnimeter tool to find Angle on Bow of a target ship. Lately I've been working on the various world views and putting them into their correct perspectives to match the views of the calibrated scopes. The flack gun gave me the most trouble with trying to get the aiming mark to line up with the column of fire after having the target sized correctly. I still need to check the other flack guns for their correct view. I'm going through the individual ship dimensions and changing them as needed. If you haven't guessed, I'm intending on this mod to be a comprehensive replacement to my SCAF mod. Not only will the Optics be corrected but also accurate ship dimensions as well.

To start, I admit I cheated. I made a mission with a Japanese destroyer approaching and I fully knew what type it was (a Fubuki). So, to test the Telemeter divisions I knew what ship was coming and made the target range finding much earlier than one would do if you relied on positive identification to decide what you're up against. I did this to check the accuracy of the range finding with both Telemeter marks and using the Stadimeter. I was accurate at distances beyond normal ship identification distance, so I think this was good for checking the basic ability of the tools involved with manual targeting. The Omnimeter has two movable sliders. The top is called the AoB scale, the lower is the Telemeter scale. Both have a "red pointer" for setting the scale to whatever your doing. The scale is mouse draggable in the general area of these pointers.


I've got the game running in a 1600x1200 resolution. This first image shows the Fubuki coming from the starboard side at a little over a 3/4 telemeter mark high. The periscope is set to its High Power magnification. As you can tell at this distance making a positive ID is impossible (so shoot me). I've moved the Telemeter scale pointer to the Fubuki's mast height 73.8 ft (where the top of the flag is) and read the corresponding figure to a bit over 3/4, or about 6500 yards.

I admit, there's a bit of wiggle room at these long distances when using the Omnimeter. The scopes Telemeter reading is near the 7/8 area of a division, so you'll need to guess at the position on the range scale.



http://i175.photobucket.com/albums/w...ngeFinding.jpg



To check this finding I'm running the test with the manual targeting disabled giving me the computer found range of 6478 yards (yep, I'm cheating again). Oh, by the way. If you check the Recognition Manual page for the Fubuki, you can barely see the rising sun flag at it's corrected position for this ships height. Like SCAF, if the reference point is to be the top of the flag, a national flag is put into the RM pictures to aid you in finding range (either with the scopes Telemeter divisions or the Stadimeter).



http://i175.photobucket.com/albums/w...RangeCheck.jpg


Ok, so we have range to target found with the Telemeter marks and using the Omnimeter (and rechecked by the game itself) to be about 6500 yards. As I fooled around getting the pictures and lining up the Omnimeter, my final range I used for the Angle on Bow check was about 6200 yards. You will need to have the range to target in order to find Angle on Bow.

To find AoB, use the scopes horizontal Telemeter marks to measure the approaching target. The below image has the ship length at about 1 1/2 division marks on the High Power magnification. Now move the Telemeter scale to match the "1 1/2 High Power" figure with the approximate 6200/6300 yard range distance found on the Omnimeters center "Range in YARDS" scale. Next, read the dimension (on the lower Height/Length scale) at the Telemeter scale's "red pointer"; it reads about 130. The 130 ft reading is going to be used in relationship to the overall ships length in finding the difference between the two. This "difference" is the targets measurement of angle, at least the angle that the target is in at the time of the reading. And it's this difference that will render the Angle on Bow amount.

Move the upper Angle on Bow slider to have its "red pointer" set at the targets overall length of 380 ft onto the center Range scale (the overall length will be found in the Recognition Manual). I know, you may say this "Range" scale is set to yards, and it is when you use it for finding range. BUT, it also can be used for finding specific lengths that are not set in yards such as the length of a target in feet. The key is built into the Omnimeter comparing the "ratio" of a dimension not the actual size of the dimension. So just use the scales for the face value of the dimension, don't worry about converting feet into yards or back again.

Using the 130 ft figure, find 130 on the Range scale and correspond it with the AoB scale. I know, there isn’t really a 130 figure on the Range scale. Just pretend its just about off the scale, below the 150 mark. You end up somewhere near the upper 17 degree AoB area of the scale. You can now enter the AoB through setting the Attack Data AoB and send it to the TDC.



http://i175.photobucket.com/albums/w...e/AoBCheck.jpg



To check the figure, the next image has the computer found range in the Position Keeper and Angle on Bow showing in the Attack Data tool. Both show the AoB to be about 16 degrees, very near the Omnimeter's found result.



http://i175.photobucket.com/albums/w...FinalCheck.jpg



Of course, you'll want to make additional checks for range, AoB, and do a timed assessment for target speed but, what else do you have to do? This ship traveling at the speed of 5 knots will take 30 minutes to cross into firing range! Plenty of time to make corrections and further observations.

In an earlier post I told you that there will come a time when the Omnimeter runs out of room on the Height/Length scale (it only goes up to 200ft), and you'll have to divide the range in half to keep the Height/Length scale within its parameters. Just remember to multiply back into the Height/Length dimension what you divided by to use on the center "Range" scale. As in this example double the 130 to 260 and find it on the "Range" scale. No need to double the AoB, just read the AoB at the 260 mark.

So far I've been very satisfied with the results. The nearer the target, the more precise the reading will be. I'm planning on helping the Omnimeter with creating more divisions so an easier read can occur at these long distances. If the Omnimeter works this well at long distances it should work equally well at shorter distances.

Excellent again :up:

It's also good to know that the ruler can be used inversely, i.e. you make the estimate of AOB by naked eye and knowing the size of the target after a positive ID you can calculate range :yeah:That's according to the Torpedo Fire control manual 1951 the primary use, but it's nice how you reversed it help finding the AOB in the always limited 2D environment of a screen :up:

Thanks Hitman,

You're very observant!! :salute:

The "Torpedo Fire Control Manual" illustrates how the Omnimeter is used to find a target length when range and an estimate of AoB is used. I just reversed the process by knowing the estimated range and target length, you should come up with AoB using the Omnimeter.

What has really helped is having the optics capable of measuring the world correctly. In other words, the Telemeter divisions really do measure 52 feet vertically or horizontally at 1000 yards distance (at least in the games terms).

Again, my focus is on completing the ship heights and lengths for the stock game, and making a Metric Omnimeter to be used for the German side before release.

Next week I'm heading East to cheer my niece on who's running the NYC Marathon. While I'm up there I'm planning to visit the Submarine Museum in Groton Conn. I know they have a TBT in the hallway leading to the Nautilus docked out in the river. I just want to see what one looks like through the lens.

Oh great and please take a picture if possible so we can see it :yeah:

Yes, I plan to. Although I'm guessing, sticking the camera up to just one lens will only show what the one lens sees. But I'll certainly try. From what I've seen of the TBT it doesn't have much capability to conform to the different eye spacing we all have. Most of the binoculars now a days have a hinged center to allow for a better "fit" to the users pupils. This usually allows for both focal views to converge into a complete circle. I'm curious to see what the TBT binoculars have if anything. I have my grandfathers WWI Artillery field glasses and they are not hinged. The view is small and depending on how far away you hold them up to your eyes, the view changes from a double circle to a single circle.

I've been to the museum several times, but there's always something new to look for. These kinds of things just never get old to me. :D

I have been to the Nautilus this past summer, and looked through the TBT. Unfortunately i can't remember if the scope had the range markings or not. When you're with youngsters they tend to get board very fast and want to rush through. The Fleetboat attack room is cool! Has a TDC and working periscopes that you could look through.If you're close to NYC, may I suggest visiting the Intrepid as well. Another great piece of history:yeah:

Thanks for the thought about the Intrepid Fish40. I've not been to the museum but it sounds really interesting. The more modern USS Growler missle submarine is there too. I'm up in New Haven now, planning on heading to the city Sunday morning to watch my niece run the marathon. We will be close to Pier 86, but we may not have time to take in the museum. :wah:

I've been to the Yorktown CV 10 (the first Yorktown CV 5 was lost at the Battle of Midway) in Charleston SC, and the carriers are huge when standing on their decks!! I'd love to visit the Intrepid, I believe it was launched just after the second Yorktown and carries the CV 11 number. It's just great these old machines of war are kept out of the salvage yard!!

As far as the TBT goes, I'm thinking no matter what the view may reveal, we will need to have the ability to judge a ships height and length with Telemeter divisions. The game takes this even a step further by having the Stadimeter in use with the TBT. In real life, the Stadimeter was never put into the binoculars of the TBT. The in-game question is, why have a TBT station if you can't use it to send a reading back to the TDC? In real life, the TBT only sent the target ships realtive bearing to the TDC operator, the range was gained by pure eyeball estimation or by the radar or sonar findings. So, some ability to do just that was put into the game and (I believe) a correct Telemeter divided TBT view should do that too. One other thing I do know about the TBT, was it had the capability of illuminating it's self to show whatever marks it had for night attacks (which is what it was mainly used for). My plan is to do just that before I'm done. Just a bit of color to the corrected division marks should do the trick.

Wasn't the illumination a rather late war addition? I thought (but could be mistaken) that for the majority of the war the TBT was just a mount for a pair of 7x50's. I'm pretty sure that O'Kane discusses this in both WAHOO! and CTB.

Regardless, very impressive work you are completing. Very much enjoying following the progress. And enjoy Groton - I can't wait to make my way out there.

Well we know that there was an official Mare Island TBT install late in the war, but we also know:

1) That skippers started adding a mount with pelorouse for their 7x50s well before that

2) That they got custom reticles engraved in their 7x50s

(Both informations from O'Kane's "Clear the Bridge")

So I guess it would be fine to have a 7x50 with telemeter divisions as if we had requested the yard to add it for us. In that regard, the slide out ruler for distance calculation does actually make more sense than ever, because the 7x50s didn't have a stadimeter as C.Scurvy already pointed out. :up: