Photo # NH 69722 distance evaluation

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Antonio Bonomi
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Photos evaluation

Post by Antonio Bonomi »

Ciao all,

I am back home so lets continue :D

@ Ulrich,

thanks for the addittional infos, YES that is exactly the photo taken after the battle as Fritz Otto Busch was properly captioning on his book.

Very key is the spent cartridge ( used cartridge or shell casing ) on the higher deck ( the one Marty has placed into a green box ) as it is confirming the direction ( across the stern backward ) of firing of the C turret during the battle (unloading from the back bottom of the turret).
The majority of the other spent cartridges are on the lower main deck on the starboard side, that means C and D turrets as we know fired mainly to port at British ships.
But that one is up there and it confirms that C turret ( and D too ) fired for some time straigth back across the stern ( during the turning manoeuvres ) exactly as written by F.O. Busch on his books as well as L. Kennedy one, and confirmed by Jasper report too.
That is when the fire control passed from Jasper ( main ) to Albrecth ( aft ) and they could only fire the aft group straight back.

@ Marty,

very good job :clap:

1) Depth charge rack.

YES, it is the same rack moved ahead toward the stern.
Your positioning looks good on the drawing, unfortunately I do not know the correct dimensions, I will look at it, but I have a better photo take during refuel training that I can post so you can see it better th earea with persos around.
If you write me privately I can send it to you on big format which can be better.

It is the photo Nr. 30 here in :

http://www.kbismarck.com/photos2.html

I assume you have noticed that the photo as been censored removing the 2 reafuelling rings used to hold in position the fuel tubes.
The rings have always been there on all photos ( I have a not censored one ).


2) YES, those are bollards.
I see your point as those are not exactly in the same position showed on the drawings, probably re-located as you suggest, the photos of course show were they really were.
I will look for their dimensions.

3) Yes, it looks like a man, but again if you have the other photo I am referring to everything will be easier for the comparisons.

and also :

YES, the 2 cm flak gun looks ok to me.

As said you placed perfectly the 203 mm shell used cartridge ( shell casing as you call it ) and this is a key position as said.

Same for the position were you placed the photographer wich as you can see is one of the favourite places of Mr. Lagemann to take photos.

Let me know if I can help more, and again congratulations for your skill and the very good job done so far :clap: :clap: :clap:


Ciao Antonio :D
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Antonio Bonomi
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Another one

Post by Antonio Bonomi »

Ciao Marty and all,

of course this can help you too.

http://www.history.navy.mil/photos/imag ... h69733.jpg


As you can see the rack is fully loaded with 3 depth charges, so either this photo was taken before the battle or after when they re-loaded the rack that was having only one depth charge left at the end of the battle as we saw on other photos.

This photo is very good also to properly estimate the shadow of Bismarck been so low on the water with the hull if compared to the previous suggested photo during training refuel when she was well up on the water.

Ciao Antonio :D
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Ulrich Rudofsky
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Post by Ulrich Rudofsky »

How on earth would anyone know what time and day this photo was taken? It looks like Bismarck is too close for comfort to Prinz Eugen. But it does show WABOS in place on their racks for measurement.
Ulrich
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Antonio Bonomi
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Last photo of Bismarck

Post by Antonio Bonomi »

Ciao Ulrich and all,

very good point my friend, as usual :D

In fact there are 3 WABOS there in the rack just like before the battle as well as after the battle, as confirmed on PG Rheinubung film at counter 09.46 during the refuel Prinz Eugen had in the ocean after the separation from Bismarck.

During that film sequence the rack is partially showed and it is full of 3 WABOS again.

So it can be that the caption of the photo is correct as well as the photo was taken before the battle in the morning of May 24th, 1941 after the change of position between Prinz Eugen and Bismarck ( because it is back ) that occurred between midnight and 2.30 that morning.

To solve the mistery we need more infos, the full film or more photos, .. maybe one day .. who knows :shock:

You will all agree with me that Bismarck is very low on the water and the hull is amost not visible from this front view, this is why I underlined it to compare with Nh 69722 first salvo one, as on the ocean the fully loaded ship from a front view like this will not look like the photos on the Baltic sea or in the Elbe river when the water was calm and the ship was light and not sailing too.

Ciao Antonio :D
marty1
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Post by marty1 »

Hi Antonio & Ulrich:

Thanks you for your replies. Unfortunately I have been particularly busy with work over the last week, so I have been unable to indulge in my favorite hobbies.

I hope to jump back on my range estimate for the shell cartridge photo over the next few days.

I would be interested in a less grainy photo of the depth charge rack if one exists. I will send along my email address this afternoon.

Does a clearer version of the shell casing/cartridge photo also exist?

Regarding the bollard locations – does the PE plan view you used to show Lagemann’s position for the previous range estimation photo (the photo with the rear 20,3cm turrets in a traversed position) show the actual bollard positions? I hope to use the bollards as another check point for the range estimation back to Bismarck. But this assumes that the bollards real (as-built) location can be determined on a plan view of PE.

Best Regards
marty
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Post by marty1 »

Antonio:

I do not have your email address so I sent an email to you through the KBismarck.org forum email member option. I do not know if the email will go directly to your personal email account, or your KBismark Forum email account.

marty
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Antonio Bonomi
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Material

Post by Antonio Bonomi »

Ciao Marty,

OK, I have got it :D

I have sent you some material ( photos, drawings ) so your fantastic job can be hopefully easier.

YES, that drawing I have sent you shows the bollards location too ( I have other drawings as well but they are always there on same position ).
I have snet you also 2 other photos taken on Philadelphia of PG stern were you can see the bollards very well.

I will look for the shell/cartridge better photos even if on one photo I sent over you should be able to see them a lot better.

The depth charge ( Wasser bomb or WABOS ) rack photo is on your reader too.

Take it easy and obviously work and family first, as this as you said is just our favourite hobby.

Have fun and enjoy, anything else you need just let me know as you are doing really a good job :clap:

Ciao Antonio :D
marty1
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Post by marty1 »

Thanks very much Antonio. I received the images -- all excellent.

The much higer quality shell casing picture you sent, as well as the Philidephia images you forwarded along raise a couple of additional questions in my mind. The first question regards the location of the bollards. I think I am suffering from the optical illusion of foreshortening of the shell casing photo. The bollards appear closer to the stern than they actually are. The Philidelphia photos seem to confirm that the plan view I have been using of PE actually does place the bollards in the correct locations. This unfortunately makes trying to guess at where random objects on the deck appear very difficult. In other words unless the object is fixed -- like turrets, railings, gun mounts, etc -- the actual distance from Lagemann's presumed position to the non-fixed object is very difficult to estimate. The optical illusion/foreshortening effect. This will potentially result in a fair amount of error when guessing the range from Lagemann back to Bismarck if relying upon a guesstimate as to either shell casing locations -- the depth charge rack -- or crewmen, etc.

To guess at range I need to develop an angular scale for the photo. This means I need reasonably accurate horizontal distances from Lagemann's presumed position to an object on PE with either a known height or width. The more of these objects one can single out within a photo, the more accurate the guesstimate as to the angular scale of the photo -- and thus the more accurate is the range estimate from Lagemann back to Bismarck. The first photo was easy to develop an angular scale as the rear of both 20,3cm turrets as well as the range finder on Turret-C were all well defined.

I think I will have to develop an angular scale from the 2cm Flak gun elevation (or traversing wheel?). As well as the bollards.

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marty1
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Post by marty1 »

The second thing that popped into my head after looking at the higher quality shell casing image you sent to me was the aspect of the Bismarck. I had not noticed this before, but it looks like the Bismarck's bow is down -- plungging through a swell. I assume this would effect the presumed height of the Bismarck? Or; since we are measuring off the mast -- the centroid of the ship -- would this effect have much influence on the presumed height of Bismarck -- (33m)? What do you think -- what is your opinion?

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Bill Jurens
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Photogrammetry

Post by Bill Jurens »

I must begin by thanking Jose for issuing me a new password which allowed me to enter the forum again. I have been having difficulty logging on over the past few days.

I have been following the thread regarding the analysis of Denmark Strait photography for several days now. With respect, I'd suggest that you are, by and large, barking up the wrong tree.

The difficulty in determining the range to Bismarck does not really revolve around the size and definition of objects in the foreground, nor is it in any way particularly sensitive to the exact position of the photographer aboard Prinz Eugen, as even quite a massive error in where the photographer was standing would only affect the overall range estimate by a hundred meters or so. In practical terms, the characteristics of the camera itself are reasonably well understood, and little can be gained there without measurement and calibration of the actual instrument itself. This lack of knowlege and calibration in and of itself would suggest an overall limiting precision of approximately +/- 0.5 to 1.5% on any measurements taken therefrom.

The difficulty was (and remains) the measurement and interpretation of the image of Bismarck itself, which was (and to my best knowledge, remains) very poor. Unless a better image of Bismarck can be obtained -- and that would take high enlargement of the original image on the closest-to-first generation negative -- all analysis in the final analysis must revolve upon a rather subjective interpretation of what is, in reality, a rather amorphous 'blob'. Uncertainty in the interpretation of the 'blob' would be expected to reduce all other uncertainties, e.g. the exact location of the photographer and/or the precise characteristics of the camera, to second order effects.

So, if further understanding is to be obtained I'd (again respectfully) suggest that efforts be focussed (no pun intended) upon resolving and interpreting the 'blob' rather than in attempting to establish the position of various benchmarks aboard Prinz Eugen.

In the spirit of cooperation...

Bill Jurens
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Antonio Bonomi
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Photo evaluations

Post by Antonio Bonomi »

Ciao Marty, Bill and all,

first of all let me say I am very happy to work with you on this, it is very interesting and everybody is applying a lot of value add :D .

Now with Bill Jurens joining back in I am sure we will have even better results pretty soon.
You know Bill that when it comes to photogrammetry you are my unique reference :D.

I hope Marc will have soon time to come back on this as also his inputs do always provide lot of value to the discussions, he helped resolving so many critical ones recently .... Nh 69726, Nh69730 just to say a couple.

So let me recap and provide you what I currently think.

@ Marty

as I wrote you I see what you mean and the bollards were on the drawing on the correct locations as you verifyied too.

I agree about the need to develop a new simulation model ( keeping in account the angular scale as you defined it ) to make more precise calculations, and probably you will need one for each photo given the references you use and the photographer distance from them, it is a matter of the angles of the photo according to my view.

That is why I used my Tangent X model with trigonometry on the first photo evaluation, as that was let me say built in having better references ( the turrets lateral plates ).

But I only did that one, now you are playing with multiple photos and as you very well realized the difficulties and differences using your methodology do change a lot making it more difficult.

I fully agree with your second as well. The Bismarck shadow or ' smudge' as you properly called it ( on the first salvo photo Nh 69722 ) is the real difficult and key on those photos ( as obviously well known by Bill Jurens too since we worked a lot on this photo togheter in the past ).

That is the key for what we want to know which is the real distance ( with good approssimation ) of Bismarck from Prinz Eugen on the first salvo photo ( Nh 69722 ).

That ' smudge' needs to be very carefully enlarged, evaluated, compared and measured with everything similar exist of Bismarck and as you very properly realized we need to evaluate the centroid ( so the real proportions of the shadow ) to be able to make the correct assesment of the whole measure to be taken on the photo ( including the portion of Bismarck hull on the water that you noticed too ) to represent the 33 meters of height we want to use to make our calculations.
Of course Bill Jurens here is absolutely correct with his statements.

I am here ready to provide all the help needed to do it with your methodology and you properly have seen I have started working on that shadow comparison too time ago.

Maybe a good idea can be to send you over the biggest photo I have of that 'smudge'.

As many as we are doing a good job with different methods comparing each others in a cooperation spirit ( I obviously agree with Bill Jurens here ) as close we can come at the end with a good result.

@ Bill

I agree with you of course my friend :D

Marty and Marc methodologies are very interesting and came very close to the values we found with different methods.

Now I a not an exeprt like you on photogrammetry to be able to provide the suggestions on how all the parameters play a role on the whole measurements due to the angles, camera characteristics and so on, as all I know I have learned from you :D .

But I am glad you came back in this discussion again, so maybe we can progress further more utilizing also different very good skills as you can see.

My dream will be to finalize your good study on this photo and as you can see we do have currently better material available.

Now the challenge is that ' smudge', we really need to make a good study on it, and agree on a way to measure it the best we can.

What do you think ?

Ciao Antonio :D
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My Guesstimate

Post by marty1 »

Hi Antonio:

Sorry – I didn’t have a chance to look over Bills comments aside from the issue associated with interpreting the edge contours of Bismarck. As we have already discussed earlier in this thread, this is indeed an issue.

I developed an angular scale based upon the linear distance from Lagemann’s presumed position to the 2cm Flak gun elevating wheel, the stern most set of bollards, and an easily defined vertical feature on the rearmost 20,3cm Turret (D?). The above, combined with the vertical height of each of these features gives me the angular height of each figure. I suspect your referal to a Tangent-X method makes our two methodologies closer to each other than it may seem. We are likely talking about a similar method of guessing at the range to Bismarck.

I back calculated an angular height of Bismarck of approximately 27.5mils. I have shown on the attached image where I am defining the top edge of Bismarck and the bottom edge of Bismarck (baed on the assumption that Bismarck is bow down -- plunging through swell) . The bottom edge I have picked for Bismarck is off course a best guess. That makes Bismarck much closer to Lagemann and PE than the previous photo we examined. This is also seems evident if you equate scales of the previous photo of PE to Bismarck to that of the Shell casing photo. The Bismarck “smudge” in the shell case photo is much taller than the previous photo.

My Best Guess: An angular height of 27.5mils puts the Bismarck at a range of about 1200 or 1300meters from Lagemann’s presumed position.

Best Regards
marty

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iankw
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maybe I'm wrong, but......

Post by iankw »

isn't it possible to use the edge of the deck of Bismarck, rather than trying to work out how low in the water the ship was? I haven't got involved in the maths going on here, since there are people much better at it than I but, looking at the enlarged insert entitled "shell case picture", the deck edge seems much more clearly defined. Isn't the height deck to mast top also known? And that figure is independent of draught, is it not?

regards
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Antonio Bonomi
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Photo evaluations

Post by Antonio Bonomi »

Ciao Marty, Iankw and all,

@ Marty,

good job once again :clap:

I like your methodology that now you have also improved with that angular coefficient too.

YES, with that we are using basically same type of approaches and in fact the results are coming our pretty close and within acceptable tolerances as far as I can say ( first salvo photo around 2400 meters with both methods ).

Now I see also this measure that seems OK to me as obviously Bismarck was much closer to Prinz Eugen than the previous one we analyzed, so 1300 meters looks good to me.

I like your graphics examples to support your explanatiosn as that makes very easy for everybody to understand what we are saying :clap: .

Very good is the comparison of the 2 shadows of Bismarck as that is the key as said to make the calculation.

You should have received also some other material on Bismarck shadows, and that can help too on the determination of the centroid of the ship in case you want to play with it too a bit more and support your measures with a larger photo comparison example of the 2 shadows.

That will be very interesting too and a lot helpful :D .

@ Iankw,

YES, you are right and we were trying to use all we can to determine exactly the Bismarck shadow profile, not only what you suggested.

Here an example.

http://www.kbismarck.org/photos/BS-proportions.jpg

Ciao Antonio :D
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Post by marty1 »

Hi IanKw:

I think you’re right. It may be easier to measure from the deck edge to the top of the mast rather than guessing at the waterline and than measuring to the top of mast.

Using my best guess at where the deck is, and using it as my lower Bismarck edge, and using the same location on the mast as my top edge – and assuming this height is ~25.55m, I get an angular height of ~21.5-mils. That puts my range estimate very close to what I guessed previously – or about 1200 to 1300 meters. So I was probably lucky in where I picked to be my bottom edge in the previous range estimate.

Antonio:

Thanks for sending along the additional reference photos. Can I ask what your’s and Marc’s estimate of range to Bismarck is for the shell case image?

One of the images you sent was a refueling drill photo. It looks like Lagemann (or whomever took the refueling photo) is in about the same position on PE as the previous two photos see have looked at on this thread. The Bismarck looks to be very close to the Stern of PE. There is therefore a great deal of detail that can be made out of on the Bismarck. No need to guess at shadows, waterline, deck location etc.

Have you and Marc guessed at the range on this photo? This one should be fairly straight forward, but I would think it would be a very good photo to use as a photo scaling methodology check. Or perhaps you already know the typical distance at which this sort of drill would have been conducted at?

Regards
marty
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