Determining Distances from Photographs

Discussions about the history of the ship, technical details, etc.

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Bill Jurens
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Speed changes during maneuvering

Post by Bill Jurens » Sun Feb 12, 2006 12:39 am

I am not certain how well the new -- or for that matter the old -- track charts account for the speed losses typically experienced during turns, which can be quite considerable. The exact amount of the speed loss during turns varies quite a bit with sea state, and even varies from ship to ship of the same class, but it must be accounted for in some way if the relative positions of the ships that are maneuvering is to be accurately reconstructed.

There are many potential sources of error, especially if one is constrained to look through the 'keyhole' of the camera lens. The relative positions of ships can APPEAR to change very rapidly if one assumes they are maintaining straight courses but they are actually maneuvering. If two ships are steaming in line ahead, for example, and the forward ship turns rapidly to port, the trailing ship can be brought on the beam within a few seconds. If an observer on the forward ship 'looses the picture', and believes that the other ship is actually maneuvering instead on one's own, this can be very confusing, as it then appears that the trailing ship has somehow managed -- almost at 'super speed' -- to have overtaken you on your port side and is now on a collision course. The possibilities for confusion in these sorts of circumstances are endless, or nearly so.

Assessing these sorts of relative maneuvers after the fact by examining isolated photographs taken at unknown times, unknown distances, and exposed in an unknown sequence can very easily lead to quite considerable errors in interpretation. In such situations, it is all-to-easy to transform the photos into a sort of historical Rorsach test -- where one sees what one wants to see and disregards the rest.

That is one reason why I have been extremly reluctant to consider them as serious research tools at all.

Bill Jurens.

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Antonio Bonomi
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Distance from photos

Post by Antonio Bonomi » Sun Feb 12, 2006 1:47 pm

Ciao all,

@ Bob,

the 2500 meters evaluation of the first salvo photo ( nh 69722 ) is not only my evaluation.

It is my average assumption based on several estimations made by several people using various methodologies.

Now all the above persons do have provided their estimations showing their methodologies, calculations and assumptions.

There are various dedicated post about it, just about that single photo.

At the end all of them are in between 2300 meters ( my personal opinion ) and 3000 meters.
That is why, as said, I use 2500 meters average.

But you can always show us why you do not agree and based on what assumptions.

I do not understand which map you are looking at to position those 1275 yards at 06.03 from my side, it can be one of teh old ones, but really I do not know.

Surely not my latest ' STORIA MILITARE ' published map I reccomand you to use for future evaluations.

As I wrote you just few days ago the average distance I use at 06.03 is between 1400-1600 meters, it can be even a bit more than that.

Now you have my article map and you can double check the distances at 05.55 and at 06.03 as the map do have the scale both in meters and in yards/sea miles.

I just did it again now and at 05.55 it shows 2500 meters while at 06.04 shows the 1500 meters I wrote you. It is confirmed.

Sorry for the readers that do not have it yet, .. I am working on it to make you able to see it soon,.. but you can always order the magazine for 5 Euros and have it in printing with all the photos, .. the quality is good and it is well spent money I suppose for Bismarck lovers.

Instead of running to the PG various turns at the end of the battle, I suggest we focus on the initial part of the battle from 05.55 till 06.03 and the first important starboard turn, when the PG film starts as well.

I hope you agree so we do not loose focus and the readers do not get lost because there is too much meat on the fireplace.

I recap what we are looking at :

1) Bismarck first salvo photo ( nh 69722 ) and her distance evaluation from Prinz Eugen on the lead.
Current distance evaluation around 2500 meters.
German ships course 220 degrees.

2) Schmitz-Westerholt painture showing were Bismarck sailed compared to Prinz Eugen during this battle phase till Hood exploded ( 06.00 ).
Bismarck sailed to starboard astern of Prinz Eugen closing distances.
Distance not yet evaluated but decreasing compared to first salvo photo.
German ship course 220 degrees.

3) Start of PG Rheinubung film at 06.03 or -06.04 showing Bismarck on Prinz Eugen starboard side running a west course in parallel.
Distance evaluation around 1500 meters between PG and BS.
German ships now on course 270 degrees.

According to my opinion there is no other official photo/film or sketches/paintures material currently available to see what happened between 05.55 and 06.03.

I hope one day we will be able to have the full batlle film, but today is not available if ever preserved.
That film should show Bismarck surrounded by shell splashes and been hit 3 times by PoW, plus the obvious turns made by both German ships to avoid been hit by British ships salvoes.
I suppose it is easy to understand why for a German war time propaganda film ( the one we currently have ) they cutted and censored those film sequences.

Last, about the bearing of British ships from Bismarck and Prinz Eugen.
At 05.55 the British ships ( PoW ) were firing with bearing 330 ° degrees to Bismarck.
Consequently Bismarck was responding with a bearing of 150° degrees to them.
But Germans do not use the same British methodology to communicate target bearings.
They do use how many degrees ahead or aft the beam despite the ship couse.
So to understand what they wrote ( F.O. Busch on '' Prinz Eugen im ersten gefecht '' on 1943 ) you must know this.
Busch wrote Jasper ordered to point the guns 20 degrees ahead on the beam ( which for them is 270 degrees and 90 degrees compared to the sailing direction of course ) to port side.
Now lets make an easy calculation :

90-20 = 70 degrees

So Jasper wanted the guns 70 degrees left compared to the ship course.
Ship course was 220 degrees.

220 - 70 = 150 degrees.

I hope you followed my calculation.

So with the guns 20 degrees ahead of the beam on left ( port ) side while sailing 220 course Prinz Eugen was firing to a target bearing 150 degrees.

Just perfect and in fact returning fire to enemy shooting at you bearing 330 degrees.

Same applies for Bismarck ( with obvious small tolerences ).

@ Iankw,

YES, the PG will made several turns, we can see them later.

Kpt Ltnt Jasper will say ' it was flying like a crazy bedstead '.

Right now we are only evaluating the delta speed during a '' theoretical straight '' run on course 220 degrees.
Delta speed between Prinz Eugen sailing at 27 knots versus Bismarck sailing probably at 30+ knots catching up to Prinz Eugen on her starboard side.

I wrote ' theoretical straight ' because a ship under fire will simply do not run a ' straight ' course, just to avoid been hit, .. and Prinz Eugen was under Hood main guns fire, .. so I suppose Brinkmann turned a lot,.. and frequently,... as he was a lot worried ( obvioulsy ) been hit by a 15 inch shell while up there first in line of battle against 2 battleships with a cruiser only :wink: .

@ Bill,

YES, I agree, .. it will be difficult to evaluate how those turns did play on BS vs PG closing distance ratio on this battle phase, .. that is why on graphics I use straight lines and just talk about them, .. without very precise infos it will be impossible to evaluate them.

Ciao Antonio :D

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Post by Robert J. Winklareth » Thu Feb 16, 2006 7:30 pm

Hi Antonio,

I did not use your new battle diagram from “Storia Militare” at first due to its small scale. Instead I reverted back to your last 27-page formal presentation “The Denmark Strait Battle by Antonio Bonomi published on the Bismarck-class website by John Asmussen at your request. While that was two years ago, you continued to refer to that document in later postings, so I assumed that it was still current.

I enlarged the critical area from your new diagram in “Storia Militare,” and I found a couple of serious discrepancies in your presentation. In your earlier “official” version of events, you had the Bismarck crossing over the track of the Prinz Eugen from port to starboard at about 0603. Now you have the Bismarck continuously on the starboard side of the Prinz Eugen from as early as 0516.

According to the Prince of Wales Salvo Plot, the Bismarck sailed on an overall course of 212 degrees, 8 degrees to port of the Prinz Eugen’s course of 220 degrees, from 0553 until 0602. While the plot does show some shallow turns during that period, possible to avoid shell fire from the Prince of Wales, the overall course of the Bismarck was nevertheless 212 degrees.

Assuming a crossover at 0556 when the Bismarck was directly astern of the Prinz Eugen, the Bismarck would have been several hundred yards to port of the Prinz Eugen by 0602 when she began her turn to starboard. You accepted that in your earlier “official” version of events, so what is the basis for the your revised track of the Bismarck? Why are you ignoring the evidence provided in the Prince of Wales Salvo Plot?

Your new diagram in “Storia Militare” does now show a separation of 2325 yards at 0556 when Photo NH69722 was taken. However, in measuring the track of the Bismarck, I noticed that you had increased her speed to 1054 yards per minute or 31.2 knots. The maximum sustained speed of the Bismarck has been reported to be only 30.0 knots.

The increase in speed of the Bismarck from 30.0 knots to 31.2 knots translates to a new delta speed between the two German ships of 4.2 knots, a 40 percent increase in closure rate from 100 yards per minute to 140 yards per minute. That would account for the greater distance to the Bismarck at 0556, but it would only be valid if the Bismarck actually did attain a sustained speed of 31.2 knots. What is your basis for assuming that the Bismarck did achieve a speed of 31.2 knots?

Both of the above discrepancies could be interpreted as attempts to distort the facts to achieve a desired outcome, which is not the accepted scientific or professional way for resolving issues. I sincerely hope that you can provide satisfactory explanations for the above discrepancies so that we may proceed with our analysis of the situation. With estimates of the distance to the Bismarck at 0556 ranging from 1100 yards to over 3300 yards, we have some further work to do to resolve the issue.

Best regards.

Bob

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Antonio Bonomi
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Closing rate on distance

Post by Antonio Bonomi » Fri Feb 17, 2006 12:00 pm

Ciao Bob and all,

I am glad I was able to diverge your current attention from an old map of mine ( that is what I thought due to your statements ) to a current one I am working on.

YES, you got the key points changed correctly now.

That old map, and the whole Denmark Strait re-construction posted on the website you referred to is now to be considered obsolete.

Soon I will be able to provide the English translation of my current version which as been printed on STORIA MILITARE last December in Italian, ( with updates available on next April issue ), so everybody will be able to see my latest map you have and read the whole story.

Initially, I thought like almost everybody that Bismarck was sailing on Prinz Eugen port side on this phase of the battle ( 05.55 till 06.03 ).

My erroneous assumption was mainly due to my first evaluation of Nh 69730 ( the flash effect photo ), and I think this is probably still valid for you currently.

This photo :

http://www.history.navy.mil/photos/imag ... h69730.jpg

But after we ( it was not my initial finding ) discovered that on the photo there is the Prinz Eugen wake clearly visible ( from Bismarck bow till the right end of the photo on the horizon line ).

This finding of course changed completely the position of Prinz Eugen compared to Bismarck, and the positioning of the photo during the battle.

The Prinz Eugen 105 mm gun barrels analysis ( done by another person, so it was a team work ) confirmed the evaluation and helped the assesment that Prinz Eugen was really sailing from right to left on that photo, according to her own battle map at 06.08 more or less.

Without that photo there was nothing else to be used to assume that on that battle phase ( 05.55 till 06.03 ) Bismarck was sailing on Prinz Eugen port side.

Sorry, but on PoW salvo plot map there is NOT the reference of Bismarck track compared to Prinz Eugen.
So you cannot use it to position the Bismarck track showed in there in relation to Prinz Eugen track showed only on his own battle map.
Otherwise I was never going to make the earlier mistake of course.

This said, that discovery opened the possibilities to any of the 3 available run done by Bismarck following Prinz Eugen astern : on Port side, directly on the wake of Prinz Eugen or starboard side astern !

Just as I showed time ago as well on a map called ' the 3 options map '.

Than last May on Bundesarchiv-Koblenz I found that B/W photo, showing Ltnt Schmitz-Westerholt painture.

That explained to me the whole scenario :shock: .

Ulrich Rudofsky after was able to bring out also the colour version and the painture story and the very important related informations that do provide the highest credibility to the painture itself :clap: :clap: .

Here the link to the post we wrote time ago :

viewtopic.php?t=280

That painture is as important as a photo :!: .

It as been made by a battle witness at work on board Prinz Eugen for that pourpose and owned by such important personalities ( OberKommando of Kriegsmarine and after Admiral Lutjens family ).

I read above that you now realized were Bismarck is positioned compared to Prinz Eugen at 06.00 when Hood exploded as the painture shows.

That painture is simply excellent as Ltnt Schmitz-Westerholt positioned the view point behind Bismarck, astern starboard, in order to be able to show the whole battle scenario, with all the key 4 ships ( Bismarck, Prinz Eugen, Hood and Prince of Wales ) clearly showed at 06.00.

But as you easily realize now, for us what counts is the Bismarck position compared to Prinz Eugen, that was my doubt on the 3 options map.

Without any doubt, as Prinz Eugen wake is clearly painted on Bismarck port side, Bismarck sailed on Prinz Eugen starboard side astern.

So thanking a painture of a battle witness telling us how things really went, we can now make our selection and correctly position the 2 German ship tracks.

There are several post you probably missed to read were this is explained, but it is not a problem, now you got it right as said.

Now I am sure you understand better my current evaluation of this battle phase written above .

At 05.55 I assume 2300-2500 meters between Prinz Eugen on the lead and Bismarck on her wake astern moving to starboard.

Than I assume a Bismarck starboard run ( with zig-zag to avoid shells as PoW salvo plot shows 212, than 195, than 226, than 272 degrees course by Bismarck ), and I assume a 'theoretical straight ' run on graphics as I do not know really what happened ( I could have placed the exact PoW plot Bismarck track in scale, but on that small graphic map we decided not to do it ).

And finally as I wrote you I am currently assuming a 1500-1600 meters distance between Prinz Eugen and Bismarck when the PG Rheinubung film starts and photos like Nh 69728 were taken, at 06.04.

http://www.history.navy.mil/photos/imag ... h69728.jpg

With both German ships on course 270 west as you can verify on my map and as PoW salvo plot you refer to shows as well.
But now I have found other 2 Prince of Wales official battle maps showing that 270 course track as well.

Summarizing, 2300-2500 minus 1500-1600 makes a delta of 700 ( best case 2300-1600 ) or 1000 ( worst case 2500-1500 ) meters between my 2 evaluation points.
Sorry for some not precise proportions on the map, but you can easily realize the graphic needs, the map is very small and not done for this purpose.

Now you have a gap of 700-1000 meters compensated by delta speed of 27 vs 30+ knots within 9-10 minutes by Bismarck on Prinz Eugen.

As said the 2 ships were surely not running a straight course, but doing zig-zag to avoid enemy salvoes ( PoW salvo plot shows some from Bismarck confirming it ).

You can read on PoW gunnery report that British ships obviously were doing exactly same things :wink: :

'' It had been decided after Prince of Wales' last firing to use a 200-yard as opposed to a 100-yard zigzag, as the spreads were in the nature of 350 yards ''.

http://www.hmshood.org.uk/reference/off ... 9guns.html

So now the real evaluation comes down to realize what Prinz Eugen under Hood main guns fire did as zig-zag, what Bismarck really did for zig-zag, and how that played on the overall ' theoretical straight ' run on 220 course closing ratio till the starboard turn at 06.03 on course 270 west due to the torpedo ALARM by Prinz Eugen.

You know like I do that at 27 knots ( Prinz Eugen speed ) versus 30 knots ( for Bismarck speed ) the delta closure is 93 meters each minute, so on 10 minutes 930 meters.

As you can see well inside the gap we need to explain.

I am still using Bismarck at 30 knots when Bismarck could have sailed a bit faster.

But I wanted you to have my current whole scenario clear.

That is why I added the zig-zag surely occurred, and be sure that in order NOT to be hit by Hood, the very ' worried ' Kpt Brinkmann ( and I justify him completely :clap: ) not only used the depth charges as I have demonstrated with the photos, but turned a lot and succesfully to confuse both Hood spotters and first artillery director and avoid the 15 inches ( 380 mm ) directed to his cruiser.

As you can see no discrepancies from my side, clear distances and explanations for every evaluation than translated to a map ( with normal graphic limits tolerances ).

Margins are still available like Bismarck speed and best vs worst distances scenario.

I have no need nor intention to distort anything to protect my previous works, and as you can easily realize yourself there is embedded the confirmation of some initial failures from my side.

This is the true spirit of an history researcher, not blindly defend what you realize been wrong because you made it time ago, but update your work according to verified evidences and continue the research.

Who does the work can fail, who does nothing do not run this risk.

I am on the first group :wink: .

Any clever person will understand and I am not afraid of any judgement on my works as they are all done with the correct spirit and intentions.

I am sure we are not finished, and as I wrote you just on 2 months I had some corrections to be made on my December article due to new recent findings.

But I am sure this is also your spirit and after having evaluated all the new evidences you have obtained recently you will be able to evolve your way to look at this battle too.

Ciao Antonio :D

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Post by Robert J. Winklareth » Fri Feb 17, 2006 10:03 pm

Hi Antonio,

I’m sorry, but your explanation does not resolve the two issues that I raised. Unfortunately, it only reflects your own personal interpretation of the situation rather than being based on hard cold facts. It is interesting to note that you now consider “obsolete” your one and only official version of events that was endorsed by all three webmasters. And yet you cruelly attacked those who tried to point out the fallacies of that version in the past.

The Prince of Wales Salvo Plot, as refined to correct for “overs” and “unders” and conform to official estimates of opening and closing ranges in Admiralty reports, clearly places the Bismarck on a course of 212 degrees from 0553 when the Prince of Wales opened fire until 0602 when the Prince of Wales first turned from the scene. This was 8 degrees to port of the Prinz Eugen’s course of 220 degrees.

I never claimed that the Prince of Wales Salvo Plot directly linked the Bismarck’s track with that of the Prinz Eugen, as you stated. I merely pointed out what should be obvious to you and everyone else, that if the Prince of Wales Salvo Plot shows the course of the Bismarck to be 212 degrees, that could be applied to the Prinz Eugen’s Battle Sketch at 0556 when the Bismarck was directly astern of the Bismarck to get the relative tracks of the two German ships. What don’t you understand about that?

The position of the Bismarck to port of the Prinz Eugen in the 0553-0602 time frame is also fully supported by the photographic evidence, as you yourself once agreed to. Photo NH69729 clearly follows NH69722 ib showing the Bismarck coming up on the port side of the Prinz Eugen at about 0559. The next obvious photograph is NH69730, which shows the Bismarck off the port quarter of the Prinz Eugen at about 0601.

The next photograph in the series is of course the uncataloged broadside view of the Bismarck passing the Prinz Eugen off the port beam of the cruiser at about 0605. Those four photographs show a contiguously series of views of the Bismarck as she came up on the port side of the Prinz Eugen to position herself between the Prinz Eugen and Prince of Wales to protect the cruiser from heavy gunfire in accordance with established German naval operating procedures to protect more lightly armored units of the fleet.

Despite the perfect logic of this sequence, you opted to place the latter pictures at the end of the sequence to serve your own purposes even though there is no obvious connectivity to the other photographs in the series. You can’t honestly claim that your arrangement is the one and only official sequence of the photographs when I have shown you another alternative which is equally if not more valid by virtue of the complete connectivity to other photographs in the series.

Secondly, you state that you are still using 30 knots as the speed of the Bismarck. This is not true, as I explained in my prior posting. My enlargement of your diagram measures 0.540 inches between minute marks on the track of the Prinz Eugen, representing a speed of 911 yards per minute or 27.0 knots. The distance between minute marks on the track of the Bismarck measures 0.625 inches, which equates to 1054 yards per minute or 31.2 knots.

The real significance of this difference is that it increases the rate of closure between the two German ships by 40 percent from 100 yards per minute to 140 yards per minute. If that is false, then your entire diagram of the battle is invalid. Perhaps it would be better if you came up with a new large-scale diagram on a scale of 1-inch = 2000 yards or 1cm = 1000 meters showing in detail the tracks of the Bismarck and Prinz Eugen between 0552 and 0610.

Best regards.

Bob

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Antonio Bonomi
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Distance from photos

Post by Antonio Bonomi » Sat Feb 18, 2006 10:20 am

Ciao Bob and all,

I closed my previous post inviting you to evolve your view of the events based on the findings.

I restart this post with same argument, because this is what happened to me and be sure it will continue, as this is the key to find the truth doing history research.

When you face a new important evidence you must change and admit previous failure.

That is simply what happened with Nh 69730.
Long before I moved Nh69729 and the similar photo to the end of the battle; the Prinz Eugen side railing on those photos as demonstrated by Wadinga ( Sean ) do not leave any doubt there.

If you want to understand more about those photos I suggest you to deeply study the Prinz Eugen configuration of railings and how those can be taken into a photo, and especially realize that many foldable ones were down during the battle.
Than you will understand how those determine photos and film unique possibilities and exclude others.

I have deeply explained the PoW plot Bismarck track, and how that is made by several course changes I did not showed on my map.

I explained you how I made the calculations on the distance closing ratio and I am glad you did not find any mathematic error as everything matches perfectly as you can see, with addittional margins.

You should not loose to much time on the explanation re-production in scale of my map, this is not what counts.

I am sure you got exactly my calculation points and everything fits perfectly.

I can easily draw a new details map about it, but not knowing the zig-zag this is an useless exercise.
That is why I went with ' straight lines'.

Now you know that the closure by Bismarck on Prinz Eugen running starboard side it is possible and with lots of margins.

Now you know about the painture showing it.

We obviously do not agree about the sequence and the position of those photos.

But on my current view everything is supported and with a battle witness painture to confirm, the moved photos do have a reason clearly showed on them, on all of them.

I have simply evolved my work based on real findings.

What about your view ??

What about the mathematics on the closure closure ratio ??

What about the painture ??

What about the evidences showed on the photos that do not fit on a port side view ??

Your turn to evolve your view.

But please, do not forget the reason of this post that was the determination of the photo distances, so I do not want to restart a full Denmark Strait battle discussion here in.

So I suppose at this point you agree about photo Nh 69722 ( first salvo photo ) distances and way to evaluate them.

The methodologies are many and all drive for same results, 2300-3000 meters.

The lens was a 50 mm and everything matches with the results obtained by several people.

Do you agree ??

Ciao Antonio :D

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Post by Robert J. Winklareth » Sat Feb 18, 2006 7:56 pm

Hi Antonio,

At first I was puzzled by your reluctance to provide a large-scale diagram of the tracks of the Bismarck and Prinz Eugen from 0552 to 0609 to clarify your position. All you have to do is make a few changes to your earlier diagram which you now say is “obsolete.” That should have taken less time than it took to respond to my last posting. What “zig-zag” are you referring to that would absolutely preclude you from drawing a new detailed diagram as requested?

When I first came up with the speed of the Bismarck on your new overall diagram published in “Storia Militare,” I merely measured the distance along the straight line from 0554 to 0602 and divided that number by 8 to get the average distance. I wanted to ba absolutely fair about the matter and not try to take advantage of any one segment that might be a bit longer than the others. I assumed that the remaining segments from 0602 to 0610 would be the same length.

Since I asked you to cover the entire period from 0552 to 0610 in your new diagram, I decided to also measure each segment in the curved portion of Bismarck’s track from 0602 to 0610. Instead of being the same length as in the earlier part of the track, I was surprised to find that the average distance between minute marks in the curved section of the Bismarck’s track actually measured 0.667 inches. That equates to 1125 yards per minute or 33.3 knots, which is utterly absurd and even ludicrous.

In that entire 8-minute period from 0602 to 0610, you have shown the Bismarck going 6.3 knots faster than the Prinz Eugen when the maximum possible speed differential could only be 3.0 knots. This gives the appearance that you may have deliberately manipulated the evidence to effect a closure rate over two times greater than possible to make the chart fit in with your own predetermined distances.

This new revelation makes it even more important that you be given the opportunity to present a large-scale diagram of the tracks of the Bismarck and Prinz Eugen from 0552 to 0610 to clarify your position. Mere words on other aspects of the issue will not suffice. You were never hesitant before about providing a detailed map to support your position, and now is the critical time for you to do so again.

Best regards.

Bob

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Antonio Bonomi
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Photo distances

Post by Antonio Bonomi » Sat Feb 18, 2006 9:17 pm

Ciao Bob and all,

NO.

Sorry, but I will not make any new map.

The zig- zag is the one surely Prinz Eugen and Bismarck have done to avoid been hit.

I have nothing critical to manage.

The work is published and who wants to undertand how it went can do it.

As you very well realized the 2500 meters showed by the first salvo photo and the painture do create big problems, but not to me now.

Good luck on trying to explain how your theory can manage those 2 evidences.

To do that it is not enough to make a new map with or without the precision level you are looking for on my one.

Ciao Antonio :D

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Post by Robert J. Winklareth » Sat Feb 18, 2006 10:12 pm

Hi all,

The purpose of my original posting under this topic was to present a methodology for determining the distance to a ship in a photograph by an analysis of the photograph. Since the distance to the Bismarck in Photo NH69722 had already been subject to considerable discussion, it seemed appropriate that that my methodology be applied to that photograph for comparison purposes.

I had used as a basis my glossy print of NH69722 acquired from the U.S. Naval Historical Center since I believed that it would be least subject to cropping than printed versions of that photograph in commercial publications. It was soon pointed out that the version of that photograph included in Fritz Otto Busch’s book “Prinz Eugen in the First Battle” actually covered greater a wider area than my glossy print of NH69722.

By proportional analysis, I was able to expand the size of NH69722 to cover the same area as the version in the Prinz Eugen book. Using my methodology for determining distances and assuming a normal 50mm lens on a 35mm type camera being used to take the photograph, I came up with a figure of 2700 yards as the distance to the Bismarck in NH69722.

Having drawn many diagrams of the battle scene over the last 12 years or so, the figure of 2700 yards seemed extremely high to me, leading me to believe that perhaps NH69722 had been taken with a wider angle lens, such as one with a 35mm focal length or even 28mm, both of which were available at the time. I still believe that this might be a possibility.

I have studied Antonio’s earlier diagram, which he has now declared to be “obsolete,” as well as his new diagram published in “Storia Militare.” To me, neither diagram seems to support a separation of 2700 yards between the two German ships at 0556. If it proves to be physically impossible for the Bismarck to have been at that distance in light of other compelling evidence, then obviously a wider-angle lens must have been used.

Since Antonio insists that it was a normal 50mm lens that was used to take NH69722, it is incumbent upon him to justify the 2400-yard separation between the two German ships at 0556 that he claims. This can best be achieved by Antonio providing a large-scale diagram of the respective tracks of the Bismarck and Prinz Eugen from 0552 when the battle began until 0610 when the battle ended. That would resolve the issue once and for all.

Best regards.

Bob

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Distances and mathematics

Post by Antonio Bonomi » Sun Feb 19, 2006 11:17 am

Ciao Bob and all,

it should not be so difficult to realize :

1) 2 ships are separated by 2500 meters at a certain time ( 05.55 ).

2) One ship sails faster than the other ( Bismarck at 30 knots catching up to Pring Eugen at 27 knots ).
Doing so Prinz Eugen will cover 833x10=8330 meters on 10 minutes
Similarly Bismarck will cover 926x10=9260 meters on 10 minutes

3) Making the difference 9260-8330= 930 meters delta recovered

4) Now if you subtract 2500-930= 1570 meters ( which is the distance left between the 2 ships at 06.04, so 10 minutes after when photo NH69728 was taken and PG Rheinubung film starts).

Summarizing : 2500 meters at 05.55 and 1570 at 06.04.
Of course with due tolerances and approssimations.

Are you OK with the mathematics ?


Ciao Antonio :D

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Matthias
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Post by Matthias » Sun Feb 19, 2006 2:10 pm

*controls the calculations*

Well, I guess there's little to disagree about this numbers...mathematic is not an opinion after all. ;)
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Post by Robert J. Winklareth » Mon Feb 20, 2006 7:33 pm

Hi all,

Antonio’s refusal to provide an updated large-scale diagram to clarify his position comes as no surprise to those of us who have followed the matter very closely. We know that a detailed diagram of the true situation would not support Antonio’s claim that the Bismarck was 2400 yards away from the Bismarck at 0556, and therefore he has no alternative but to refuse that request.

Since Antonio will not provide an updated large-scale diagram of the tracks of the Bismarck and Prinz Eugen to support his point of view, it becomes necessary for us to determine the amount of error of the Bismarck’s speed introduced by Antonio. This can readily be accomplished by closely examining his new diagram recently published in “Storia Militare,” and I will go over the procedure step-by-step for you.

To have a diagram of convenient size to work with, I scanned the portion of Antonio’s new diagram covering the tracks of the Bismarck and Prinz Eugen from 0556 to 0609. I then enlarged the area by about four times so that it would fit on standard size paper. The average distance between minute marks on the track of the Prinz Eugen on my enlarged diagram was 0.542 inches, which equates to a distance of 911 yards and a speed of 27.0 knots.

By dividing the 911-yard figure by 0.542 inches, I derived the scale for my new enlarged chart of 1-inch = 1680 yards. By proportional analysis, I divided the 30.0 knot speed of the Bismarck by the 27.0 knot speed of the Prinz Eugen and multiplied that ratio by 0.542 inches. That game me 0.602 inches as what the measurement between minute marks on the track of the Bismarck should be to reflect a distance of 1013 yards and a speed of 30.0 knots.

I then measured the distance between minute marks on the straight line track of the Bismarck from 0556 to 0602, and those measurements averaged 0.625 inches. That represented a distance of 1054 yards and a speed of 31.2 knots. The difference between the 1054 yards and the 1013 yards amounts to an error of 41 yards per minute of a total error of 246 yards over the six-minute period from 0556 to 0602.

Likewise, I measured the distance between minute marks on the curved portion of the Bismarck’s track from 0602 to 0609, and those measurements averaged 0.667 inches. That represents a distance of 1125 yards and a speed of 33.3 yards. The difference between 1125 yards and 1013 yards amounts to an error of 112 yards per minute or a total error of 784 yards for the seven minutes between 0602 and 0609.

It is indeed strange that Antonio would show the Bismarck traveling at a faster speed in the curved section of her track from 0602-0609 (33.3 knots) then on the straight portion of her track from 0556 to 0602 (31.2 knots). If anything, it would seem that the Bismarck would have lost some speed while traveling on the curved portion of her track.

For one thing, the two turns themselves would have slowed the Bismarck down a bit due to the increased water resistance inherent in turning actions. Also by that time, the Bismarck would have taken on enough water as a result of the three hits that she suffered from the Prince of Wales to further reduce her speed.

Anyway, the total error in the distance traveled by the Bismarck is the sum of the error in each segment of her track, 246 yards plus 784 yards, or a total of 1030 yards. When the total error of 1030 yards is subtracted from the separation of 2243 yards measured at 0556, we get 1213 yards as the true separation between the two German ships at 0556.

Not surprisingly, the figure of 1213 yards separation at 0556 is remarkably close to the 1275-yard separation depicted in Antonio’s diagram of the battle. So we are right back to where we started from before Antonio decided to modify the Bismarck’s speed in his new diagram to support his new theory of a separation closer to 2500 yards.

If a separation between the two German ships of around 1300 yards is sustained by all of the hard-core evidence on hand, then it appears that Photo NH69722 may have been taken with a 28mm focal-length lens as I suggested. Another possibility exists that NH69722 was taken with another camera, such as a large format 4x5 sheet film camera with a wide-angle lens, before Lagemann reverted to the use of a 35mm camera for his remaining photographs.

Best regards.

Bob

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Post by Robert J. Winklareth » Mon Feb 20, 2006 9:31 pm

Hi Antonio,

Sorry, but I do not understand your mathematics. It seems a bit too convoluted to me. Using your approach, let’s look at the actual situation:

a. The Prinz Eugen traveled 11,843 yards at the rate of 911 yards per minute and a speed of 27.0 knots in the 13-minute period from 0556-0609.

b. The Bismarck traveled 13,169 yards at the rate of 1013 yards per minute and a speed of 30.0 knots in the 13-minute period from 0556-0609 in the same general direction as the Prinz Eugen (southwest).

c. Both the Bismarck and Prinz Eugen come abreast of each other at 0609 when the Bismarck is directly between the Prinz Eugen and the Prince of Wales causing the order to be given for the Prinz Eugen not to shoot over the Bismarck.

d. How far astern of the Prinz Eugen was the Bismarck at 0556? The answer is simple: 1326 yards, the difference between the distance traveled by each of the two ships.

That is what I have been trying to tell you for the last three years. If you consider the relative speed between the two ships and the total elapsed time of only 13 minutes, all you can possibly get is a separation of 1326 yards. Comparable turns by both ships would probably cancel each other out and have little appreciable affect on that separation figure. You just can’t get to 2500 yards from here.

This will be my last comment on the side issues regarding other aspects of the Bismarck operation. I am only interested in pursuing the technical issues associated with this topis of determining distances by means of photogrammetric analysis.

Best regards.

Bob

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Photogrammetry

Post by Bill Jurens » Tue Feb 21, 2006 2:36 am

For what it is worth my photogrammetric analysis of this photo strongly suggests that it was indeed taken with a 50mm lens on a 35mm camera. The general field of view of what appears to be a nearly full-frame reproduction closely matches what might be expected using a 50mm lens on 35mm film, and other checks -- which are independent of camera type or lens type -- tend to confirm this finding.

In that regard, it should be emphasised that changing the focal length only changes the field of view; it does not change the perspective projected upon the film plane. So, if the focal length were changed, then the size of the image would change but the geometry of the image would not. The only way to change the geometry of the image is to move either the camera or the subject.

Fortunately the photograph in question supports a variety of independent measurements. One of these is the vertical position of the horizontal horizon line behind the target as projected upon the target itself. The curvature of the earth (and other things) means that the line of sight from the observer to the horizon is tilted slightly downwards from the observation point. This is known as the 'dip'. The net result of this is that if an observer stays at constant height, then the position of the 'cut' of the horizon line drops as the target gets farther and farther away.

Basically, the dip angle (in radians) is equal to (2h/R)^0.5, i.e. to the square root of 2h/R, where h is the observer's height and R is the radius of the earth. If we take h to be 10 meters, which would seem reasonable, and take the earth radius as roughly equal to 6,275,000 meters, the dip angle would then equal 0.1015 degrees. The tangent of 0.1015 degrees is roughly 0.0018, which means in effect that moving the target ship 1000 meters farther away would move the cut line about 1.8 meters down.

Clearly, the range computed for the horizontal cutline on the target should correspond at least roughly to the distance measurements obtained via other means. The cutline is consistent for a target something like 2500-3000 meters away.

Had another lens been used, e.g. a 28 mm, then for a given image size the position of the cutline would not agree with the other measurements. It is consistent for the range computed for a 50mm focal length lens. Basically, for a given height of observer, the vertical position of the horizon cutline defines the range independently of manipulations in focal length.

Bill Jurens.

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Post by Robert J. Winklareth » Wed Feb 22, 2006 9:33 pm

Hi all,

I agree with much of what Bill Jurens had to say, but I must admit that I got lost in his calculations, especially when he introduced radians into the equation. I question any method that produces a wide range of possible answers, such as 2500-3000 meters, since it appears that these are only estimates based on rules of thumb. I much prefer to use a method that produces a single result with the realization that there is a certain margin for error.

I came up with another method for determining the angle of view of the lens that was used to take NH69722, and it turned out to be surprisingly accurate. All you need are scale drawings of the top and side view of the Prinz Eugen so that you can locate the exact point where the camera was located and from there you can draw lines outward to encompass the area covered by the lens.

I would agree that this procedure might not always be practical, but in this case, there is enough of the Prinz Eugen showing to make it rather easy. Photo NH69722 was obviously taken on the starboard side of the second deck at the narrowest portion of the deck just aft of rear twin 105mm AA gun position.

On the horizontal profile, I used my Photoshop software to turn turret Caesar perpendicular to the centerline of the ship as shown in NH69722. Since there is nothing on the left side of the photograph, I used only the right half for drawing my lines along the centerline of view and just to the right of the forward edge of the rangefinder housing on the side of turret Caesar as shown in NH69722.

On the vertical profile, I drew my upper line to just above turret Caesar as shown in NH69722. The lower line was a little more difficult to judge where the lower edge of the photograph cut the upper deck and the main deck. Since the camera was tilted slightly downward, the upper angle from the line to the horizon was somewhat less than the lower angle down from the line of sight to the horizon.

The angle between the two lines in the horizontal profile measured 22 degrees, but since only half of the photograph was used, the total angle of view was 44 degrees. In the vertical profile, th upper angle measured 17 degrees while the lower angle measured 27 degrees, making a total of 44 degrees. This confirms that NH69722 was taken with a normal lens with an angle of view of about 44 degrees.

I of course expected the results to show that NH69722 was taken with a 28mm wide-angle lens, but that was not the case. I was a bit reluctant to post these results since they are so close to the 46-degree actual angle of view of a 50mm focal length lens on a 35mm film camera and my method cannot be considered to be all that precise, but that’s the way it turned out. Perhaps I was just lucky in determining the location from where NH69722 was taken.

So now we still have a conflict between the distance determined by photographic analysis and the time-distance relationships established by the other evidence. I still do not accept Antonio’s method of resolving the problem, so where do we go from here? Are there any physicists in our group who can shed any more light on the subject?

Best regards.

Bob

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