Photo # NH 69722 distance evaluation

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

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marty1
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Post by marty1 »

Hi Antonio:

Ok – I think I am on the same page now. I can see there are a number of great advantages to this method. Simplicity and speed being chief amongst these advantages. My approach is much more complex and time consuming, and relies upon photo depth scaling of objects within the photo.

However, I can also see a number of drawbacks to the focal length approach. Unfortunately we will not always know the camera employed, nor it’s focal length, nor its negative size. In the case of Lagemann images this approach is obviously much preferred, but if I wish to guess at object distances for photos in which less background information is available, I will have to rely upon a different approach to estimate distances.

The other problem – as you have already described -- is guessing at what sort of cropping occurred of our working photo relative to the negetive image. Although in playing with this approach it seems that reasonable guesses at possible cropping will limit the magnitude of error in our range guesstimate.

Best Regards
marty
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Antonio Bonomi
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Methods of evaluation

Post by Antonio Bonomi »

Ciao Marty and all,

YES, I agree with you.

Knowing focal lenght of 50 mm and negative format of 24x36 mm makes it very useful.

Differently it becomes much more impredictable.

Ciao Antonio :D
marty1
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Post by marty1 »

Antonio:

I was looking at your battle plot for Denmark Straits.

Image

I assume the first photo we examined represents points 56 (5.56) for both the Bismarck & Prinz Eugen course plots. By the way I ran thru my range estimation calcs for the first photo (NH69722) again using the focal length & negetive to real photo scaling method and arrived at a range estimation of ~2350meters. However, I am not exactly sure how my working image had been previously cropped/cut relative to the negative -- so I will guess that the range between Bosmark & PE is about 2300 to 2500meters.

Where on your course plots for Denmark Straits would the shell casing photo have been taken from -- or was this photo taken somewhere "off of" the course plot map?
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Antonio Bonomi
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My plot and the photo

Post by Antonio Bonomi »

Ciao Marty and all,

YES, you are right :D .

The initial photo we had been measuring is the first salvo photo of Bismarck (Nh 69722) during the battle taken from Prinz Eugen at 05.56 ( ref. 56 on my tracks chart).

The range you are estimating between 2300 and 2500 meters is just the one I am using, more 2500 than 2300 currently, and it is measurable on my track as well ( that time I was using 2300 meters ).

Some things I can anticipate now from that chart to the one I am currently working on for my article that will be soon published are :

1) the measure will be moved to 2500 meters at 05.56.

2) the Bismarck track will be moved from port side of Prinz Eugen to the starboard side of the German heavy cruiser as it is demonstrated by this paint made by Ltnt Julius Schmitz ( a battle witness on board Prinz Eugen ) :

viewtopic.php?t=280

3) There will be many more photos including the British ones and also key prints too :shock:

4) My full battle article map will cover from 05.20 till 06.40 and 6 ship tracks.

The photo you are referring to ( shell casing ) was taken more likely well after 06.30 ( when both ships were again sailing south west on course 220 ° degrees ) but surely before 10 am, so probably out of my full plot map too and surely out of the one you showed for sure.

Ciao Antonio :D
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Post by Robert J. Winklareth »

Hi all,

I'm sorry that i had nothing to contribute on this subject last summer while you all were engaged in this very interesting discussion. i had not yet worked out in the own mind how to tackle the focal length issue and i did not have a suitable print of NH69722 to work with.

That has now been corrected, and I have posted the results as well as the methodology under a broader topic in this forum. Based upon my methodology, i deterrmined that the distance between the Bismarck and the Prinz Eugen was at least 1580 yards. If the glossy print that i have had been cropped to any degree, than the figure would be correspondingly higher.

I must now admit that my earlier estimate of 1100 yards based on the speed of the Bismarck being 30.0 knots versus 27.0 knots for the Prinz Eugen must be in error. All of the pieces still do not fit together, so there is more work for us to do before we can nail down this issue.

Best regards.

Bob
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Antonio Bonomi
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Nh 69722 photo distances

Post by Antonio Bonomi »

Ciao Bob and all,

this topic as you can read as been quite well covered both here in as well as on another forum a year ago.

Several methodologies as been used to try to determine the distance between Prinz Eugen and Bismarck on the photo that as you shoud have clearly understood is not the one showed by Nh 69722 but it is much larger and complete.

The full size photo was printed full size on the 1943 edited book ' Prinz Eugen im ersten gefecht ' written by Fritz Otto Busch ( I have it on original version ).

I have worked with many persons on it, among them Bill Jurens, Herr Nilsson, Marty, ... plus many good inputs from others as well, .. and at the end I think right now all our different methodologies used as driven for a range of distance between 2300 and 2700 meters showed by that photo.

So far I am using 2500 meters as an acceptable average estimated distance based on the above.

Here in this thread you can see some calculations and methodology samples, but there is much more.

Please do not get confused with other measurements we made after, as we than measured also other photos were it is possible to evaluate Prinz Eugen versus Bismarck distance.

It would be interesting to see and realize which type of assumptions and calculations you used to determine your current estimation of the first salvo photo, the one partially showed on Nh 69722 you are referring to.

Ciao Antonio :D
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