Which camera? Help!!

drighi · Jan 15, 2020

Hello all, my first post here.

First of all, I'm NOT a photographer. But I'm on a mission to determine what was the focal length of the camera was that took this picture:

I know it was taken between 1894 and 1930 at the latest - most probably around 1900. I need the focal length so that I can plug that number into an equation that will help us locate foundations on the island in the picture.

Thanks for any opinions / information!!

Damian

DWThomas · Jan 15, 2020

Hmmm - I'm having trouble figuring how the focal length helps, as I'd think you need more independent variables. The focal length would need to be related to the negative size/film format to get an angle of view -- is anything known about that? There's also the possibility the image is cropped, which would argue for using proportions and ignoring the focal length.

Basically everything is tied together by some sort of proportion. You've got the width of the tops (presumably the same) of the two stone piers for one ratio. But is there any information (or at least educated guess) where the camera was positioned? Are there any old-time engineering drawings giving some dimensions of the pathway width or rail spacing or even the dimensions of the stone piers? Height and width are self-evident, but the depth needs some way to establish a reference. If it could be assumed the camera was approximately at the river's edge, I suppose that and the far edge that's visible could be used to guesstimate the away-from-the viewer distances.

Odds are the intermediate pier is halfway between the two sides of the river, although some peculiarities of the riverbed could no doubt shift that.

Anyway, this caught my eye because it's not too far from home (and I've always been intrigued by things mechanical and structural!)

4season · Jan 15, 2020

Maybe taken with a small and inexpensive camera such as this?

https://www.photothinking.com/20160907kodak-no-0-brownie-model-a-shooting-at-over-100-years-strong/

Mostly idle speculation on my part, but photo appears grainy with blurry corners which suggests simple lens and small negative, and Kodak Brownie No 0 would have been a popular choice meeting those criteria.

pentaxuser · Jan 15, 2020

drighi I am sure you will have anticipated why DWThomas or any other photographer would ask the same question as he has. So please give us the reason why the focal length of an unknown camera( unknown to you it would seem and certainly likely to be unknown to the rest of us) will help establish the date of the picture.

This equation you mention seems critical in establishing a date as this will give you a date. If it is it might help if you explain why. Forgive me but it sounds as if we simply nominate a focal length this will result in a date for the picture, am I right?

pentaxuser

DWThomas · Jan 15, 2020

pentaxuser said:
if we simply nominate a focal length this will result in a date for the picture, am I right?

I read it as wanting to be able to plot the location of the bridge pier foundations. And whilst I admit retiring from engineering sorts of work nearly 20 years ago, my aging brain fails to see how knowing the focal length tells us much without a distance reference of some sort. Knowing the relative angles subtended by each of the two piers would provide some information, but unless you have a dimension -- of something identifiable -- I'm befuddled by how you're going to derive measurements. (And I don't think we would actually need the focal length to do whatever gets done.) None the less, it's an interesting idea, as well as a curious bit of history.

BobD · Jan 15, 2020

Treasure hunting?

removed account4 · Jan 15, 2020

it might taken with 3.5x4.5 ( like quarter plate ) roll film ( point and shoot box camera ) and was most likely a 100mm ( +/- 10mm ) lens. the print was probably a contact print not enlarged . or it was taken after about 1930 and was an argus 35mm camera and the standard 50mm lens. the film was enlarged. either way it has that not much in focus box camera lens look.

or ... not

awty · Jan 15, 2020

If the main cable is still there like in the Wiki link wouldn't that lead to the foundations?
https://en.wikipedia.org/wiki/Chain_Bridge_(Easton,_Pennsylvania)
Also other historical photos.
http://www.delawareandlehigh.org/talesofthetowpath/lehigh-canal/glendon/
The rails will probably be a standard spacing like 6', add them up might give you a length.

DWThomas · Jan 15, 2020

According to one picture on that Wiki page, the central pier is among the remaining structures (now I'm even more confused ... ).

(Maybe the OP is a geometry test ... )

drighi · Jan 17, 2020

Hello all,

After another review of the formula I have, it turns out that you’re correct, I don’t need the focal length. An explanation of the formula had mentioned the focal length and I thought that I would need it.

I’ve been able to solve the distance through proportions as one of you described. (My formula)

We took measurements of the piers in person, and I know the height of the tower, so I had what I needed right in front of me.

Incidentally, my mom has an old brownie camera she got from my grandmother. I should get that camera working and take a “new” picture!

Thanks so much!
Damian

drighi · Jan 17, 2020

BobD said:
Treasure hunting?

More like historical documenting! Not looking for gold at this place, lol!

Ray Morgenweck · Jan 25, 2020

Its composed in a manner that suggests it maybe part of a Stereo Camera image. Also, Stereo was very popular in that era.

ic-racer · Jan 25, 2020

Focal length will not help you without knowing the original size of the image on the negative. Since you posted a print, I presume you don't have the negative. Who is doing the math, do you know what you are doing?

Which camera? Help!!

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