Compression Problem

[seawolf66]

I have a photographic Problem which I given myself, I hope to express it correctly here for any help I can get on this matter:

Think of a wall about forty feet wide and eight feet height, Now this wall has twelve holes in it which are evenly spaced apart;

Now what I wish to do, is photograph this wall so as to have the last eight holes almost merge together in a way of see-ing or should I say I want to compress the last eight holes to look almost like One!

Now I have tried a 101.6mm lens and a 150mm lens but to no avail , so I am here to discuss my options , My thinking now is that to get this to work I should be use-ing a 270mm, 360mm or 380mm lens to get this to work of course one does need some swing to get it to work / Right!

Thanks , and I hope I have explained this well enough for you to understand: :confused:

[Bill_1856]

Huh?

[Kirk Gittings]

Sounds like you want extreme convergence? I would think you would want a wider lens rather than longer if I am reading this right.

[seawolf66]

Kirk: I do not know and is why I am asking for help here!

[Peter K]

As Kirk mentioned take a short lens and taken from one side of the wall you have to swing the camera back up to the point all holes are in focus. As shorter the focal lenght and/or as smaller the angle between camera and wall as more the holes would be "compressed".

[domenico Foschi]

If I have understood what you are trying to do, a wideangle is the lens that might help you the best. Bear in mind that such a lens will render the furthest holes pretty small, I wonder if you will be able to even discern them depending by the size of the holes.

[Nathan Potter]

Sounds like you need to employ some sort of nonlinear perspective distortion which implies a wide angle lens as others have suggested. By employing an extreme tilt (say left to right) at a pretty acute angle to the wall with a wide angle lens well stopped down you might come close to what you want - but I doubt it. If you can get say a 75 mm. FL lens or smaller (for 4X5 format) and try looking at the wall from an angle of 60 degrees normal to the wall or greater (30 degrees or less off parallel to the wall) and start tilting the backplane like crazy till all holes are in focus you might approach what you are looking for. The perspective distortion should render the distant holes closer together than the nearer holes. But if the lens is basically rectilinear then progression of gaps between the holes will be uniformly decreasing from near to far. To force the gaps between the holes into an uneven arithmetic progression implies the use of some nonlinear optical element in the image path.

Good luck!

Nate Potter

[seawolf66]

Thank you all: And those who answered ,you Did understand what I am trying to do , always the imposible for me , so in fact I was going in the right way,with wide angle lens , : Now to find good old 75mm cheap! [LOL]

[Nathan Potter]

Lauren, possibly you could rent or borrow? Got any benevolent local friends?

Nate Potter, Austin TX.

[Jeff Keller]

If the wall runs in a direction nearly straight away from you, then you want a very long focal length lens and to take the picture from far away.

If the wall runs perpendicular to your line of sight (from left to right) then you want a very short focal length lens to cover a very wide angle of view.

[seawolf66]

Here are the two fotos of what I am trying to compress at one end of the foto as you can see in fountain-normal the space between to spouts is normal and NOW in the fountain-swing you can the spouts getting closer together at one end the farthest:
Still not the way I want it ,but gething there! But also now need to deal with swing problem: Lauren

[Nathan Potter]

Lauren, you mentioned earlier that you wanted the distant falls to be virtually on top of each other while maintaining a good space between the nearer falls. Yes you're getting there with second photo.

Now that I'm loaded with coffee I had a couple of thoughts.

You're trying to do this using a rectilinear lens on a flat film plane so you can't go much further than your second photo. Beyond what you have done you need an optical algorithm to introduce a nonlinear element in the system. It occurred to me that you can do this with the lens you have. Introduction in the light path of a hyperbolic function can do this. What I mean is that your scene is perceived as a rectilinear X Y coordinate system by the lens and film plane. If you transform this image to a spherical coordinate system with the distant falls at the limit of the sphere as viewed by the film plane then I think you are there.

To be clearer and more practical simply photograph the scene as a reflection in a large silver coated sphere. Place the distant falls at the edge of the sphere. Two things may be objectionable. First your camera will be in the photo (but possibly you can crop it out). Second all elements in the picture will be rendered curved. Despite the drawbacks this approach is mathematically attractive since the gaps at the edge of the sphere become infinitly small. This is the consequence of a rectilinear film projection onto a spherical surface and the hyperbolic function having an infinity bound.

Another way, more elegant, to deal with your problem is to use a 180 degree fisheye lens that will cover 4X5. Don't know if such exists but other lens gurus on this forum may know.

If the silvered sphere (I'm thinking big Christmas ornament) is tried you'll need to be close the the sphere to fill the frame but yet focused as you normally are since the lens/film dosen't know the sphere is there.

Nate Potter

[Peter K]

Lauren,

you're on the right way. With a shorter lens and possible one leg of the tripod in the water you will get what you want. But the camera should be equipped with a WA bellows also.

Peter K

[seawolf66]

Nate Porter: Thank you for time and Information, will sit for awhile and ponder your information here , Thanks a lot : Lauren

[seawolf66]

Peter K; Its bad enough to be looking for a wide angle lens , but now you throw in bag bellows ( LOL) speaking of a wide angle lens also The tripod leg has been in the water all the time. I am tracking three of them on ebay:
Angulon 1:6.8 90mm or Wollansak 3-1/2inch F:12.5 or Optar 90mm F-6.8

Thanks as always peter for all your information: Lauren

[Peter K]

Another way, more elegant, to deal with your problem is to use a 180 degree fisheye lens that will cover 4X5. Don't know if such exists but other lens gurus on this forum may know.
There was a prototype of a Komura 33mm f/4.5 fish-eye for 4x5. As I know it was never on production. But with a rectilinear wide-angle lens and some Scheimpflug one can get the desired image without distortions.

[Peter K]

Lauren,

with a 90mm lens you don't need a WA bellows, but with a shorter lens like 75mm or so it depends on the camera, lensboard etc.

I've only worked with an Angulon 90mm. With an image circle of 154mm at f/16 it fills 4x5" exactly.

Peter K

[Mattg]

Hi Lauren,
it seems you're talking about a matter of camera position and angle of view. I think a wide angle lens will be the right choice but you can do a lot of work before getting your hands on the lens.

In your "swing" example above it looks to me like you've moved closer to the fountains (moved to the left of the first shot). If this is still not what you want then you will need to move further to the left until you get the far fountains merged. At that point you could use a wide angle lens to include the fountains to your immediate left. The wide angle of view will let you include the first couple of fountains where the gaps appear largest while the relationship between the further ones will not be changed.

If you use swing on the rear standard to get the fountains in focus you will not have the coverage problem evidenced in the example photo. You will also cause a distortion that will produce a greater separation on the film in the near fountains (assuming the middle fountains are centered on the back). You may not like the result though as you will be accentuating any wide angle distortion caused by the short focal length by asking those light rays from the near fountains to strike the film at an even more oblique angle.

Can you visit the spot and establish the best camera position? If you use a digi P&S you could share that position here and get a feel for the appropriate focal length to include the nearest fountains. You could take a couple of shots if you can't include the near fountains in just one, as long as they're from the same position. If you know the approximate 35mm equivalent focal length of the digi then you're on your way to a very good estimation of the required focal length. I think you might want something like a 75mm for 4x5" for maximum effect.

Without going down the path Nate suggested (Nate:wouldn't you want the inside of part of a silvered cylinder?), you won't get the far ones exactly merged and the near ones separated. You'll have to compromise.

[Allen in Montreal]

If the wall runs in a direction nearly straight away from you, then you want a very long focal length lens and to take the picture from far away.........

This was my understanding of the task also,

May I suggest you take a 35mm, play with framing and see what best meets your vision and then pursue the lens that will suit your needs? Is that an option, do you have 35mm kit with a wide and a long zoom?

[seawolf66]

Ok , I got a Wollansak Extreme wide angle lens 1:12.5 3-1/2inch 90mm thanks all:

[Jim Ewins]

Jeff's short message is on point. Suggest you try it first with a 35mm zoom lens, then scale up to whatever negative you will intimately use.

[Maris Rusis]

Fish-eye lens! Anything at the periphery gets extremely mini-fied while detail in the middle looks almost normal if you are close enough.

I use an auxiliary fish-eye converter lens (Marexar Ultrawider that I bought in 1972) screwed on the front of the view camera lens to get a field of view of about 140 degrees and all the barrel distortion that goes with it.

[seawolf66]

To: Jeff Keller & Jim Ewins & Maris Rusis : Gentlemen: I did do this shot in 35mm My Dlsr eos 20D with a `17-85mm Lens . and that is when I got my Idea to obtain this view for the fountain , I am learning to go slowly and I need to look better at my Ground glass and whats on it : I thank you all: Lauren