Capturing Aerial Image

I have need to provide 35mm negatives of architectural models and

similar subjects photographed with a view camera having the

necessary swings and tilts to bring all parts of the scene in focus.

I would like to avoid the process of making larger prints and then

scanning them onto the 35mm format. Is it feasible remove the ground

glass screen after correct focus and other adjustment and capture

the aerial image with a 35mm camera focused in close up mode with a

50mm prime lens? I have several bellows outfits and it would be

little trouble to rig the connecting machinery. It would save a lot

of scanning. If it is feaible, what would be the extention of the

50mm lens w/bellos. I can rig a light tight tunnel from the focal

plane of the view camera to the taking lens of the 35mm camera. Am I

wrong in assuming that I can capture the aerial image this way? I

have not worked with this phase of optics for over fifty years and

my recollection of the theory is a somewhat rusty todsy. Thanks. HG

In principle, yeah, sure, why not? The hard parts are supporting the little camera and keeping the dark in. Timing the exposure may be a problem too. As you pointed out, nothing insoluble.

 

More seriously, think a little about the aspect ratios. The exposed area of 4x5 film is 90 mm x 120 mm. The exposed area of 35 mm film is 24 mm x 36 mm. 24/90 = 0.257, 36/120 = 0.300. So to get the 4x5 film's area in you need to shoot at a magnification of 0.26. Shade it a little to 1:4.

 

At 1:4, the lens is extended 0.25 focal lengths from its infinity position. What you need is a macro lens, not a bellows, and Bob's your uncle. Any old macro lens for 35 mm still will go to 1:4 on its own mount.

 

Cheers,

 

Dan

The problem here is that the 35 mm camera will only receive the central rays - the rays headed out to the outside of the view camera frame will continue on and miss the 35 mm camera lens. All you will see is the central part of the image. You will get improved depth of field though - ie the depth of field of the 35 mm image will be greater than the dof was on the ground glass.

 

To avoid having to use the view camera, you can't use a stopped-down very wide angle lens (to imitate a shift lens) or a shift lens on the 35 mm camera can you? What sort of 35 mm camera do you have?

 

Best, Helen

Harry, I'm probably missing something here, but are you describing something like a tandem camera setup? This is bulky and a bit of a kludge, but it lets you use the view camera as a bellows, with the added benefit of tilts + shifts. It's described in one or more of Alfred Blaker's books.

 

I'd forget about the 50mm lens for the reasons Dan brought up-- to free up the bellows you'd have to be at 1:1 or greater. You could start with something like a Graphic or a view camera with a Graflok back, and secure a 100 - 150mm enlarging lens in a lensboard with a #1 hole. Then with an hour or two's work in your basement, you can rig an adapter panel to hold your 35mm body on the Graflok back, and you're in business.

 

I made something like this out of a piece of hardboard and a T-mount microscope adapter, the whole thing spray-painted flat black. Works OK-- I've used it with a 1938 105mm Tessar to take pictures of my kids on a modern Canon body. It's flarey, and it's cumbersome, but something like this might be a very good answer for your purpose.

Thanks, Guys! I have a Leica M6 & bellows 1&2. I also have access to a 4x5 Graphic View. My idea is to focus the Leica lens (it would seem the shorter focal length. the better) to cover the 4x5 focal plane. I also have a junk 4x5 series D Graphlex from which I can salvage the back, ground glass, and bellows. I would then construct a framework to hold the Leica and connecting bellows to the focal plane of the view camera. <p> First the view camera would be adjusted to the correct perspective and focus of the subject and then the Leica focused on the ground glass, the ground glass pannel would then be removed and the exposure made with the Leica. It might simplify the operation to use the Visoflex to focus the camera lens which would require an extension of approximately 8". I have the necessary aluminum angles and a well equipped home shop; also an additional bellows for the Leica/ground glass connection. My main concern is whether the Leica will properly capture the aerial image at the focal plane of the view camera. I just want to be assured that my arithmetic is correct before I start cutting angles and boring holes. More later.

Hm...maybe I'm missing something, but the method you're trying to use seems about 100 times more difficult than simply having a 35mm copy of a 4x5 negative made. Surely there is some place that scans 4x5 negs and could then make 35mm negs from that. Or I assume there must be some wet darkroom method of doing that too.

(Hey, when you say "Thanks, Guys!", that includes Helen, oui?)

 

Harry, not to rain on the parade, but I suspect you're going to take a picture of a blur. Maybe I just don't understand the optics of what you have planned. I've never heard of this method myself, but of course that doesn't mean anything. It sure seems like a lot of trouble.

"First the view camera would be adjusted to the correct perspective and focus of the subject and then the Leica focused on the ground glass, the ground glass pannel would then be removed and the exposure made with the Leica. It might simplify the operation to use the Visoflex to focus the camera lens which would require an extension of approximately 8"."

 

Harry, if you are going to use a 50 mm lens to capture an image 90 x 120 mm, you need magnification of 1:4. To get this magnification, the lens' rear nodal point must be .25 focal lengths in front of the infinity position, or 1.25 focal lengths from the film plane.

 

I don't know where you got 8". Check your arithmetic. Did you have in mind to use a longer lens than 50 mm?

 

With a 50 mm lens, extending the lens 8" (= 4f) from the infinity position will get magnification of 8:1. At this magnification, you'll be able to capture only a tiny part of the 90 x 120 aerial image on your little 24 x 36 piece of film.

 

And a Leica with Viso isn't the right tool for the job. The Visoflex is too deep to get the low magnification you need with a 50 mm lens in Leica mount. Beg or borrow any 35 mm SLR you can, with a 50 mm or so macro lens to fit it. Leicas are wonderful tools, but Leica + Visoflex = about a 17th rate SLR.

 

Cheers,

 

Dan

Harry, I just made a rough setup: a Crown Graphic as the primary camera and a SLR with 50mm macro lens for catching the aerial image. What you will get at best is a big dark area( the inner side of the bellows ) having within a circular field ( the exit pupil of the LF lens ) showing indeed the aerial image. By moving the SLR one only scans other parts of the image a 4x5 film would register in total. So Helen is right. Uli

Harry, You will be able to focus the aerial image with the Leica, but you will only see a small part of the image - not the whole 4x5. Do a simple ray diagram. The rays going from the 4x5 lens aperture to the outer parts of the 4x5 image plane will miss the Leica lens entirely. The ground glass diffuses those rays so that some of them head more towards the axis - remove the GG and they carry on. There are a number of similar systems used in the movies to increase or decrease dof, so this is not just me theorising, I've tried all this stuff to see what happens.

 

You may be interested in doing something else: you can use a short-focus lens, such as a standard lens intended for 16 mm cine (f=25 mm). These can be had at low prices. Mount one of these in your view camera and use the Leica to take a picture of the aerial image formed by the cine lens. This is a proven technique (albeit mounted in a double-bellows) for giving very deep focus, not an experimental set-up. The drawback is that you are magnifying the aerial image, so the Leica lens and bellows need to be able to do this. One answer is to use a reversed lens on the Leica. This technique can give you usable shift, and make tilt unneccessary.

 

A version of this was covered in an article on deep focus in the good old BJ a while back, as I recall.

 

Best, Helen

I wrote the above post while Uli was writing his. I wouldn't have written the same post if I had seen Uli's post.

 

Best, Helen

what am I missing?

 

You keep saying that it isn't possible to capture an image nominally 4"x5" on 35 mm film. Why not? I ask because I regularly make closeup shots of objects in that size range with my Nikons. How does what I do differ from what Harry wants to do, except of course that Harry wants to use an RF Leica. As I mentioned to him, these are fine cameras but not the right tools for his job.

 

Also, Helen, why do you believe its possible to get more DOF with a shorter lens? As a practical matter, DOF in the final print is controlled by magnification and aperture; focal length is pretty irrelevant. Yes, I know that it sometimes makes sense to shoot at a lower magnification and then enlarge more, but in my experience this trick isn't worth a lot. The snag is that the emulsions I use don't record fine detail well enough for the trick to buy much.

 

Cheers,

 

Dan

Parenthetically, thanks to all of you for educating me about catching the aerial image.

I used "Guys" in the inclusive sense, realizing that both genders had offered answers. It seems I have opened a can of worms which was not my intention. I don't like trolling and would hope my motives are not misjudged. My main concern is whether the image that would have shown on the ground glass of the view camera can be captured by the Leica if the ground glass is removed. I am presuming that the aerial image is in focus at the focal plane of the view camera which has by means of tilts and swings of its lens, corrected the perspective of the scene. I have a Visofles. I don't have a SLR. Actually it isn't needed but it provides a means to observe the image that the Leica would receive. I have used the Visoflex & bellows with short focal length lenses for macro work. I am lazy and wish to avoid making the images first on MF film and then re-photographing it on 135. In a binocular or telescope the aerial image if forme by the objective lens and captured by the occular lens. In the system I am investigating the Leica's lens would then become the occular lens and instead of transmitting the scene to the eye it would project it onto the 135 film. The trouble with this hypotheses is that my basic premises may be incorrect in which case the whole proposition is futile.

"I am presuming that the aerial image is in focus at the focal plane of the view camera which has by means of tilts and swings of its lens, corrected the perspective of the scene"

 

The trouble is that the groung glass is the focal plane. By removing it, there is nothing to stop the rays of light at this point in space. They will continue past the focal plane and even past your 35mm camera at the same angle they exited the LF lens.

 

The best sollution I can think of for the idea you have proposed is to use a flawless ground glass & leave it in place. Effectively replace your eye with the 35mm camera and photograph the focused image on the ground glass. Rig a dark bag from the view camera around the 35mm for obvious reasons.

 

Of course, wouldn't it be easier to rent a TS lens and if needed the 35mm body to go with it? How much movement do you actually need?

Sorry, I skimmed through the other responses, but not very well as I missed Helen's first response completely. Had I read this, I would have simply stated, "I agree with Helen".

Harry, - I also use 'guys' in an egalitarian sense, so no problem there.

 

Dan, the difference is that the 4x5 objects you are photographing with a 35 mm camera are (probably) reflecting light in a diffuse manner - ie there is light travelling from all points on the object towards your camera lens. This is not the case with an aerial image. The easiest way to explain is to draw a sketch. I hope that I manage to attatch it.

 

Deep focus by using two (or more) lenses. Before writing any more on that I really need to try to remember more details, check my notes and my original references - which I don't have at the moment. What I'm thinking of is not the aerial image relay system mentioned in Ray's Applied Photographic Optics. meanwhile, you might like to do a google on 'Frazier lens' - though I don't know if the Frazier is the same as the system I've seen, or if it's all smoke and mirrors.

 

Decreasing depth of field is a simpler issue.

 

More later...<div></div>

Thanks to everyone for the good counsel though I am not satisfied that the question can be resolved short of building a mock-up and see if the two systems can be coupled to elliminate making silver images at the view camera's focal plane. Off to the shop!

Canon FTb body off ebay $90.00

 

CLA to said FTb body %65.00

 

35mm f2.8 Tilt And shift lens for said FTb body $450-500.00 or rent if possible.

Helen, thanks for the reply.

 

As I understood and still understand it, the aerial image is in the plane of the ground glass, and one just focuses the second camera's lens on it. It is not somehow magically intercepted by the second camera's film plane, it is projected by the second camera's lens, which acts as a relay that also magnifies. This is basically how my Canon 310XLS viewfinder works, how the relay lenses behind my other Canon S8 cameras' beamsplitters work, and very much how a compound microscope works.

 

Given that, your advice to Harry mystifies me. So does his failure to understand what's involved in imaging a 90x120 mm object on a 24x36 mm piece of film. Sorry for being so dense.

 

Cheers,

 

Dan

I set up a 2x3 Speed Graphic with its f/2 normal lens wide open and a Nikon with a 55/2.8, focused the Speed, set the 55/2.8 to 1:2, removed the Graphic's focusing panel, and looked for the aerial image. What I got was an image of the Graphic's lens' exit pupil. Moving the Nikon off axis didn't see much more, the image cut off.

 

So I took out the 12x magnifier I use for critical examination of slides and scanned the aerial image with it. This time I saw everything, but not much of it at one time.

 

I got the same results when I stopped the Graphic's lens down except that when its exit pupil was smaller I saw less through the Nikon. Again, the magnifier saw everything, a little bit at a time.

 

Aaargh! So my advice doesn't work, Helen and Uli's and Kevin's does. What am I not understanding here? I have few problems with eating crow, I've had it many times before, but I'd like to know why this time.

 

Cheers,

 

Dan

Dan, doesn't my ray diagram explain it?

 

Best, Helen

Helen, I'm not sure that it does.

 

If I understand y'r sketch correctly, if I position the SLR so that its lens axis is on a ray coming from the big camera's lens' exit pupil to the edge of the big camera's gate, I should see the edge of the aerial image. This didn't happen when I tried, I just saw the exit pupil. When I was using the magnifier, I held it with its axis normal to the big camera's film plane and saw the edge of the aerial image very clearly.

 

Its occurred to me that I may have positioned the SLR so that its lens was focused on the big camera's lens' exit pupil, not on the big camera's film plane. I'll try again tonight and will report back.

 

Thanks for your patience, best regards,

 

Dan

Helen: Thanks for posting the ray diagram. It is more or less the way I diagrammed it. However, I believe the client camera must be on axis with and normal to the focal plane of the view camera. I have puzzled with the idea of the client not being able to capture the rays absent the GG; however I believe you and Dan both overlook the telescope analogy: the objective lens forms the aerial image and projects it to its ocular where the eye perceives it at a point determined by the eye relief of the system. The view camera's lens has been raised, tilted, or otherwise moved to shorten the object distance on one side and lengthen them on the other side of the axis to correct for perspective. These rays, passing through the node become the image distance and are corespondingly lengthened or shortened in their passage to the focal plane. Again to the telescope analogy wherein the aerial image is captured by the occular lens and projected to the point of eye relief. The client lens is assumed to be analogous to the eye as the receiver of the aerial image. <p> If the Visoflex is used the normal 60mm lens will require an object distance or bellows extension of approximately 9" to cover the 4x5 VC format. The bellows salvaged from the old Graflex will be substituted for the compenium shade of the Visoflex to provide a light tight tunnel from the Viso to the View camera. <p> You and Dan are both correct in suggesting that I might be overlooking some critical factor. In any event the worst scenario will be that I will have to resort to scanning 4x5 prints the avoidance of which was the purpose of this whole proposition.

Harry, a telescope is designed so that the rays (within the narrow field of view of the telescope) from the objective travel into the ocular. There's no way that all the rays forming the virtual image in the 4x5 image plane will enter the lens of the client camera - but I'd be very interested to see your version of the ray diagram to show me what I am missing!

 

Best, Helen