The Front Standard

I am kind of going by intuition here, so if anyone sees me going completely off track, let me know.

I finished taping up the joints on the front standard and devised a pocket for the pinholes to slide into (also with gaffer's tape). I generally use gaffer's tape to "mount" the pinholes which I got from Earl over at f295.org. The holes come as 3mm disks with the hole in the center, so I tape around them. You can see better below than I can explain here.

So I started with the standard with a big-ish hole so that the edges of the foam core don't interfere with the light transmission to the outer edges of the image. I folded a piece of gaffer's tape in half and punched a hole in it using a regular paper hole punch. That got taped over the hole in the front of the standard. This pic is blurry, but I think you can make out what is going on there.

I made a flap where the pinholes slide into the pocket so that I don't get light leaks behind the pinhole.

The pinhole is mounted in a 'standard' (for me) square of gaffer's tape, so that all of my pinholes look the same except that the diameter is written on the tape. So these now slide behind the smaller hole piece.

So this is what it looks like with the pinhole inserted. The flap sticks out a bit, so it might even make a small rudimentary lens hood for mid-day shots!

Going For It

Ok, enough thought and practice. I am going to make the 8x10 pinhole that I want, not the one I think I can build in a weekend. This is going to have interchangeable pinholes and adjustable focal lengths. It will use a bag bellows with incorporated 'sleeves' for changing film (like a changing bag).

Here is step one. The front standard.
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It is 4"x4"x2" (10x10x5cm). Stay tuned for step 2!

Flawed Mod

If you were fortunate enough to read my scintillating previous post about the pinhole camera, you probably finished it scratching your head, thinking... "Why would he shorten the focal length to get more coverage on his film?" The truth is that I was doing the same thing. It didn't make sense intuitively. If the pinhole is closer to the film, that should just make the image smaller. How would that effect the area of coverage? The answer is this... it actually doesn't make the image smaller, but it does change the magnification. It is the same effect of changing from a 50mm lens on your 35mm SLR to a 28mm lens. Things get smaller but the image stays the same size (36x24mm). This is done through the magic of optics. The glass lens elements manipulate the light path so that you can change focal length and aperture and not change the size of the projected image circle. I don't have any glass lens elements on this camera though. So changing from 115mm focal length to 81mm focal length has the effect of reducing the magnification of the scene, and if the image circle of the pinhole is big enough to cover the size of film you are using, all is copacetic. However, in my case I also changed the size of the pinhole from 0.5mm to 0.4mm, a gigantic 20% decrease! Guess what. When you reduce the size of the pinhole, you reduce the size of your image circle! So now I have an 8x10 pinhole that has an image circle big enough to cover a 4x5 piece of film. Seriously, I kept thinking to myself, "you shouldn't cut that camera down... just make another back for it." and now that is what I will be doing. I will need to calculate the right distance to cover my curved 8x10 (~126°).

For your viewing pleasure, here is a crappy still life I took after cutting down the camera. Back to the drawing board.

New 8x10 Design

So, the last foamcore pinhole camera was a lesson in light leaks. I tried a number of things, but the fact is that hand-cut foamcore is never going to form a light-tight butt joint. So the way I designed the two parts of the box did not have enough overlap all the way around to keep the light out. The other thing I learned was that I did not really need anything to keep the film in a curved plane. The dimensions of the box were such that the film naturally lay in a curved shape.

So I decided to make another 8x10 pinhole camera with these things in mind. This first picture is just for the youngsters out there (like my oldest son) who think, "I'm never going to use geometry in real life! Why do I have to take it in school!??". I probably thought that same thing in high school, but here I am in my mid 40's with a hobby that demands the use of math on an almost daily basis. I couldn't have predicted that I would ever want to build a curved plane camera, but had I not been diligent in my math classes, I couldn't; 1.) build this camera, or 2.) help said son with his math assignments. Stick with the math people. It is an investment that will pay dividends later.
Here is my Moleskine with design calculations.

The construction is simple, so I won't spend a lot of time explaining cutting, gluing and taping foamcore other than to say that you should use a 'fresh' x-acto blade when you start. The foamcore will shred if the blade is not razor sharp, making joinery difficult.

Here is the inside of the 'back' of the camera. Note the "lugs" and the flap of gaffer's tape.

The film sits under the lugs, keeping it in place and centered and curved to the right arc.

The flap of tape allows me to pull the edge of the film away from the side of the camera. Otherwise, it is difficult to get the film out of the camera without scratching the emulsion.

The front of the camera is simpler. Just a box 2" deep that fits over the opening of the camera back. It fits snugly, so no need for more light sealing. The shutter is again a simple 'drain plug' type since exposures are consistently in the >10s range. The focal length (I know it isn't the right term, but everyone knows what I mean) is 115mm, the pinhole is 0.5mm, the effective aperture is f/230 and the field of view is about 109°.

Here is the first shot with this camera. The field of view doesn't quite cover the film, so I cropped it square. This can be remedied by shortening the focal length to about 82mm which should be pretty easy to do. I probably would also need to change to a .4mm pinhole in that case. This picture was made by wedging the camera into a tree. This pointed the pinhole to the sky which is a problem for this x-ray film (blown highlights) it also caught the sun, which I couldn't really tell since the camera was above my head. That accounts for the characteristic pinhole flare. BUT! there are no light leaks that I can see and so I think that this camera with a little modification will be a nice addition to the toolbox. I may even take it to the wedding I am shooting next month. Leave your questions or comments here or on the forum that brought you here. I am glad to answer.

New 8x10 Pinhole

So I decided to make another pinhole camera. For this one I had contact printing in mind. That meant BIGGER NEGATIVES! So I have a box of 8x10 sheets of Kodak CSG x-ray film in the freezer that I have been cutting down to 4x5 for the Speed Graphic. Why not burn through some of that cheap stuff and have some fun along the way? I also happened to have some left over black foam core from my previous 6x12cm pinhole camera. So I went to the drawing board (literally) and sketched out some ideas. I like the curved film plane, but this time I thought I would keep a constant distance to the pinhole instead of the constant f-stop of the 6x12cm. I went and downloaded Pinhole Designer to do the calculations for me. That is a really great program and I highly recommend it to anyone interested in making a pinhole camera. I found the optimal pinhole size and it also gave me the right angle of view so that I could make the curved plane the right radius. I came up with a 115mm film distance with a 0.5mm pinhole. That makes an f/230 camera with a field of view around 109°. Here are some crappy phone digipics of the camera as it is today.
This is the back where the film sits. There are four stand-offs in the corners to make it curve upward on the ends. You can see too that I put some camera flocking material in the back since x-ray film doesn't have an anti-halation layer and the foam core is not perfectly flat black.



Here is the same piece with a sheet of film in it.



Here is the front of the camera. There are two stand-offs that hold the center of the film's long edges down against the back of the camera, keeping the curve 'curvy'. The other pieces on the short ends are light traps that just slide down inside of the back. They also create friction that keeps the whole thing together without rubber bands.



And here it is going together.



Finally, I just used a 'drain plug' style of shutter. The exposures for this f/230 camera are long enough, especially with iso 80 x-ray film, that I don't need anything mechanical or spring loaded.



Here is my first 'successful' 8x10 image from this camera. Obviously, I need to put something in that will keep the film centered and I also have some light leaks to deal with. But for a first image from a basically cardboard camera, it's not too bad.

Unsafe Light

I had had a couple of failures using Kodak CSG x-ray film in my pinhole camera. They came out WAY over-exposed. One was this photo of Jim's Beemer. I had a nagging suspicion in my head that the problem was with my safelight. I used a 3-LED headlamp. It is pretty bright, but I usually point it at the ceiling and not directly at the film. However when I was developing these, I had shone the light right down into the developing tray. So I needed to do some experiments. What if I cut, loaded and developed in complete darkness? That would give me information about the safelight variable. I was also curious about whether the film had somehow changed or maybe the pinhole had been damaged and I was over-exposing in the camera. So I took the same photo twice; once at my 'normal' calculated exposure (47 sec in this case), using iso 80 for the CSG. Then I took another photo one stop down (24 sec). This would tell me something about the accuracy of my exposure table. So here are the results.

I developed these together in the same tray of 1+100 Adonal for 4 minutes in complete darkness. Don't mind the scratches. I wasn't being particularly careful with this film, I just wanted to get an idea of the exposures. You can see that both exposures are passable. The one stop 'push' came out with a bit more contrast as you would expect, but both negatives are of normal density.
So I think I narrowed the problem down to the safelight. The LEDs must just be too bright. It could also be a wavelength thing. I am not sure what the spectrum looks like for these led lights. They might have an overlap with the sensitivity of the x-ray film even though it is classified as 'orthochromatic'. Anyway, there you have it. X-ray film will be developed in the dark from now on and I will continue to use my same old pinhole exposure chart with this film rated at iso 80 or 100.

The destruction of Jim's Beemer

Ok, the BMW wasn't destroyed, but the image nearly was. i was cutting down some 8x10 sheets of Kodak CSG x-ray film for the Speed Graphic and I noticed that I had some sort of oddly sized pieces of film in the bag with the 8x10's. So I decided to go grab my homemade pinhole camera and cut one of these down to fit in it. It only takes one 'sheet' at a time, so I don't load it very often, but this was just sort of asking to happen. So I load it up and set it in my 'take to work' pile with my sunglasses and keys.

About mid-day the following day, I was looking out my window and discovered that Jim's beemer was in the parking lot, which was unusual since he normally works in a different building. It was parked in front of a sort of dirt embankment that I decided would provide an adequate place to set the camera since the exposures are generally too long to hand-hold. I went out and made a little shelf in the dirt upon which to set the camera. Then I took an f/16 meter reading with my Sekonic L-508 at iso 80 and consulted my exposure table to find the f/217 exposure time. Three seconds! That sounds long, but my shutter is a piece of gaffer's tape stuck over the pinhole (did I mention this camera was homemade?) and I wasn't sure I could take it off and put it back on in 3 sec without shaking the camera a lot and making a blurry pic. So I took another reading holding the light meter vertically and sort of in the shade of the car. Another consult of the exposure table and I got 12sec! Perfect! That is enough time so that the jiggling of the camera won't cause significant blur.

I went home that evening and decided to do the development in Adox Adonal at a dilution of 1+100. I mixed the chemicals and got everything together in the bathroom. I had read that you can monitor development of this film under a safe light and since I wasn't exactly sure of the development time, I decided to keep my red LED headlight turned on. That was the first bad decision. I turned out the room lights and took the film out of the camera. Placing it in the chemicals, I started the timer. I had set my 'safe light' up on a shelf pointed toward the ceiling so as not to risk fogging the film. But then for some reason I started to worry because I could not see an image appearing. I took the light down and shone it right down into the tray where the film was. There was a bit of an image starting to emerge, so I put the light back, but the damage was done. About 20sec later the film was almost completely black. I took it out of the developer and after a quick rinse under the tap, I put it into the fixer. Six minutes in the rapid fix and I figured it was done, but it was still just black. I turned on the lights and started the final wash with little or no hope of getting anything out of my labors. I held it up to the light and could see the faint but distinctive BMW grill. It was really dark, but my scanner is pretty good at pulling out contrast where there seems to be none.

So here it is. Low contrast, extreme grain, but not completely offensive or even unartistic. I think the combination of the grain and the distortion of the curved-plane pinhole image makes a sort of interesting image. The really fun thing about this camera is that I don't really have any idea at all what kind of image is going to come out of it. That may drive the 'control your process' photographers crazy, but I like to have fun with it.

Worldwide Pinhole Day

April 28th was Worldwide Pinhole day. It is a day when photographers set aside their glass and make images without the benefit of a lens. A pinhole camera is simply a dark box that can hold a piece of photo-sensitive material opposite a very small hole through which light can enter. They can be very simple like those made from oatmeal boxes or 35mm film canisters, or they can be more complicated, incorporating bellows and mechanisms for winding roll film. Even a highly sophisticated DSLR can be converted to a pinhole by removing the lens and putting a small hole in the body cap. I chose to make my own pinhole camera that would shoot medium format images (6x12 cm). I used black foam core from the craft shop, glue and black gaffer's tape. I bought a laser cut pinhole from a guy over on f295.org, but you can pretty easily make your own. The image above is my WWPD submission (see pinholeday.org). I just took a vase of sunflowers out onto my patio and set the camera on a chair. The exposure was about 90min. The highlights are totally blown and the composition is not very good. Admittedly, I didn't give it much thought. The point was just to make an image on that day. It was fun though. I took the picture using Ilford Harman Direct Positive Paper, so there is no negative, you just get the image out (after developing), sort of like a Polaroid in slow-mo. So a couple of days later, I decided to make another image with my pinhole camera.




There is an office complex nearby where I work that is called Wateridge Plaza. There are a lot of water features around the grounds, but the most noteworthy is the large waterfall in the central courtyard. I set the camera on a little precipice that hangs out over the water and exposed for 47sec. There were people walking around up above the waterfalls, but as long as they keep moving, they do not appear in the final image. I like this photo much better. The stillness of the scene contrasts well with the movement of the water. The highlights of the sunlight filtering through the buildings and the trees gives a nice feel to the image. The contrast is high, but I like the shadowy feel of the dark parts of the scene. Let me know what you think of this image. I value any critique.

You have an entire year to plan how to celebrate WWPD 2014. So go make a camera and have fun being creative. That's what photography is all about!

Another Pinhole Image

Here is another image from my home-made pinhole camera. This was taken in full sun for 47sec. I was hoping to get a better feel of flowing water down this cascade fountain, but the real "splashy" stuff is sort of in the distance in the upper part of the frame. I keep forgetting that this panoramic pinhole is like having a really wide lens on a conventional camera, so stuff sort of disappears into the distance rather quickly. I really like the aesthetic of the pinhole image and the 1:2 aspect of the frame lets the scene unfold nicely.

This was taken on Ilford Harmon Direct Positive Paper. It was then left in the box for about 5 days. I didn't really have much hope of recovering an image after that time because the instructions with the paper say to develop immediately. I mixed up a batch of Caffenol-C-L and gave it a try anyway, and what do you know, it developed just fine with no problems.

Let me know what you think.

Reality So Subtle

Jimmy Guerin is a pinhole photographer who I admire a lot. I can't link directly to his photos here, but they are well worth the time to go and see. Take a look at his blog.

http://realitysosubtle.com/

Pinhole Camera - First Shot

I decided to make a pinhole camera. Simple, right? There are hundreds of tutorials on the web explaining how to make a pinhole camera out of almost anything that is or can be made light-tight. Oatmeal boxes, beverage cans, 35mm film canisters, the list goes on. Did I make the easy first step and use one of these simple and fully functional ideas? No, of course not. I looked around at some of the pinhole calculation sites and decided that it would be 'neat' to make a camera that took a 6x12cm image, but that also had a film path that would maintain a constant aperture (f) value. A little background might be in order at this point. For a pinhole camera, the aperture (f-stop) is the ratio of the distance to the film to the opening. I came up somewhat arbitrarily with a 65mm focal distance. So from the opening straight back to the film is 65mm. The optimal pinhole size for that focal length turns out to be 0.3mm (or thereabouts). Now the problem I saw was that as you go further away from the center of the film, the angle of the light gets shallower, and the apparent size of the opening gets smaller. This causes the vignetting/light fall-off that is characteristic to many wide format pinhole images. I think that this is definitely a valid way to make photos and I completely respect an artist's choice and ability to create wonderful images this way. However, it was not the look I wanted for my images. I wanted a more constant exposure across the entire image. Constant exposure (in a simple camera like a pinhole) means constant aperture.

So, I wanted to make the film follow a path that would maintain a constant ratio of the focal length to the apparent opening. The problem is that the apparent opening is not constant. The opening is a cylinder. As an extreme example, think of looking through a tube like what is used for bathroom tissue. If you look straight down the middle, you see a circle, but as you move your head to the side, the circle starts to get 'squeezed' into a sort of football shape until it is just a tiny sliver and then finally disappears all together. So the opening is getting smaller as the angle of view changes from 90° to 180° or to 0°. I had to enlist the help of a mathematician friend to get the formula for calculating the opening. Here is what he came up with...

EA = x - y*tan(Θ)

where EA is the Effective Aperture (really it's the lateral diameter of the eliptical shape)
x = diameter of the pinhole
y = thickness of the material
Θ = the angle at which light enters the pinhole

So, I plugged this formula into handy dandy Excel and calculated EA for every angle from 0 to 90. Then I figured the zero case where the EA=x and the focal length is 65mm. That gave me a value of f/217. Now I just needed to calculate focal lengths for the rest of the angles. What I eventually came up with was something roughly elliptical with the pinhole at one end.

I will talk about the actual construction of the camera in another post, but for now suffice it to say that I didn't get the film winding mechanism right in the first version, so I ripped it out and just put in a film path that would work for paper. I bought some Ilford Harmon Direct Positive paper and cut a piece to size. The paper tech sheet said that it rates around iso 3. I took a reading with my handheld light meter and got the EV for the scene so I plugged that into the pinhole exposure calculator and got 61s.

I developed the paper in Caffenol-C-L and here is the image.




There is good detail in the shadows and the highlights aren't really too blown out, so I am pretty pleased with this image. There is still some fall-off on the right side, so I will need to investigate why that happened. The white blotch near the bottom was something on the glass of the scanner. The mottling of the sky is because of the staining of the caffenol, but I kind of like the look. I will eventually build a 'film' version of this, but for now, I think this is a good working model of what I was trying to accomplish. Let me know what you think.