Building a Pinhole

I really liked the idea of making a working pinhole camera and was intrigued by the numerous custom designs; so I thought I should build a more sophisticated design than the pringle pot camera.

The pringle pot camera had some disadvantages, one of them and most important being, the size of paper I could fit on the lid. Many people used the body of the pot to load the paper and a hole across it, but I didn’t like the idea I knew how wide angled photographs they’d be. The second issue was the focal length. Because of its shape and the way I placed the paper and the hole I had a focal length of 237mm, which limited my field a lot.

I went ahead to build a new one, that would be rectangular, flexible and user friendly. As I was leaving Ellen Terry building I noticed the staff had put out many file folders and boxes that were second hand, but in a good shape. I picked three of them to have options in case my experiment didn’t go well.

The advantage with these boxes is that they are ready-made and the only things left to modify is the light-proofing capability as well as make a hole. I used mostly electrical tape, gaffer tape and some packaging carton paper and a paper cutter. The camera can hold up to 5x7in paper negative, it has an aperture of 108.33 and a working aperture of 128. The focal length is 70mm, but it can be adjusted to smaller focal lengths. The size of the hole is about 0.6mm and that can change when need to. I tested it and there were no light leaks.

   

 

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negatives and positives

photography area negatives
photography area test strips
photography area positive prints

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bike stands negatives
bike stands test strips
bike stands final positives

(more prints on Task 1 post.)

Because with this pinhole I didn’t plan and just added up features along the way, it had some small issues. So I decided to start a new one from scratch, build it after I have designed it and buy proper material instead a ton of tape. I bought some pva glue, more tape if in need, found more carton paper and started. My main concern was to make it light-proof without compromising its outer structure so as to open and close like it was made to. Unfortunately it’s not ready yet, because other things came up but I have got photographs of it to show you how it looks so far.

                  

   

Camera Obcsuras

As explained in the first post on Basic Pinhole, camera obscura works on fundamental principles of physics and it’s fairly easy to make one yourself. So right after we finished the Advanced Pinhole session with George, we had planned to convert a room into a giant pinhole. George had with him big pieces of black paper to cover the windows and tape. I took us while to cover every window of the room, but in the end we had a pitch black room.

The area behind the window, where the light will be projected had a magnetic wall material, which allowed us to hang the photo-sensitive paper. The paper was about 4 x 1.5 metres and quite heavy to hold it with magnets. That is why the project was better in this collaborative way of working instead individual work. Two people were holding the paper still; one person was operating the shutter, two people taking readings with light meters in and out of the camera obscura. Melissa Stapleton was operating the digital camera and of course everyone helped out in light proofing the room. When we were putting up the paper we used a couple safelights in order to find our way in the room.

Thanks to a useful application on my phone I was able to take readings of the environment outside the camera as well as keep them logged.

   

 

Below are some digital photographs from inside the camera obscura, taken by Melissa Stapleton.

Light-proofing the room
Long exposure digital still of the obscura image
The inverted image

After we exposed the paper we rolled it up and put in two lightproof bags and moved it straight in the darkroom. We cleaned up the room and head to the darkroom to find out how we were going to develop this massive negative. We used two big tanks we have in the darkroom. The first one filled with developer and the second one with water. Happily Jason Tilley was around at the time and he gave us hand rolling the negative in and out of the developer, the water bath, the fixer and finally washing it. We sure did a mess in the darkroom, but it worth the time and effort.

Below is the converted digital positive of the negative, by George Rippon.

The final print. Printing assistance from Joseph Kesisoglou.

 

Finally a photograph from the inside of the camera.

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Advanced Pinhole

In our next session with George we moved on to more advanced pinhole building and calculating. A conventional camera uses an on-board light meter to calculate the amount of light coming the through the lens or an external one, like the Seconic L-308S.

The calculations of an exposure metering device like the one above are depended on several factors which are defined by the user. The three key inputs are the ISO (sensitivity scale of the film or sensor to light), the shutter speed and of course the aperture. The specific light meter is not configurable in such way, but gives some of the information automatically. Before getting any reading, the first thing you have to set up on the light meter is the ISO number. It needs to match to the film’s ISO or the sensor’s. The next step is to point it at either the direction of your subject to get the amount of light falling on it, or approach your subject and take a metering from as close to it and facing the light meter’s sensor towards your camera lens to get the amount of light falling on the camera.

The aperture is a mechanical device located inside the lens, which can adjust in size and therefore make the diameter of the lens smaller or bigger. So that means less or more light through the lens. Below you will find an elaborative video for all the technical background of the aperture.

The pinhole cameras have a fixed aperture and in order to find its value you need the focal length and the diameter of the aperture. There is a formula that gives you the aperture 
where ø the diameter and focal length is the distance from the hole to the film or paper. We calculated these values and converted them in millimetres. In this way I had my values ready to input them in the light meter and get the amount of time I needed to expose the paper. With some contribution from other photography students Pete Lord, Alex Edwards and George I found out that the paper I was using had an ISO of about 3 – 8. ISO 3 for indoors because of the day-lights we have in the building and about 6 – 8 outdoors where you can get the full spectrum of the visible light.

Other very useful tips on building such cameras are to paint black the entire box from the inside in order to keep light reflecting from the inner walls to the photo-sensitive material. We also talked about DIY film pinhole and converting a digital SLR camera into pinhole. The digital pinhole gives you more possibilities, one of them being video!

Thanks to George and his extensive knowledge on pinhole cameras we got some pretty good sources of information on pinhole photography.

Sources and information: