Worldwide Pinhole Photography Day 2013 takes place on the last Sunday of April each year and I plan to take part for the first time on Sunday. I’ve never made a pinhole photograph before and I’ve left it a bit late to dabble in any impressive DIY pinhole construction attempts. But it suddenly dawned on me that we have a paper pinhole camera kit that has yet to be built and that I could use the pinhole on the Speed Graphic by simply taping it to a lens board.
Before committing myself I turned to the brilliant MyPinhole.com calculator to figure out the variables. But first, following Iain Kendall‘s advice, I scanned the pinhole to determine the diameter of the hole. I left the settings from a previous B&W negative scan (6400dpi) and got the following… this is a 100% crop of the scan:
Using the measuring tool in Photoshop, I measured the diameter of the hole – it was 100 pixels:
To work out the size of the hole in millimetres required some simple maths:
6400 pixels per inch = 251.968 pixels per mm
100 / 251.968 = 0.3968mm The size of the pinhole!
Now to use the MrPinhole.com calculator to figure out the other variables. The Speed Graphic takes 5×4 sheet film. In order for the pinhole to provide a sufficient image circle I had to measure the diagonal of a sheet – it turned out to be approximately 150mm.
Measuring the distance between the film plane and various positions of the front standard I found that a 90mm focal length was almost exactly in line with the front opening of the camera – nice and easy to set in the field without a ruler and it has an optimal diameter of 0.4mm. Perfect! The resulting image diameter is 173mm, enough to cover 5×4 film. The angle of view will be 79.7 degrees, which I believe is like 25mm (on a 35mm camera) so pretty wide angle. Lastly the F Stop is f/227. Everything looked good on paper – the next step was to mount the pinhole and test it out before Sunday!
Mounting the pinhole onto a lens board – I just used some electrical tape and some cardboard behind to add support and fill the gaps.
After mounting the pinhole I pointed the camera at a halogen desk lamp and looked at the ground glass – it worked!
The following day I decided to test the pinhole out on some Fomapan 100 5×4 sheet film. I walked a few metres from our front door and set up the tripod and camera pointing towards the crags in front of our house. Being such a wide angle it wasn’t the most suitable scene really, so I made sure to include a wall for some foreground interest. It would also be interesting to demonstrate the DOF recorded by a pinhole photograph. Below are some pictures showing the camera set up:
I took a reading with my Sekonic light meter – the wall and grass were showing an reflective reading of f/8, 1/60s @ ISO100. I used a fantastic iPhone app called Pinhole Assist that helps with all aspects of photographing with a pinhole. Plugging in the values from my light meter showed the EV of 12 and the exposure time for f/226 aperture is 13 seconds
Compensating for reciprocity failure of Fomapan 100 meant I had to multiply the exposure time by 8 giving 104 seconds. I rounded this down to 1 minute 40 seconds exposure time.
After developing the sheet in my
Here is the scanned result!