Tag Archives: Pinhole

Reciprocity failure

Recently I have been doing a lot of pinhole photography, and due to that I have had to explain to a number of people (unfamiliar with the more technical parts of photography) what reciprocity failure is.

Reciprocity is the relationship between shutter speeds and apertures, which means that as you reduce exposure with a change in, lets say the shutter speed by one stop, then increase the exposure by one stop with the aperture, you will have exactly the same exposure. Each one-stop adjustment of the shutter speed, is equivalent to a one-stop adjustment of the aperture. This holds true throughout the normal use of the camera in most lighting situations.

This linked relationship begins to slip away with exposures longer than one second, and the longer the indicated exposure, the more of a difference there is between the indicated exposure and what is actually needed. Many years ago I included in my book on night photography, a chart for working out the amount of exposure correction you might need in situations where exposures were between 1 second and 17 minutes. I have been referring to this chart for my extended pinhole exposures, and I include a link to a word document here which shows the full chart:

https://dl.dropboxusercontent.com/u/88621650/Reciprocity%20chart.doc

Walker Titan Pinhole 5×4

Using the Walker Titan pinhole 5×4.

I have been using the Walker pinhole camera for a few months now, though not exclusively because I’ve been busy with a lot of paper negative stuff. Having shot with it in a few different locations, I have really grown to love it.

When I’ve shot pinhole stuff before, I’ve always enjoyed making the cameras, -and for me this has been an important part of the satisfaction at the end result. I thought at first that using an ‘off the shelf’ camera would be less likely to satisfy and wouldn’t have the quirks of a home made one. I have been surprised to find that this simple plastic box is actually one of my favourite pinhole cameras of all time, -and I’ve been making them since 1978!

Angle of view. I prefer wide and super wide pinhole cameras over ones that mimic a standard lens, mainly because I enjoy the distortions that occur when objects are placed close to the camera. The Walker has an equivalent angle of view to a 70mm lens on a 5×4 camera and considering that 90mm is a pretty wide lens on this format, it would seem that this was in the realm of super wide. It is roughly equivalent to an 18mm lens on a 35mm camera, so that gives you some idea. Previous to using this, I had been using a home made 10×8 pinhole camera which had an angle of view equivalent to an 11mm lens on 35mm. This really did distort and had quite dark vignetting in the corners. Mike seems to have got the angle of view exactly right with this camera, as there is sufficient distortion (yes, I know it’s rectilinear, -no pedantry please), but virtually no vignetting.

Using it is simplicity itself. A standard 5×4 dark slide fits in with a pleasing click and you are ready to expose by removing the tethered plastic cap. With home made pinholes, especially if made from tins or cardboard boxes, there is always the problem of positioning and stability. Unless you go to the trouble of gluing a threaded nut to the base of your tin (no point doing it with cardboard), you are limited to shooting from the ground or any place you can rest it, -this severely limits your compositional options. With a properly made camera you are provided with a tripod bush -two in fact on the Walker Titan, so shooting from a tripod becomes the normal method and opens up all sorts of image making possibilities.

All of the shots I have shown here, were done on Ilford Ortho film. It is great for this kind of thing because long exposures give nicer results (Ortho is 25 ISO -or less, if you want more tonality out of it). I like long exposures for pinhole, because things happen during the exposure which you hadn’t planned for, and provide unexpected and interesting results.

All exposures were all 90 seconds, and during that time people have stood in the scene for a while and then wandered off, leaving a ghost (beach scene) and the boats sitting in the corner of the harbour were bobbing about violently, as the sea was quite rough and have become very indistinct on the pinhole shot.

Screen Shot 2015-01-17 at 18.50.17

Screen Shot 2015-01-17 at 18.50.35

Screen Shot 2015-01-17 at 18.50.54

Screen Shot 2015-01-17 at 18.51.09