Pinholes in stereo

Pinhole images – why be satisfied with one when you can get cross-eyed over a pair?

A few weeks ago while spending a dull, wet weekend clearing up my photo stuff I came across a box of odd bits of Harman Direct Positive paper left over from a workshop I ran quite some time ago. I was pretty sure the paper hadn’t been handled in entirely light-safe conditions and would be fogged but rather than waste it I loaded it into a variety of cans and boxes all of which had been converted for pinhole use. When the weather improved I could have a play and see what transpired from the paper!

Anything that can be made light-tight is potentially a pinhole camera.

One of the converted boxes had been a Father’s Day gift containing whisky flavoured truffles. Once the contents had been dealt with the true purpose of the box was realised as a two-shot pinhole camera, allowing for two separate exposures to be made before having to return to the darkroom or fumble in the dark bag for a change of paper or film. Two chambers and a frame to hold media in place was formed from foamcore, the interior was given a spray of flat black paint, two holes were cut in the lid and pinholes taped over the holes.

Components of the camera

Coincidentally, I had been reading of my friend Oonagh’s endeavours in 3D imaging with an antique Wray Stereo Graphic 35mm camera. It occurred to me that my two-pinhole Whisky Truffle Pincam could be adapted to make a stereo pinhole camera.

To make images suitable for viewing as a stereo pair, they need to be taken of the same view but from viewpoints slightly apart. That is taken care of by the two adjacent pinhole apertures. The exposure given to each needs to be as near as possible the same – that will depend on how well I can make two equal pinholes!

Ideally to view the 3D effect requires a stereoscope which optically overlaps the images so that the viewer sees a virtual third 3D image. However at the cost of a little discomfort, By squinting at the two images they can be made to overlap in the same way. This would do me for now!

test stereo shot on old, fogged paper

The original pinhole apertures were just as they had been made. In true pinhole fashion there had been no attempt to match them. My first test stereo image confirmed that my Direct Positive paper was indeed fogged but as my purpose was to compare the differences in aperture, the expected fogging was not important. More significantly, the first pair of images show that the Right pinhole (the one on the left!) was wider than that on the Left (the one on the right!). This would need to be corrected if I was to make a successful stereo image pair.

result of enlarging the pinholes in an attempt to balance them

Having made my initial assessment, I decided to balance the apertures by attempting to enlarge the Left pinhole just a smidge. Of course having made the intended adjustment I felt the smidge was perhaps a tad too much and so adjusted the Right pinhole by the said tad, more or less. The result was not pleasant with both images now overexposed, too soft and neither a match for the other.

There was only one thing for it: re-make the pinholes from scratch, aiming for a matched pair. The optimum aperture diameter for a pincam with a projection distance (i.e. focal length) of 36mm is around 0.25mm so that’s what I was aiming for although size was less important than equivalence.

high resolution scan of pinholes and millimetre rule

By laying the pinholes alongside a millimetre rule on the bed of my scanner and scanning them at its highest resolution I was able to make reasonably accurate measurements of their respective diameters and an assessment of their regularity. The Left pinhole measures 0.33mm and is quite a clean, round hole while the Right pinhole is 0.30mm, more elliptical and a bit rough on one side. With a projection distance of 36mm the relative apertures were f/110 and f/128.

final attempt – not quite there but getting close

The difference between f/110 and f/128 would have been neither here nor there in a single exposure ‘regular’ pincam but I was surprised by the effect on the final pair of stereo images of such an apparently small difference in aperture. Ideally for a stereo pair, the exposure given to each image should be precisely the same. That said I’m satisfied with the closeness achieved.

(I had attempted in the final image to add an extra layer of depth in the form of a ghostly selfie in the gap between the foreground stump and the distant tree. Unfortunately I missed my positioning but look carefully and I can be seen directly in front of the tree!)

A microscophotography project

Ten glass microscope slides, hand-coated with SE1 print emulsion and exposed in an adapted 35mm camera. This is how it all worked out.

In my last blog post I showed how I made a simple adapter that would enable me to load glass microscope slides instead of film in a 35mm camera.

After my experiments about eight months ago with self-coated glass plates for my large format and pinhole cameras I had a small amount of emulsion left over. Rather than discard it I coated some standard 75mm x 25mm microscope slides. At the time my thought was to build a small pinhole camera to expose them in but I’d also seen some larger slides being fitted in a Rollieflex medium format camera and realised there was potential to perhaps fit my slides in a 35mm camera.

The coated slides have been tucked away at the back of a drawer, securely packed in a light-tight box and wrapped in an opaque black plastic bag. However with the passing of time since the slides were coated and the likelihood that being the end of the batch the emulsion was probably not in the best condition, I knew not to raise my hopes of too much success when exposing them now.

Nonetheless, I was keen to use them and decided to do so as a series. I could only expose one slide at a time and rather than carry a cumbersome changing bag my decision was to expose just one slide per day over the period of two working weeks, changing the slide at home each evening. My daily commute to work takes me to the seaside town of North Berwick and for years my lunchtime walk around the town and beaches has been with a camera of some sort over my shoulder or in my pocket. With a digital camera I can easily clock up fifty or more shots over the course of a half-hour wander, with a film camera I am more choosy but with just one opportunity this time to make an exposure I would have to be particularly careful to pick my subject.

I focussed my attention on the views of North Berwick that I have known since childhood when we came twice-yearly for family holidays continuing a tradition going back to my grandparents’ generation. Quite by coincidence, about midway through the second week I was asked if I would agree to my photograph being taken for a recently launched ‘Humans of North Berwick’ Facebook page. My initial response was that I am not a North Berwick resident but I was assured that the page was intended to feature all who contribute to the community which I do as one of the local opticians. I had my photo taken, camera in hand, on the last day of shooting for my series.

The encounter made me think. Although I know North Berwick very well and for the past twenty years have commuted to the town for work, I have never really considered moving to the town to live! For me it has always been a place to visit. My grandparents visited here for holidays, as did my parents with my sister and me. My parents moved here in the 1970s in anticipation of retirement (instead of which my father set up the optical practice that my sister and I now run) after I was married, and I visited the town to visit them. All of the locations that I was choosing for my series were in fact locations which held special memories for me and that in some strange way mark out North Berwick in my mind as a place for me to visit rather than to live.

The developed slides drying in a blotting paper lined tray

Developing the slides was quite straightforward. SE1 Emulsion is an orthochromatic print emulsion so it can be handled in a darkroom under a red safelight and processed in much the same way as developing a print on photographic paper. It is gelatin based and so care has to be taken with temperature control of the chemicals and with handling the slides as once wet the gelatin swells and becomes quite fragile until processing is complete and the emulsion is fully dry.

The developed slides looked quite dense suggesting that I may have overexposed them a bit but I could see good detail in them.

setting up my temporary darkroom

With the stronger sense of purpose to the series that I had found I was keen to make the best of them and so decided to make prints using a 35mm enlarger. I spent a frustratingly enjoyable day setting up my small dark space and engrossing myself in the black art of producing prints with combinations of filters, time and chemistry. SE1 emulsion has very little exposure range and I found it extremely tricky obtaining good highlight detail without loss of shadow detail and vice versa. In fact for most of the prints I had to decide between one or other. However I finally emerged from the dark of my room into the dark of the late evening with a set of prints that I was more or less happy with. I laid them out to dry overnight, tidied up and went to bed.

In the morning I reviewed my work of the previous day and picked a set of ten prints to mount on card for protection and presentation.

The final set of ten mounted prints

The final mounted prints are actually quite pleasing to me. The emulsion has clearly deteriorated a little over time with signs of contamination and incomplete coating that are magnified in the enlarged prints. But those imperfections in the prints are their charm and what makes each image unique. I need to decide now what I will do with this little set of memories and there is a story to tell with each one.

Raising the slides off the scanner bed to avoid Newton Rings

Just for the record, with the print set made I also scanned the slides to computer and edited the digitised images by setting black and white points and tweaking the levels a tad. For the nerdy, I used strips of 35mm negs to lift the slides off the scanner bed to avoid Newton Rings. It worked a treat!

The edited files certainly show more detail than I’ve managed to bring out in the prints but I have to say the digital images just don’t have the ‘feel’ of the prints.

Here are the scanned images. Click to see them full size.