Within the darkness of the obscura, light reached in to every corner.
The twentieth celebration of Worldwide Pinhole Photography Day fell on 26th April 2020. Pinholers and would-be pinholers around the world are invited to participate in pinhole photography on the last Sunday of April each year and to upload a single image made on the day to the WPPD website for display in that year’s gallery Exhibition.
I have participated in WPPD for several years and this year was to be no exception. For some weeks I have been thinking of subject matter and what ‘equipment’ I might use or make with which to capture an image. My planning actually began six months prior to the day with the placement of four coffee-can solargraph pinhole cameras. The intention was to have at least two of these exposing for the full six months ending on 26th April. One was removed from it’s post, never to be seen again, a second was opened after three months to check that all was in order, leaving two to run the full course.
Of course, six months ago coronavirus was not known. There was no pandemic and no lockdown restriction on movement. The two remaining pincams were placed on each of my two daughters’ homes. With a few weeks to go I realised that I might need to rely on my daughters closing the shutters on my behalf and to store the pincams until they could be retrieved and the images within scanned. I needed a Plan B.
Initially Plan B was to prepare pincams to use while out for my permitted exercise and my previous blog post shows some images made on a trial run. However as WPPD drew nearer I wanted more to make an image that somehow reflected on the strange times of the pandemic lockdown. I decided to make a room into an obscura into which a view of the outside world would be projected and in which I could sit in solitude and in silence, watching around me an inverted mirror image of a world from which I was isolated.
The obscura idea developed. I could attempt to make a long exposure photograph of the image within or I could attempt to set up photographic paper on which to record the image. In the UK social distancing measures required that individuals remain a minimum of two metres apart. I decided to set up my paper two metres from the pinhole. A 2mm hole drilled in aluminium reclaimed from a beer can was placed in the blackout material covering the window. I looked out an old projection screen that would assist in framing my image and to act as a support for an array of 10″x8″ sheets of Ilford MGRC paper – the largest I had to hand. The paper array would have to be assembled by safelight once the room/obscura was closed and packed away in a like manner after exposure and before I could emerge from the room. I would be alone for some time.
The image was made not long after sunrise. I had to guess at an exposure and allowed 40 minutes. Allowing for setting up, taking down and just sitting in the quiet of the obscura soaking up the experience, I was in the world of the outside within for about 90 minutes. I watched and listened to birds flying upside down in front of me, the occasional vehicle or pedestrian passing the wrong way, the trees sweeping the sky in the easterly breeze that seemed to be coming from the west. I thought of those whose lives at this time are topsy-turvy, confused and worse, confined to a narrow, unchanging view of a world from which they have been isolated.
But the feeling was not a negative one. In my head I had imagined sitting alone in the dark but in fact I found myself surrounded by light. From a hole just two millimetres in diameter, light and with it the life of the outside world seemed to permeate every nook and cranny of the room. There was light and the light was good.
With just one week until Worldwide Pinhole Photography Day 2020, I’ve been dusting down old and creating new pincams.
WPPD2020 is almost upon us! This is its twentieth year and will be celebrated across the globe in a variety of coronavirus lockdown conditions.
Six months ago I set up solargraph pinhole cameras at four locations. One was vandalised about five weeks in and I took down another after three months to check that an image was being recorded as I would expect. The remaining two should each have a 6-month record of the sun’s path as seen from each of my daughters’ homes. Lockdown means I may not be able to retrieve the cameras and will have to rely on my daughters closing the shutters for me.
With thoughts of possibly not having one of my planned images to upload to the WPPD2020 website gallery, I’ve been thinking of alternative pincams to use on the day and testing out a few ideas.
Just before Christmas 2017 I received the gift of a vintage VistaScreen 3-D viewer and over that holiday period I made a stereo pinhole camera. Here it is with some of the prints I’ve made from the Ilford MGRC paper negs I exposed over the past couple of days: (To see the 3-D effect, stare at each dual image in turn and slowly cross your eyes to create a virtual third image in the middle)
Another possibility might be to take my Food-Caddy Bincam pincam for a spin. Here it is with an image made on Harman Direct Positive Paper while cycling with the camera mounted on the rear rack of my bike:
Or I could go back to one of the first pincams I ever made. This foamcore box-within-a-box pincam was made for WPPD2014 and is one of my favourites. I gave it a go last week with some Harman Direct Positive Paper:
Lockdown hasn’t been easy. With regular liquid refreshment running low and visits to the shops even for essentials, limited, I’ve been resorting to retirement gifts stored away for a rainy day. The Balvenie Doublewood 12 Year Old Malt was much enjoyed in relieving it’s packaging for alternative use as an anamorphic cylindrical pincam. This image was also on Harman Direct Positive Paper:
I am quite fortunate in living within very easy reach from home of woodland and open space which can be enjoyed in relative solitude. Lockdown restrictions here allow for leaving home each day for one form of exercise, maintaining social distancing. Whether going for a walk or a cycle ride it is quite possible to pack one or two pinhole cameras for when I pause for a rest!
What? … A camera made from a red pepper? … OK, why not?
A red pepper. Not a green one or a yellow one, a red one and the redder the better. Why? Because the colour of the skin will act as a filter and if the pepper can be loaded with media that can be handled in a darkroom with a red safelight, such as photo paper, the pepper should provide safelight darkroom conditions.
I had to give it a go! This is how I made my first red pepper pincam:
With the pincam made, all I needed was enough light to try it out. The projection distance is about 60mm and the pinhole diameter about 0.4mm so my effective aperture is f/150 or thereabouts. The weather has been wet, windy and dull. Very, very dull. I waited a day but the weather remained very, very dull so on my workbench I set up a pile of empty photo paper boxes and the second red pepper as a still life, lit it with a powerful LED worklight and made an exposure.
Five minutes later I had a paper negative in the developer …
and here it is scanned, inverted, flipped with some levels tweaking:
I’d been concerned firstly that moisture from the pepper would contaminate the image but although there was some slight staining, the paper came out remarkably clean.
Secondly, there was a risk that the electrical tape would not seal sufficiently and allow light leaks but it adhered well. After 24 hours it held together and there is little evidence of light leaks.
Thirdly, would the red skin of the pepper do the business as a safelight? It did! There are interesting markings on the negative that coincide with natural markings on the surface of the pepper that I think are quite cool but the pepper did the job!
I kept a second pepper until the results from this one were known. I’ll be waiting for beter weather and a more exciting choice of subject matter to set it up.
A recent spell of miserably dull weather where every colour was less exciting than a palette of nothing other than 18% grey had me rooting around the garage to find something to keep me out of mischief.
I found an offcut from a wooden plank, carefully put aside for one of those ‘just-in-case’ moments. It was 100mm wide and 28mm thick. Now for those whose brains are so wired, 100mm is also the width of 4″x5″ sheet film and 28mm is a fine pinhole projection distance. My brain must be so wired – I immediately saw a pinhole project to occupy my time!
Initially , my plan was to cut the plank into 125mm lengths and drill through it as large a hole as I could find a hole saw to do the job. I had some spare foam core from which to make a tray into which I could place a sheet of film or paper. The block of wood would be secured over it to form the camera body. The drilled out hole would have a pinhole secured in place and use a piece of electrical tape for a simple shutter.
As can be seen from the photograph above, I had sufficient wood and foamcore to make four cameras, each with its own film tray. However as I was cutting the wood my idea developed: I would prepare a template to stick onto some mat board and drill through to create pinhole-related words with pinhole dots. A second copy of the template would position the large hole and be pinned or nailed to the front of the wooden block to support the pinhole and shutter.
I would then make two exposures: First, the word-drilled template held against the film or paper would be exposed under the light of my enlarger. Then the template would be replaced with the wooden camera block and a regular pinhole exposure made, although I would have to wait for an improvement in the weather for that second stage!
I’ve had the enlarger attachment for my Intrepid camera for a few months but haven’t used it, finding setting it up on my tripod just too much hassle. I’ve been looking for a decent copy stand to use and struck lucky a couple of weeks ago, finding a Kaiser stand on Amazon described as having cosmetic damage and being offered for substantially less than half the going rate for a new one. I took a chance and was rewarded with a packaging-damaged, as-new copy stand. I took me quite a while to find the cosmetic damage: a slight ‘bruise’ on the corner of the base-board. It was a good buy and now I am able to use my Intrepid Enlarger for the first time to make the first exposures for my new pinhole cameras.
Bad weather never lasts and this weekend I got out in crisp, bright conditions to try out my new pinhole cameras. I’m running out of both film and printing paper and an order placed earlier in the week has been delayed. I found at the bottom of a box, a couple of sheets of MGIV RC satin paper that I cut to size for paper negatives and in another box was half a dozen sheets of Kentmere Select VC lustre that I could use for printing. I had to make do with just a couple of sheets cut up for test strips and had only one shot at making a final print from each negative! With that in mind, I’m pretty pleased with the results below and the knowledge that refinement can be made in future.
I set out to discover, through a pinhole, images of the landscape left behind as I travel through it on my bicycle.
For some years I’ve been intrigued by the idea of moving a pinhole camera through the landscape to discover what images might be revealed. One of the first such images I made was in 2014 with my then new Harman TiTAN 4×5 pinhole camera. Taken through the front window of the top deck of a bus as it followed a cyclist along a busy Edinburgh street, the cyclist was rendered relatively recognisable in a streaked world of mystical shapes. It was an image that time and again has me taking a pinhole camera out for an adventure in time travel through the landscape.
Two years ago I blogged such an adventure with the pincam mounted behind the windscreen of my car (http://pinhole-time-travel). At other times I’ve carried a pincam as I walked or ran but the one thing that I could never quite work out was how to mount a pincam on my bicycle such that I could operate it while on the move.
The answer came to me a couple of months ago and gave me a new perspective for the image – I could mount a 35mm camera fitted with a bodycap pinhole to a board fixed to the pannier rack and operate it on the ‘B’ setting by a long cable release threaded through the frame and attached to the crossbar!
That the camera would face backwards to where I had been rather than forward to where I was going seemed appropriate to the idea of photographing what has been. The moment we think of as ‘now’ immediately becoming the past as it passes into memory (I sometimes wonder whether ‘now’ ever exists at all) and the long exposure of the pinhole image blurring the memory as so often happens in the mind.
My first attempt was with an old Zenit camera. It’s shutter has been dodgy for ages, slow and often sticking, but the ‘B’ setting worked – or at least it did! The vibration on the bike was too much for it. Although several successful frames were made, it was curtains for the shutter. My attempts at repair were to no avail but I had been prepared to make the sacrifice. With lessons learned I changed the Zenit for an Olympus OM1, this time with some cushioning and I’m pleased to say that the OM1 is going strong after a couple more outings.
The images may not be to everyone’s taste but they work for me! Getting the exposure ‘correct’ has been and continues to be a challenge. Scanning the Kentmere 400 negatives produced files that I found unworkable but I picked a few frames to print on Ilford MGIV FB glossy paper (all I have at the moment). Without further comment, these are what follow:
The paper had been loaded in my darkroom under the glow of my red safelight. It is an AP ‘Dark Red’ light, basically a mains powered 15W lamp with an appropriately coloured plastic cover. I have previously found that DPP can be fogged by over exposure to the safelight but have never attempted to quantify the ‘problem’.
Furthermore, the plastic of which the food-waste caddy is constructed is well weathered and I wanted to assess if and by how much the opacity of the plastic had been affected by the weathering.
I started with a 10″x8″ sheet of DPP from the same pack as had been used for the original image. In total darkness I cut it into approximate 5″x4″ sheets, two to be used for testing, one as a control and one as a spare.
My first test was to expose one sheet in the darkroom as a test sheet at five-minute intervals. The safelight was positioned 2 metres away, just above the level of the test strip gadget. When developed, I was surprised at how sensitive to the red light DPP was:
It may not show too clearly here but just five minutes was enough to visibly fog the paper!
In complete darkness I placed a second sheet inside the Bin-cam pincam and put the camera outside in bright autumnal daylight for three hours. The lid and shutter remained closed for the duration of the test. This sheet was developed and compared against the above test strip and the third sheet which was developed completely unexposed.
Again, it may not show clearly here, but there is visible fogging of the ‘exposed’ sheet compared to the unexposed control sheet, comparable with the 5-minute test strip.
The paper of the original Bin-cam image was exposed to the safelight for two to three minutes while being loaded and the exposure was made in bright sunlight. From my tests, the paper would have been fogged to some extent both by the safelight and the less than perfect opacity of the camera.
With the knowledge I now have, I can take steps to minimise fogging in future, primarily in loading the paper but perhaps also making some alteration to the camera with paint or lining paper.
… Or I can live with it and find pleasure in serendipitous imperfection!
How I recycled a redundant food-waste caddy as a pinhole camera.
My local council recently made some changes to our waste recycling collections. Food waste would no longer be collected separately but would instead be put in the garden waste bin. However, residents were told that the redundant food-waste caddy would not need to be returned.
I couldn’t not recycle it and let it go to waste!
The food caddy is a simple moulded plastic design with fixings for the handle and the hinge for the lid being part of the moulding. So apart from the lid opening, there are no holes in the container. Furthermore the lid, which is locked in place by the rotation of the handle, closes over a raised lip on the container’s top edge. The construction is perfect for adaptation as a pinhole camera and the internal size just about right to take a 10″x8″ sheet of photo paper.
I reckoned it only needed a hole to be drilled over which a pinhole could be fitted, something to ensure the top lip would function as a light seal, and a shutter mechanism fitted.
With a piece of paper taped in place I worked out the best position to drill a 25mm diameter hole in the front of the bin. Once drilled, I measured the projection distance and used Pinhole Assist to calculate the ideal pinhole diameter.
The optimal pinhole diameter of 0.72mm is a bit wider than my pin cams usually require (0.3 to 0.5mm) and needed a wider pin than I am accustomed to using. However I found a larger pin and punched first-time a clean hole which measured 0.79mm, checked by high resolution scan, in aluminium cut from a beer can. The pinhole was fixed in place inside the bin with glue and electrical tape, later reinforced with duct tape.
I stuck strips of sticky-backed black foam to the inside of the lid where it would close on the moulded lip of the container. Initially, I had intended to use black electrical tape as a shutter but the tape wasn’t adhering well to the plastic surface of the bin. I decided to craft something more elegant from offcuts of plywood and sticky-backed black felt. A handle moulded as part of the front edge of the container provided a pivot point that I could drill through without going through the container wall.
All that was left to do was to test it. My favourite location for testing new cameras is Queensferry and the Forth Bridge. I took advantage of a convenient brief sunny interlude and with the help of Pinhole Assist, gave a sheet of Harman Direct Positive Paper a 7min 36secs exposure.
Here’s a straight scan of the result. There’s some fogging but the image is well exposed and pleasingly sharp (I never expect or look for sharpness in a pinhole image!). I’ve had issues with fogging DPP in the past and need to work out whether this was due to over exposure to red safelight when loading, to less than perfect opacity of the (well weathered) plastic from which the bin is made, or a combination of the two. There’s nothing in the image to suggest light leaks which I would expect to see as specific areas or streaks of over exposure.
With the benefit of scanning and thus having a digital file to play with, this is what a little tweaking of the histogram produced.
Pinhole images through a vortoscope: Is it a first?
Worldwide Pinhole Photography Day (WPPD) is celebrated annually on the last Sunday of April. For several years I’ve joined my friends in the Edinburgh Lo-Fi Photography Group for a pinhole photowalk and trying each year to do ‘something different’ with a light-tight space, some form of light-sensitive media and a very, very, small hole.
While the ultimate goal in celebrating the Day is to produce a single image that will be uploaded to the WPPD website, it is also a fun, social occasion with friends, a sharing of ideas, coffee, an interesting location, cake, pincam comparisons and inevitably food and drink in a pub or restaurant afterwards. To make the day interesting photographically I usually prepare several pincams and this year I carried three. My intention was to make one pre-planned image for WPPD19 and to simply have fun with the others to see how they turned out.
First was the ‘Not Just Any Belgian Collection Biscuit Tin’ pincam, then came the ‘All Butter Scottish Shortbread Collection Penta-pinhole’ pincam and finally, the ‘Olympus OM1n Vortoscopic Bodycap Pinhole’ pincam. Each will be explained below in some detail. (This will be a long blog post)!
The Not Just Any Belgian Collection Biscuit Tin pincam
I last used this 90mm deep biscuit tin which holds a sheet of 10″x8″ paper, a few months ago while experimenting with SE1 emulsion on tracing paper. The success of that experiment was iffy at best but it did confirm the accuracy of the f/360 pinhole apertures (it has three to choose from) and the angles of view achievable. It seemed a safe bet to put it to use for WPPD19 loaded with a sheet of Harman Direct Positive Paper which would subsequently be developed in fresh Ilford Multigrade.
Our walk passed a large concrete arrow set in the grass. Apparently the arrow had served some purpose to the RAF during the second world war. It seemed an ideal subject for pinhole imagery. I set up the pincam on a high tripod, aiming downward and used the lower landscape pinhole so as to raise the horizon and include the shadow of the pincam in the image.
The All Butter Scottish Shortbread Collection Penta-pinhole pincam
Like the Belgian Biscuit tin, this pincam had been last used in my experiments with emulsion on tracing paper. It is much shallower at only 55mm and although very wide, the angle of view of each pinhole is insufficient to cover the 10″x8″ paper that fits inside the tin. By using multiple apertures light would be projected by the peripheral ones into the areas of the paper unexposed by the central one. This would also create the interesting idea of overlapping image planes.
The challenge would be to produce five near identical pinhole apertures. This would ensure evenly balanced exposures in the periphery while the central area would receive light from all five apertures. From experiments with three holes I reckoned I could meter the subject, divide by five and deduct that well-known pinhole unit of measure: the ‘bit’. I marked out and drilled holes in the tin lid. The f/160 pinhole apertures were created by pushing a dress-making pin part-way through squares of thin aluminium foil which were then measured for accuracy and consistency before attachement to the inside of the tin. Measurement was made by scanning each pinhole at 9600dpi, measuring onscreen at full size and comparing against the known measurement of a steel rule scanned and viewed at the same resolution and size.
The twist I wanted to put on the image made with this camera was based on the fact that the meeting point to start our walk was to be outside a theatre. Now the universal symbol for the theatrical arts is a mask and with the potential for the overlapping image produced by this pincam to ‘mask’ the subject, I thought I would take it a little further and make a mask for a member of our group to wear while posing for my WPPD19 image!
Unfortunately the person I had in mind (whose ‘big’ wild hair would have set off the mask very well) was unable to attend the meetup so I ended up wearing it myself and taking a selfie! I quite underestimated just how close the pincam to subject distance would need to be: this was taken at about 30cm – it really needed to be half that or even closer!
The Olympus OM1n Vortoscopic Bodycap Pinhole pincam
It was while browsing my local craft store for mask materials that I spotted some 5cm square mirrors. Some years ago I had been introduced to vortographs, an interesting technique that once tried quickly found its way to the dark recesses of my memory. Something clicked and I decided it would be fun to make a vortoscope through which to make pinhole images. (A good starting point to learn about vortoscopism is https://en.wikipedia.org/wiki/Alvin_Langdon_Coburn)
A vortoscope is a gadget that produces kaleidoscope-like images. It is made up of three (I guess it could be more) mirrors formed into a tube-like construction of triangular section which is placed over a lens (or in my case, over a pinhole aperture). The resulting image consists of a central direct section surrounded by peripheral reflections. The ‘diameter’ and length of the vortoscope affects the size and clarity of each of these sections and the abstraction of the image.
I made mine from a pack of 5cm square mirrors which I cut to size with a glass-cutter, a toilet roll core, copious amounts of hot-melt glue and some sticky-back foam. The bodycap has long been adapted for pinhole but to be sure I did re-make the pinhole aperture to the optimum 0.29mm for the 49mm projection distance when mounted on my old Olympus OM1n camera.
I was pretty pleased with the results. The camera was loaded with Kentmere 400 film from a bulk roll and subsequently developed in Ilfosol 3. I make no apology for showing all of the images here, warts and all, because I think they are quite cool! These have been scanned and slight adjustments made in Afinity Photo for exposure and levels. Most of the images were between half and one and a half stops underexposed which was probably down to my poor metering!
WPPD19: which image to submit?
At the time of writing, I have not yet decided which of all the pinhole images made on the day I should submit as my WPPD19 image. I’m open to suggestions.
Pinhole day this year was the first in a long time that I can remember having good, almost too good, weather for pinhole photography. It was unusual for me to come home with nothing I could call a failure!
The best thing about the day? Time spent with friends, sharing our enjoyment of simple image-making pleasures.
A final anecdote
We came across many bird watchers, apparently drawn to reports of two rare species of duck having been spotted along the coast where we were walking. Like us, each of them carried the tools of their hobby: while ours were tin cans and changing bags, theirs were tripods, spotting scopes and big digital cameras with huge long lenses surely capable of resolving the tail-feather detail of sparrows in flight at 1000 metres!
One of them was passing me when he spotted the Olympus round my neck: “Oh! What sort of lens is that? I’ve not seen one of these before.” he asked. Willing to be engaged in a spot of photographic gear talk I removed said ‘lens’ from the camera to show the pinhole end of the device. “It’s not a lens, it’s a vortoscopic bodycap pinhole.” I replied.
Oh dear! The clues were written all over his face. This conversation was going nowhere. It was quite clearly considered that I was some wacko with a screw loose! I need to invest time in the study of ornithology.
In my previous blog post I wrote about the difficulties of obtaining consistency across a construction of eight pinhole cameras in order to accomplish a single composite image. Following through on what I’d learned, I made adjustments to cameras and method and went out to give it another go.
The results this time were better than before. However, to make all eight exposures involved spending two hours or so hovering around my pincam construction in the woods on a fairly cold, breezy afternoon in fading, changing light with the sun dropping in an increasingly cloudy sky. In such conditions it’s not difficult to believe that surely the shutter’s been open long enough!
I failed to make sufficient allowance for the changing light during what were already long exposures in the two central images. Then the image showing the solarised path of the sun was too bright to match with the exposure required for the final image on the left.
I’m tempted to re-think my use of Harman Direct Positive paper with its low sensitivity and very high contrast but it is those very qualities that I love about it and I know they can be harnessed. I really just need better self-discipline. But perhaps too, I just need to take a break from it for a while.
With taking a break in mind I looked out my Harman TiTAN camera, loaded a couple of holders with Ilford FP4+ and went for another walk in the same woods. It’s a safe setup but I needed to make images that pleased me. Though made with a commercially produced pinhole camera and an easy-going emulsion, these retain the softness, vignetting and framing serendipity that to me make pinhole images special:
The trials and tribulations of using multiple DIY pinhole cameras to produce consistent exposures across a single project.
My ‘best’ pinhole images, in terms of how I perceive the way others appreciate them, have usually been made with my commercially produced Harman TiTAN Pinhole Camera. For myself, however, the images I find most satisfying to create are those made with DIY pincams created from boxes, cans and bits of card or foamcore with a true pin hole punched in foil or sometimes directly into the material of the camera.
Amongst the seemingly endless proliferation of commercially made pincams all with accurate, etched or laser-cut pinhole apertures the aesthetic of what I think of as true pinhole images is becoming lost in the quest for detailed resolution and sharpness. What I seek from a pinhole camera is a serendipitous softness in which light and time create something unseen by the naked eye.
However when multiple cameras are being used to create several discrete images which will ultimately be presented as one, the serendipitous nature of the DIY pincam has to be somewhat controlled in order to achieve a degree of consistency.
For the past few months I’ve been working on the idea of using eight coffee cans to create what I imagine to be a circular, overlapping 360º presentation of the images made in each pincam. The assembled 8xIllyCoffeePincam is shown above.
Each can is fixed to a circle of plywood which has a tripod quick-release plate bolted through its centre. The interior of each can has been sprayed with flat black paint and the lids have been lined with a strip of black felt. The cans are made of steel and two holes have been punched directly through the side of each with a regular dress-making pin. Exposure time is controlled by a strip of black electrical tape. One aperture is positioned centrally on the vertical and the second is one third up from the bottom. This second aperture enables a raising of the horizon line (or lowering if the camera is positioned upside-down!) recorded on the image, i.e. the same effect as lowering or raising the front standard on a large format view camera. Because the media (paper or film) in the can is curved, using the lower aperture will also cause the horizon in the image to bow depending on the width and curvature of the media.
My idea is to select a position to locate and level the camera and then to evaluate and record individual images, one at a time, with each of the eight pincams. I’ve experimented with the camera before, each time resulting in a few tweaks and a refining of my technique as a result. Now I need to know if these refinements are enough for success.
For this outing I had the camera positioned fairly centrally in Aberdour Harbour at low tide on a bright afternoon. Each pincam was loaded with a 5×4 sheet of Harman Direct Positive paper mounted vertically and the lower aperture was used to raise the horizon and include more foreground than sky. I used the Pinhole Assist iPhone app to determine each exposure, assuming that the aperture in each can was around f/150 and by holding my iPhone directly above and perpendicular to the central view of each pincam.
Here are the eight images that I recorded. Although each exposure was measured in a consistent manner, it is plainly obvious that my assessment of the size of each aperture was far from consistent. Only one or two (E and SE) were anywhere near accurate and even so they are underexposed by at least a stop.
To resolve the problem, I need to do two things:
Reassess and adjust each aperture to get all of them as near as possible the same.
Review how I measure each exposure.
Starting with the pincam used for the ‘E’ image, I took a standard dressmaking pin and marked it with some tape at the furthest point it penetrated the pin hole. I then went round each pincam to make comparison and was actually quite surprised at the range and amount of adjustment needed on each pin hole! The aperture on the pincam used for image ‘N’ was by far the smallest, confirming the almost non-existant image produced.
Having made the necessary adjustments I then had to establish the actual diameter I now have in each can. For this I took a piece of aluminium drinks can and with the same pin punched a hole up to the marker. I scanned this alongside a metal rule at 9600dpi and made relative measurements of the full size image on screen. On screen, the pin hole measured 25mm in diameter and a 5mm section of the rule measured 217mm. Simple arithmetic then determined my actual pinhole diameter to be 0.576mm. Measurement of the paper in the can showed the projection distance to the centre as 80mm. This produces an effective aperture of f/138 centrally.
For future outings with the 8xIllyCoffeePincam I will assess exposure using a spot meter to measure the deepest shadow in which I want to record detail and reduce the exposure given for that by two stops thus placing the shadows on zone III with mid greys falling on zone V. (NB: This is a very much simplified implementation of the Zone System and should not be followed without greater understanding of the system’s complexity). For convenience I will base the exposure on f/128 with a bit added for the sake of serendipity!
Now, confident that this time I’ve got it right, all I need is another fine day to go try it all out, again.