Getting back to silver gelatin on glass

A first attempt at making an anamorphic pinhole image inside a marmalade jar, and it won’t be the last!

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At the back of a cupboard I came across a bottle of SE1 Emulsion. It was the remains of the emulsion I had used when I last coated a batch of glass plates, way back in July 2016 and even then it had been several months since the bottle was first opened. From my notes on the box, the emulsion was diluted with 16% Photo-Flo and amounted to about 50ml. I wondered if it would still work.

With Worldwide Pinhole Day 2018 just six weeks away, I have also been trying to think of something new (at least to me) to do this year. How about preparing and coating the inside of a glass marmalade jar with a pinhole in the lid, to create an anamorphic image around the inside of the jar that could be viewed from the outside? It’s not such a crazy idea but subject matter would need to be carefully chosen and exposure might be tricky.

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emulsion and marmalade jar

I made up a small quantity of gelatin (1g in 200ml water) with chrome alum hardener (4ml of 2% solution in water) to sub the inside of the cleaned glass jar which I did by pouring in the hardened gelatin solution and flowing it over the entire area by gently rolling and rotating the jar before pouring away the excess. The jar was left aside to air dry, ready for coating with emulsion.

To protect the emulsion from light, I prepared a two-part light-seal from black card and Duck Tape. The jar would fit into one piece and a second piece with a hole in the top for access to the pinhole, would slide down over the first and the hole sealed to the lid of the jar with black PVC tape. A pinhole was punched/drilled into the centre of the lid and a piece of black PVC tape used for a shutter. From a high resolution scan of the pinhole I measured its diameter as 0.37mm.

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light seal for the marmalade jar

Now sometime over the winter I had tidied out some of my early glass plate attempts, cleaning off the images by immersing them in very hot water and bleach, scrubbing them clean and then re-subbing them ready for re-use. The 50ml of emulsion that I had would cover quite a bit more than the marmalade jar so I used the excess to coat a few glass plates too: four each of 5×4 (for my Intrepid plate holders) and of 5×3 (for my pincam constructed for WPPD2014). Coating the marmalade jar was achieved in the same fashion as I have already described for subbing it. The coated jar and plates were left in a cool, dark place for a few days to dry completely.

With everything prepared, I was now ready to test out whether my well out of date, diluted emulsion would still work. I planned to set the jar on the floor of my old garden shed, thus exposing an image of the underside of the shed roof on the base of the jar and the shed interior around the sides. By way of a check I would also expose a plate of the outside of the shed, in the WPPD2014 pincam.

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the marmalade jar pincam in position in the shed

From past experience I rated the emulsion at ISO 5. For the shed interior I metered EV(100) 8 and thus a 60 minute exposure, and for the outside of the shed EV(100) 13 which gave a 2 minute exposure.

For developer I used Ilford Multigrade diluted 1+19 at approximately 20ºC. The marmalade jar image was developed, as for subbing and pouring, by pouring developer, stop bath and fixer in turn into the jar and swilling it around to cover the surface. Fixer was poured back into the jar and left to stand until the image cleared. The plate from the WPPD2014 pincam was tray developed as normal. Both the jar and the plate were then rinsed in fresh water for a couple of hours before being left to dry.

Unfortunately the marmalade jar image was completely overexposed. The fact that the emulsion is black at least tells me it was still ‘active’ and it is just possible to make out some faint detail in the dried image.

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grossly overexposed, it’s not what I’d been hoping for!

On the other hand the plate from the WPPD2014 pincam was perfectly exposed!

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a perfectly exposed plate, 2 minutes on ISO 5 rated emulsion
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the plate image from the WPPD2014 pincam scanned and inverted

I’m glad to have decided to expose a plate as a check. It tells me the emulsion is still good and that I need to be more careful with my metering for the marmalade jar. For the marmalade jar exposure I think I was fooled by the amount of light entering via the windows and door (which was left open during the exposure), having metered for the dark recesses of the shed. Unfortunately I only prepared one jar so it will be a wee while before I can have another go … but there’s still plenty time before Pinhole Day!

Negative scanning experiments

I spent a day scanning and rescanning at different settings, the same negative to discover what works for me.

My ongoing frustration with viewing scanned images on my Light Moments blog and Flickr with my MacBook Air led me to spend a day experimenting with various methods of scanning and processing 35mm negatives.

Whether or not the method I use to scan and process my negatives has any bearing on their being viewable on any particular device is unlikely to be determined by these experiments but it might at least give me an idea of what output quality is achievable from my scanning setup.

My scanner is a flatbed Epson Perfection 4990 Photo, capable of scanning negatives up to 10″x8″ at up to a claimed optical resolution of 4800 dpi and a Dmax of 4.0. My scanning software is Epson Scan as supplied with the scanner and my editing software is Serif Labs’ Affinity Photo.

Poor weather during the week left me effectively snowed in at work for three days with little work to do. Fortunately I’d taken my camera and a couple of rolls of film with me and was able to spend some time taking pictures of the snowy scene in which I found myself. I’ve chosen a single frame from the processed negatives to illustrate the results of my experimentation.

The film is Kentmere 400 developed in Ilfosol 3 at the standard dilution of 1+9 and at 20°C, Ilfostop and Ilford Rapid Fixer. Scanned frames were output to TIFF files for processing. The files uploaded here were all resized to 1200dpi wide JPEGs at 85% compression quality.

For my scanning experiment I started with a 16-bit greyscale scan at 1200dpi to a TIFF file.  Exposure and image adjustment settings were the standard auto settings provided by Epson. The resulting TIFF was so rough that I didn’t bother attempting any further processing. Scans 2 and 3 were made with the same settings but at 2400dpi and 4800dpi respectively. At full size they show some improvement in resolution which is just discernible here, but not in image quality.

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Scan 1: 16-bit greyscale @ 1200dpi. Epson Auto settings. TIFF file size 3.4MB.
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Scan 2: 16-bit greyscale @ 2400dpi. Epson Auto settings. TIFF file size 13.5MB.
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Scan 3: 16-bit greyscale @ 4800dpi. Epson Auto settings. TIFF file size 53.9MB.

Based on what I could learn from the first three scans I decided to use 2400dpi for the next three.

Scan 4 was also a 16-bit greyscale scan but with manual over-ride of Epson’s auto adjustment of the histogram. I set the black and white points to just left and right respectively of the ends of the histogram, the grey point value to 1.00 and set the output to stretch the histogram from 0 to 255. I also unchecked the unsharp mask setting. The output gave me full histogram values to work with using Levels in Affinity Photo and to my eye produced a much more acceptable result.

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Scan 4:: 16-bit greyscale @ 2400dpi. Histogram manually set in Epson Scan, adjusted in Affinity Photo. B&W conversion in Affinity Photo. TIFF file size 12.8MB.

Scan 5 was made just as Scan 4 except as a 48-bit colour file. Not only does this give me the option to make adjustments to levels but also allows control over the conversion to Black & White and the opportunity to emulate the use of filters on the camera.

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Scan 5: 48-bit colour @ 2400dpi. Histogram manually set in Epson Scan, adjusted in Affinity Photo. B&W conversion in Affinity Photo. TIFF file size 40.5MB.

Pleased with the progress I seemed to be making, Scan 6 was also 48-bit colour but this time with all Epson settings turned off: No auto exposure or colour management, no auto histogram, no unsharp mask and no auto setting of the scan marquee. I was able to manually select for scanning, a little more of the negative than had been automatically selected by the Epson software, hence the slightly larger file size. I was also sufficiently pleased with this one that I took the time to spot and straighten the file once in Affinity Photo.

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Scan 6: 48-bit colour @ 2400dpi. All Epson Scan auto settings turned off. B&W conversion and all adjustments made in Affinity Photo TIFF file size 46.3MB.

I was really very pleased with this. So much so that I repeated it at 48oodpi just to compare the resolution. The 4800dpi at full size is just noticeably better. I also made a slight change to the brightness – not sure I made the right call on that but like everything else that’s a subjective judgement!

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Scan 7: 48-bit colour @ 4800dpi. All Epson Scan auto settings turned off. B&W conversion and all adjustments made in Affinity Photo TIFF file size 185.1MB.

As I said at the top, none of this is likely to have any bearing on my MacBook Air problems (I’m beginning to see the problem being something to do with it, either hardware or operating system) but it’s been an interesting day making these comparisons. For the extra effort and disk space, scanning at higher resolution in 48-bit colour and with no Epson software intervention  makes a huge difference to what is achievable. And the beauty of making edits in Affinity Photo (and I guess any Photoshop-like software) is the flexibility and ability to go back to make adjustments.

Working in a blackout

This blog is primarily about my film and emulsion-based expoits. In order to show the results of those exploits I have to scan the images and upload the resulting processed digital files to WordPress either directly or via Google Photos.

A few months ago I noticed that when viewing my blog on my laptop (a 2011 MacBook Air) some of my uploaded images appeared as totally black rectangles. Not just newly uploaded images but when I looked back through my blog, images which previously rendered as expected were displayed blacked out too.

I checked my blog on other devices: iMac, Windows PCs, iPhone and Android devices. All the images appeared correctly. I then checked how the same image files appeared on different online sites: Flickr, Facebook, Google Photos and Dropbox. When viewed on my MacBook Air, on all but Flickr the images appeared as expected but on Flickr the same files were blacked out. When viewed on other devices all the images appeared correctly.

The common factors among the failing files appears to be that they are scanned images, my MacBook Air, WordPress, Flickr and that the problem only began a few months ago. I’ve painstakingly reviewed my scanning and editing workflow to almost no avail.

I thought I’d cracked it when I scanned a set of black & white 35mm negatives last week:

  • Turn off all editing functions on my Epson Perfection 4990 Photo scanner.
  • Scan as 24-bit colour at 2400 dpi. Save images as .tif files on my 2009 iMac. (Iwould normally scan 16-bit grayscale to either 1200 or 2400 dpi .jpg files).
  • Open files in Affinity Photo, process as RAW files in Develop Persona, converting to black & white. Save as native .afphoto file.
  • Edit .afphoto file to spot, crop and straighten as necessary. Adjust black and white points in levels.
  • Export to .jpg files, resized to suit intended use. (For online, 1000 or 1200 pixels on longest side at 72 dpi).

Here are some of the resulting files that I uploaded both to Flickr and to WordPress:

 

I went to Flickr first and when viewed on my MacBook Air these images appear correctly. They were previously blacked out. The only change I had made was to scan as 24-bit colour files rather than 16-bit greyscale (which was previously my standard method). I was hopeful for my blog …

But here on my WordPress blog they remain blacked out. They appear correctly on other devices (iMac, Windows PC). I’m stumped. Did something change on my MacBook Air towards the end of last year? If so why does it only affect WordPress? Why only scanned images? There’s another thing too: it’s not just my images on my blog or on my Flickr account – I’m seeing the same thing on other blogs and other Flickr accounts. As far as I can tell it’s happening to scanned images and is only apparent on my MacBook Air.

Unfortunately my most used means of reading blog posts and updating Light Moments is via my MacBook Air. Until I can identify the problem and find a solution, my enjoyment of WordPress is being severely frustrated to the point of not maintaining my blog … at least for now.

Film: when ‘analogue’ becomes digital

A pinhole project in the making that prompts a question about digitising images made on film.

With a break over the festive season from the routine of work, I’ve had the chance to get stuck in to a photographic project or two (or three, or …).

Inspired by a photograph I saw some years ago in a book about pinhole photography and continuing from my last blog post, I made a body-cap pinhole to mount on a 35mm SLR, loaded the camera with a roll of Kentmere 400 film and took it for a walk through the woods. The pinhole was about 0.17mm diameter and mounted 50mm from the film plane, giving an aperture of about f/290. In the late afternoon winter light my exposure times for the 400ISO film ranged from about 20 seconds to over a minute.

My aim was to make images of the landscape as I passed through it, handholding the camera as steadily as I could in front of me with the shutter open on the ‘B’ setting, counting out the exposures in time with my footsteps. As with all things pinhole, this would be a serendipitous adventure into light, time and landscape.

With the first film exposed and developed (yes, I’ve been out again, repeating the exercise having learned lessons from the first) I had a choice to make. Would I scan the negatives, edit them and be done with viewing them on my computer screen, perhaps having prints made from the now digital files, or would I attempt to print them ‘old school’ in the darkroom? The negatives were all similar in being of limited tonal range with little discernible detail. It could be difficult to make anything of them either way.

I decided to do both! First, I scanned them then cleaned up dust marks and stretched the histogram in levels by setting black and white points. Images were obtained, albeit rather grainy and a bit harsh looking, that met my expectations and with which I was quite pleased.

Knowing that images were there to be seen, I picked a dozen or so frames, set up my darkroom and disappeared for a rather marathon printing session! My main challenge would be to get contrast into the prints from the very flat, mid-range negatives. Using split-grade printing I determined a base exposure with a grade 5 filter for the darks and grade 1 or 2 filters for the lights. The resulting prints were pleasing enough to be going on with, enough for me to see an ongoing project to develop as time allows.

What I found interesting was the comparison between scanned negatives, adjusted on-screen images from the scans, and darkroom prints made from the negatives. Here are three images all originating from the same frame:

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unedited scan of the negative (inverted)
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the negative edited with black and white points set in levels
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unedited scan of a darkroom print made from the negative

There’s always a wee voice at the back of my mind when scanning negatives that questions why I didn’t just use a digital camera – after all, once scanned I’m working with a digital file! It takes longer to make a darkroom print but the soothing red glow of a safelight is so much kinder on the eyes than the glare of a backlit computer screen and the end product in this example is more in keeping with the gentler, mysterious image that I had in mind when I set out with the camera. The digital version seems harsher, more contrasty, perhaps better defined if that’s what the viewer wants or expects and is certainly more reproducible, but the darkroom print has the feel of something crafted and unique – and to my mind it looks so much better too!

I guess both routes to an image have their place and of course the final irony is that to share the darkroom print here, I have to scan it and upload a digital file!

Pinhole time travel

Pinhole photography has for me been most satisfying and most successful when the resulting image represents the passage of time in a manner that is not immediately visible to the eye: Shapes and textures formed by water flowing in a river, by vegetation blown in the wind, by clouds moving across an open sky. It is the motion in subjects such as these, recorded over necessarily long exposure times that produce the otherwise unseen images in which I find another world to contemplate.

To achieve the images I seek, the camera is usually mounted on a stationary support such as a tripod for the duration of the exposure. I have occasionally experimented with handheld pinhole photography with mixed results but rarely as interesting as I have seen from other pinholers. It’s a direction I’d like to take further at some time, just not now!

Some time ago while reading Eric Renner’s book Pinhole Photography, I was intrigued by examples of images created within a moving van (the van was the camera) over distances of some 100 or so kilometres, and of images made with a camera attached to the wheelhouse of a boat as it pulled away from the quayside. Dreamily abstract images that brought time and distance together in a new way. I have often wondered how I might use a pinhole camera similarly … and so last weekend it came to pass!

For my experiment I chose the camera I made for Worldwide Pinhole Photography Day back in 2014. Constructed from foamcore and with a sliding shutter it takes media 5″ x 3″. Using Velcro ties I mounted it upside down to the passenger-side sun visor of my car such that it did not obsruct my view of the road when driving and that I could open and close the shutter easily and without taking my gaze from the road ahead. There was sufficient friction in the shutter to hold it open unaided.

For paper negatives I cut a few sheets of Ilford MGIV RC Satin to size, packed a changing bag and separate boxes for unexposed and exposed paper and set off on a short road trip. The light was such that I reckoned on exposures around six minutes each and my route would take in undulating, twisty rural roads, two bridge crossings and motorway. After each exposure I found a place to stop and fumble in the changing bag to swap out exposed paper for unexposed.

Although these are my first attempts and I can see things I would try to improve on, I’m happy with the images: happy to have made them and happy to contemplate what they tell me about my time and its relationship with the time and space of my subject. My original intention was to post these with an explanation of what and where each is, even with some ‘proper’ dashcam images but after much thought I have removed it all, even titles to the images as I feel that such information is irrelevant and a distraction from what the images have to say.

 

 

Down by the riverside

Last weekend I made the best of good winter light and time to spare for clambering up and down the rather slippery bank of the River Avon.

My cameras were almost ancillary to the restful experience that comes from the concentrated effort to find viewpoints and to set up for an exposure yet it is they and the images that ensue that give purpose to the solitary expedition. Here are a couple of memories from my day:

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Shoebox pincam, Ilford MGIV RC Satin paper negative contact printed onto MGIV RC Satin
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Intrepid 5×4, Rodenstock Sironar-N 150mm lens, Harman Direct Positive Paper

Shoebox pincam update

The shoebox pincam comes of age. It’s a keeper!

Making images with the shoebox pincam is a slow process. Four sheeets of paper or film have to be taped together then loaded together into the camera in the darkroom. Once exposed, the camera has to be returned to the darkroom for unloading and developing of each sheet. Getting to and from a previously scouted location takes time, the camera has to be set up and of course a pinhole exposure, especially on paper, is never done in a fraction of a second! As a result, it is likely that only one exposure can be made on any one day!

It’s almost two months since I idly picked up an empty shoebox and had the thought that it would be cool to convert it into a pinhole camera. That thought has turned into quite a project with teething problems to challenge me, lessons to be learned and only now can I say that I’m beginning to get a feel for what it can do.

The camera records a panoramic image covering about 145º horizontally, undistorted due to the constant radius curved image plane. The vertical perspective is similar to that of a ‘standard’ focal length 35mm camera, so is not the typical wide-angle view of a typical pinhole camera. So far I’ve used it to record river scenes, mainly because I like the effect that long exposures give to the movement of the water.

Here are four ‘useable’ exposures made so far. As each image comprises four sheets I’ve mounted them on board to ensure they are flat and accurately butted together. Unfortunately the assembled images are too large for my scanner so I have had to photograph them instead which doesn’t reproduce them as well, particularly for shadow details.

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This first ‘successful’ image was considered so for the reason that I had overcome the safelight fogging problem that had dogged my first few exposures. I was being overoptimistic for the Direct Positive paper’s ability to record such a high contrast scene with one river bank in direct bright sunlight and the other in deep shadow!

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For my second image I tried to cut down on exposure time by using film. I used Ilford FP4+, each sheet being subsequently contact printed onto Ilford MG Art 300 paper. While I achieved the aim of reducing the exposure time, the reduction was only slight due to accounting for reciprocity failure. Using film created its own challenges. First I had to tape together four sheets of film and load them into the camera in total darkness, then I had to determine a print exposure to be applied to each sheet when contact printing. To ensure accurate registration of the joined together contact prints, each negative had to be 100% accurately aligned to the paper. It was a tricky task and I spent rather longer in the darkroom than I had anticipated! Once again contrast was an issue but I’m pleased with the result and would give more thought to the camera position and lighting in future.

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This is probably about one stop underexposed and I knew it at the time I made the exposure. It was a fifty minute exposure started about two hours before sunset and to give another stop in fading light would have added well over an hour for very little benefit. As it is there is very subtle shadow detail that doesn’t show up here and I absolutely love the wispy shapes formed by the water in the darker regions of the print. I’m not at all disappointed with this one. It’ll probably go into a frame, at least temporarily!

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Finally I have this. I’d say I got the exposure just about right at 25 minutes or so, with good shadow detail in the actual print as well as here. I could have framed the shot better to take in less shadow area on the left and a better ‘flow’ downstream. The setting sun is directly in the picture and it’s path can be traced in the sorarisation that causes a ‘black sun’ effect from which the diffraction flare is seen. I quite like that and from time to time will set up a pinhole shot just to get that effect although that wasn’t my primary purpose with this one.

So there it is. I’m getting the hang of this ‘chance’ pinhole camera. It has a quite different perspective to any other pincam I have and I need to find the right subject matter to make the most of it. But it’s a keeper for sure!

A fitting tribute

Having been inspired to and informed about salt printing by workshops at Stills, it seemed fitting that one of my salt prints should be auctioned to raise funds for Stills.

Over the spring and summer, one of my projects was to prepare a set of salt prints to be displayed as part of an Edinburgh LoFi group exhibition that was scheduled to take place during September. Unfortunately, at the last moment the exhibition was cancelled due to emergency building works necessitating closure of the venue.

News of the exhibition being cancelled coincided with an appeal from Stills for print donations to a fundraising auction in aid of the work they do to support photography in Scotland. Established in 1977, Stills was the first dedicated photography centre in Scotland and remains the only space dedicated to photography in Edinburgh. The gallery, darkrooms, editing suites and workshops have played some part in my own photographic journey and so it seemed appropriate to submit one of my exhibition prints to the auction.

But there was a snag. The auction I would be submitting to was to be an anonymous online one requiring that prints should be 10×8, unmounted and unsigned. My exhibition prints were 10×8 but were signed, mounted and framed. As such, they were ineligible!

After some thought, I realised I had a set of work prints from my penultimate printing session. Some of these were not what I was aiming for but there were a couple which I had considered using as final prints. I picked the best one, signed it on the back below my pencilled process notes and handed it in to Stills.

In due course I received an email accepting the print. The auction, for a total of eighty four anonymously donated prints would go live at the beginning of October, culminating in an exhibition of the prints in Stills Gallery from 18th until the afternoon of 20th October when the online auction would close.

In the evening of 20th October a live auction was held of prints donated by named artists well known in Scotland and beyond, many of whom have had exhibitions within Stills. Some of the reserve prices in the catalogue were eyewatering! I went along after work to experience the live auction, have a look at the exhibition of online auction prints and to find out if mine had sold.

I never scanned or photographed the print that was auctioned but I do have photographs of the set of mounted exhibition prints. Here they are. The print submitted to the auction was the work print for ‘Sinuous Attachment’, second in the set.

Of the eighty four anonymously donated prints, ten were unsold, most sold for prices between £20 and £100 and just two sold for more. The top price was £160. I was astounded to learn that my salt print raised the second top price of £120. I know and respect many of my fellow anonymous print donors. Although this was in no way a competition, to be judged by public auction has been a surprising, humbling, and ultimately encouraging experience.

Between them, the online and live auctions have raised much needed thousands of pounds for Stills at a time when arts funding is tight. I’m pleased to have made a small contribution. Stills introduced me to salt printing through one workshop and gave me the knowledge to develop my own process though another so it seems fitting that the print I donated was the product of that involvement.

Shoebox pincam: Problem analysis and resolution

My shoebox pincam wasn’t performing as expected. I couldn’t rest until I had it sorted.

The problem

The shoebox pincam has been more difficult to master than I had anticipated. In my previous blog post I recorded the design and construction, followed by a test exposure which I estimated to be a little over exposed. This was followed by an exposure that I expected to be good, taken on an outing to a tidal island and for which the pincam had been planned. That second exposure was uselessly overexposed and after some consideration I put the reason down to my error in metering the scene. Yet I’ve been unable to settle comfortably with that conclusion and so I set out this last weekend to have another go with the camera.

To recap: the camera has a constant radius curved image plane to be loaded with four (originally five) 5×4 sheets of direct positive paper taped together to make a 5×16 (originally 5×20) image. After the first two exposures I realised that the angle of view did not extend to a full 180º, but only to about 145º. By adjusting the support for the paper to accommodate only four sheets not only did I save a sheet but I avoided an ugly vignette at either end of the image.

For my testing on Saturday, I returned to the same riverside location that I had used for the original test. Conditions were much as they had been before and I made a similar exposure. When the image was developed I was surprised to find that each of the sheets making up the image were differently exposed/fogged. On the one hand I was puzzled by this while on the other I was relieved that the problem was clearly not one of my metering of the scene as each sheet had received the same exposure!

Assuming a light leak, I made some alterations to the light baffling on the lid of the shoebox, reloaded and returned again. This time all four of the sheets were clearly fogged, but not to the same degree. On one of the sheets there was even a clear difference in the pattern of fogging across it. It was enough to make me suspect either my safelight or (less likely) that the box of paper was bad.

Sunday was a dull, wet day but I have a pincam made from foamcore that is completely covered in gaffer tape rendering it effectively rainproof. I decided to make two exposures with it, one on paper loaded in the total darkness of a changing bag and the other on paper handled as it would have been for the shoebox pincam under the regular safelight in my darkroom. The results convinced me without any doubt that the paper was being fogged by proximity to and time under the safelight.

Towards the end of the afternoon the rain eased and the sky began to clear. By that time I had devised a support-cum-guide to speed up the process of lining up and taping together the individual sheets of paper. I had also relocated the safelight so that I would be working in its shadow and further away from it. With about two hours of daylight left and I decided to head out again for the riverbank. I had no expectation of there being enough light to make a full exposure but actually a couple of stops underexposure would better show up any fogging.

Analysis

First test image

First testMy darkroom is a temporary setup in a shower room. The walls are matte white and the work surface glossy white. For a safelight when taping together and loading these sheets I had used an old bicycle rear light which gives off a weak red glow, set on the work surface.

Had it not been for what I now recognise as fogging in the right-most sheet, I would have said this image is just overexposed a little with perhaps a light leak from somewhere. However with hindsight I realise that the rightmost sheet was exposed longest to the safelight and closest to it. The light edge to the  left-most sheet should also have alerted me to fogging as the cause.

Second image (not originally intended as a test!)

IMG_5922Again, I should have realised this was fogged rather than overexposed. The vignetting at either end is clear and with direct positive paper any unexposed portion should be black.

When loading these sheets I had set up my regular deep red safelight, positioned on a hook about 1.2 metres above the work surface. Taping each of the five sheets together takes some time and I was doing so with the paper face down on the glossy white surface. Under the red glow it was difficult to see where the edges butted together to place the tape. I took all five sheets from the box at the same time so all were exposed to the safelight for the same length of time, probably three or four minutes.

Third test image

IMG_5923These sheets were loaded under the regular darkroom safelight as before but this time removed from the box one at a time, as needed, and kept face down on the work surface as much as possible. I had to reposition the tape on the third sheet and it probably had more direct exposure to the safelight as a result. The light edges all around each sheet suggest that fogging was occuring from light reflected off the work surface.

Fourth test image

IMG_5924This was loaded much the same as for the previous image. At this stage I was looking to the camera construction as the source of the fogging and had reworked some of the light-baffling and sealing on the camera. I was becoming more proficient at taping the sheets together which I think has led to more consistency in my handling of the paper and the subsequent degree of fogging.

Fogging test and resolution

 

This is the test pincam in the rain (left) and the two images which clearly show the difference between the paper being loaded entirely in darkness (centre) and having been handled under and exposed to for a couple of minutes, the darkroom safelight (right).

To resolve the fogging problem I moved the safelight to a different hook so that it would be further away from the work surface and in such a position that I would be working with the paper in my shadow. IMG_5920

I also made from black foamcore and mountboard, a support and guide that would both prevent surface reflections affecting the emulsion side of the paper and assist lining up and taping of the sheets. A second piece of mountboard was used to cover each sheet as the taping progressed, thus minimising and equalising the exposure each sheet received from the safelight.

Final test

IMG_5931Although this is almost completely black due to underexposure by two to three stops, the black is actually quite a joy to see. Had the paper been fogged while being loaded, that black would at best have been a lighter shade of grey. There is no suggestion of fogging around the edges of each sheet and consistency of exposure across the entire image is clear.

Conclusion … and a final thought

It has taken an entire box of Direct Positive Paper to reach but I reckon I can safely and comfortably conclude that the problem has been fogging due to overexposure to the safelight. I can also conclude that a resolution has been found.

One final thought: I’ve been using Harman Direct Positive Paper for almost four years. Why have I not noticed this before? The answer is that without realising it, there have been times that I have! Mostly I load single sheets directly from packaging to camera or film holder, often in a changing bag, and there has been no problem. However there have been times when paper has to be cut to size. Often, cutting a single sheet does not expose it sufficiently to be fogged but if I’ve been cutting a batch I’ll have had a growing pile of paper sitting in the light. Those are the cut sheets that didn’t produce the same contrasty ‘punch’ that I expect and love about this paper. Lesson learned!

All that remains will be for me to make a few good exposures in the weeks ahead. And they will have to be good as I have only one box of paper left. There’s no room for error either as I’ve discovered that it is currently unavailable from Harman and out of stock wherever I’ve looked!

The Shoebox constant radius pincam

More pinhole fun, this time with a shoebox.

The plan

It seems to be the way of things with me that ideas spring to mind in the oddest of places at the oddest of times. Sometimes they are gone forever before I have the opportunity to make a note, or they reappear in search of recognition at another odd time. Occasionally I get lucky and the idea stays with me long enough for consideration, perhaps acceptance and ultimately is put into practice.

So it was a couple of weeks ago on a crowded commuter train home at the end of a busy day, that I had the idea of creating a constant radius curved image plane pinhole camera out of a shoebox. A geometric puzzle to keep my mind awake amidst the noise of the train and the jostling of my fellow passengers.

The mental conundrum was too much to deal with but my mind wandered to thoughts of how I would record such an image. Perhaps a strip of art paper with SE1 emulsion brushed on? That would be cool – but it would be a negative image and how would I develop what would likely be a quite long strip of paper? Would I be able to make a positive contact print from it, perhaps on to another strip of SE1 coated paper?

Problems to be surmounted already and the idea still just at the stage of bouncing around inside my head. But how about direct positive paper? Would I be able to tape together enough of the 5″x4″ sheets I use in film holders to fit the image plane? It’s paper that I’m well accustomed to and as individual sheets it would be simple to develop. If nothing else it would be a good way of testing the camera design before moving on to ideas for other, more tricky media.

As I alighted the train for the short walk home my mind was buzzing. I had a plan. I had a project. I was going to create some pinhole art!

Construction

Sturdy shoeboxes are too good to throw away. They make useful storage boxes but better still, can be adapted to make pinhole cameras. It happens that I had two or three going spare. The box I chose has approximate internal dimensions of 33cm wide, 18cm deep and 13cm high.

Once made light-tight, the box could be fitted with a curved support on a radius of 16.5cm with a pinhole set centrally in the long side. Assuming full 180º coverage, the image plane would extend to 518cm wide by 12.5cm high and because it follows the radius of the curve, it would be free of both distortion and light fall-off along its entire length. The optimum pinhole diameter for a 165mm projection distance is roughly 0.6mm.

To ensure that the pincam would be light tight, the box and its lid were lined with thin black card. A strip of sticky-backed black felt was attached inside the lid to seal against the tops of the sides of the box. The card lining the sides of the box was extended about 1cm above the rim and folded inwards to form an additional light baffle.

The pinhole was made by pushing a dressmaking pin through a 3cm square of ArtEmboss mat black aluminium foil and positioned with black PVC electrical tape in the centre of the front panel of the box. More black PVC tape positioned over the pinhole aperture served as a shutter.

To form an image-plane support I cut a strip of card 518mm long by 130mm high, the length being calculated as the semi-circle of radius 165mm. A couple of spare pieces of foamcore served as a filler to support the back of the strip within the box.

Under safelight in the darkroom, I joined together five sheets of Harman Direct Positive paper with masking tape to make a strip 500mm long by 125mm high. This fitted neatly inside the box, supported by the image-plane card. With the top of the box secured by a couple of lengths of string I was almost ready to make my first test image.

Tripod support

I know from experience that although a viewpoint might be found, it is often unworkable because there is no way to support for the pincam in position! To get around this I like to make some provision for attaching my pincams to a tripod.

For the Shoebox pincam I took an offcut of plastic rectangular conduit cut to a couple of centimetres longer than the pincam is wide. I drilled a 7/32″ hole in the centre of the base and screwed the 1/4″ thread of a tripod quick-release plate into the hole. The metal thread of the mount effectively acted as a die to cut a thread in the softer plastic. To avoid stripping the new thread by over-tightening, I then fixed a 1/4″ threaded nut to the inside of the conduit, with the help of a big dollop (technical term!) of hot glue.

When the top of the conduit is slid back in place, the support is quite rigid and can be carefully mounted on a tripod. The pincam and support are held together by the string which also keeps the lid of the box in place. It may not be rock-solid but in pinhole terms it does the job perfectly! Being tripod mounted opens up a whole range of viewpoint options, levelling and height adjustment.

First test

I took the Shoebox pincam to the banks of the River Almond on a bright Saturday morning. Shaded by the trees, my hand-held Sekonic L-308S meter and the iPhone Pinhole Assist app agreed on an EV(100) of 9.8, giving an exposure time of 53 minutes for direct positive paper rated at ISO 3. During exposure the light changed as the sky cleared and the sun lit the trees on the far bank of the river, so I reduced the exposure time given to 45 minutes.

Back in the darkroom I opened the shoebox to find that the semi-circulat image-plane support had slumped a bit towards one end of the box. That would need to be fixed.

With the masking tape holding the five sheets together removed carefully so as not to tear the back of the paper, I proceeded to develop each sheet individually, paying particular attention to time (3 minutes each) and temperature (19ºC) to ensure consistency from one to the next as all five would make up the single final image.

Exposure was good, perhaps a little over exposed for my taste. There was distinct vignetting at the end that had slumped while at the other end the print was lighter with lower contrast. Overall I was extremely happy with the result and after making an adjustment to the image-plane support, loaded up the pincam for a second test to be made next day.

Adjustments

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To resolve the problem of the image-plane support moving, I strengthened it with four pieces of flower arranging wire taped to the back, and pushed two drawing pins through the centre into the foamcore filler at the back. My expectation for the second test would be to find out whather the vignetting noticed in the first was due to movement of the paper or actual cut-off of the field of view.

Second test

For the second test I joined a couple of friends for a walk across the tidal causeway to Cramond Island, with an idea to make a pinhole exposure of the war-time gun emplacements and concrete huts. It was another bright day, this time with steady soft light from a light grey backlit sky.

Again, my Sekonic and iPhone agreed on the light, metering EV(100) of 11.8. To allow for yesterday’s perception of slight over-exposure I rated the paper at ISO 4 (1/3 Stop faster) and gave the metered 12 minute exposure.

Back in the darkroom again, the fix made to the image-plane support had done its job and I processed the paper as before. Two things were immediately obvious: Clear vignetting at either end of the image suggesting an effective field of view amounting to about 145º rather than the full 180º semi-circle I had hoped for; and rather disappointingly an inexplicably overexposed image!

The puzzle

The over exposure of the second image was quite unexpected. I rechecked all of my measurements and calculations and finding them all correct I proceeded to remove the pinhole to accurately check its diameter.

I mounted the pinhole alongside a steel milimeter rule on the bed of my scanner and scanned at maximum resolution. Viewed at full size on screen I was able to measure the pinhole and by reference to the magnification of the known milimeter rule, calculate the diameter as 0.612mm, exactly as intended and giving an aperture of f/269.

With all the variables checked and found correct, I was left with only one conclusion to explain the over exposure -human error – mine! On the first test the sky had been obscured by the trees while the second was under an open sky. I can only conclude that on the second test I have pointed my meters at the wrong part of the scene and failed to account for the brighter conditions.

More care needed next time methinks! And I do intend that there will be a next time as soon as possible. I want something worthy of a frame on my wall.

EDIT:

There is a follow up to this in my next blog post. In it I come to the correct conclusion and find a resolution!