This post is about testing a pinhole camera, an activity I started in week nine and finished here in week ten. Over the past few weeks, as time allowed, I assembled a Polaroid pinhole camera from various parts I already had, or which came available locally just when needed. If you are interested in how I did that, check out my post Making a Polaroid Pinhole Camera. The first shot was taken indoors and worked out deceptively well. The outdoor tests produced some very disappointing results, but I think I am close to understanding the camera and exposure determination now that I have shot this first pack of film.
The technical synopsis for this camera is:
- 0.566 mm diameter pinhole,
- aperture of f-327,
- 185 mm focal length,
- 35.5° angle of view,
- built-in shutter with only a bulb setting – opened and closed with a cable release,
- Polaroid Land 100 series film pack holder,
- shoe-mounted view finder,
- 58 mm threaded filter mount,
- tripod mount.
The film of choice is Fuji FP-3000B black and white instant film – it is one of only two films made to fit the Land camera, the other is Fuji FP-100C, which is rated more suitably for pinhole photography at ISO 100, but it is a colour emulsion and the Fuji data sheets show the reciprocity effect of longer exposures requires some heavy colour correction with filter types not readily available. The FP-3000B is rated at ISO 3000 which translates with this camera to a 1/8th second exposure in bright sunlight. Reciprocity effect is limited to making a longer exposure as there is no colour correction necessary. To get long enough exposures that they can be accurately made by hand with a cable release requires an ND filter. I have a 58 mm Cameron Fader ND filter that changes opacity by ~7 f-stops as the outer ring is rotated. I marked the edge of the filter for ~1 stop increments, markings I have confirmed for this project.
There are three areas that my initial tests have concentrated on – getting rid of random light flares on the images, figuring out the view finder framing and most important learning how to get a decent exposure.
The first outdoor tests were made next to the ocean on a bright sunny afternoon so the ND filter was necessary (see the exposures section below for the photographs). I quickly found that there were light flares on the image. At first I thought it was sun on the filter glass, so took additional shots with the front of the camera in the shade of my body, but without much improvement. That led me to think there was a problem with the filter, so I removed it and took a couple of shots trying for “fast” shutter speeds by hand. But even this way, there was flaring. Which led to the conclusion that either there were light leaks into the back of the camera, or the shiny black opening tube in front of the shutter was reflecting light and causing the problem. So back home for a modification made with some dense black foam with adhesive backing as a lining to the front opening, and then another try a few days later.
At the end of the first outdoor trial, the camera had remained in full sunlight on the tripod for 10 or 15 minutes after I had pulled and peeled the last image taken that day. This was partly by way of checking for light leaks – my thought was to take another shot in conditions that replicated those of the first indoor shot and if there was no flaring (absent in the first shot) then light leaks could be ruled out. So, the next shot I took was indoors, once again of a small doll and vase of flowers next to the window. Not great lighting for a test I realised as soon as the shot was developed. But the camera was firmly on the tripod, so I could use this shot to gather information about view finder coverage. Also, the test did not have unexplained light flares, so I could conclude there were no light leaks. This, like the first shot I took indoors, did not use the ND filter, nor was there full sunlight to contend with.
The last three shots in the pack were taken at another beach in bright sunlight though facing even further away from the sun than the first outdoor images. The first two of these were with the ND filter, the last without. The result of those shots shows that most of the light flaring has been eliminated by controlling reflections in the front opening. However, there is some residual flaring which is almost certainly related to the filter, even though the front of the camera was shielded from direct sun. I think the glass is catching light from the sky or perhaps the water.
Edit: I just thought of another source for flares. Perhaps the filter mount on the front of the camera is leaking light as it is only held on with 4 screws without a light seal. Easily fixed, so I will try that as well. It is a logical source of leaks since it would only show when the filter is in place for long exposures.
View Finder Alignment
I wanted a more precise idea of the image alignment vs what is seen in the viewfinder. The view finder is marked for 35 mm and 50 mm coverage in a full frame 35 mm camera. I marked the alignment of what I could see in the viewfinder on the paper backing clinging to the edges of the freshly peeled image, scanned it and then pulled off the rest of the paper and re-scanned the clean print.
In the image below, the green line shows what I see outlined within the 35 mm inner rectangle in the view finder. The angle of view of the pinhole camera is equivalent to a 42 mm camera. This framing, while a bit off centre, is more than adequate for framing the shot and I don’t think I will be adjusting it at all. In fact, I am quite pleased it came out this close because aligning the flash shoe during installation was fussy and time consuming.
Getting a good exposure is proving to be the steepest part of the learning curve. Not least because I know too little about using spot meters and about selecting parts of the scene to take a an exposure reading. It has not been helped by the distractions of light flares and fiddling with the ND filter and the calculations necessary to accommodate the ND filter settings. But fundamentally, the problem is that I have never learned how to meter a scene well. Usually I just let the camera do it for me, and even when shooting long exposures with my DSLR, I rely on the camera’s readings, shoot brackets, and adjust after looking at the display, as needed. But at $3/shot I am reluctant to bracket.
What I should have done, and should really still do, is to set the camera up, take a mass of spot readings as well as incident light measurements and note them all down and then shoot multiple exposures of the same scene with different times. That should generate data useful for calibrating this camera’s exposure readings in the future. While I did not do that I did keep notes on each exposure (small miracle, that part) and have been trying to work with them to make some sense of how to shoot this camera and film. Below are some of my notes, numbered to match the shots below each paragraph. Each of those images under the paragraphs are in a gallery so if you click on one of them, you can navigate to the other(s) within each small group to quickly compare the print with the inverted negative.
1. The first shot I took was indoors without the ND filter. The exposure reading was taken from the highlights in the doll’s dress – not the absolute brightest areas, but nearly. An 8 second exposure was metered, and reciprocity effect indicated a bit less than one additional stop of time, so I exposed it for 14 seconds. I think the highlights are a bit blown out, so probably if I had stuck with an 8 second exposure it would have been better.
2. The second image is taken with the ND filter. The light meter was adjusted to account for 7 stops less light and indicated an exposure of 8 seconds based on a general incident light reading at the camera location. Considering the first shot, I reduced the reciprocity compensation to almost nothing, shooting at 10 seconds. This was a bit short for the sky and distant mountains, though not by much. It was however a few stops too short for the foreground rocks and the ocean (see the negative scan for the missing information). I should have respected the reciprocity compensation for this shot.
3. Next I re-positioned the camera pointing it down at the rocks but did not re-meter the shot. This one was taken at 14 seconds, which probably would have been good for the sky, of which there is none.
4. The next shot I reduced the ND density by 2 stops and took it at 14 seconds as well, based on the results of the previous shot. I would have been better off reducing it by another stop or two.
5. I was getting distracted by the flares on the prints, so for the next shot I removed the filter, spot metered the shadows and roughly timed a 1 second exposure. This was more about testing without the ND filter than about getting the correct exposure, but obviously I should have metered for a lighter part of the scene, and exposed for 1/4 or 1/2 second, if I could control that with a manual shutter.
6. The last shot from this set up was also without the ND filter and for this one the meter reading was 1/8th of a second. I pushed the shutter release cable in and out as quickly as I could – I expect I was probably around 1/4 or perhaps 1/8 second, but will never really know. This too was about testing without the ND filter. You can see in this shot, and also in number 5 that there is some light flaring even without the filter and with relatively short exposures.
7. The next shot was taken indoors after I put the non-reflective foam on the inside of the front opening. The main purpose was to test if there were light leaks left over from leaving the camera standing in the sun after image 6 was taken. I metered for the doll’s shoulder where it faces the camera, and for its forehead. The meter indicated 15 seconds. The reciprocity chart only goes to 10 seconds, so I extrapolated along an imaginary curve and decided on a bit more than 1 stop adjustment and shot at 35 seconds, keeping in mind the results from the first image. At least I could see that there were no light leaks from exposure to the sun, and the camera was pointing into a quite bright back-light and yet there were no flares, suggesting that reflections in the front opening must have been the main problem.
8. Back to a beach to shoot the last three shots in the pack. This rock is a transformer stone called Sahsima in local indigenous histories. It is granite and quite light coloured compared to the surrounding bedrock. I metered from the brightest area of Sahsima, this time metering through the ND filter set at 5 stops prior to attaching it to the camera. The meter reading was 4 seconds and that is what I shot it at. Given where I metered the scene, it is a pretty good exposure, just not quite what I imagined. I did not shield the front of the camera from direct sunlight, but it was pointing well away from the sun.
9. For this one the ND filter was left on at the same setting and I mindlessly reduced the exposure to 2.5 seconds, when I was intending to increase it by about one stop. Thus, it is not as ‘good’ as exposure 8. For this one I did shield the front of the camera from the sun, so the flare is coming from another direction. And what the heck is that white patch in this and number 2 as well? A film defect?
10. For this one, I needed the filter off the camera again to study flares. I took an incident light meter reading which was 1/2 second. I tried to approximate this time by reference to the stopwatch in my phone app. This shot is getting to be the kind of exposure I was looking for. Had there been one more shot in the pack, I probably would have tried one more exposure pushing the shutter cable in and out as fast as I could, just to get a sense of whether I can get away with doing that in bright sunlight more of the time, rather than using the ND filter.
For this post I have included the scanned negative images that are on the paper that is peeled from the print after it has developed. As you will have noticed the negatives very often have a lot more information in them than the prints do, especially in the shadows. They also get pretty beat up while drying in my camera case out of direct sunlight. To me these factors offer intriguing possibilities and I have been editing those negatives to get images that are often more pleasing to me than the straight up positive prints. I am publishing a concurrent post on my blog (Pinhole Polaroid Negatives) which has edited versions of each negative from this pack of film to explore their potential. I am pretty pleased to have salvaged several interesting images from the otherwise failed exposures seen here. I have included a teaser below which, if you click on the image, will also take you to the other post; so go check out that post too!
And thanks for reading all the way down to the end, it is appreciated 🙂 If you have read this far, and have any helpful suggestions, please make a comment.