Solargraph camera placement and retrieval

Purpose

To leave a sealed pinhole camera outdoors for months and come back with three things: the camera, a scan of the sheet in it, and a log of what the exposure was.

When to use it

Every camera left in place unattended — the two cans of Part VII’s night and very long exposure assignment, and any solargraph after them, from choosing the site to the scan reaching its envelope.

It does not make the camera — Part VI makes and measures the pinhole and loading a pinhole back covers the sheet — and it ends in no tray: a solargraph is a printing-out image and is never processed. For a session you stay with, use the outdoor or night session.

Before you start

You should already have read the unfixed silver photogram, which owns why this sheet is never developed and why its image fades out of the can. Have your latitude, the can’s internal diameter and the measured hole: a can camera’s axial focal distance is its internal diameter, so those two numbers are its aperture.

Level A on the classification rubric: no substance is handled, nothing is weighed, dissolved, heated or processed, and there is no waste at all. The hazards are the mount and the ground — the camera must not fall on anybody, must obstruct nothing, and must not be fixed to property that is not yours. Sun protection is the outdoor session’s.

Packed: the sealed can in its light-tight box; waterproof tape; a strap or cable ties; a weatherproof label; a compass; notebook and pencil; and a camera.

Procedure

Choose the site and the aim, in daylight

1. Choose a site you have visited in daylight, where the camera can face the sky the sun crosses — south, in the northern hemisphere.
2. Write down the two solar-noon elevations for your latitude: 90° − latitude + 23.44° in June and 90° − latitude − 23.44° in December, from NOAA’s zenith relation at hour angle zero and NASA’s Earth obliquity.
3. Ask permission in advance from whoever owns the thing you will attach it to, and record who and when. The course requires that you asked; the law of fixing objects to trees, railings and buildings varies, and this makes no claim about it.
4. Look for what will change over the months: a tree in leaf, a hedge cut, scaffolding, anything that will shade the low December arc.

Build, load and seal, indoors

5. Blacken the inside of the can with matt paint or tape.
6. Make and measure the pinhole by the Part VI method, and log the hole diameter with the can’s internal diameter.
7. In the dark or in a changing bag, by handling paper in dim light, wrap one sheet of resin-coated paper around the wall opposite the hole, emulsion side inwards. Return the rest of the packet to its original packaging, cool and dry, as ILFORD instruct.
8. Seal every joint and the lid with waterproof tape, and cover the pinhole with a tab of tape you can lift with cold fingers.
9. Fix the weatherproof label: your name, a contact, and the date you will collect it.
10. Carry the can to the site inside its light-tight box.

Site it and start it

11. Mount it where it cannot fall on anyone and obstructs nothing, strapped to something that will still be there, clear of any passing width.
12. Set bearing and tilt so both elevations from step 2 fall inside the frame. The can’s field is wide; aim at the middle of the sun’s annual band.
13. Lift the tape tab and write the date and clock time down at once: that is the start of the exposure.
14. Photograph the mount, and record what the camera is fixed to and which way it faces.
15. Set a calendar reminder — about six weeks for the first camera. Longer durations are quoted everywhere, but the previsualisation lesson records that the course could not verify one.
16. Site the second camera the same way and leave it longer: one will be lost or opened.

Retrieve it

17. Collect on the date on the label, or sooner if the site changes.
18. Tape over the pinhole before the camera leaves the mount, and log the closing date and time.
19. Take down every strap, tie and fixing you put up.
20. Open the can indoors, in subdued light and never in sunlight.
21. Handle the sheet by its edges, with freshly washed hands or nitrile gloves, and do not touch the image surface, which is the Library of Congress’s handling rule.
22. Scan it immediately, face down on the platen with the lid closed, and invert the scan.
23. Put the sheet straight into a light-tight envelope labelled with the start date, the end date and the site, by storing unfixed prints.
24. Do not develop, stop or fix it. The Getty atlas records that a printing-out image loses intensity during processing, and Part I owns what a fixer does to this one.

How you know it worked

• Start and end times are both in the log, and the interval between them is the exposure.
• The scan shows bright arcs on a pale ground, broken where cloud passed.
• The highest and lowest arcs sit near the two elevations from step 2 — the only check there is that the aim was right.
• The sheet reached its envelope within minutes of the scan, and the scan — not the sheet — is the record.
• Every camera you sited is back with its fixings.

If a step fails

Step 3, the owner cannot be reached. Site it on your own property, or do not site it. An unanswered request is not permission.

Step 6, the hole cannot be measured. Make another and measure that one. With no diameter there is no aperture, and the arcs answer no prediction.

Step 13, the start time was not written down. Log the date you are certain of and mark it an estimate. The arcs count days, not seconds.

Step 17, the camera has gone. Record the loss, the site and the date you noticed. This is what step 16 is for.

Step 18, the tape will not stick in the cold or the wet. Do not open the can at the mount: box it closed and tape it indoors.

Step 20, it was opened in bright light. Close it, scan at once, and log it: the sheet will read darker than it should.

Step 22, the sheet is blank. Clear everywhere means the tape tab never came off; dark everywhere means a leak, or step 20. The assignment’s troubleshooting table separates them.

Step 24, the image is too faint to show and fixing is tempting. A fixed solargraph is a blank sheet with a faint stain. Print the scan.

What to record

One line per camera on the exposure log: the site, with bearing, tilt and what the camera is fixed to; who gave permission, and when; the can’s internal diameter and measured hole, with the aperture from them; the light you loaded under; the start date and clock time; the intended and actual retrieval dates, and the days between; the arc count against the sunny days in the period; the highest and lowest arcs against the two elevations from step 2; the scan’s file name; and where the envelope is. Then unfold the prediction sheet and put the observations beside the predictions.