A Hole Has No Focal Plane

A Hole Has No Focal Plane

What this makes

Hand it a photograph and it takes the picture again through a pinhole — no lens, so nothing is ever truly sharp and nothing is ever more blurred than anything else, with the corners falling away because of simple geometry. Two fields.

You are given ONE photograph. Return ONE image: the same scene photographed again through a pinhole, with no lens at all. Follow every line. Replace only the FIELDS block; everything after it is fixed.

First — do you have the photograph and the fields?

Say what this makes before you ask anything, in one or two sentences of their own words. Someone who has just pasted this has no idea what they are being asked for, and questions arriving cold are questions answered badly.

If no photograph is attached, stop and ask for one. This re-photographs a particular scene, so there has to be a picture of it.

If either field below still has braces around it, stop and ask. Put both questions in one short message, and show the example under each one so they can see the shape of a useful answer. Wait for the replies, then work. Never fill a brace yourself.

Ask in whatever language they are writing to you in. Translate the questions and the examples; do not make someone read English to tell you what they want.

If the photograph is attached and both fields are filled in, ignore this and carry on.

Fields — replace these two lines only

• How big the hole is, said as how soft the sharpest thing gets: {a named thing, and what you can still tell about it}
• How long the exposure ran, said as what has left the picture: {something that is no longer there}

The law everything else follows from

The object is untouched. The photograph of it is taken again.

Everything about the recording changes: no lens, a hole instead, and an exposure measured in minutes. Nothing about the scene changes. Same building, same trees, same road, same arrangement, same light direction. It is that place, photographed through a hole in a plate.

A hole has no focal plane

This is the whole rewrite, and it is one sentence of geometry.

A lens bends light so that one distance lands sharp and the rest does not. A hole bends nothing. Every point in the scene throws a small disc onto the film, and that disc is the same size whatever the distance, because it is set by the hole and not by focus. So:

• Everything in the picture is soft, and everything is soft by the same amount. A wall two feet away and a hill two miles away are equally unsharp.
• Check it as a comparison, not as a setting. Pick the nearest thing in the photograph and the furthest thing in it, and make those two exactly as sharp as each other. If you can read one better than the other, start again.
• Nothing can be brought into focus. There is no plane where a thing goes crisp; the softness is the resolution of the camera.
• There is no bokeh. No creamy background, no round out-of-focus highlights, no separation between subject and setting. That is a lens effect and there is no lens.
• The softness is even, not directional. It is a small blur in every direction at once, the same in the middle as at the edge.

If anything in the result is crisp, or if the background is softer than the foreground, a lens was used and this has not been done.

The corners fall away because of geometry

• The middle of the picture is brightest and it darkens smoothly toward every corner, because light arriving at an angle spreads over more film and passes through an oval of the hole rather than a circle.
• The falloff is circular and centred, and the corner is about half as bright as the middle — dark, but never black, and never a hard-edged circle with the picture sitting inside it.
• It is smooth the whole way out, with no ring, no edge and no sudden step. Trace a line from the centre to a corner: the brightness should fall a little at every point along it and never drop away all at once.
• Nothing about it is a filter. No black oval, no soft-edged rectangle, no darkening that follows the subject.

The exposure is minutes long

• Whatever the second field says has left the picture is not there at all — not faint, not ghosted, absent.
• Anything that moved a little is drawn out: leaves become a soft mass, water goes flat, cloud streaks along the wind.
• What held still is as detailed as this camera can manage, which is not very, but its edges are in exactly the right places.
• Bright areas may run right up to white and stay there.

The place does not change

• Same viewpoint, same framing, nothing cropped, nothing added.
• Very wide, and straight. A pinhole has no distortion at all: straight lines stay straight right into the corners, with no barrel and no pincushion.
• Same buildings, trees, road and their positions.
• Colours are the scene's, a little desaturated by the long exposure, not recoloured.

Never

• Text, numerals, a date, a caption or a watermark anywhere, in any script.
• Light leaks, grain overlays, scratches, sprocket holes, film borders or applied age.
• A vignette that is oval, rectangular, soft-edged or off-centre.
• Selective focus, bokeh discs, tilt, or a sharp subject against a soft background.
• A subject the photograph did not contain.

What it should read as

A picture made by a box with a hole in it — soft the whole way through, dark in the corners, and quite still.