Free 1.5 Rectangle Dynamic Symmetry Grid Generator

Draw both diagonals, drop a perpendicular from each corner onto the diagonal it misses, and the four feet land at 0.30769 of the width and of the height. That is four thirteenths, and it follows from the family rule: the eyes of a rectangle of ratio r sit at 1/(1 + r²), and 1/(1 + 2.25) is 1/3.25, which is 4/13.

Photographers who use thirds and photographers who use dynamic symmetry talk past each other, and this is why. Both are correct within their own system; they simply produce points that are two and a half percent apart on the frame everyone is actually shooting.

The clean way to settle it for yourself is to put both overlays on the same photograph at once and look. In most images the difference is invisible and either system will do. In a few — a horizon, a strong vertical, a face at the edge — the difference is exactly the amount by which the composition feels resolved or slightly restless, and then it is worth choosing deliberately.

Worth knowing too: on the rectangle the root 2 armature generator draws, the two systems agree exactly, because root 2's eyes are at precisely one third. So the disagreement is not general — it is specific to the proportion you are working in, and 3:2 is one of the proportions where it shows.

Cut a 3:2 rectangle at one third and two thirds of its long side and you get three rectangles of 1:2 — three double squares. That is a genuinely useful structure and it is produced by the proportion rather than imposed on it.

For a triptych it is the natural division: three panels, each a clean double square, and each able to carry its own armature at a proportion that is itself part of the family. For a single image it gives a three-part reading of the frame that sits underneath the eyes without competing with them, since the subdivision is at thirds while the eyes are at 4/13 — near each other but never coincident.

Load the image and the rectangle fills it. If it does not, your file is not 3:2 — 4:3 from a phone or a micro-four-thirds camera, 16:9 from video, 5:4 from a large-format scan — and the letterbox is telling you so. That is worth noticing before you compose, not after.

Then use the eyes as candidates rather than as instructions. Four points and two diagonals do not decide a photograph; they tell you where the frame's own structure puts emphasis, and the useful question is whether your subject is near one of them and, if not, whether a crop would put it there. The transform makes that testable directly rather than speculatively.

For portrait orientation, everything holds with the axes swapped — the eyes are still at 4/13 of each side, the subdivision still gives three double squares, and the vertical version is the frame most portraiture is shot in. The armature does not care which way the camera was held.

The 3:2 rectangle overlay page works this through, beside the rest of the root rectangle overlays, and the rule of thirds overlay tool draws the system it gets confused with. The root and golden rectangles as a compositional system come from Hambidge's dynamic symmetry (1920), and his claims about Greek design are contested. The 3:2 frame has no such baggage: it comes from Barnack's decision about film transport, which is documented and entirely practical.

So this rectangle's armature is not a claim about tradition at all. It is what happens when you apply a well-defined construction to the proportion photography happens to have settled on — which is a modest thing to say and, for anyone composing in that proportion, a more useful one than a disputed history.

Because 3:2 is what the camera gave you, the interesting question is what the armature does when you crop. Every crop changes the ratio, and every ratio change moves the eyes — so the placement that was correct at 3:2 is not the placement that is correct at 4:5 or 16:9.

The direction of travel is worth carrying: crop wider and the eyes move outward toward the ends; crop squarer and they move inward toward the centre, until at 1:1 all four collapse onto the middle and the armature stops distinguishing anything. That is the same collapse the diagonal method has on a square, and it is a real reason square crops need a different system.

In practice that means testing the crop and the placement together rather than in sequence. Drag the overlay's transform to the crop you are considering and watch where the eyes go; if your subject sits on one at 3:2 and nowhere near one at the crop you were planning, that is information about the crop, not about the subject.