Composition Proportions

How much of the frame should we fill in photography? What percentage, ratios, and proportions?

I had this vision:

Composition is all about proportions and the proportion of the frame you fill with your subject.

How to proportion the frame when you’re making images

This is the basic notion:

Shoot with a prime (non zoom) lens
Keep moving closer to your subject until you fill the frame to the according proportions which you like

Studying the composition proportions of the greats

For example, see how close Robert Capa got to his subjects, and how he filled the frame with them:

See the percentage of the frame he fills with his subject:

For example this image it seems the subject is around 80% of the frame: