Two lens terms, defined

Crop factor and field of view matter to a rating because they decide how close you stand and how much perspective distortion the photo carries. A wide lens used up close makes near parts look disproportionately large, and a tool scores that distortion as if it were the subject.

Field of view, defined

Field of view is how much of the scene a lens captures at a given distance - a wide field of view takes in more of the surroundings from the same spot; a narrow one takes in less, framing tighter on whatever it is pointed at. A phone's "wide" and "ultra-wide" lenses have different fields of view from each other and from the "main" lens, even though all three sit on the same device.

A wider field of view exaggerates the size difference between near and far objects in the frame, because it has to compress more of the scene's depth into the same image. That is the mechanism behind why a subject close to the lens looks disproportionately large relative to the rest of the frame - the closer something is relative to the lens's field of view, the more that distortion shows. Strictly, the distortion comes from camera distance, and a wide lens is what lets you stand that close while still filling the frame. Its size is measurable: Ward and colleagues (2018, JAMA Facial Plastic Surgery) calculated that a face photographed from 12 inches shows a nose 30% larger in men and 29% larger in women than an undistorted projection, and essentially no difference from 5 feet.

Crop factor, defined

Crop factor is a way of comparing one sensor and lens combination's effective field of view to a reference, historically a 35mm film frame. A phone lens quoted as "26mm equivalent" is being described in terms of what a 26mm lens on that reference would capture, even though the phone's actual sensor and optics are much smaller. It is a translation, not a physical measurement of the lens itself.

For a submission, the number that matters is the field of view it implies, not the equivalence figure by itself. Two phones quoting different equivalent focal lengths for their "main" lens will render the same distance and framing differently.

Why both matter for the protocol

Which lens a phone selects, and therefore which field of view is in play, is a hidden variable if a set mixes lenses between photos without noticing - some phones switch lenses automatically based on how far you stand back or how much you pinch to zoom. Two photos taken at what feels like the same distance can be using two different lenses, and therefore two different fields of view, without any obvious sign in the result.

The fix is the same as for any other condition: pick one lens - usually the main, non-wide one - and use it every time, at the same distance, so field of view stays fixed across a series. That choice belongs in the same written record as everything else about a slot, alongside angle, distance and light. Rate Cock's per-axis entries make a proportion axis that shifts unexpectedly worth investigating for exactly this kind of lens switch before assuming anything else changed.

None of this touches a physical read - a tape has no field of view to hold constant, which is one more reason a measurement and a rating tool's proportion axis are answering different questions. A human reviewer working from a photo is subject to the same lens effects as a model is, and Bryan, Perona and Adolphs (2012, PLoS ONE) found that face photos taken from within personal space drew lower ratings of traits including attractiveness than photos taken from further away, which is part of why judges tend to prefer a plain, unzoomed shot over anything taken on a wide or telephoto setting.