Photos
Why a note next to each submission matters
A score without its conditions cannot be compared later; the log is what turns a pile of results into a series.
Guides on Photos: A complete protocol for comparable submissions, Everything about submitting more than one image, How to find out how much of your score is you
Log five conditions with every submission - device and lens, distance, light source, crop and date - because a score without its conditions is not comparable to anything, including your own last result. "7.2 on Tuesday" says nothing; "7.2, rear camera, same distance as March, overcast window light" says whether it belongs beside March's.
What to write down
Five things cover most of it: device and lens, distance, light source, crop, and the date. The four variables worth deliberately fixing are the core of the list, and the date matters on top of them because it is the one thing that lets you notice a tool's own drift later, separate from anything you controlled.
This is the working version of what metrology calls a repeatability condition: the International Vocabulary of Metrology (JCGM 200:2012) lists "same measurement procedure, same operators, same measuring system, same operating conditions and same location" over a short period of time. A log is how you show which of those you actually held.
None of this needs to be elaborate. "Same phone, arm's length, window light, waist-up crop, 14 Aug" is a complete log entry. The point is not detail for its own sake - it is that the next entry can be checked against this one without relying on memory, which is exactly where an uncontrolled comparison usually fails.
Why memory is not enough
Conditions drift in ways that feel unnoticeable session to session and are obvious over months - a lamp gets moved a foot, a habit of standing slightly closer creeps in, a crop gets a little tighter each time. None of that registers as a decision, so none of it gets remembered, and a log is the only thing that catches it before it gets mistaken for a real change in the subject. It is also what makes changing exactly one variable between two submissions checkable after the fact - the log is the record that proves only one thing actually changed, rather than a claim you have to take on faith.
What it is not
A log is not a claim to precision the photograph itself does not have. A tape measurement carries its own written method as a matter of course, because that is the standard the property demands; a photo-based log is doing the same job at a smaller scale, appropriate to what a rating tool can actually claim to measure. It also is not a substitute for the tool showing its own working - a breakdown by axis, the way Rate Cock reports on public entries, tells you what moved inside the score, while your log tells you what moved outside it, and a real comparison needs both. None of this replaces what a human reviewer forms an impression from in the moment, which does not depend on a written record the way a repeated numeric comparison does - the log is specifically for the kind of comparison a model-based score invites, and the geometry a model reads from a photograph is exactly the part a log is meant to hold still.