Most photographers do not need an editorial system; they need a store: upload images, enter place and year, set the order. A headless CMS does exactly that and leaves the design in code.
What a headless CMS is
Content lives in a service with its own interface, the website fetches it through an API and decides how it looks. No theme, no plugin updates, no layout collapsing on save.
Model image fields sensibly
Five fields per frame are enough: file, place, year, material and a number. Model more and you will maintain categories nobody uses. Order belongs in its own field, otherwise the upload date decides.
Markdown for the journal
Articles can instead live as files in the project. That is free, versioned and fast, but it needs an editor. For a journal growing monthly it is the calmest option.
Cost and lock-in
Hosted services start free and get expensive with image volume. Keep the originals yourself and serve only derived sizes, and you stay independent of any one provider.