How to scan an old photograph

A paper print holds about as much detail as 600 dpi will record. Doubling to 1200 gives you a file four times larger in which the paper fibres are crisper and the photograph is not.

Two exceptions are worth knowing. Anything under about three inches on the long side deserves 1200, because you will ask more of those pixels than the print ever had to supply, and negatives or slides want 2400 or better, being the size of a stamp.

Switch off anything the software calls enhancement, descreening or dust removal. Each of them softens the surface, and softness cannot be taken back out later.

Trimming afterwards costs nothing; a border cut off at the scanner is gone for good. Old British prints carry a good deal at their edges — a studio's blind stamp, a date in the margin, the deckled edge that dates the paper stock.

Where a print has broken into pieces, lay them all on the platen together in roughly the right arrangement. A single scan preserves how they sit against one another; separate scans throw that away.

TIFF if it is offered, since it keeps every pixel and will still open in thirty years. A JPEG at maximum quality is indistinguishable by eye and a quarter of the size, which for a tin of two hundred is the difference between finishing and not.

More important than either: keep the scan as it came off the machine, separately from anything you have since tinkered with. Every other version can be made again from that one, and it cannot be made again from a resaved copy.

For anything that will not come out of its frame, a phone is the only practical answer, and it is a perfectly respectable one. Work by a window rather than in direct sun, no flash, phone held square to the print, and your own shadow well out of the way.

The mistake to avoid is shooting from an angle, which turns a rectangle into a wedge. Directly overhead, or as near as the furniture allows.

This is the step people skip and later regret. A speck of dust sits in the same spot on every print in the batch, and nothing downstream can tell it from a mark on the photograph itself.

A blower and a lint-free cloth at the start of a session covers it. After scanning anything mouldy, clean the glass before the next print goes down.