How the Darkroom Enlarger calculator works
Print exposure, contrast, magnification, and dodge/burn timing.
Where to find it
Tools tab Darkroom Enlarger
Summary
Calculator for darkroom printing: works out exposure time for variable paper sizes and magnifications, multigrade contrast settings, and dodge/burn moves you can rehearse before committing the print.
Detail
How it works
Printing in a darkroom is exposing photographic paper to light projected through your negative by an enlarger. This modal helps you work out the exposure time, the contrast (multigrade) setting, the magnification, and any dodge or burn extras for the print you are making.
Negative format and paper size
Tells the modal the magnification you are working at. A 35mm negative blown up to 16x20 inch paper is around 13x. A 4x5 negative blown up to the same paper is only 4x. Bigger magnification needs longer exposure (and shows more grain).
Base exposure
Your starting time for the print, found by test-stripping. The modal lets you save it and adjusts when you change paper size or magnification so you do not have to test-strip every time.
Multigrade contrast
Variable-contrast paper changes contrast based on the colour of the enlarger light. Numbers from 0 (very soft) to 5 (very hard) correspond to different filter values. Pick the grade that matches your negative's contrast.
Dodge and burn
Dodging holds back light from a part of the print to lighten it (less exposure). Burning adds extra light to a part of the print to darken it (more exposure). The modal lets you queue up dodge and burn moves with their times so you can rehearse the print before you commit it.