Enlarging Lens
A lens optimised for projecting a flat negative onto flat paper at close range.
Measured in
mm
In depth
Unlike a camera lens, an enlarging lens is corrected for a flat field at modest magnification rather than for distant subjects, which is why a camera lens makes a poor substitute. Focal length should roughly match the negative diagonal — 50 mm for 35 mm, 80 mm for 6×6 — and the lens is normally used two stops down from wide open.
Examples in practice
A 50 mm enlarging lens at f/8 covers a 35 mm negative evenly with its best corner-to-corner sharpness.