Glossary
Aperture
Also called: f-stop, f-number
The opening inside the lens that controls how much light passes through.
People get the f-number backwards at first. f/2.8 is wider than f/11, which is a bigger number but a smaller hole. A wide aperture like f/1.8 lets in a lot of light and throws the background out of focus. Stop down to f/16 and you get a much sharper background but you need more light to compensate. Every whole stop, whether f/2.8 to f/4 or f/8 to f/11, halves the light exactly, same as one stop of shutter speed or ISO.
Where this shows up in the app
Aperture f/0.95 to f/64 with half/third stops
Pick aperture in full, half, or third stops across the entire practical range.
Viewfinder > Aperture chip, or Equipment tab > Lenses
Custom f-stop entry
Type any f-number for unusual or vintage lenses.
Equipment tab > Lenses > Add Custom Lens, or Viewfinder > Aperture chip > Custom
Aperture Priority
Hold aperture; the solver picks the matching shutter.
Viewfinder > Priority Mode chip > Aperture