Variable vs Fixed F-Stops What's the Difference?
Ever wondered why some zoom lenses have a fixed maximum aperture while others change as you zoom?
In this Foto Tip, I'll explain the difference between fixed and variable maximum apertures, how they affect exposure and what to consider when choosing a lens.
Watch the video and explore the foto examples below to see how aperture works.
Fixed vs Variable Aperture – Foto Examples
Fixed Maximum Aperture Lens
A fixed maximum aperture lens maintains the same widest available F-stop throughout its zoom range. For example, a 24–70mm f/2.8 lens can shoot at f/2.8 whether you're at 24mm or 70mm.
Shallow Depth of Field – Blurred Background
These two fotos show how changing your aperture affects depth of field. A wider aperture (smaller F-stop number) creates a shallower depth of field, making the background appear more blurred. A narrower aperture (larger F-stop number) keeps more of the scene in focus.
Variable Maximum Aperture Lens
A variable maximum aperture lens changes its widest available F-stop as you zoom.
For example, an 18–135mm f/3.5–5.6 lens can open to f/3.5 at 18mm, but only to f/5.6 at 135mm.
These lenses are often lighter and more affordable than constant-aperture zoom lenses.
