Equivalent focal length
See how a lens on medium or large format compares to a 35mm field of view.
About this tool
Different film formats crop the image circle differently, so the same focal length frames a scene differently on each. Enter a focal length on one format and pick a target format, and this tool returns the focal length that gives the same angle of view. It is the quick way to translate a favourite 35mm lens into medium or large format terms.
How to use it
- Select the source format and enter the focal length you know.
- Select the target format you want to match.
- Read the equivalent focal length that reproduces the same field of view.
FAQ
Does an equivalent focal length change depth of field?
It matches the angle of view, not the depth of field. A larger format needs a longer lens to frame the same scene, and that longer lens renders shallower depth of field at the same aperture.
Which measurement is used to match formats?
The tool scales by the diagonal of each frame, so the equivalent lens reproduces the same diagonal angle of view. Slight aspect-ratio differences between formats can still shift horizontal and vertical coverage.