1
Focal length is physical
A 35 mm lens remains a 35 mm lens on every camera; the sensor changes how much of its image circle is captured.
Lens basics
Lens Equivalent Calculator
Inputs
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How to use this lens equivalent calculator
- Choose the source format. This is the camera or sensor size where the lens is currently used.
- Choose the target format. This is the system you want to compare or match.
- Enter focal length. The result shows the focal length that gives a similar field of view.
- Enter aperture. The equivalent f-number compares depth of field for matched framing, not exposure.
- Use full-frame equivalent carefully. It is a comparison language, not a change to the physical lens.
5 Fun Facts about Lens Equivalence
2
Crop factor compares diagonals
Most crop factors compare sensor diagonals against full frame, not just width or height.
Format math
3
Exposure does not change
F/2.8 meters as f/2.8 on any format; equivalence is about framing, depth of field, and total image noise context.
Exposure truth
4
Medium format goes wider
A crop factor below 1 means the same focal length looks wider than it does on full frame.
Big sensors
5
Speed boosters reverse crop
Focal reducers concentrate the image circle, reducing effective crop and increasing light per sensor area.
Adapter trick
About this lens equivalent calculator
Lens equivalence helps photographers and filmmakers compare the look of camera systems with different sensor sizes. The most common use is matching field of view: a 25 mm lens on Micro Four Thirds frames similarly to a 50 mm lens on full frame because Micro Four Thirds has roughly a 2x crop factor. The lens itself has not changed, but the smaller sensor records a narrower portion of its image circle.
Aperture equivalence is a separate comparison. The exposure setting does not change across formats; f/1.8 still passes the same exposure per unit area. Equivalent aperture describes depth of field and overall image rendering when framing and viewing conditions are matched. That distinction matters when comparing background blur, subject separation, and noise expectations between full frame, APS-C, Micro Four Thirds, and medium format systems.
Use this calculator when planning a camera switch, matching A-cam and B-cam framing, buying lenses for a new mount, or translating recommendations from one format to another. It is especially useful for hybrid productions where one camera shoots full frame and another uses APS-C crop, Super35-style framing, or Micro Four Thirds. Treat the numbers as a practical starting point, then verify composition and focus behavior with the real lens.
For practical shot planning, combine equivalence with actual tests. Two lenses with equivalent numbers can still render differently because of optical design, focus breathing, close-focus behavior, coatings, and bokeh shape.