Optics calculator

Crop factor calculator

What your lens frames like on a full-frame camera, the equivalent aperture for depth of field, and which lens gives the view you want.

Camera

Lens

Focal length (mm)

Aperture (f-number)

Distance

Unit

The equivalent focal length you want (mm)

Sharpness convention and framing

Circle of confusion

Your circle of confusion (mm)

Subject height (in the distance unit)

35 mm-format framing

28.8 mm equivalent

Canon EOS R50 · 18 mm · f/4.5 · 3 m

Crop factor (the maker's convention): 1.6×
Equivalent aperture, for depth of field: f/7.2
For a 50 mm-equivalent view: 31.25 mm on the lens

Exposure still uses f/4.5: the same light reaches the sensor whatever its size.

18 lenses on this camera cover 31.25 mm

and 6 more on the camera's page.

EOS R50 lenses This lens Build a kit with it

Two cameras, one lens: what each frames

Slide the focal length and compare the view on two cameras from the same spot.

First camera

Second camera

Focal length on the lens: 50 mm

Full frame: 50 mmEOS R50: 80 mm

The same 50 mm lens frames tighter on a smaller sensor: the highlighted frame is the first camera.

Sensor sizes and crop factors

The crop factor is the full-frame diagonal (43.3 mm) divided by the sensor's diagonal. Makers round it: Canon quotes 1.6, Sony, Nikon and Fujifilm 1.5.

Format	Size	Crop factor	50 mm frames like	Examples
Medium format (44 × 33)	43.8 × 32.9 mm	0.79×	39 mm	Fujifilm GFX cameras
Full frame (35 mm)	36 × 24 mm	1.00×	50 mm	Canon EOS R6, Sony a7, Nikon Z6, the reference format
APS-C (Sony, Nikon DX, Fujifilm)	23.5 × 15.6 mm	1.53×	77 mm	Sony a6400, Nikon Z50II, Fujifilm X-T5
APS-C (Canon)	22.3 × 14.9 mm	1.61×	81 mm	Canon EOS R50, R10, R7
Micro Four Thirds	17.3 × 13 mm	2.00×	100 mm	Panasonic Lumix G and OM System cameras
1-inch type	13.2 × 8.8 mm	2.73×	136 mm	Sony RX100 and many bridge cameras
1/1.3-inch type	9.6 × 7.2 mm	3.61×	180 mm	Large phone main cameras
1/2.3-inch type	6.17 × 4.55 mm	5.64×	282 mm	Small compacts and action cameras

Our APS-C cameras

Camera	Sensor	Maker's crop
Canon EOS R100	22.3 × 14.9 mm	1.6×
Canon EOS R50	22.3 × 14.9 mm	1.6×
Canon EOS R50 V	22.3 × 14.9 mm	1.6×
Canon EOS R10	22.3 × 14.9 mm	1.6×
Canon EOS R7	22.3 × 14.8 mm	1.6×
Sony a6000	23.5 × 15.6 mm	1.5×
Sony a6100	23.5 × 15.6 mm	1.5×
Sony a6400	23.5 × 15.6 mm	1.5×
Sony a6600	23.5 × 15.6 mm	1.5×
Sony a6700	23.3 × 15.5 mm	1.5×
Sony ZV-E10	23.5 × 15.6 mm	1.5×
Sony ZV-E10 II	23.3 × 15.5 mm	1.5×
Sony FX30	23.3 × 15.5 mm	1.5×
Nikon Z30	23.5 × 15.7 mm	1.5×
Nikon Z50	23.5 × 15.7 mm	1.5×
Nikon Z50II	23.5 × 15.7 mm	1.5×
Nikon Z fc	23.5 × 15.7 mm	1.5×
Fujifilm X-T5	23.5 × 15.7 mm	1.5×
Fujifilm X-T50	23.5 × 15.7 mm	1.5×
Fujifilm X-T30 III	23.5 × 15.6 mm	1.5×
Fujifilm X-T30 II	23.5 × 15.6 mm	1.5×
Fujifilm X-S20	23.5 × 15.6 mm	1.5×
Fujifilm X-S10	23.5 × 15.6 mm	1.5×
Fujifilm X-M5	23.5 × 15.6 mm	1.5×
Fujifilm X-E5	23.5 × 15.7 mm	1.5×
Fujifilm X-E4	23.5 × 15.6 mm	1.5×
Fujifilm X-H2	23.5 × 15.6 mm	1.5×
Fujifilm X-H2S	23.5 × 15.6 mm	1.5×
Fujifilm X-T4	23.5 × 15.6 mm	1.5×
Fujifilm X-Pro3	23.5 × 15.6 mm	1.5×

How the numbers are worked out

These are geometric estimates from the thin-lens model, not a sharpness test. They leave out focus breathing, distortion and close-up magnification; distance is measured from the sensor.

Depth of field depends on the circle of confusion: the blur diameter on the sensor you accept as sharp. Equivalent focal length compares framing with full frame; equivalent aperture compares depth of field at the same framing and distance, and never changes exposure.

Where the inputs come from

Sensor sizes and crop factors are each camera maker's. Focal ranges, the widest apertures at the ends of a zoom and closest focus distances are each lens maker's, checked 2026-10-09. A zoom's widest aperture between its ends is not published, so it is not checked there.

Formulas and assumptions

Questions

Does crop factor change the aperture?

Not for exposure: f/1.8 lets in the same light per area on any sensor. For depth of field at the same framing, multiply the f-number by the crop factor: f/1.8 on APS-C looks like about f/2.7 on full frame.

Why is Canon 1.6 and the others 1.5?

Canon's APS-C sensors are a little smaller (about 22.3 × 14.9 mm) than Sony's, Nikon's and Fujifilm's (about 23.5 × 15.6 mm). Each maker quotes its own figure, and we use the maker's.

Which lens gives a 50 mm look on APS-C?

About 33 mm on Sony, Nikon or Fujifilm and about 31 mm on Canon. The reverse result lists every lens in our catalogue that covers it on your camera.

Does a full-frame lens on an APS-C camera have a crop factor too?

Yes. The crop comes from the sensor, not the lens: a full-frame 50 mm frames like 75 mm on Sony APS-C, exactly as an APS-C 50 mm would.