Crop factor and lens equivalent calculator
Pick the camera and mode you know, a focal length, and the camera and mode you will shoot. You get the lens that gives the same angle of view on the second, and the crop factor between the two frames.
The camera you know
The camera you will shoot
With JavaScript off this shows a 35mm on a Canon EOS C70 in Super 35 4K UHD matched on an ARRI ALEXA Mini LF in 4.3K LF 16:9.
35mm on the Canon EOS C70, Super 35 4K UHD 16:9 frames like 50.7mm on the ARRI ALEXA Mini LF, 4.3K LF 16:9, matched on the horizontal angle (24.6 mm against 35.64 mm).
| On the first | On the second | Angle |
|---|---|---|
| 14mm | 20.3mm | 82.6° |
| 18mm | 26.1mm | 68.7° |
| 24mm | 34.8mm | 54.3° |
| 35mm | 50.7mm | 38.7° |
| 50mm | 72.4mm | 27.6° |
| 85mm | 123.1mm | 16.5° |
| 135mm | 195.6mm | 10.4° |
On this page
What a crop factor really compares
A crop factor is the ratio between two frame sizes. Lenses do not change: a 35mm is a 35mm on every camera. What changes is how much of the lens's picture the recording mode reads. A smaller frame sees a narrower slice, so it looks like a longer lens.
The trouble is that a camera's sensor name says little. "Super 35" covers frames from about 22 mm to 28 mm wide, and most cameras record crops of their own sensor in some modes. That is why one site says the Super 35 crop factor is 1.44 and another says 1.6: they measured different frames. This calculator uses the recording mode's own size from the Cutvey Viewfinder gear list, so the answer is for the frame you will actually record.
Horizontal, vertical or diagonal
| Match on | Use it when | Ratio |
|---|---|---|
| Horizontal angle | You frame to the width, as almost every film and video shot is framed | width ÷ width |
| Vertical angle | You deliver vertical, or a squarer frame inside a wide one | height ÷ height |
| Diagonal angle | You compare against a photo spec sheet, which quotes the diagonal | diagonal ÷ diagonal |
Two frames with the same width but a different shape (a 3:2 open gate against a 16:9 crop of it) match exactly on the horizontal angle and not on the others.
A worked example
The director knows the look of a 35mm on the Canon EOS C70 in Super 35 4K UHD (24.6 mm wide). The job shoots on an ARRI ALEXA Mini LF in 4.3K LF 16:9 (35.64 mm wide). The matching lens is 35 × 35.64 ÷ 24.6 = 50.7mm, so a 50mm in the kit is the close match. The second frame is 1.45 times as wide as the first, which is the factor every focal length is multiplied by.
Against the usual references, a 35mm on a frame 24.89 mm wide matches a 50.6mm on full frame (36 mm wide), a ratio of 1.45.
Why matched lenses still look different
The angle matches; the rest does not. On the bigger frame the matched lens is longer, so at the same stop and framing the depth of field is shallower and the background is drawn larger behind the subject. To keep similar depth, multiply the stop by about the crop factor (T2.8 becomes about T4 for a 1.45x step): the depth of field calculator shows the change for your lenses.
Check it through the phone
Cutvey Viewfinder draws both frames on your iPhone or iPad: set the camera and mode you will shoot, add your kit, and Overview shows every lens at once. Read why a frame can look wider than the camera, the guide sensor size and field of view, or look a camera up on the camera pages.
Questions
Is the crop factor of Super 35 1.5, 1.44 or 1.6?
It depends on the frame you call Super 35. Against a 36 mm wide full frame, a 24.89 mm wide Super 35 frame is 1.45x, a 22.3 mm APS-C stills frame is about 1.6x, and a 27.99 mm ALEXA 35 open gate is 1.29x. Pick the real recording modes here and you get the right one.
Does a speed booster change the result?
Yes. A 0.71x speed booster makes a 50mm behave like a 35.5mm on the camera, so multiply the focal length by the adapter factor before you match. The app has adapter presets for this.
Can I match an anamorphic lens?
Match the spherical focal length here, then use the anamorphic calculator to add the squeeze, which widens the horizontal angle.
Related
See the frame before the camera arrives
Cutvey Viewfinder frames any camera, recording mode and lens on your iPhone or iPad. $19.99, once.