Sensor size and field of view

"Super 35" and "full frame" describe a sensor's family. What decides your frame is narrower than that: the patch of the sensor the camera reads in the recording mode you pick. Many cinema cameras offer several modes of different sizes, so two people with the same body and the same lens can be looking at different pictures. This guide shows how big that difference is, why crop factors disagree, and how to convert focal lengths between formats without getting caught.

The recording mode decides the frame

A lens projects an image circle; the sensor catches a rectangle of it; the recording mode decides how much of that rectangle becomes your picture. Shoot 4K on a camera whose sensor is wider than 4K needs, and the camera reads a smaller window in the middle. The lens has not changed, but it now sees less.

The table gives real modes from the gear data. "Crop (diagonal)" is the full frame diagonal of 43.27 mm divided by the mode's diagonal; "crop (width)" is 36 mm divided by the mode's width. The last column is what a 35 mm lens covers across in that mode.

Figures computed from the recording mode sizes in Cutvey Viewfinder's gear data, counted November 2, 2026, with the app's own rules. Each figure is computed from the mode's active area; a body's headline sensor size is never used.

Read down the ALEXA 35 rows. The same camera runs from open gate to a Super 16 window, and the 35 mm lens goes from 43.6° across to 20.2°. The angle more than halves, on one body and one lens. The ARRI ALEXA Mini LF and the Sony VENICE 2 do the same in the other direction: large format bodies with Super 35 modes.

Two crop factors, and why both exist

A crop factor compares a format to full frame, 36 × 24 mm. There are two common ways to make the comparison, and they give different answers for any frame that is not 3:2.

• By diagonal. The photo convention. Divide 43.27 mm by the mode's diagonal. It treats both frames as the same shape, which they rarely are on a cinema camera.
• By width. Divide 36 mm by the mode's width. This matches the horizontal angle, which is what you compose to on a 16:9 or 2.39 frame.

On the ALEXA 35 in 4K 16:9 (24.88 mm × 14 mm), the two give 1.52 and 1.45. A 35 mm lens there frames like a 51 mm on full frame by horizontal angle, or like a 53 mm by diagonal. Calculators differ on which they use, so check before you compare figures from two sources. The full frame equivalent that Cutvey Viewfinder prints on a shot list (marked "35mm") is the horizontal one: the focal length that gives the same horizontal angle on a 36 mm wide frame.

The Super 35 disagreement

Search for the Super 35 crop factor and you will find 1.44 in one place and 1.6 in another. Both are real numbers. They describe different frames:

The Canon APS-C row is the size shared by 31 of the Canon APS-C 3:2 stills modes in the gear data. Figures computed from the recording mode sizes in Cutvey Viewfinder's gear data, counted November 2, 2026, with the app's own rules.

So 1.44 is the Super 35 film frame's width against 36 mm: 36 ÷ 24.89 = 1.446, usually cut to 1.44. 1.6 is Canon's APS-C photo sensor by diagonal, smaller than any Super 35 frame in the table. A 16:9 Super 35 frame by diagonal lands near 1.5. Digital "Super 35" modes also vary in width by a few millimeters from maker to maker, which moves the figure again. The useful habit is to stop asking what Super 35's crop factor is, and ask what your mode's width is.

Converting a focal length to full frame

For the ARRI ALEXA 35 in 4K 16:9, here are common focal lengths with their horizontal angle and both full frame equivalents:

The two equivalents differ because a 16:9 mode is wider for its diagonal than a 3:2 frame. If you are matching framing for a 16:9 or wider delivery, use the width. Stills photographers usually work by the diagonal, so ask which one is meant when a figure comes from that side.

The crop factor calculator runs both for any two modes in the database, and the field of view calculator gives the angles.

Where the mode sizes come from

Every frame on this page rests on the size of one recording mode. In Cutvey Viewfinder's gear data, counted November 2, 2026, 958 of the 2,309 modes are read from a published figure and 1,245 are worked out from the published pixel pitch and pixel count; the rest are derived another way or matched to the maker's own field of view figure. 108 modes carry a Provisional badge until a second check. The app prints a line under each mode saying which applies and when it was retrieved.

That is why the app asks for the recording mode before anything else, and why its frame is as accurate as its sources. If a frame ever looks wider than your camera, the usual cause is a mode set to open gate while the camera shoots a crop: the frame looks wider than my camera has the fix. Every body and mode in the data is listed in the gear search.

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