The frame looks wider than my camera
Most often the recording mode is set to open gate while the camera will shoot a crop. Pick the exact mode you will record and the frame tightens to match.
Viewfinder works the frame out from the size of the recording mode, not the whole sensor. On the same lens, 4.6K 3:2 open gate on an ALEXA 35 sees 47.2° across at 32mm, and 4K 16:9 sees 42.5°.
- Tap the strip at the top of the viewfinder (camera, mode and aspect) to open Setup.
- Choose the recording mode you will actually shoot, for example 4K 16:9 rather than 4.6K 3:2 Open Gate.
- Read the line under the mode. It says who published the size, or that it was worked out from the pixel size.
- If you will use a speed booster or an extender, set it under Lens Adapter so the focal length is right.
If that didn't work
Every iPhone camera is a little different from the next one. Measure yours once in Settings, Calibration, and Viewfinder uses that correction from then on. A mode marked Provisional is still waiting for a second check of its size, so give it a little more room. Why the mode matters as much as the lens is in the sensor size guide, and the crop factor calculator compares two formats.
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Updated November 2, 2026