Director’s Viewfinder: Frame Lines for Any Lens

As accurate as the phone camera’s angle is known. After measuring with a sheet of A4, the frame differs from the real shot by a few percent: slight distortion in the phone’s lens and how squarely you hold the phone to the sheet both play a part. Without a measurement a typical angle is used and the error can be noticeable — the page warns you about that.

In video mode the phone crops the picture: to 16:9 and for stabilization, and differently from browser to browser. So the angle in the spec sheet doesn’t match what reaches the page. The measurement takes a minute and is remembered for that camera.

A frame wider than the picture isn’t drawn — the page names the widest lens that fits. Step back to judge the composition, or switch to another of the phone’s cameras if the browser offers one.

Usually there’s nothing to enter: the phone writes the 35 mm equivalent focal length into the photo, and the page reads it by itself. If the record is missing — for example, the photo went through a messaging app — enter the number from the main camera’s specs: most often 24–26 mm.

The same lens sees narrower on a smaller sensor. 35 mm on Super 35 gives the same frame as roughly 50 mm on full frame, and on Micro 4/3 the same as 73 mm. Choose your camera’s sensor and the frames are recalculated.