Why Fast Pans Bend Straight Lines

Most CMOS sensors don’t expose an entire frame at once — they scan it line by line from top to bottom. If the camera or subject moves fast enough horizontally during that scan, each line ends up capturing a slightly different moment, skewing verticals into a diagonal lean. This tool estimates how much skew a given pan speed and sensor readout time will actually produce.

Readout Time Is the Key Variable

Sensor readout time — how long it takes to scan a full frame — varies enormously between cameras. Global shutter sensors read the whole frame at once (zero skew, but rare and expensive). Fast stacked CMOS sensors read out in around 16 milliseconds. Older DSLR video modes and many smartphones can take 30 milliseconds or more, making them far more prone to visible skew on the same pan.

Reading the Severity Estimate

The tool converts pan speed and readout time into a skew angle, then expresses that as both a pixel count and a percentage of frame width, since the same angular skew looks more or less severe depending on your field of view. Use it before a fast whip pan or a fast-moving subject shot to decide whether you need a global-shutter camera, a slower pan, or a wider lens to keep the effect under control.

This tool is especially useful for:

• Cinematographers planning fast pans or whip pans on rolling-shutter cameras.
• Drone and gimbal operators shooting fast lateral motion.
• Anyone choosing between cameras for a shoot involving fast horizontal motion.