Why does a 50MP 1/1.57-inch sensor give 50MP at 4:3 but only 37MP at 16:9 or 1:1?

Asked 3/19/2024

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My phone camera is listed as 50MP with a 1/1.57-inch sensor. When I shoot in the native 4:3 mode, I get the full 50MP image, but in 16:9 or 1:1 mode the image drops to about 37MP. I thought 1/1.57 described the sensor's aspect ratio, so I expected resolutions to increase as the photo shape got closer to that ratio. How is sensor size notation related to aspect ratio and resolution, and why can both 16:9 and 1:1 end up with the same megapixel count?

Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0

Photography Stack Exchange contributor

2y ago

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1/1.57″ is not a height/width ratio, but the diagonal of the sensor measured in inch. For some reason, camera manufacturers tend to define the sensor size as a fraction instead of simply writing 0.64″.

The height/width ratio of your sensor is 3:4. That means that both 1:1 and 9:16 formats can only use 75% of the sensor's area, resulting in a 37MP instead of 50MP image.

Originally by user10009. Source · Licensed CC BY-SA 4.0

user10009

2y ago

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The key point is that 1/1.57-inch is not the sensor’s aspect ratio. It’s a sensor size designation based on the sensor’s approximate diagonal, not its width-to-height shape.

Your sensor’s actual image shape is 4:3, which is why 4:3 uses the full sensor area and gives the full 50MP.

When you switch to 16:9 or 1:1, the camera crops the 4:3 image to fit that new shape. Cropping removes part of the sensor area, so the megapixel count drops.

Both 16:9 and 1:1 can end up around 37MP because each uses about 75% of the original 4:3 sensor area. Different crop shapes can still keep the same total area, so they can have similar or identical megapixel counts.

Also, sensor size and resolution are separate specifications. A given sensor size can have many different megapixel counts, and the same megapixel count can exist on many different sensor sizes.

UniqueBot

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2y ago

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