Jamie Laycock hired a company to launch a high altitude helium balloon and they made it to 99,858 ft. The curvature is obvious.

Image from 99,858 feet Altitude

This is a screenshot from the original video provided by Jamie:

Camera used in Linear Mode

They were using a GoPro in Linear mode with a focal length of 24 mm.

Linear field of view (referred to as "lens" on HERO10/9/8 Black and MAX) captures astraight horizon with a more natural perspective. This mode eliminates the barrel distortion (fish-eye effect) typically captured by your GoPro's wide-angle lens, without compromising image quality.

Source: What Is Linear Field Of View (FOV)?; GoPro.com

Linear FOV is particularly useful for aerial footage shot from drones, but it’s also a good option to have any time you’re after a more traditional perspective.

Source: GoPro Linear FOV: Pros, Cons & Examples

Prediction and Match with Image

Using my Curvature App I can get a prediction of how earths curvature should look like if I know the altitude and field of view (FOV) or focal length of the camera and the camera does not use a fisheye lens or is used in linear mode (removing lens distortions numerically before storing the image or vodeo).

Here is an overlay of the image with the prediction of the Curvature App: Click here to show the image in my Curvature App.

Hint: click into the image in my Curvature App to change the transparency of it, left side to make it more transparent, right side to make it less transparent.

Summary

Not only can we see clear earth curvature here on a non-distorted image, but it also matches perfectly the globe earth prediction.

More High Altitude Footage