A fisheye lens distorts images. It results in images having barrel distortions. In a fisheye lens, a straight line can appear curved. But some flat-Earthers don’t realize that the opposite is also true, a fisheye lens can easily make a curved line look straight.
High-altitude balloon footage is often abused by flat-Earthers to show us that the Earth is flat when seen from a high altitude.
We analyzed more than two dozens of footage taken from high-altitude balloons on YouTube, and we can easily conclude the curvature is there and usually easy to spot, including in the cases where flat-Earthers use the video as ‘proof’ of a flat Earth.
Little Piggy is the nickname of a helium balloon launched by IndianaCaver. It reached the altitude of almost 37 km, before it finally ruptured and fell to the Earth. Before that, it took several hours of video, and IndianaCaver made these video available on YouTube.
Then, some flat-Earthers cherry picked bits of video where the horizon looks flat and presented it as ‘proof’ of flat-Earth. These are widely circulated in various memes and forms, even years after the originals were published.
But, can we really use these videos as ‘proof’ of flat-Earth?
A good majority of pictures of Earth taken from space are being dismissed by flat earthers simply because they are taken using fish-eye lenses. They believe any curvature of Earth shown in these picture are caused by fish-eye effect, and thus, cannot be used as evidence of Earth curvature. They even take a step further: any picture showing curvature of Earth must have been taken by a fish-eye lens.
These claims are, of course, ungrounded. In some cases, we can conclude the curvature is there, even when a fish-eye lens is being used. We can use this useful property of any photographic lens:
A straight line will appear straight as long as it crosses the center point of the image.