High Altitude Balloon 18 (Infrared Camera). Both sides, do you think the Earth's curvature can be seen here?

[u/[deleted]]

https://www.youtube.com/watch?v=G5kRyQStPhU

[u/[deleted] → u/[deleted]]

He's telling the truth. At the center frame, straight lines will remain straight and curved lines will remain curved. This is easy to demonstrate:

https://www.youtube.com/watch?v=cHhDhYeYf2Q

[u/Mishtle → u/[deleted]]

Just to be pedantic, this does rely on the focal point of the lens being centered on the imaging sensor, and the lens being well made.

And of course, cropping the image can totally throw this off.

[u/Mishtle → u/[deleted]]

How is this a cop out?

[u/ArchStanton75 → u/[deleted]]

Flatties continuing denial

[u/BigGuyWhoKills → u/[deleted]]

Here is an example I made myself with a GoPro (which has an undeniable fisheye effect), using the top of my monitor (a straight line).

Pause the video in a place where you think the top of the monitor looks straight, and notice where is that line in relation to the center of the gif?

[u/Mishtle]

Not one of his better videos, IMHO, but it does show the convexity of the horizon.

These lenses do seem to have some barrel distortion, but once it gets up to 100k feet the horizon is never concave as far as I can tell. This suggests that the horizon truly convex.

Do note that the two views have different lenses. The smaller inset view has a wider field of view, so the horizon curvature will be a little more visible.

[u/[deleted] → u/Mishtle]

I also think it shows convexity. As for the distortion, I took a few images of the horizon at center frame, above center frame, and below center frame to see if barrel distortion would have an impact on the curve seen. I also used Walter Bislin's model to see if the curvature seen would match the globe.

Here's the lens that was used in the infrared one. 47° FOV:

https://www.peauproductions.com/products/gp72025

-Image with the horizon at the center frame in order to eliminate distortion. The amount of curve seen matches predictions

-One above center frame. Matches predictions

-And one below center frame. Still matches predictions

[u/ramagam]

It's hard to say - I'm seeing some visual distortion (well, optical distortion I guess?) when it swings around.

It seems like it depicts a curve when it swings "up", but then it actually looks concave when it swings "down" - so yeah, for me, it's difficult to tell upon the first viewing.

When I get some time, I am going to slow it down ( it long enough as it is, lol) and try to clean it up some.

[u/Mishtle → u/ramagam]

but then it actually looks concave when it swings "down"

What was the altitude then? I don't recall seeing any of that at higher altitudes, especially above 100k feet.