Dwayne Kellum

Dwayne Kellum’s video “High Altitude Balloon 24 (I_See_Stars!)” shows the curve of the horizon.  This is visible when the horizon is both above and below the center of the frame.

The camera is a Sony A7s II.  The Lens is a Sony FE 50mm F1.8.

This lens is very rectilinear.  Here is the quantification of the rectilinear properties:


This grid shows the non-fish nature of this lens. A fish-eye lens or one with strong barrel distortion causes straight lines to curve.  This lens does not have such a problem.  It does not matter if a line is above or below the center of frame.  There is not induced curve from the lens.

Screen Shot 2020-06-13 at 3.38.53 PM

Here is a screenshot from Dwayne’s video  at 117,431 feet, the yellow line is added to see the curve:

Dwayne-24 with line

Here is the same screenshot compressed to 10%:

Dwayne-24 compressed

At launch the height is 121 feet, the pressure is 29.88 inHg. https://youtu.be/JkrIm0ZUyJY?t=81

121 feet = 0.022917 miles = 36,881 meters = 36.881 km

29.88 = 758.95211 torr = 101,185 Pascals

At apex the height is 121,196 feet, the pressure is 0.15 inHg. https://youtu.be/JkrIm0ZUyJY?t=8058

121,196 feet = 22.95 miles = 36,941 meters = 36.941 km

0.15inHg = 3.81 torr = 507.9583 Pascals