wide(r) angle view for your old ATC2K action cam

Step 6 Evaluation

I tested the cam in a large black bucket.
From a standard distance I shot video of a ruler. Then I counted the amount of millimeters on the ruler in the video.
distance between the cam and the ruler is 240(ish) mm

in air, no lens : 135 mm seen

in air with lens : 225 mm seen

in water, no lens : 105 mm seen

in water with lens : 150 mm seen

if my math skills are still intact I guess this is a viewing angle of
15 deg.
25 deg
11 deg[
17 deg
respectively.

I calculated the angle between the center of the picture and one of the sides.
you could argue the angles should be multiplied by 2 (i.e. measured from side to side)

a very nice improvement for a 5-dollar lens...

and just for fun :
jellylens without cover in water :

a leak in the lens (after I demolished lens #1)

a video riding on the back of a model submarine (this was long before the hack ...)

Have fun !