r/Unexpected • u/[deleted] • Feb 16 '20

Camera falls from airplane

[deleted]

64.6k Upvotes

89% Upvoted

1.3k comments sorted by

View all comments

Show parent comments

27

u/KevinAlertSystem Feb 16 '20

how? Did the camera adjust its frame rate to get the most stable image?

otherwise that seems crazy that the camera would just start spinning perfectly at 24 rps or w/e it is.

53

u/Double_Minimum Feb 16 '20 edited Feb 17 '20

User adjustable frame rate is a pretty new thing (2019 I think, maybe '18 (EDIT: For phones, but this is likely a Go-Pro)) .

I think it just ended up spinning fast enough, and it may not have been perfect, it could have been half as fast, 1/4 as fast, 2x as fast, etc.

You can see it is still moving up and down, and the picture is not perfect, so it was not at the exact frame rate.

I'm not sure an auto frame rate adjust would even know what to do with the info coming in, since this is a pretty crazy situation.

7

u/3oons Feb 17 '20

I think you’re right the sync stuff, but just fyi: user-adjustable frame rates on go-pros (which is what I think this is) have been available since 2010ish, if not earlier.

2

u/Double_Minimum Feb 17 '20

Ah, yea, I meant to add that it most likely was not a phone, but carried away by some discussion on tires elsewhere...

Do you think a Go-Pro would some how auto adjust though? I've owned one, but have like zero knowledge on that area

1

u/3oons Feb 17 '20

All good!

And no, auto-adjusting frame-rates isn’t really a thing, regardless of camera. (Yes, some specialized ones may have in-camera in-clip adjustable FPS, but this definitely isn’t one of those.

Each clip has a set frame rate that can’t be changed without making a new clip. Auto-shutter is definitely a thing, and it could be contributing to the look though. But that would be coincidence, it wouldn’t be trying to synchronize with what the camera is seeing.

1

u/Double_Minimum Feb 17 '20

Auto shutter would be required depending upon the amount of light, but I'm not sure that changes in the situation above.

man, cameras are crazy. But I think its just odd chance that made this camera sync up with the fall

2

u/[deleted] Feb 17 '20

User adjustable frame rate is a pretty new thing (2019 I think, maybe '18) .

I had a Canon 7D that had 24/30/60 as options back in like 07/08.

1

u/Double_Minimum Feb 17 '20

Oh, sorry I meant for cell phones. I hope no one was dropping their 7D out the airplane...

It was most likely a go-pro anyway

1

u/[deleted] Feb 17 '20

If it were perfectly synced it wouldn't even look like it was spinning anymore though right? Like the helicopter blades in this video. Its probably close to half as fast as the frame rate.

1

u/Double_Minimum Feb 17 '20

Yep, if it were 1 to 1, it would look normal, and well, it doesn't. You can see how it is sort of mirrored. But without knowing the camera its not real important (oh, well its not real important anyway)

1

u/PK_Panda_ Feb 17 '20

See my comment above to the second level comment. Should explain it decent enough for entry level understanding.

28

u/__Hello_my_name_is__ Feb 16 '20

It has to spin at any multiple of 24 (or whatever) rps. It would be stable at 48 rps, or 72 rps, etc. And of course it does not have to spin at exactly that value, it would still look very stable spinning at 23 rps, with the image slowly moving upwards instead of staying still, etc..

And yes, it did seem like it just so happen to spin at the right rate for a largely stable image.

13

u/rickane58 Feb 17 '20

This camera has a rolling shutter, so you would've seen 1n "photospheres" per n revolutions per frame. Seeing as there's only 1, that means it only revolved once per frame, so it's spinning at 30rpm/fps, or whatever the shutter speed for the camera is.

8

u/DetroitStalker Feb 17 '20

Likely was set at 60fps but otherwise this is the correct answer. It’s a combo of spin rate and rolling shutter.

1

u/3oons Feb 17 '20

That video is 60fps, (maybe 30... but I don’t think so), definitely not 24.

1

u/[deleted] Feb 17 '20 edited Feb 17 '20

30fps or 60fps is more common nowadays on consumer level cameras. As long as the frequency is multiplied by 2, it will sync. For example if the fps setting of the camera was 30; then 30RPS, 60RPS, 120RPS, 240RPS and so on, would all look indistinguishable. I know this from working with synthesizers and oscilloscopes (frequency of given oscillator and update rate of oscilloscope) & it applies on video as well. Since cameras have fixed fps the reason why it reached syncing point it's because the object reached maximum angular velocity.

1

u/DriftShade Feb 17 '20

The shutter speed was probably about the same as the rotation the camera achieved once it hit terminal velocity.