Anyone know what causes this?

[Paul Harvey]

The attached is four still frames from a video I took of my MA2s taking off. I shot the vid at 30 frames per second (I know...it should have been 60 :/)

Anyway, note how the props look like they're flying off in pieces in the top two images and the props look curved in all of them.

Of course, the props were fine, straight, and intact. Does anyone know what causes this optical illusion?

Thanks,
Livingston

 

[akdrone]

It’s normal. Due to the way the camera takes the image.

 

[kodiak]

That's classic rolling shutter. Many detailed explanations exist online you can research but it's essentially caused by the way the camera sensor records each frame. The sensor scans the image one row of pixels at a time, from one side to the other, from top to bottom. When attempting to record something with extremely fast motion, like a drone rotor, the scan speed of the sensor is not fast enough to accurately capture the object in motion. So you get those weird looking bend and tear artifacts. There are cameras with what's called global shutter and they don't suffer from that issue. They expose an entire frame instantaneously (just like a film frame) and are ideal for capturing fast motion. They also have other benefits. But they are significantly more expensive and not common in consumer gear.

 

[Yorkshire_Pud]

Great captures.

 

[Yaros]

This is rolling shutter. This happens to all cameras that have an electronic shutter. Depending on your shutter speed it might not happen, instead, the props will look blurry. I also found it looking funny, it happened to me too when I took a photo with my phone of my S500 drone:



At first I really thought the props were bending, but of course that isn't possible because they are made of plastic.
But when I was taking a photo of a mavic from a mavic, this didn't happen, probably because the shutter speed is different, the props just got blurry instead, just like they appear in reality, here is a photo:

 

[spamgnome]

The Phantom 4 Pro line has a global shutter, which makes it pretty much the only consumer level drone that can do mapping.

 

[Paul Harvey]

It’s normal. Due to the way the camera takes the image.

Thanks

 

[Paul Harvey]

That's classic rolling shutter. Many detailed explanations exist online you can research but it's essentially caused by the way the camera sensor records each frame. The sensor scans the image one row of pixels at a time, from one side to the other, from top to bottom. When attempting to record something with extremely fast motion, like a drone rotor, the scan speed of the sensor is not fast enough to accurately capture the object in motion. So you get those weird looking bend and tear artifacts. There are cameras with what's called global shutter and they don't suffer from that issue. They expose an entire frame instantaneously (just like a film frame) and are ideal for capturing fast motion. They also have other benefits. But they are significantly more expensive and not common in consumer gear.

Thank you! Never heard of rolling shutter before :/

 

[Paul Harvey]

Great captures.

Thank you

 

[Paul Harvey]

This is rolling shutter. This happens to all cameras that have an electronic shutter. Depending on your shutter speed it might not happen, instead, the props will look blurry. I also found it looking funny, it happened to me too when I took a photo with my phone of my S500 drone:

View attachment 145543

At first I really thought the props were bending, but of course that isn't possible because they are made of plastic.
But when I was taking a photo of a mavic from a mavic, this didn't happen, probably because the shutter speed is different, the props just got blurry instead, just like they appear in reality, here is a photo:

View attachment 145544

Thanks, I'm going to try my mirrorless slr. Also shooting down on it at different shutter speeds...great idea!

 

[Chaosrider]

That's classic rolling shutter. Many detailed explanations exist online you can research but it's essentially caused by the way the camera sensor records each frame. The sensor scans the image one row of pixels at a time, from one side to the other, from top to bottom. When attempting to record something with extremely fast motion, like a drone rotor, the scan speed of the sensor is not fast enough to accurately capture the object in motion. So you get those weird looking bend and tear artifacts. There are cameras with what's called global shutter and they don't suffer from that issue. They expose an entire frame instantaneously (just like a film frame) and are ideal for capturing fast motion. They also have other benefits. But they are significantly more expensive and not common in consumer gear.

This explains something that's been bugging me for years!

I've taken a lot of film pictures out of the windshield of single engine prop planes, and there was never an issue. Then, when I went to taking them with a digital lens, I started getting these same weird artifacts.

It was so annoying that I just stopped doing it.

But at least now I know what it is!

Thx!



TCS

 

[PHZ]

The Phantom 4 Pro line has a global shutter, which makes it pretty much the only consumer level drone that can do mapping.

The Inspire 2’s X4s camera and x7 camera have global shutters. In fact, the X4S was essentially the same camera as the Phantom 4.

 

[jimlips]

The Inspire 2’s X4s camera and x7 camera have global shutters. In fact, the X4S was essentially the same camera as the Phantom 4.

Please explain "global shutter". I understand that the Phantom 4 was the only DJI product you could buy that had a mechanical shutter, which keeps the image from being distorted like the prop examples above. Here is a good article that explains the benefits of each: Electronic Shutter Vs. Mechanical Shutter | Pros & Cons

 

[BethanyFerrell]

This is similar to an effect found in old mechanical scanning panoramic cameras that sweep the lens from side to side, such as those used for wide-angle school portraits. Kids who were on one end of the scan would sometimes duck and dash over to the other end, so they appeared twice in the same photo.

Double Exposure: A Clever Photo Prank From Half a Century Ago

When the engineering students and staff of King's College in London gathered together to take a faculty portrait, the photographer used an old camera that

petapixel.com

In this case the scanning was much slower, of course, so distortion of shapes wasn't as evident.

 

[Harro]

There are 1080 lines in a HD picture, the camera scans the scene line by line just like a photo copier, and this takes time. Consequently each line is exposed a little later than the previous one and your propeller has moved to a new position as seen in the resulting final image.

 

[PHZ]

Global shutter is a mechanical shutter. Same thing.

 

[Deleted member 93449]

Was that before or after you left the bar?

 

[NG Wildman]

...always reminds me of the bending pencil...lol.

 

[BethanyFerrell]

...always reminds me of the bending pencil...lol.

A truly uncanny demonstration that the eye/optic nerve/brain system doesn't provide 100% accurate perception. However, since our vision doesn't use anything remotely resembling raster scanning, some other mechanism must be at work there.

As a child, I convinced several other kids that I really could make pencils become rubbery, and even vary how floppy it became (by varying how tightly I held the pencil and how I moved my hand).

 

[Bodkin's Best Photography]

The attached is four still frames from a video I took of my MA2s taking off. I shot the vid at 30 frames per second (I know...it should have been 60 :/)

Anyway, note how the props look like they're flying off in pieces in the top two images and the props look curved in all of them.

Of course, the props were fine, straight, and intact. Does anyone know what causes this optical illusion?

Thanks,
LivingstonView attachment 145539

An effect called "rolling shutter". Look it up.