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Earth rotation limits in-body image stabilization to 6.3 stops (2020)

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Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#11

Post by tetris11 »

seszett wrote: post #5
tetris11 wrote: post #3

I still don't quite follow the explanation. The duck and I are on the surface of the same body and are rotating together, maintaining a constant distance... why does Earth rotation need to be corrected for?

It's explained here: > Your camera, which is using its IBIS system to attempt to keep everything as still as possible, may not realize that you are rotating with your subject and will instead try to zero out any rotation of the camera, including that of the Earth The problem is that the stabilization system tries to compensate for the rotation of Earth (because it can't make the difference between the rotation of Ear…

I guess I couldn't quite grok how IBIS would measure the Earth's rotation whilst being on Earth, but as I've now just learned (through various slaps of the forehead) a perfectly vertical spinning gyroscope will definitely tilt with time due to the Earth's rotation and this is measurable to high degrees of precision.

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#13

Post by isoprophlex »

> The second solution is much more plausible, but still very difficult. The user would have to be pointing the camera at the subject for long enough such that the drift in their aim at the subject is smaller than the drift from the rotation of the earth. This is also implausible. What is concerning though, is that this second method is one that could work very well to cancel out Earth’s rotation on the CIPA specified stabilization test apparatus.

So, basically dieselgate but for image stabilization

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#14

Post by anilakar »

tetris11 wrote: post #11
seszett wrote: post #5

Earlier quoted context omitted.

It's explained here: > Your camera, which is using its IBIS system to attempt to keep everything as still as possible, may not realize that you are rotating with your subject and will instead try to zero out any rotation of the camera, including that of the Earth The problem is that the stabilization system tries to compensate for the rotation of Earth (because it can't make the difference between the rotation of Ear…

I guess I couldn't quite grok how IBIS would measure the Earth's rotation whilst being on Earth, but as I've now just learned (through various slaps of the forehead) a perfectly vertical spinning gyroscope will definitely tilt with time due to the Earth's rotation and this is measurable to high degrees of precision.

Not just randomly tilt - it will align itself with the poles of a spinning celestial body. It's used in applications that can't rely on correct magnetic variation, like surveying and aircraft inertial navigation systems.

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#15

Post by DoctorOetker »

This can be fixed in software:

you can back calculate orientations with high pass filterd gyro data, to rotate the unfiltered gyro date into the current reference frame, then low pass the unfiltered but rotation corrected gyro data to get the earth rotation axis in the current reference frame, then one can estimate the expected rotation that should be ignored.

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#17

Post by Gravityloss »

tetris11 wrote: post #3

I still don't quite follow the explanation. The duck and I are on the surface of the same body and are rotating together, maintaining a constant distance... why does Earth rotation need to be corrected for?

There was an escape system in the Soyuz rocket that fired if the rocket tilted too much. It was based on gyroscopes.

Once, a launch was aborted just before liftoff. The rocket stayed on the pad and the cosmonauts were sitting in the spacecraft for some time. Suddenly the abort system fired and pulled the capsule from the rocket. They landed safely on parachutes.

It was discovered that earth had rotated and the gyroscope had detected the tilt of the rocket, so it fired the escape system.

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#18

Post by nimbleal »

kqr wrote: post #2

6.3 stops is a lot, though. That's basically the fully usable aperture range of a kit zoom lens.

Yes, or considered another way 1/25th shutter vs almost 1/2000th, ie a lot of motion blur vs. virtually nothing will be able to provoke blurring

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#19

Post by thrdbndndn »

seszett wrote: post #5
tetris11 wrote: post #3

I still don't quite follow the explanation. The duck and I are on the surface of the same body and are rotating together, maintaining a constant distance... why does Earth rotation need to be corrected for?

It's explained here: > Your camera, which is using its IBIS system to attempt to keep everything as still as possible, may not realize that you are rotating with your subject and will instead try to zero out any rotation of the camera, including that of the Earth The problem is that the stabilization system tries to compensate for the rotation of Earth (because it can't make the difference between the rotation of Ear…

Why does it stop at Earth's rotation? What about revolution around the Sun?

Re: Earth rotation limits in-body image stabilization to 6.3 stops (2020)

#20

Post by blueflow »

thrdbndndn wrote: post #19
seszett wrote: post #5

Earlier quoted context omitted.

It's explained here: > Your camera, which is using its IBIS system to attempt to keep everything as still as possible, may not realize that you are rotating with your subject and will instead try to zero out any rotation of the camera, including that of the Earth The problem is that the stabilization system tries to compensate for the rotation of Earth (because it can't make the difference between the rotation of Ear…

Why does it stop at Earth's rotation? What about revolution around the Sun?

It doesn't.
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