4 ms·

How is this actually accomplished, though?

diggernet 3y ago
The camera was on an equatorial telescope mount. "An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, the polar axis, parallel to the Earth's axis of rotation."
taejo 3y ago
An equatorial mount keeps the camera pointing in a fixed celestial direction by rotating at the same rate as the Earth in the plane of the equator. It's essential for any long exposure of the sky where you don't want star trails, the unusual thing here is having the horizon in frame.
shagie 3y ago
Mount Sky-Watcher Star Adventurer Tripod Manfrotto MT055XPRO3 The tripod is a good, heavy, stable one. https://www.manfrotto.com/us-en/055-aluminum-3-section-tripod-with-horizontal-column-mt055xpro3/ https://www.manfrotto.com/us-en/055-aluminum-3-section-tripo... The head is https://www.skywatcherusa.com/collections/star-adventurer/products/star-adventurer-pro-pack https://www.skywatcherusa.com/collections/star-adventurer/pr... which is a bit more fancy than the old school equatorial mounts.... but Star Adventurer 2i multi-function equatorial tracking mount with built-in Wi-Fi control It's still an equatorial mount. https://astrobackyard.com/equatorial-telescope-mount/ https://astrobackyard.com/equatorial-telescope-mount/ https://en.wikipedia.org/wiki/Equatorial_mount https://en.wikipedia.org/wiki/Equatorial_mount You adjust the base to the latitude that you are at so that the mount can rotate to match the Earth's rotation on one axis, and then the other axises can track ascension and declination - which remain constant in the sky. This differs from the altazimuth mount ( https://en.wikipedia.org/wiki/Altazimuth_mount https://en.wikipedia.org/wiki/Altazimuth_mount ) where a celestial object is that that location now, but moves. Sirius is at 06h 45m 08s RA and -16° 42’ 57”... but as I type this, as seen from Greenwich, United Kingdom it would be at -27.4° altitude (below the horizon), 277.5° azimuth - and that coordinate system moves.
worldsavior 3y ago
Instead of turning with the earth, it stays "in place". Meaning it turns to the opposite of the Earth's rotation.
Smoosh 3y ago
It is easier to understand if you imagine that the observer is at the south pole looking up, instead of thinking of them on the equator going around. In reality, they are somewhere between the two extremes.
travisjungroth 3y ago
You could also get the same effect with a regular tripod, time-lapse photography and a rotation effect. The sky would look normal though, not like in this. https://en.wikipedia.org/wiki/Time-lapse_photography https://en.wikipedia.org/wiki/Time-lapse_photography
OJFord 3y ago
Sibling comments say/explain how it is done 'properly', but surely you could just 'lock to the ground' and then animate it flipping 'in post'? It's not like we need the fancy camera mounts to know how the rotation goes?
- poglet 3y ago
  Wouldn't the equatorial mount prevent star trails? I guess you could compensate with a shorter exposure time, and perform the rotation in post. I assume it's only possible to do from some angles of the sky.
- taejo 3y ago
  The linked source names the mount used, the Sky-Watcher Star Adventurer, but yes, you could replicate this in post, except that the frames have exposure times of up to 45 seconds, which would give star trails within individual frames.

The camera was on an equatorial telescope mount. "An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, the polar axis, parallel to the Earth's axis of rotation."

taejo 3y ago

An equatorial mount keeps the camera pointing in a fixed celestial direction by rotating at the same rate as the Earth in the plane of the equator. It's essential for any long exposure of the sky where you don't want star trails, the unusual thing here is having the horizon in frame.

shagie 3y ago

Mount Sky-Watcher Star Adventurer Tripod Manfrotto MT055XPRO3 The tripod is a good, heavy, stable one. https://www.manfrotto.com/us-en/055-aluminum-3-section-tripod-with-horizontal-column-mt055xpro3/ https://www.manfrotto.com/us-en/055-aluminum-3-section-tripo... The head is https://www.skywatcherusa.com/collections/star-adventurer/products/star-adventurer-pro-pack https://www.skywatcherusa.com/collections/star-adventurer/pr... which is a bit more fancy than the old school equatorial mounts.... but Star Adventurer 2i multi-function equatorial tracking mount with built-in Wi-Fi control It's still an equatorial mount. https://astrobackyard.com/equatorial-telescope-mount/ https://astrobackyard.com/equatorial-telescope-mount/ https://en.wikipedia.org/wiki/Equatorial_mount https://en.wikipedia.org/wiki/Equatorial_mount You adjust the base to the latitude that you are at so that the mount can rotate to match the Earth's rotation on one axis, and then the other axises can track ascension and declination - which remain constant in the sky. This differs from the altazimuth mount ( https://en.wikipedia.org/wiki/Altazimuth_mount https://en.wikipedia.org/wiki/Altazimuth_mount ) where a celestial object is that that location now, but moves. Sirius is at 06h 45m 08s RA and -16° 42’ 57”... but as I type this, as seen from Greenwich, United Kingdom it would be at -27.4° altitude (below the horizon), 277.5° azimuth - and that coordinate system moves.

worldsavior 3y ago

Instead of turning with the earth, it stays "in place". Meaning it turns to the opposite of the Earth's rotation.

Smoosh 3y ago

It is easier to understand if you imagine that the observer is at the south pole looking up, instead of thinking of them on the equator going around. In reality, they are somewhere between the two extremes.

travisjungroth 3y ago

You could also get the same effect with a regular tripod, time-lapse photography and a rotation effect. The sky would look normal though, not like in this. https://en.wikipedia.org/wiki/Time-lapse_photography https://en.wikipedia.org/wiki/Time-lapse_photography

OJFord 3y ago

Sibling comments say/explain how it is done 'properly', but surely you could just 'lock to the ground' and then animate it flipping 'in post'? It's not like we need the fancy camera mounts to know how the rotation goes?

poglet 3y ago
Wouldn't the equatorial mount prevent star trails? I guess you could compensate with a shorter exposure time, and perform the rotation in post. I assume it's only possible to do from some angles of the sky.
taejo 3y ago
The linked source names the mount used, the Sky-Watcher Star Adventurer, but yes, you could replicate this in post, except that the frames have exposure times of up to 45 seconds, which would give star trails within individual frames.