5 ms·

ahh wouldn't the star tracker require pretty specialized or higher powered hardware? seems a bit much to cram into a camera no? unless you want the cost to incr

by dmead 5y ago

ahh wouldn't the star tracker require pretty specialized or higher powered hardware? seems a bit much to cram into a camera no? unless you want the cost to increase by the cost of 1 cell phone?

KMnO4 5y ago
The hardware is already there. You don’t need to move much to counteract the movement of the stars. Many cameras have in body stabilization, which can move the sensor around. Pentax had had this for a while (as early as 2011). https://www.ricoh-imaging.co.jp/english/explore/astro/ https://www.ricoh-imaging.co.jp/english/explore/astro/
user_7832 5y ago
I doubt you need that much hardware/costs, given that even an Arduino can do it [1]. From an outsider's perspective though, camera companies are probably hesitant to shake up what's already there which is probably they don't add such features. 1. https://blog.arduino.cc/2020/02/26/openastrotracker-is-a-tracking-and-goto-mount-for-dslr-astrophotography/ https://blog.arduino.cc/2020/02/26/openastrotracker-is-a-tra...
gridspy 5y ago
Sounds like it's a pretty simple loop of 1. Find bright spots in last second of exposure (which is then added to a sum for the final picture) 2. Compare their locations to bright spots in the previous second 3. Move the sensor slightly so the bright spots remain "in the same place" on the sensor. Note that cameras with integral anti-vibration do that by moving the sensor, so they already have the hardware for (3). For star tracking there would be a max speed of stars based on Earth's rotation multiplied by focal length you could use to set a reasonable cap on movement. You could also expect similar movement for each second to the seconds before. The camera could have a data structure per star being tracked, capping the number used to say 32 or 64 "stars" for accuracy. Each "Star" would "vote" how much movement has occurred. You'd gain faith in various stars as analysis frames go by if they keep giving valid results, a black-list of "not stars" would also be useful. Some would be stationary, like lights on the ground. Some would be bogus, such as navigation lights on aircraft. Actual stars should expect similar movement and "agree" though if the zoom was low it might change across the image.
azalemeth 5y ago
I have a Pentax camera (it's great -- they're undervalued by the market). The astrotracer uses GPS lookups and needs either a K-1 or a (very overpriced) GPS dongle that plugs in via the flash hotshoe. It gets an accurate lock and moves the sensor about its 5 axes of magnetohydrodynamically-controlled freedom in order to emulate, to some degree, an equatorial mount. No image-domain tracking required -- purely physics. The things people get are insanely good (c.f. [1]) [1] https://www.flickr.com/groups/2598208@N22/ https://www.flickr.com/groups/2598208@N22/
- formerly_proven 5y ago
  Mechanically there's only three degrees of freedom (translation in the plane and rotation about the optical axis), the cameras just calculate an approximately correct translation for pitch/yaw movements. Pitching or yawing the sensor itself would take it immediately out of the depth of focus (the image side equivalent of depth of field) and the image would be a blurry mess.

by dmead 5y ago

ahh wouldn't the star tracker require pretty specialized or higher powered hardware? seems a bit much to cram into a camera no? unless you want the cost to increase by the cost of 1 cell phone?

KMnO4 5y ago

The hardware is already there. You don’t need to move much to counteract the movement of the stars. Many cameras have in body stabilization, which can move the sensor around. Pentax had had this for a while (as early as 2011). https://www.ricoh-imaging.co.jp/english/explore/astro/ https://www.ricoh-imaging.co.jp/english/explore/astro/

user_7832 5y ago

I doubt you need that much hardware/costs, given that even an Arduino can do it [1]. From an outsider's perspective though, camera companies are probably hesitant to shake up what's already there which is probably they don't add such features. 1. https://blog.arduino.cc/2020/02/26/openastrotracker-is-a-tracking-and-goto-mount-for-dslr-astrophotography/ https://blog.arduino.cc/2020/02/26/openastrotracker-is-a-tra...

gridspy 5y ago

Sounds like it's a pretty simple loop of 1. Find bright spots in last second of exposure (which is then added to a sum for the final picture) 2. Compare their locations to bright spots in the previous second 3. Move the sensor slightly so the bright spots remain "in the same place" on the sensor. Note that cameras with integral anti-vibration do that by moving the sensor, so they already have the hardware for (3). For star tracking there would be a max speed of stars based on Earth's rotation multiplied by focal length you could use to set a reasonable cap on movement. You could also expect similar movement for each second to the seconds before. The camera could have a data structure per star being tracked, capping the number used to say 32 or 64 "stars" for accuracy. Each "Star" would "vote" how much movement has occurred. You'd gain faith in various stars as analysis frames go by if they keep giving valid results, a black-list of "not stars" would also be useful. Some would be stationary, like lights on the ground. Some would be bogus, such as navigation lights on aircraft. Actual stars should expect similar movement and "agree" though if the zoom was low it might change across the image.

azalemeth 5y ago

I have a Pentax camera (it's great -- they're undervalued by the market). The astrotracer uses GPS lookups and needs either a K-1 or a (very overpriced) GPS dongle that plugs in via the flash hotshoe. It gets an accurate lock and moves the sensor about its 5 axes of magnetohydrodynamically-controlled freedom in order to emulate, to some degree, an equatorial mount. No image-domain tracking required -- purely physics. The things people get are insanely good (c.f. [1]) [1] https://www.flickr.com/groups/2598208@N22/ https://www.flickr.com/groups/2598208@N22/

formerly_proven 5y ago
Mechanically there's only three degrees of freedom (translation in the plane and rotation about the optical axis), the cameras just calculate an approximately correct translation for pitch/yaw movements. Pitching or yawing the sensor itself would take it immediately out of the depth of focus (the image side equivalent of depth of field) and the image would be a blurry mess.