Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-28-2011, 07:54 PM   #1
Site Supporter




Join Date: Nov 2006
Location: Candiac, QC, Canada
Photos: Gallery
Posts: 338
Interesting GPS astrotracer mathematics.

What the astrotracer function does is simply to keep startrails out of the picture. Those startrails happen because the earth is rotating 15 seconds of arc each second of time. What the gps does is move the sensor in the camera to compensate this startrailing which makes a star picture elongated. To emulate an equatorial mount, the sensor has to move up and down, sideways and also rotate. We are tempted to think that these movements have to be big but that's not the case at all. I have done some calculations for the worst case which is a star on the horizon. The biggest sideways movement that the sensor has to do would be 1.19 mm which is not a lot. The formula for startrails at the horizon is (Lens focal length X exposure time in seconds X .00007). I have used the data given by Pentax for the astrotracer function. What I find fascinating is the huge amount of calculations that the software inside the camera has to do to correct the three movements of the sensor, it's simply incredible that it works at all. Correct me if I'm wrong. Comments appreciated.

08-03-2011, 06:50 PM   #2
Senior Member
CP140's Avatar

Join Date: Jun 2011
Location: Greater Vancouver
Photos: Gallery | Albums
Posts: 185
I agree, it's a lot of number crunching... and of course the numbers change with latitiude, the star being "looked" at, the angle relative to North....

73
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
astrotracer, calculations, camera, function, gps astrotracer, horizon, k-r, kr, move, movements, pentax k-r, sensor, star, startrails
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-5 and GPS vikingo Pentax K-5 2 07-15-2011 04:00 PM
Gps Photography With the Kx? OrangeBrian Pentax DSLR Discussion 10 03-29-2011 04:00 AM
K-5 and GPS encoding navcom Pentax K-5 3 03-26-2011 10:25 PM
gps for k20 alainm Ask B&H Photo! 2 02-04-2011 04:51 PM
Photography Mathematics Buschmaster Photographic Technique 6 05-20-2008 07:52 PM



All times are GMT -7. The time now is 08:58 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top