Re: Progress On Tracking Satellites With A (Used!) Digital Camera

From: Marco Langbroek via Seesat-l <seesat-l_at_satobs.org>
Date: Tue, 17 Dec 2019 17:58:53 +0100
Op 17-12-2019 om 17:18 schreef Charles Phillips via Seesat-l:
> Apparently when you set exposure
> time to 10 seconds the Nikon does NOT take a 10 second exposure! 


This is the case for most brands of DSLR camera - e.g. also the Canon EOS
cameras I use. There can also be small delays in opening of the shutter as well.

Unclassified satellites in steady, well-tracked orbits can be used to calibrate
the true exposure times. I have used Iridium satellites in the past to calibrate
my Canon camera timings.

Take images - as many as possible - of Iridium passes, measure the start- and
endpoints of the trails, and then take a TLE with epoch close to the observing
time, and compare. The delta-T's you find are then informative about the
exposure timing accuracy of the camera. Take a large number of such
measurements, and a pattern appears. Note that for different exposure times, the
difference is not the same - e.g. a Canon EOS 60D camera's 5 second exposure is
very close to 5.0 seconds indeed, a 10-second exposure is 10.05 second, and a
15-second exposure is close to 16 seconds in reality.

- Marco


-----
Dr Marco Langbroek  -  SatTrackCam Leiden, the Netherlands.
e-mail: sattrackcam_at_langbroek.org

Station (b)log: http://sattrackcam.blogspot.com
Twitter: _at_Marco_Langbroek
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Received on Tue Dec 17 2019 - 10:59:38 UTC

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