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Old 18-04-2016, 05:52 PM
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Shiraz (Ray)
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Join Date: Apr 2010
Location: ardrossan south australia
Posts: 4,918
guiding update rate

Hi

I measured the performance of my EQ8 system in very good seeing and with phd2 guiding exposures of 0.5, 1, 2, 5 and 10 seconds. The performance measure was the FWHM (from PI) of 2 minute subs, with the average of 3 such subs taken at each guiding exposure.

To ensure that seeing variability did not influence the results too much, the process used was to take an image for each of the 5 guide exposure times and then go through the same sequence twice more. Focus was not changed during the process, but there was no evidence of any drift (the results at each guide exposure were quite consistent).

The results contradict the conventional wisdom that short guide exposures encourage "chasing the seeing" and reduced resolution. There is fairly convincing evidence that the shortest guide exposure (0.5 seconds) resulted in quite significantly better resolution - maybe I should try 1/4 second guide exposures. The data quantify the subjective impression that the subs taken at short guide exposures were noticeably sharper than those taken with long guide exposures.

thanks for looking. regards Ray
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Last edited by Shiraz; 18-04-2016 at 06:03 PM.
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