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Re: On The Water Trial of Digital Camera CN
From: Marcel Tschudin
Date: 2010 Jun 19, 11:53 +0300
From: Marcel Tschudin
Date: 2010 Jun 19, 11:53 +0300
Greg, Sorry, but I think your following comparison is not really valid: 3. Precision 0.4' vs 0.1' of a sextant. Assuming that you estimate your H.E. to +/-20% and the timing is exact to +/-1 sec you have a resulting observational error of +/-0.6 moa which is independent of the instrument you use. From your results I would conclude that the photometric errors are smaller and contribute only marginally to the final result. I indicated previously that the observations should be analysed the same way as the calibration has been done. Were the 3093 pixels derived the same way as you used for your calibration measurements, e.g. the mean of 6 individual measurements? Regarding your conclusion "... with the bonus of improving photo editing skills". I hope you don't edit your photos too much before measuring ;-) However it is true that changing brightness and/or contrast influence the measurement. That's at least partially the reason for obtaining slightly different results when we compared our measurements, which were taken from the same photo, but using different programs. It looks like the different programs had different default settings for showing a photo. Marcel