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The reason why I say this is that while the object is rising, you may not want to collect blue filtered or luminance data due to atmospheric extinction scattering light or low resolution. Hence, while the object is rising, you may only want to collect red filtered data that is not compounded by atmospheric extinction. A common method I use in data acquisition is a stepped approach. As the object rises, I collect red filtered data. Once it hits approximately 70 degrees start collecting green, then followed by blue. This minimises the scattering of blue light. As the object approaches meridian or is as high as it will get, collect luminance to improve resolution. So the sequence is RRGGBBLLLLBBGGRR as it crosses the meridian. This is somewhat off topic considering we are not talking exposure times, but it re-emphasises the point that you’ll go to extremes to ensure you collect quality data, even if that includes a few long exposures.
That's a good tip Jase. I haven't come across that before but I have obviously noticed how much nicer images are when imaging at or near the zenith. I strive to image an object during that period and time when I will image it to catch it there if at all possible.
Greg.
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