by florid_snow » Sat Oct 19, 2024 9:51 pm
There is no certification or evaluation for the title of "expert" astrophotographer, only experience, so I will slightly disagree with Chris here and agree with the commentator who provided order-of-magnitude reasoning. I could claim to be an expert myself, I have decades of experience with astrophotography, but that doesn't matter, there is no real authority from experience that can overturn sound reasoning.
The full moon is bright, and not just a little bit bright, it is incredibly bright, because moon dust is made of tiny glass spheres that reflect sunlight with significant directionality. The brightness of the sky on a full moon night is exponentially brighter than the night before or after, the moon's brightness does not increase linearly with increasing fractional illumination, because of the scattering properties of the little glass spheres of dust.
I will agree with our francophone commentator that the brightness of the comet with respect to the background sky is significantly affected by the brightness of the moon which is also illuminating Earth's atmosphere, increasing the brightness of the sky. The photographer also changed locations from a dark site to a more urban location. All these factors add up to make me think the comet has dimmed in these photographs because of other factors besides distance from the sun.
But that doesn't contradict the message of the image, which is that astrophotography is an ephemeral activity, significantly affected by many other factors, if you want to get a good image, you need 5/5 conditions, not 4 things right and 1 thing wrong, all good conditions are required for a good image. These conditions are: No clouds or moisture in the sky, no urban light pollution, no sky brightness from the moon, no fogging of the lens because of radiative cooling caused by the previous conditions, and finally, no impairment of the photographer, that is to say, caffeine not alcohol.
There is no certification or evaluation for the title of "expert" astrophotographer, only experience, so I will slightly disagree with Chris here and agree with the commentator who provided order-of-magnitude reasoning. I could claim to be an expert myself, I have decades of experience with astrophotography, but that doesn't matter, there is no real authority from experience that can overturn sound reasoning.
The full moon is bright, and not just a little bit bright, it is incredibly bright, because moon dust is made of tiny glass spheres that reflect sunlight with significant directionality. The brightness of the sky on a full moon night is exponentially brighter than the night before or after, the moon's brightness does not increase linearly with increasing fractional illumination, because of the scattering properties of the little glass spheres of dust.
I will agree with our francophone commentator that the brightness of the comet with respect to the background sky is significantly affected by the brightness of the moon which is also illuminating Earth's atmosphere, increasing the brightness of the sky. The photographer also changed locations from a dark site to a more urban location. All these factors add up to make me think the comet has dimmed in these photographs because of other factors besides distance from the sun.
But that doesn't contradict the message of the image, which is that astrophotography is an ephemeral activity, significantly affected by many other factors, if you want to get a good image, you need 5/5 conditions, not 4 things right and 1 thing wrong, all good conditions are required for a good image. These conditions are: No clouds or moisture in the sky, no urban light pollution, no sky brightness from the moon, no fogging of the lens because of radiative cooling caused by the previous conditions, and finally, no impairment of the photographer, that is to say, caffeine not alcohol.