by Chris Peterson » Fri May 30, 2014 5:40 pm
Psnarf wrote:Doctor Adam Block created that image with a 32" telescope? LRGB = 7:3:3:3 I don't know what that means.
It means that the luminance channel exposure time was 7 units (hours, perhaps), and the RGB channel exposures were 3 units each.
The grayish haze is probably the result of high-altitude dust.
Probably not. At a dark site, haze, dust, fog all make the sky darker, not lighter.
The background is NOT an artifact. It is real. The sky does not produce zero signal between light emitting objects. The upper atmosphere glows, and depending on the object, there may be interstellar dust adding signal, as well.
In processing, we typically set the black point just below the sky background level. That results in the background not being clipped to black, but just a touch above that. We want to just barely see the noise floor. In today's image, the background has a count of around 10, and is almost completely neutral, which demonstrates good processing.
[quote="Psnarf"]Doctor Adam Block created that image with a 32" telescope? LRGB = 7:3:3:3 I don't know what that means.[/quote]
It means that the luminance channel exposure time was 7 units (hours, perhaps), and the RGB channel exposures were 3 units each.
[quote]The grayish haze is probably the result of high-altitude dust.[/quote]
Probably not. At a dark site, haze, dust, fog all make the sky darker, not lighter.
The background is NOT an artifact. It is real. The sky does not produce zero signal between light emitting objects. The upper atmosphere glows, and depending on the object, there may be interstellar dust adding signal, as well.
In processing, we typically set the black point just below the sky background level. That results in the background not being clipped to black, but just a touch above that. We want to just barely see the noise floor. In today's image, the background has a count of around 10, and is almost completely neutral, which demonstrates good processing.