This is why in astronomy we prefer black and white cameras as you get the true resolution of the sensor as compared to a camera with a bayer matrix. They also tend to be approximately 20% more sensitive in low light and provide better sensitivity in the infra red side of the spectrum. Another consideration that has to be taken into account is the arc-seconds per pixel image resolution. Basically, in astronomy we try and get the combination of lens/telescope and camera sensor that gives a resolution of no more than 1 arc-second per pixel. There is very little benefit going for more resolution as the atmospheric distortion alone will not let you get any sharper images . So most astronomers actually look for bigger pixels not smaller pixels.
Nothing shows off defects in your optical train like a point source of light, i.e. stars. All the chromatic aberrations, coma, astigmatism sensor tilt etc... will show immediately when taking an astro-photo. Your eyes will immediately notice when your stars are ovals instead of circles. Chromatic aberration will immediately show as a purple haze around your stars. Focus issues will show as stars will look bloated instead of nice sharp points.
Many times when using a camera lens for Astronomy work, you have to stop down the lens to f4 because f2.8 will just not give you the image quality expected.
So basically, if you savor challenges in your photography, you would get into astro-photography. Did I mention that my tripod and mount weighs close to 40 Kg? Makes that Manfroto 405 look rather flimsy doesnt it? Well, what if I told you my mount is considered entry low end of the good type of mounts and many people would complain that it is not stable enough to do some of the more serious work.
Ever tried to perfectly track a moving target for a 20 minute exposure.. I could keep on going, the list is endless
Biting the hand that feeds IT
