This clearly illustrates that focal reducers are in order with typical schmidt-cassegrains. Typical pixel sizes for CCDs range in size from 9 microns to about 25 microns. This is a huge advantage for the signal in overcoming the random noise component present due to light pollution. While the noise component is very large in a light polluted site, it is minimized under certain weather conditions. The amount of light scattered at any observing site can fluctuate greatly from night to night depending on weather conditions.
Light pollution is only a problem because the light is scattered by the atmosphere.
If you were an amateur astronomer living on the Moon, any nearby lights would not be a problem since there is no atmosphere to scatter the ambient light. From your Earth based city site, imaging galaxies should be done on nights when the ambient light is scattered the least by atmospheric conditions. The main components which scatter light besides the air molecules themselves are industrial pollution, water vapor and dust. These light scattering components are minimized under certain weather conditions such as after the passage of frontal systems. Cold fronts are frequently accompanied by wind and rain which blows and washes dust and pollution out of the air.