One of the most interesting features of night sky photography (or astro photography) is that your camera can often see more the stars in the sky than you can with the naked eye. The human eye is one of the most complex and sophisticated lenses, but it can’t compete with a wide open lens and a long shutter speed when it comes to images of the cosmos. I haven’t ventured into deep space photography, but I have started to take images of the Milky Way and of the rotation of the stars around the North Star.
To capture images of the Milky Way, you really have to get out of the city. Preferably, thirty to fifty miles beyond the point that light pollution would prevent you from seeing the galaxy with the naked eye. You’ll need to set your camera up on a tripod, and use the f/2.8 aperture and, usually, a 30 second shutter speed setting. The actual shutter speed will be a function of the focal length of your lens. Boosting the ISO up to 3200 or 6400 will allow the deepest light from the cosmos to flood into your camera. The best times to see the Milky Way is when it arcs high above the horizon. For the northern hemisphere, this happens in the summer. However, this may mean very late nights or early mornings if you are in more northern latitudes. A good compromise is in October, when the arc is not too low on the horizon, and the night is dark enough at a more reasonable time.
Capturing the rotation of the stars about Polaris (the North Star) is more complex. Again, you’ll need to avoid light pollution, but it is possible to get a reasonable shot with the more prominent stars in urban areas. My experience is to set your remote release (Giga-T pro is good) to 120 frames of 30 second bursts, merging the images together in the most appropriate editing software. The key is where to point the camera. You’ll want to aim the camera north, and pointed upward at an angle corresponding the the latitude you are at. This means you would point the camera at a higher angle in Scotland than you would in, say, Mexico. The results are images that really pop out of screen, and it is one of the most deeply satisfying photography genres that I have dabbled in over the years.