Focusing seems such a simple thing,

just turn the knob until the image is sharp. What could be simpler than that?

Well if focusing is so easy why do all modern cameras, whether they be the camera in your phone or a digital SLR, have autofocus? Yet even with these marvel of modern camera technology, how many times does the photo look sharp in the camera but when you get it home and pop it up on your computer its blurry? Perhaps the light level was a bit too low? Were you hands shaking while you were shooting the picture? Was the subject of the photo moving? Were you using a telephoto lens?

Now just imagine trying to get it all correct in the dark for eye and camera with the ultimate telephoto lens. In other words; little light, high magnification, shaky hands, shaky telescope, spinning earth... what could possibly go wrong? In the following tutorial, we walk through all the disparate aspects of focusing, for both eye and camera, manual and autofocusing, to make it easier, faster, sharper.