Despite the advent of photography and CCD imaging, many amateur astronomers today prefer to chronicle their observations by making eyepiece renderings. Sketching at the telescope, however, does more than create a personal observing record. It hones the observer’s perception skills.
Say you look at a star cluster for a few minutes. In that time you may note whether it is rich or sparse, contains predominately bright stars or dim or a mixture of both. Afterward, you would come away feeling as if you "saw" this cluster.
But let’s say you sketch it. Now you may notice that some of its brighter stars appear reddish; that the chains form a kind of pattern; that what you thought was a sparse cluster actually contains myriad faint members. Instead if five minutes, you may spend half an hour scrutinizing this object, after which you would come away feeling that you "observed" this cluster.
All you need to get started is a red astronomer’s flashlight, an inexpensive sketchpad, and a sharp pencil or two. Before making your sketch, circumscribe a circle—not too small—representing the field of view and note where the cardinal directions fall in the eyepiece. Don’t forget to write down the date and time of the sketch, the telescope and magnification used, and a brief description of seeing conditions.
The eye may not be able to accumulate light like a photograph, but it often can see finer detail. That faint, fuzzy thing you saw last night might not appear as faint or fuzzy once you try sketching it!