There are as many ways to sketch astronomical objects as there are observers doing it. While I can’t cover every possibility, this list summarizes some key points about the various materials you can use to create astronomical sketches. If you have any other favorite items, or other thoughts about the items listed, please speak up in the comments!
You’ll need something on which to rest your sketch paper.
Clip Board/Sketch Board
Available in a variety of sizes and forms, this is an affordable, mobile surface. Look for a clipboard that is at least large enough for the sheet of paper you typically use. Some boards designed for sketching have an opening for your thumb, so you can hold the board steady. The benefit of using a clip board is that it is portable and can hold your paper and drawing tools while you are positioned at the eyepiece.
If your sketch paper comes in a pad, you can use the pad itself as a drawing surface. Like a clip board, it is portable and you can work with it while you are at the eyepiece. If you keep your finished sketches in the pad, take care that you don’t allow page shuffling, pressure and dew deteriorate your existing drawings.
A portable desk or table provides a convenient place to support all your sketch materials and observing equipment. At the eyepiece, you won’t be distracted by the need to hold the clipboard; although you do need some additional maneuvering to go from eyepiece to sketch paper.
An easel may be needed for larger format or pastel sketches. This will place the larger drawing in a position where the full sheet is within easy reach and is fully visible. This will also allow excess pastel dust to be tapped loose so it falls off the sheet.
For deep sky observing, dark adaptation and sketch illumination are a difficult balance to maintain. It is important to select a light that gives you the best chance of maximizing both needs.
Adjustable red light
In my opinion, the best solution for sketch illumination, is red observing light that has adjustable brightness. This will allow you to dim the light to a level that intrudes as little as possible on your dark adaptation while still having enough light to see your sketch. Without this capability, you lose some flexibility to adapt your lighting to your observing conditions and degree of dark adaptation. The biggest challenge is that the popular adjustable red observing lights sold by Orion Telescopes are meant to hang from a lanyard or be handheld. This creates a challenge when juggling your sketch, drawing tools, and the light itself.
It is possible to lay the light sideways on your clip board or sketch pad and aim it at your drawing. However, this can be frustrating since the illumination is uneven. If the light has a lanyard, you can hang it from something (the focuser or a tripod, for example) and position yourself so that the light falls on your sketch. Other home-made solutions may help with positioning the light. I combined a gooseneck lamp clamp with other clamps to create an adjustable holder for the light.
As a hands-free lighting solution, headlamps can be a very convenient way to light your sketch. Many of them have red LEDs as a lighting option. However, two things need to be taken into consideration: brightness and courtesy to fellow observers. Even at lower settings, the default brightness of red headlamp LEDs can be too bright. Consider adding masking tape or something semi-opaque to the lens to dim the brightness to a level that won’t overwhelm your dark adaptation. Also, be considerate of the effect the headlamp will have on other observers when you turn to face them. When that happens, the direct red light is dazzling to someone who is dark adapted and can be very frustrating.
Add a bit of red cellophane or paint to the lens of a book reading light, and you have a light-weight solution that is easy to aim and hands-free. Although the brightness level may not be adjustable, you can add additional semi-opaque material to the lens to dim the light to a suitable level.
The selection of paper you can choose from is enormous. I’ll try to cover a few of the basics here. Feel free to suggest other paper types and their benefits in the comments and I’ll try to update them here when possible.
Basic White Copy/Printer Paper
It’s affordable and easily accessible. Many observers use it with great success. The smooth texture generally produces clean, even shading. Since the stock is made for copying and printing, it is sized for most printers and is a ready media for printed observing forms. Be aware that some brands and weights may not hold up well to repeated re-working of the same area (e.g., multiple erasures or successive layers of blending).
Acid-free Sketch Paper
Artist grade papers are often noted as being acid-free. Over time, naturally occurring acids in paper stock will degrade the paper causing it to become yellow and brittle. Acid-free papers have had these acids neutralized so that the paper lasts longer, particularly when stored away from light and moisture.