Just as the brightest field stars anchor the telescope view, they also anchor the drawing. Bright stars provide reference points against which all other stars within the field of view can be placed. By taking a little more time to carefully position these anchor points, everything else will naturally fall into place. In this drawing of NGC 2324 (Monoceros), 14 stars anchor the sketch. The seven stars in the upper-right quadrant range from 8.2 magnitude to 10.2 magnitude in brightness. The two stars in the upper-left quadrant shine at 8.5 magnitude and 9.1 magnitude. The five stars in the bottom half of the sketch aren't as bright but do serve to define the space in that part of the drawing.

With the sketch anchored, it's time to fill out the field. I begin by drawing the house-shaped, six-star asterism to the right of center in the drawing. Although the sketch does not reflect it at this stage, this asterism is quite prominent in the eyepiece of my 10-inch, f/4.5 Newtonian. While in the area, I use a #4 pencil to tap out the stars around the house asterism. Typically, I don't like to change pencils during a sketch. The #4 is a good blend between a hard #2 and a soft #6. This step usually takes me from 10 to 20 minutes to complete.

Averted vision is a powerful observing technique. In a brightly lit environment, rod cells dominate as the human eye's photon receptors. Under low light conditions, the eye relies on its cone cells to see the world. While the color-sensitive rod cells are clustered around the fovea centralis, the cone cells have their highest density about 18-degrees away. Averting your gaze slightly allows the light-sensitive cone cells to detect the feeble glow of faint stars and extended objects. Using averted vision, I am able to detect the subtle glow of numerous unresolved stars within NGC 2324. This is confirmed by turning off the telescope clock drive and allowing the cluster to drift through the field of view.

One of the toughest challenges when sketching deep-sky objects is rendering the personality of these delicate treasures. A technique that works for me is scaling star sizes to indicate relative brightness: the larger the star, the brighter the star. I use MegaStar as a reference when finishing sketches. If you compare the final version of this drawing with the three previous, you should see that the anchor stars are generally brighter than the others. Also, notice how prominent the house asterism appears in this final sketch. And the glow of the unresolved cluster stars appears more delicate by comparison. Finally, this technique of scaling star sizes adds a sense of depth to the image. The end result is a much more aesthetically appealing sketch that does a better job of capturing the essence of my observation.

This sketch of M62 (Ophiuchus) is anchored by seven stars. The two stars closest to the field center, though not terribly bright, play a valuable role by defining the location of the globular cluster. The remaining five stars define the field's outer limits, with two stars at the 12 o'clock position, and one each at 3, 6 and 9 o'clock. As the sketch progresses, these anchors serve as reference points for the entire field.

Although we're working in a two-dimensional plane when sketching, it is important to layer extended objects. Globular clusters nicely illustrate the value in taking this approach. Most large globulars display at least three distinct features: a bright central core region, a fainter outer halo, and resolved stars. I begin by using an HB pencil to sketch the core. After applying some lead to the page, I rub with a finger tip to smooth the core. Using the same pencil, I then draw the outer halo and rub across both layers. With the unresolved glow of the cluster drawn, I turn my attention to the remaining field stars. I've been working on the sketch for about 15 minutes to this point.

The time spent anchoring the sketch, roughing out the globular cluster and framing the drawing with additional field stars has allowed my eyes to improve their dark adaptation. Now, I'm ready to use averted vision to study the cluster. I'm looking for the degree of resolution or the number of stars which can be seen. M62 features a distinct bar of stars running across the core. These are added with the #4 pencil. More stars are glimpsed around the globular's periphery and these are drawn. All the while, there is the constant temptation to start tapping the pencil on the page. It would be so easy to do that, rather than drawing just the stars I see. But it is important to resist that urge. Random tapping usually gives a sketch an unnatural appearance. Rather than yield to temptation, it is better to draw a select few stars, which are actually seen.

As with all my sketches, I turn to MegaStar to apply the finishing touch. Stars are sized to indicate relative brightness. Notice how M62 appears to become almost a background element with respect to the brightest stars in the field. Of course, the globular is much farther from Earth than any visible star and this technique of scaling star sizes helps convey that fact.