Posted 02 April 2013 - 12:17 PM
I always do the circle first , using a white gel pen.
Then because the paper is never black enough for me , I use the blackest pastel in the box to make the circle black.
That leaves me with a very black circle with a white rim on a grey page. Then I seal it with matt varnish spray.
It is then ready for my drawing on top. If I am in the mood and the seeing is good, my circle might be a dinner plate size. If I want a compact but still detailed drawing my circle for M42 could be a CD size circle.
If I am drawing the sun in h aplha my circle is usually side plate size and yes I use my delph for circles.
When the drawing is finished I take a high res photo of it before sealing it with a light spray of matt varnish. If you use the spray before you take a photo you risk blowing some of the pastel away.
Circles give the viewer a look through your telescope.
With comets in particular , circles help give both the viewer and the sketcher a clear sequence over time of changes that occur in the life/shape/ structure of the object.
With M42 most likely nothing will change except the seeing , sharp one night , dull the next. Or the eyepiece /scope you use. However you never know a iridium flare, or a meteor might enter your fov and what a great inclusion that would be. :-)