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Fastar Configurations
The following is a brief description of the advantages of imaging at each f-number configuration and the
proper equipment needed to use the telescope in any of its many settings. Refer to
Figure 9-7
for a more
detailed description of the accessories offered for each configuration.
Imaging at f/1.95
As stated above, the exposure times are much shorter at f/1.95 then at f/6.3 or f/10. The field-of-view is
wider, so it is easier to find and center objects. Also with a wider field-of-view you can fit larger object
(such as M51, The Whirlpool Galaxy) in the frame. Typical exposure times can be 20-30 seconds for many
objects. With the Track and Accumulate function on the PixCel software (see the PixCel Operating Manual
for more details about its software features), the camera can shoot and stack several images automatically
without ever having to guide the exposure. Under dark skies you can get an excellent image of the
Dumbbell Nebula (M27) with only a few 30 second exposures (see figure 9-5 below). The spiral arms of the
Whirlpool galaxy (Figure 9-6) can be captured with a 30 second exposure and can be improved upon
dramatically if several 30-60 second exposures are added together using the Track and Accumulate feature.
When imaging some objects like planetary nebula (for example M57, the Ring Nebula) and small galaxies
(M104, the Sombrero Galaxy), larger image scale is needed to resolve finer detail. These objects are better
shot at f/6.3 or even f/10.
Imaging at f/6.3 (Medium size to small galaxies)
F/6.3 imaging gives you finer resolution then at f/1.95, but the slower f-number will usually
require you to guide the image while you are taking longer exposures. Guiding can be
accomplished by using an optional Radial Guider or a piggyback guidescope. The exposure
times are about 10 times longer but the results can be worth the extra effort. There are some
objects that are small enough and bright enough that they work great at f/6.3. M104 (the
Sombrero Galaxy) can be imaged under dark skies with a series of short exposures using Track
and Accumulate. Ten exposures at 15 seconds each will yield a nice image and is short enough
Figure 9-5 M27 – The Dumbbell Nebula
4 exposures at 30 seconds each!
Figure 9-6 M51 – The Whirlpool Nebula
9 exposures at 60 seconds each.
