Celestar Manual
Celestial Photography
55
guiding with a high power telescope, the margin for error is very large. Small mistakes made while
guiding the telescope will not show up on film. To attach the camera to the telescope, use the piggyback
mount (#93598). This can be purchased as an optional accessory.
As with any form of deep-sky photography, it should be done from a dark sky observing site. Light
pollution around major urban areas washes out the faint light of deep-sky objects.
1.
Polar align the telescope (using one of the methods described earlier) and start the clock drive.
2.
Load your camera with slide or print film, ISO 400 or faster!
3.
Set the f/ratio of your camera lens so that it is a half stop to one full stop down from completely open.
4.
Set the shutter speed to the "B" setting and focus the lens to the infinity setting.
5.
Locate the area of the sky that you want to photograph and move the telescope so that it points in that
direction.
6.
Find a suitable guide star in the telescope field. This is relatively easy since you can search a wide
area without affecting the area covered by your camera lens. If you do not have an illuminated cross
hair eyepiece for guiding, simply defocus your guide star until it fills most of the field of view. This
makes it easy to detect any drift.
7.
Release the shutter using a cable release.
8.
Monitor your guide star for the duration of the exposure making all corrections using the standard
hand controller (optional on Celestar 8). If not using the optional DEC motor (standard with the
Celestar 8 Deluxe), then corrections to the declination axis must be made carefully turning the DEC
slow motion by hand as needed.
9.
Close the camera's shutter.
As for lenses, use only those that produce sharp images near the edge of the field. The lenses should have
a resolving power of at least 40 lines per millimeter. A good focal length range is 35 to 200mm for lenses
designed for 35mm cameras.
The exposure time depends on the film being used. However, five minutes is usually a good starting point.
With slower films, like 100 ISO, you can expose as long as 45 minutes. With faster films, like 1600 ISO,
you really shouldn't expose more than 5 to 10 minutes. When getting started, use fast films to record as
much detail in the shortest possible time. Here are proven recommendations:
•
Ektar 1000 (color print)
•
Konica 3200 (color print)
•
Fujichrome 1600D (color slide)
•
3M 1000 (color slide)
•
Scotchchrome 400
•
T-Max 3200 (black and white print)
•
T-Max 400 (black and white print)
