Celestron 31058 Instruction Manual page 50

50 • Celestial Photography
9. Close the camera's shutter.
As for lenses, use good ones that produce sharp images near the edge of the
field. The lenses should have a resolving power of at least 40 lines per millime-
ter. A good focal length range is 50 to 500mm 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)
• T-Max 3200 (black and white print)
• T-Max 400 (black and white print)
As you perfect your technique, try specialized films, that is films that are
designed or specially treated for celestial photography. Here are some popular
choices:
• Ektar 125 (color print)
• Fujichrome 100D (color slide)
• Tech Pan, gas hypered (black and white print)
As with all forms of photography, keep accurate records of your work. This
information can be used later if you want to reproduce certain results or if you
want to submit photos for possible publication.
Once you have mastered piggyback photography with wide angle and normal
lenses, try longer focal length lenses. The longer the focal length, the more
accurate your guiding must be. You can continue to increase the focal length
of the lens until you are ready for prime focus photography with your Celestron
telescope.