Celestron G-9.25 Instruction Manual page 46

The exposure times listed here should be used as a starting point. Always make
exposures that are longer and shorter than the recommended time. Also, try
bracketing your exposures, taking a few photos at each shutter speed. This will
ensure that you will get a good photo. If using black and white film, try a yellow
filter to reduce the light intensity and to increase contrast.
Keep accurate records of your exposures. This information is useful if you
want to repeat your results or if you want to submit some of your photos to
various astronomy magazines for possible publication!
This technique is also used for photographing the Sun with the proper solar filter.
Celestial Photography • 43