4 correct shutter speeds vary widely, depending on lighting conditions and film used. Trial and error is the best way to determine proper shutter speed in any given application. NOTE: The camera used with your telescope may have an exposure meter that is still active when the standard lens is removed and the body is connected to the telescope with the T-Mount. If used for terrestrial photography the camera meter should be acceptable. If used for astrophotography, the meter probably will not provide good results since camera meters are not made to compensate for a dark sky. 5. Terrestrial photography through the Lx9o is sensitive to heat waves rising from the Earth's surface. Long distance photography is best accomplished in the early morning hours before the earth has had time to build up heat. 6. Photography of the Moon and planets through the LX90 can be especially gratifying, but points 1 through 4 should be particularly noted in this case. Lunar or planetary photography requires that the telescope be Polar aligned. See APPENDIX A, page 49