ASTROPHOTOGRAPHY TELESCOPE TRACKING CAMERA PHOTOS

3

Since tracking becomes so difficult for high magnification, taking exposures of bright objects means the exposure can be kept short and tracking to a minimum. Photos will turn out smudgy, oblong and have no clear detail as tracking errors become apparent. Photographs of the Moon and planets gives you a chance to use the higher magnification of prime focus photography on these bright objects enabling you to see close up detail of craters on the Moon and detailed pictures of Venus, Mars, Jupiter and Saturn. An exposure of the Moon will be half a second or less. The planets, being the next brightest objects in the sky require short exsposures of around a second. There will be different

elapsed times for different

sized

telescopes and different

focal ratio

telescopes.

Using the camera inserted into the focuser will mean needing a lot more counter balancing since the camera is near or at the end of the telescope tube. This will make the slow motion controls and the sturdiness of the telescopes mount work at their best. Extra weight besides what came with the telescope will be needed to counter balance the telescope.

Being able to see the object your photographing through the camera's viewing area can be difficult because the glass is not clear except the small circle in the center of the viewer. This setup is useful for daytime shots, but annoying for astrophotography. Different cameras have different extents of unclear glass, yours may be alright for taking photos, but if it's hard to look through and obtain focus, then a guide scope may be needed solely to do the tracking of the object while the film is being exposed. To do this a second, small telescope is attached to the main telescope. This may be useful in a second way by the placement of the guide telescope can be used to counter balance the camera's weight. If your finderscope is up to the task, use it as the guide scope. A second way to overcome guiding difficulties through your camera is to use an off axis guider. An off axis guider allows you to view the object while your photographing by diverting some of the light to an eyepiece to one side of the focuser while still having the camera attached. These devices are specially designed for the job of astrophotography and make visual tracking easy as the eyepiece can have a reticle (cross hairs) screwed into it. The clarity of the eyepiece also enables precision focus as the object can be clearly seen.

FRONT PAGE

CONTENTS