Celestron C8-S User Manual

Page 41

There are several techniques for this type of photography, and the one chosen will determine the standard accessories
needed. The best method for long exposure deep sky astrophotography is with an off-axis guider. This device allows
you to photograph and guide through the telescope simultaneously. Celestron offers a very special and advanced off-
axis guider, called the Radial Guider (#94176). In addition, you will need a T-Ring to attach your camera to the Radial
Guider.

Other equipment needs include a guiding eyepiece. Unlike other forms of astrophotography which allows for fairly
loose guiding, prime focus requires meticulous guiding for long periods. To accomplish this you need a guiding ocular
with an illuminated reticle to monitor your guide star. For this purpose, Celestron offers the Micro Guide Eyepiece
(#94171) Here is a brief summary of the technique.

1. Polar align the telescope.

For more information on polar aligning, see the Polar Alignment section earlier in the

manual.

2. Remove all visual accessories.

3. Thread the Radial Guider onto your telescope.

4. Thread the T-Ring onto the Radial Guider.

5. Mount your camera body onto the T-Ring the same as you would any other lens.

6. Set the shutter speed to the "B" setting.

7. Focus the telescope on a star.

8. Center your subject in the field of your camera.

9. Find a suitable guide star in the telescope field. This can be the most time consuming process.

10. Open the shutter using a cable release.

11. Monitor your guide star for the duration of the exposure using the buttons on the hand controller to make the

needed corrections.

12.

Close the camera's shutter.

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)

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)