Bedienungsanleitung Celestron CPC Deluxe 800 HD - 11007 (Seite 29 von 50) (Englisch)

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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 eld of your camera.

9. Find a suitable guide star in the telescope eld. 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.

>>

PEC for short, is a system that improves the tracking accuracy of the

drive by reducing the number of user corrections needed to keep a guide

star centered in the eyepiece. PEC is designed to improve photographic

quality by reducing the amplitude of the worm errors. Using the PEC

function is a three-step process. First, the CPC needs to know the current

position of its worm gear so that it has a reference when playing back

the recorded error. Next, you must guide for at least 8 minutes during

which time the system records the correction you make. (It takes the

worm gear 8 minutes to make one complete revolution, hence the need

to guide for 8 minutes). This “teaches” the PEC chip the characteristics

of the worm. The periodic error of the worm gear drive will be stored in

the PEC chip and used to correct periodic error. The last step is to play

back the corrections you made during the recording phase. Keep in mind,

this feature is for advanced astrophotography and still requires careful

guiding since all telescope drives have some periodic error.

Using Periodic Error Correction

Once the telescope has been polar aligned using the EQ North Align (or

EQ South for southern hemisphere) method, select PEC from the Utilities

menu and press ENTER to begin recording your periodic error. Here’s

how to use the PEC function.

1. Find a bright star relatively close to the object you want

to photograph.

2. Insert a high power eyepiece with illuminated cross hairs into your

telescope. Orient the guiding eyepiece cross hairs so that one is

parallel to the declination while the other is parallel to the R.A. axis.

3. Center the guide star on the illuminated cross hairs, focus the

telescope and study the periodic movement.

4. Before actually recording the periodic error, take a few minutes to

practice guiding. Set the hand control slew rate to an appropriate

guide rate (rate 1 = .5x, rate 2 = 1x) and practice centering the guide

star in the cross hairs for several minutes. This will help you familiarize

yourself with the periodic error of the drive and the operation of

the hand control. Remember to ignore declination drift when

programming the PEC.

Note: When recording PEC, only the photo guide rates (rates

1 and 2) will be operational. This eliminates the possibility of

moving the telescope suddenly while recording.

5. To begin recording the drive’s periodic error, press the MENU button

and select PEC from the Utilities menu. Use the UP/DOWN scroll

buttons to display the Record option and press ENTER. You will have

5 seconds before the system starts to record. The rst time each

observing session that PEC record or play is selected, the worm gear

must rotate in order to mark its starting position. If the rotation of

the worm gear moves your guide star outside the eld of view of the

eyepiece, it will have to be re-centered before the recording begins.

Once the worm gear is indexed, it will not need to be positioned again

until the telescope is turned-o. So, to give yourself more time to

prepare for guiding, it is best to restart PEC recording after the worm

gear has found its index.

6. After 8 minutes, PEC will automatically stop recording.

7. Point the telescope at the object you want to photograph and center

the guide star on the illuminated cross hairs and you are ready to play

back the periodic error correction.

8. Once the drive’s periodic error has been recorded, use the Playback

function to begin playing back the correction for future photographic

guiding. If you want to re-record the periodic error, select Record

and repeat the recording processes again. The previously recorded

information will be replaced with the current information. Repeat

steps 7 and 8 to playback the PEC corrections for your next object.

Does the PEC function make unguided astrophotography possible? Yes and

no. For solar (ltered), lunar and piggyback (up to 200 mm), the answer is

yes. However, even with PEC, o-axis guiding is still mandatory for long

exposure, deep sky astrophotography. The optional Reducer/Corrector lens

reduces exposure times making the task of guiding a little easier.

When getting started, use fast lms 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 lms, which are lms 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)

• T-Max 400 (black and white print)

There is no exposure determination table to help you get started. The

best ways to determine exposure length is to look at previously published

photos to see what lm/exposure combinations were used or take

unguided sample photos of various parts of the sky while the drive is

running. Always take exposures of various lengths to determine the best

exposure time.

>>

Your CPC makes an excellent telephoto lens for terrestrial (land)

photography. Terrestrial photography is best done with the telescope in

Alt-Az conguration and the tracking drive turned o. To turn the tracking

drive o, press the MENU (9) button on the hand control and scroll down

to the Tracking Mode sub menu. Use the UP and DOWN scroll keys (10) to

select the O option and press ENTER. This will turn the tracking motors

o so that objects will remain in your camera’s eld of view.

Metering

The CPC has a xed aperture, and as a result, xed f/ratios. To properly

expose your subjects photographically, you need to set your shutter

speed accordingly. Most 35 mm SLR cameras oer through-the-lens

Celestron CPC Deluxe 800 HD - 11007 Seite 29

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