OOppttiiccaall TTuubbee AAsssseemmbblly
CC88 ●●
CC99..2255 ●●
SScchhmmiiddtt--CCaasssseeggrraaiinn
y
IInnssttrruuccttiioonn MMaannuuaall
CC1111
1
●●
CC1144
t
A telescope is an instrument that collects and focuses light. The nature of the optical design determines how the light is focused.
Some telescopes, known as refractors, use lenses. Other telescopes, known as reflectors, use mirrors. The Schmidt-Cassegrain
optical system (or Schmidt-Cass for short) uses a combination of mirrors and lenses and is referred to as a compound or
catadioptric telescope. This unique design offers large-diameter optics while maintaining very short tube lengths, making them
extremely portable. The Schmidt-Cassegrain system consists of a zero power corrector plate, a spherical primary mirror, and a
secondary mirror. Once light rays enter the optical system, they travel the length of the optical tube three times.
The optics of the Celestron Schmidt-Cassegrain telescopes have Starbright® coatings - enhanced multi-layer coatings on the
primary and secondary mirrors for increased reflectivity and a fully coated corrector for the finest anti-reflection characteristics.
Figure 1-1
taawwaayy vviieeww ooff tthhee lliigghhtt ppaatthh ooff tthhee SScchhmmiiddtt--CCaasssseeggrraaiinn ooppttiiccaall ddeessiiggnn
u
AA ccu
Part Number 91024 91023 91027 91026 91036 91035 91037 91038-XLT
Focal Length
Eyepiece
Star Diagonal
Finderscope
Optical Tube
Fastar
Compatible
8” OTA 8” OTA-CF 9.25” OTA 9.25” OTA-CF 11" OTA 11" OTA-CF 14" OTA 14" OTA
2032mm F/10 2032mm F/10 2350mm F/10 2350mm F/10 2800mm F/10 2800mm F/10 3910mm
F/11
25mm –
1.25" (81x)
90° - 1.25" 90° - 1.25" 90° - 1.25" 90° - 1.25" 90° - 1.25" 90° - 1.25" 90° - 2" 90° - 2"
6x30 6x30 6x30 6x30 9x50 9x50 9x50 9x50
Aluminum Carbon Fiber Aluminum Carbon Fiber Aluminum Carbon Fiber Aluminum Aluminum
No Yes No No No No No Yes
25mm - 1.25"
(81x)
25mm - 1.25"
(94x)
25mm - 1.25"
(94x)
40mm -
1.25" (70x)
40mm - 1.25"
(70x)
40mm - 2"
(98x)
3910mm
F/11
40mm - 2"
(98x)
AAttttaacchhiinngg tthhee VViissuuaall BBaacckk
The visual back is the accessory that allows you to attach all visual accessories to the telescope. The 8", 9.25" and
11" optical tubes come with the visual back installed. The 14" OTA comes with a thread on 2" star diagonal instead
of a visual back. If it is not already on the tube it can be attached as follows:
1. Remove the rubber cover on the rear cell.
2. Place the knurled slip ring on the visual back over the threads on the rear cell (Fig 1-2).
3. Hold the visual back with the set screw in a convenient position and rotate the knurled slip ring clockwise until tight.
2
Once this is done, you are ready to attach other accessories, such as eyepieces, diagonal prisms, etc.
If you want to remove the visual back, rotate the slip ring counterclockwise until it is free of the rear cell.
IInnssttaalllliinngg tthhee SSttaarr DDiiaaggoonnaall
The star diagonal is a prism that diverts the light at a right angle to the light path of the telescope. This allows you
to observe in positions that are physically more comfortable than if you looked straight through.
To attach the star diagonal onto the 8", 9.25" and 11" optical tubes:
1. Turn the set screw on the visual back until its tip no longer extend s into (i.e., obstructs) the inner diameter of the
visual back.
2. Slide the chrome portion of the star diagonal into the visual back.
3. Tighten the set screw on the visual back to hold the star diagonal in place.
Eyepiece
Star Diagonal
Visual Back
Figure 1-2 – 8", 9.25" and
11" Rear Cell
The 14" OTA comes with a 2" mirror diagonal that attaches directly onto the rear threads of the optical tube. See
figure 1-3.
If you wish to change the orientation of the star diagonal, loosen the set screw on th e visual back until the star
diagonal rotates freely. Rotate the diagonal to the desired position and tighten the set screw.
IInnssttaalllliinngg tthhee EEyyeeppiieeccee
The eyepiece, or ocular, is an optical element that magnifies the image focused by the telescope. The eyepiece fits
into either the visual back directly or the star diagonal. To install an eyepiece:
1. Loosen the set screw on the star diagonal until the tip no longer extends into the inner diameter of the
eyepiece end of the diagonal.
2. Slide the chrome portion of the eyepiece into the star diagonal.
2" thread-on
Mirror Diagonal
Figure 1-3 – 14" Rear Cell
2" Barrel
Eyepiece
3
3. Tighten the set screw on the star diagonal to hold the eyepiece in place.
To remove the eyepiece, loosen the set screw on the star diagonal and slide the eyepiece out. You can replace it
with another eyepiece (purchased separately).
Eyepieces are commonly referred to by focal length and barrel diameter. The focal length of each eyepiece is
printed on the eyepiece barrel. The longer the focal length (i.e., the larger the number) the lower the eyepiece power
and the shorter the focal length (i.e., the smaller the number) the higher the magnification. Generally, you will use
low-to-moderate power when viewing. For more information on how to determine power, see the section on
“Calculating Magnification.”
IInnssttaalllliinngg tthhee FFiinnddeerrssccooppee
The Celestron tube assembly come with a finderscope used to help you locate and center objects in the main field of
your telescope. To accomplish this, the finder has a built-in cross-hair reticle that shows the optical center of the
finderscope.
Start by removing the finder and hardware from the plastic wrapper. Included are the following:
• Finderscope
• Finder Bracket
• Rubber O-ring
• Three Nylon Tipped Thumbscrews (10-24x1/2")
• Two Phillips Head Screws (8-32x1/2" or 10-24x1/2")
To install the finderscope:
1. Attach the bracket to the optical tube. To do this,
place the curved portion of the bracket with the
slot over the two holes in the rear cell. The
bracket should be oriented so that the rings that
hold the finder are over the telescope tube, not the
rear cell (see Fig 1-4). Start threading the screws
Finderscope
Nylon
Adjustment
Screw
in by hand and tighten fully with an Allen
wrench.
2. Partially thread-in the three nylon-tipped
thumbscrews that hold the finder in place inside
the bracket. Tighten the screws until the nylon
Finder Bracket
heads are flush with the inner diameter of the
bracket ring. Do NOT thread them in completely
or they will interfere with the placement of the
finder. (Having the screws in place when the finder is installed
Figure 1-4
will be easier than trying to insert the screws after the finder has
been installed.)
3. Slide the rubber O-ring over the back of the finder (it will NOT fit over the objective end of the
finder). It may need to be stretched a little. Once on the main body of the finder, slide it up about one
inch from the end of the finder.
4. Rotate the finder until one cross hair is parallel to the R.A. axis and the other is parallel to the DEC
axis.
5. Slide the eyepiece end of the finder into the front of the bracket.
4
Loading...