Celestron 91078 Manual De Instrucciones página 3

Cooling Down and Fan Operation
Optical performance of the RASA 36 cm will be best when it has reached thermal
equilibrium with the outside air. The greater the temperature difference between the
astrograph and the outdoors, the longer it will take to cool down. It is a good idea to store
the astrograph in a cool area, and to keep it outside for an hour or so before imaging.
The RASA 36 cm rear cell is equipped with a cooling system containing a fan to facilitate
cooling the optics to the ambient temperature. The fan pulls air through the mesh vents
located on the perimeter of the rear cell. The mesh prevents dust from entering the
astrograph. The supplied battery pack powers the fan. It requires 8x AA batteries (not
included). Install the batteries as indicated in the plastic mold of the battery holder. Plug
the battery pack into the jack near the fan to turn it on. When the optics have cooled down
and you are ready to image, unplug the battery pack to turn the fan off.
Focusing
The focuser moves the primary mirror within the rear cell. The RASA 36 cm V2 uses the
Ultra-Stable Focus System (USFS) that minimizes unwanted shifting of the primary mirror
when focusing and during long exposures.
To focus, turn the focus knob until the image appears sharp in your camera. If the knob
will no longer turn, the focuser has reached the end of its travel. In this case, rotate the
knob in the opposite direction until focus is achieved. If you turn the focus knob too
quickly, you may go right through focus without seeing the image. To avoid this problem,
try fi rst focusing on a bright star so the image is visible even when out of focus.
An essential accessory you'll likely want to add is a focus motor. The Celestron Focus
Motor is fully compatible with the RASA 36 cm V2. Please visit the focus motor webpage
at celestron.com for more information.
Attaching Accessories
The RASA 36 cm includes a CGE dovetail accessory rail that is also compatible with most
accessories which work on Losmandy-D plates. The dovetail accessory rail can be used to
mount an optional guidescope.
A Celestron fi ndescope can be attached using the pairs of threaded holes in the rear cell of
the astrograph. These holes have Phillips-head screws in them when not in use.
Mounting
holes for
fi nderscope
Removing the Optical Window
If using a fi lter somewhere in the light path, or if the camera has an optical window, we
recommend that you remove the optical window in the front lens cell. This will maintain
the best optical performance of the astrograph. The optical window utilizes M110 x 0.75
threads on the exterior of its housing.
To remove the optical window:
1. With the camera and camera adapter removed, carefully grab hold of the knurled cell
of the optical window.
2. Carefully unthread and remove the optical window.
3 | E N G L I S H
Knurled cell of
optical window
Dew Prevention
The Schmidt corrector is especially susceptible to condensation forming because the glass is
exposed to the outside air. If the temperature of the astrograph drops below the dew point,
dew may form on the corrector within minutes. The easiest way to prevent dew is to add an
optional 14" dew shield which shrouds and insulates the corrector. If conditions are more
severe, a dew heater can be added to apply slight heat to the corrector lens to keep it
dry all night.
Celestron has a full suite of dew prevention products that are fully compatible with the RASA
36 cm. Visit celestron.com for more information.
Do not store the astrograph if covered in dew. Allow it to dry fi rst without the dust cover on.
Storing optics when wet promotes mold growth on the optical surfaces.
Cleaning of the Optics
Dust, debris, and fi ngerprints on the optics will generally have little effect on imaging with the
RASA 36 cm. However, if the external surfaces of the Schmidt corrector and the lens group
become excessively dirty, they should be cleaned. Dust can be removed with a blower bulb or
a camel hair brush. Then, use optical cleaning solution and lens cleaning tissue to remove any
remaining debris or stains. Apply the solution to the tissue and then apply the tissue to the lens.
Low pressure strokes should go from the center of the corrector to the outer edge. Use a new
tissue for each stroke so as not to spread any oils or debris. Do not rub in circles.
You can use a commercially made lens cleaning solution or mix your own. A good cleaning
solution is isopropyl alcohol (99% pure) mixed with distilled water. The solution should be 3
parts isopropyl alcohol and 2 parts distilled water. You can also use soft white tissue instead of
lens cleaning tissue, as long it doesn't have added lotions or perfumes.
To minimize the need to clean your astrograph, replace the dust cap once you have
fi nished using it.
Cleaning the internal optical surfaces should only be done by the Celestron repair department.
If your RASA 36 cm needs internal cleaning, please contact Celestron at celestron.com/pages/
technical-support for a return authorization number and price quote.
Collimation
The RASA 36 cm optics are factory aligned, and should not normally need collimation
adjustments. However, adjustments can be made to the tilt of the lens assembly, if needed,
to collimate the entire optical system. The primary mirror and corrector are permanently
aligned at the factory, and cannot be adjusted.
The astrograph must be collimated with a camera installed. Using a camera that does not
obstruct the light path (i.e. the aperture of the Schmidt corrector) is recommended, as this
makes it easier to see concentricity when stars are defocused.
Equipment needed:
2 mm Hex key
3 mm Hex key
Mount and camera setup, ready to image
1. Install the camera on the astrograph.
2. Slightly loosen the retaining ring and rotate the camera adapter so the three slotted
openings allow access to the collimation screws. Retighten the retaining ring.
Collimation
screws