Celestron Astro Fi 102 Handleiding

Celestron Telescoop Astro Fi 102

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1 | ENGLI SH

Telescope Instruction Manual

Model: 91078

911

2 | ENGLI SH

Mounting the Astrograph

The RASA 36 cm has a CGE dovetail mounting rail. This is compatible with mounts that

accept a CGE or Losmandy-D style dovetail. The astrograph itself weighs 75 lb., so a mount

with a load capacity more than that is recommended. This will ensure good performance of

the mount when a camera and any accessories are added.

Because of its size and weight, moving and lifting the RASA 36 cm onto a mount will take

two people. Use the handles on the rear cell as needed.

For custom mounting applications, there are two sets of two M8x1.25 mounting holes in the

rear cell. These utilize threaded inserts for extra reinforcement.

Installing a Camera

The supplied M48 camera adapter can be used to attach a DSLR camera. It will require a 48

mm “wide T-ring” for your make of DSLR to connect to the adapter.

If you are using an astronomical camera with a smaller than “full frame” (43 mm diagonal)

sensor, you may also be able to use the supplied M48 camera adapter. This likely will require

utilizing optional adapters, such as an M48-to-M42 adapter along with M48 extension rings,

to connect your camera and place your camera’s sensor at the proper backfocus distance.

The backfocus distance when using the M48 adapter is 55 mm.

Cameras with larger sensors will require a custom camera adapter to best illuminate the sen-

sor. Refer to the “Camera Adapter Requirements” drawing on Celestron’s website, located on the

36 cm Rowe-Ackermann Schmidt Astrograph webpage under the “Support and Downloads”

tab, to determine the design needed for your camera.

Note: Due to the steep light cone provided by the f/2.2 optical system, camera housings

can be a source of vignetting. Despite the astrograph having a large illuminated ﬁ eld,

vignetting can occur with large sensor cameras when the sensor is deeply recessed within

the camera body. This is common with full-frame DSLR sensors.

To attach your camera:

1. Place the knurled retaining ring over the camera adapter and loosely thread it onto the lens

group housing. The Teﬂ on washer goes between the retaining ring and the camera adapter.

2. Thread the camera body onto the camera adapter.

3. Carefully hold hold the camera so the camera adapter seats ﬂ atly against the lens group housing.

4. Finish threading the retaining ring onto the lens group housing. Rotate the ring

until the camera adapter is snug against the housing. Do not over tighten! Camera

orientation can be adjusted later.

Caution:

Overtightening the retaining ring can cause the lens assembly to rotate

rela-

tive to the Schmidt corrector. Keep the camera adapter snug against the lens cell, but

do not overtighten the ring.

Adjusting Camera Orientation

Once the camera is installed, you can adjust its orientation by slightly loosening the retaining

ring. Loosen the ring no more than 1/8th turn, rotate the camera as desired, and retighten the

ring. Remember not to overtighten the ring.

Knurled

retaining

ring

3 4

Overview

1 Lens group 7 Cooling fan

2 Schmidt corrector 8 12V DC jack for cooling fan

3 Lens group housing 9 M48 camera adapter

4 Dovetail mounting rail Retaining ring with teﬂ on washer10

5 Dovetail accessory rail 11 8 x AA battery pack (batteries not included)

6 Focus knob

The 36 cm Rowe-Ackermann Schmidt Astrograph (RASA 36 cm) delivers a ﬂ at ﬁ eld with no coma or astigmatism across a large (60 mm) image circle and extended spectral range

(400-900 nm). The astrograph can only be used with a camera.

3 | ENGLI SH

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.

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

Product specificaties

Merk:	Celestron
Categorie:	Telescoop
Model:	Astro Fi 102
Kleur van het product:	Zwart
Gewicht:	6169 g
Soort:	Catadioptric
Vaste focale lengte:	1325 mm
Soort buis:	Aluminium
Lengte:	381 mm
Vergroting:	53 x
Vaste opening:	102 mm
Lens-bedekking:	Volledig gecoat
Maximale ondersteunde oogstuk diameter:	25 mm
Statief materiaal:	Aluminium
Altazimuth montage:	Ja
Compatible eyepieces:	10,25 mm
Focaal ratio:	13
Visuele power (max):	212 x