Installing A Camera - Celestron ROWE-ACKERMANN F/2.2 SCHMIDT ASTROGRAPH 36 V2 Instruction Manual

Overview
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1 Lens group
2 Schmidt corrector
3 Lens group housing
4 Dovetail mounting rail
5 Dovetail accessory rail
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.
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 | E N G L I S H
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7 Cooling fan
8 12V DC jack for cooling fan
9 M48 camera adapter
10 Retaining ring with tefl on washer
11 8 x AA battery pack (batteries not included)
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.
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Knurled
retaining
ring