Orion 7338 - Manual (Page 3)

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track the motion of the night sky accurately enough and long-
exposure photography will be difficult, if not impossible.
The Deluxe 100mm f/6 comes without accessories. To set
up and use the guidescope for use as a guidescope you will
need the following:
2 Guide scope tube rings
1 Guide scope tube ring mounting plate
1 Illuminated reticle eyepiece or Autoguider
1 Diagonal (optional)
First, adjust the guidescope in the guidescope tube rings so
that it is as parallel with the main optical tube. This may involve
some large adjustments to the guidescope alignment thumb-
screws. Loosen and tighten the alignment thumbscrews as
needed to adjust the direction of the guidescope.
Once you have centered the object you wish to photograph,
you will need to center the guidescope on a bright star near
the object being photographed. Look in the illuminated reticle
eyepiece (with the reticle turned on) and select a star that is
in the field of view. To center the star, loosen one guidescope
alignment thumbscrew and tighten another until the star is
centered in the reticle. Check again to make certain that the
object you wish to photograph is still centered in its field of
view. If it is not, you will have to start the process over again.
Once you begin exposure you will make any adjustments nec-
essary so that the guide star remains centered in the reticle of
the illuminated eyepiece.
Photography with the Deluxe 100mm f/6
The Deluxe 100mm f/6 refractor makes a very capable astro-
graph for your CCD or DSLR camera. With an optional camera
adapter, the Deluxe 100mm f/6 becomes a 600mm f/6 tele-
photo lens for a single-lens reflex camera. For long-distance
terrestrial or astronomical photography, you need a T-ring for
your particular camera model and a camera adapter. A 2"
prime focus camera adapter is suggested to obtain the best
focal distance for this optical tube. Simply attach the T-ring
to the camera body and thread the 2" prime focus camera
adapter into the T-ring. Insert the barrel of the camera adapter
into the 2" eyepiece holder on the focuser. Use the camera’s
viewfinder to frame the picture. Use the telescope’s focuser
to focus the image. Tighten the focus tension thumbscrew to
make sure the camera does not slip out of focus.
Most CCD cameras will have a 1.25" or 2" barrel ready to
attach directly to your telescope like an eyepiece or diagonal.
No adapter is required, simply insert the barrel of the CCD
camera into the 1.25" or 2" eyepiece holder and secure the
camera with the silver thumbscrew lock.
The Deluxe 100mm f/6 Refractors were designed to reach
focus with both DSLR and CCD cameras. However, every
camera focus point is a little different. Depending on your
camera, you may need to use an extension tube for your
particular imaging setup. Any imaging accessory, such as a
color filter wheel increases the amount of inward focus travel
required. Before attaching any extra imaging accessory, try
reaching focus first with the camera directly attached to the
focuser, then see if you have enough focus travel left for extra
accessories.
Imaging equipment is sometimes heavier than a diagonal
and eyepiece. The dual-speed Crayford focuser is capable of
handling the weight of your CCD or DSLR camera. Adding
tension to the focuser drawtube will increase the amount of
weight the focuser can handle. Install your camera onto the
2" or 1.25" adapter on the focuser during the day. Check the
focuser for any slippage. If the focuser drawtube slides under
the weight of the camera, you will need to add more tension
to the focuser.
You may want to consider using a remote shutter release
instead of the shutter release on the camera. Touching the
camera can vibrate the system and blur the resulting photo-
graphic image. Also, be sure to use a solid tripod.
Attaching the Deluxe 100mm f/6 to a Tripod
or Mount
The Deluxe 100mm f/6 can be attached to a tripod or mount
by the use of the pre-installed 1/4"-20 mounting block. The
1/4"-20 shaft of a sturdy camera tripod will thread into the
hole on the mounting block on the underside of the optical
tube (Figure 1).
Optional tube rings can also be used to mount the 100mm f/6
to attach it to an equatorial mount. Tube rings with an inner
diameter of 100mm (3.9"), such as Orion item #7371, are
needed. If you are using tube rings, you should first attach
them to your telescope mount or dovetail bar and then lay the
optical tube in the tube rings. You will need to extend the dew
shield in order to accommodate tube rings on each side of the
¼"-20 mounting block.
Calculating Magnification (Power)
It is desirable to have a range of eyepieces of different focal
lengths, to allow viewing over a range of magnifications. To
calculate the magnification, or power, of a telescope, simply
Left coarse
focus knob
Right coarse
focus knob
10:1 fine
focus knob
Focus tension
thumbscrew Linear
bearing
Figure 2: Focuser detail