Orion ED80T CF Photography with the 80mm Triplet, Care & Maintenance, 480mm 25mm =

cuser tension thumbscrew located on the bottom of the opti- cal tube, between the focus wheels. Make adjustments to this thumbscrew until the focuser motion feels smooth to turn and holds in place when you have obtained focus. It may be nec- essary to make adjustments when the weight of your acces- sories change significantly.

Photography with the 80mm Triplet

The Triplet 80mm f/6 refractor makes a very capable astro- graph for your CCD or DSLR camera. With an optional cam- era adapter, the Triplet 80mm becomes a 480mm 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 that 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 focuser 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 Triplet 80mm 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 imag- ing 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 80mm Triplet f/6 to a Tripod or Mount

The Triplet 80mm 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).

The tripod mounting block is also a dovetail bar designed to attach to any Orion mount. Simply insert the dovetail bar into the receiving dovetail cradle on the mount and tighten the mounts attachment locking screws.

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 divide the focal length of the telescope by the focal length of the eyepiece:

Telescope Focal Length (mm)

Eyepiece Focal Length (mm) = Magnification

For example, the 80mm, which has a focal length of 480mm, used in combination with a 25mm eyepiece, yields a power of:

480mm 25mm = 19x

Every telescope has a useful limit of power of about 50x per inch of aperture. Claims of higher power by some telescope manufacturers are a misleading advertising gimmick and should be dismissed. Keep in mind that at higher powers, an image will always be dimmer and less sharp (this is a funda- mental law of optics). The steadiness of the air (the “seeing”) will limit how much magnification an image can tolerate.

Always start viewing with your lowest-power (longest focal length) eyepiece in the telescope. After you have located and looked at the object with it, you can try switching to a higher- power eyepiece to ferret out more detail, if atmospheric con- ditions permit. If the image you see is not crisp and steady, reduce the magnification by switching to a longer-focal-length eyepiece. As a general rule, a small but well-resolved image will show more detail and provide a more enjoyable view than a dim and fuzzy, overmagnified image.

Care & Maintenance

Give your telescope reasonable care and it will last a lifetime. When not in use, keep its dust cover on as well as the dust cap on the eyepiece opening. Store it indoors or in a dry garage. Do not leave the telescope outside except when using it. The optical tube is carbon fiber underneath a protective surface that should resist scratches and smudges. If a scratch does appear on the tube, it will not harm the telescope. Smudges on the tube can be wiped off with standard household clean- ers such as Windex or Formula 409.

Any quality optical lens tissue and cleaning fluid specifically designed for multi-coated optics can be used to clean the telescope’s objective lens as well as the lenses of the eye- pieces and finder scope. Never use regular glass cleaner or cleaning fluid designed for eyeglasses. Before cleaning with fluid and tissue, however, blow any loose particles off the lens with a blower bulb or compressed air, or lightly brush the lens with a soft camel hair brush. Apply some cleaning fluid to a

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