Adapters and Filters

Adapters:

Adapters come in about as many shapes and sizes as there are pieces of equipment to adapt to one another. Fortunately, a few industry standards have been established out of sheer practicality, and generally manufacturers have elected to stick to the standards rather than create their own.

Some adapters allow the use of smaller eyepieces in larger focusers, others will allow the attachment of a 35mm, video or digital camera to the telescope, and some are just provide extensions to your focus range. Some are fixed and some provide adjustment. Sometimes two adapters are needed to get two pieces to mate, such as when mounting a camera. To mount a camera in place of an eyepiece on a telescope first you need a T-adapter that adapts your focuser or telescope back to a standard thread, and then you need a T-ring to go from the standard thread to your particular camera type. You get the picture? Here are some basic adapter types and an idea of what you can expect them to be worth in the used market.

Adapter Type	1 ¼”	2”
Visual Backs for SCTs:	$10-15	$20-30
T-Adapters:	$15-20	$20-25
T-rings:	$10-$15	$25-40 (large format)
Eyepiece Reducers:	$10 (to .965")	$15 (to 1 1/4")
Telextenders:	$10-15	$20-30
Variable telextenders:	$20-30	$30-50
Focus tube extensions:	$10-15	$15-20
Filter holders:	$10	$20

Filters:

Filters are used for three basic purposes. The first is to reduce the brightness of an object so as to make it possible to view or to make viewing more comfortable. Sun or moon filters fit into this category. The second is to hide certain wavelengths of light so as to make features of an obect stand out. Colored filters for planets and "narrow bandwidth" filters for deep sky objects fit this category. Finally, there are filters to block out man-made light so that deep sky objects are more visible. So called "broad band" filters fit this category.

SCT	1 ¼”	2”
$40-80	$30-60	$40-80