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What Is the Power for a 12 Inch Reflector Telescope?

A Newtonian reflector telescope uses a two-mirror optical system to capture light and direct it to a magnifying eyepiece. The magnifying power of a 12-inch reflector depends on the focal length of the telescope and the eyepieces used with it.

Magnification
- Divide the telescope's focal length by the focal length of the eyepiece to calculate the current magnification of the telescope. A 12-inch reflector with a 1,500mm focal length, for example, provides 150x magnification when used with a 10mm eyepiece. Focal lengths vary from model to model. Manufacturers typically publish the focal length in a telescope's user manual.
Usage
- A 12-inch reflector will provide low-power views of large objects, such as galaxies and nebula, when used with an eyepiece in the 20mm to 40mm focal-length range. When used with shorter focal lengths, it will produce high magnification views of the moon and planets.
Limitations
- Although a typical 12-inch reflector can provide magnifications upwards of 400x, atmospheric conditions often limit the maximum usable magnification to less than 200x. A turbulent atmosphere produces unsteady images at the eyepiece, which only worsen with increased magnification.

Astronomy