Zoom Eyepiece 1 1/4" 7-21mm

An eyepiece is part of the optical system in astronomical telescopes. The eyepiece is attached to the telescope and enables the view. It enlarges the image produced by the telescope, similar to a magnifying glass.

The zoom eyepiece features several focal lengths in one eyepiece. The focal length of the eyepiece used, along with the focal length of the telescope, determines the magnification. This can be calculated easily with the following formula:

In general: the shorter the focal length of the eyepiece, the higher the magnification. Furthermore, the longer the focal length of the telescope, the higher the magnification. Eyepieces with longer focal lengths provide a better overview of the night sky.

The zoom eyepiece 7-21mm features several focal lengths and thus several magnifications. By turning the zoom ring, you can variably change the focal length from 7mm to 21mm. This allows the magnification to be adapted to the observation object flexibly. This eliminates the hassle of changing the eyepiece.

The lens surfaces of the zoom eyepiece is covered with a multi-layer coating (multi-coating, MC). This complex coating enables improved light transmission for optimal contrast, for improved brilliance and colour neutrality. The coating also reduces reflections to a minimum.

All DÖRR eyepieces feature a standardized 1.25" diameter. That corresponds to 31.7mm. The rear side is fitted with a thread to attach a moon filter (optional accessory).