Levenhuk Skyline PRO 150 MAK [15/40] Barlow lens

A Barlow lens increases the magnifying power of an eyepiece, while reducing the field of view. It

expands the cone of the focused light before it reaches the focal point, so that the telescope's

focal length appears longer to the eyepiece. In addition to increasing magnification, the benefits

of using a Barlow lens include improved eye relief, and reduced spherical aberration of the

eyepiece. For this reason, a Barlow plus a lens often outperform a single lens producing the same

magnification. And the best advantage is that a Barlow lens can potentially double the number of

eyepieces in your collection.

Slowly rotate the focus knobs under the focuser one way or the other until the image in the

eyepiece is sharp. The image usually has to be finely refocused over time, due to small variations

caused by temperature changes, flexures, etc. Refocusing is almost always necessary when you

change an eyepiece, add or remove a Barlow lens.

Barlow lens

Focusing

In order for your telescope to track objects in the sky you have to align your mount. This means

tilting the head over so that it points to the North (or South) celestial pole. For people in the

Northern Hemisphere this is rather easy as the bright star Polaris is very near the North Celestial

Pole. For casual observing, rough polar alignment is adequate. Make sure your equatorial mount is

leveled and the finderscope is aligned with the telescope before beginning.

Polar adjustment

Look up your latitude on a map, road maps are good for this purpose. Now look at the side of your

mount head, there you will see a scale running from 0 to 90°. Loosen the mount latch slightly

rotating the lock handle counterclockwise. A thumbscrew located underneath the mount head

pushes the latch plate, thus changing the angle. Turn the screw until the pointer on the latitude

scale is set at the latitude of your observation site.

The mount has controls for both conventional altitude (up-down) and azimuth (left-right)

directions of motion. These two adjustments are suggested for large direction changes and for

terrestrial viewing. To adjust azimuth, loosen the big knob under the mount base and rotate the

mount head about the azimuth axis. Use the altitude adjustment T-bolts to set the required

altitude.

In addition, the mount has R.A. (hour angle) and Dec. controls for polar-aligned astronomical

observing. Loosen the lock knobs to make large direction changes. Use the slow-motion controls

for fine adjustment after the lock knobs have both been locked. An additional scale is included

for the altitude axis. This allows polar alignment at your local latitude.

Operating the mount