Old Pentor 500 mm or Apo telescoop

Started Nov 21, 2012 | Discussions thread
Trollmann
Senior MemberPosts: 1,271
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Re: Old Pentor 500 mm or Apo telescoop
In reply to joebat, Nov 23, 2012

Our beloved earth rotates rather quickly, and a tripod mounted lens will show star trails after a few seconds exposure (the rotation at the celestial equator corresponds to about 15 arcseconds per second, and with a telephoto lens the stars show trails even in a one to two second exposure).

A tripod may be used for wide angle night sky photography, but to get sharp images with a telephoto lens or a small telescope a good tracking mount or equatorial mount is a must.

Put the camera on a tripod. Point the lens at Orions belt and take some test exposures (one, two, four ... thirthy seconds) and judge the star trails for yourself. Pont the lens at Polaris (half a degree from the northern celestial pole) and do the same test. The test images will for sure tell a lot about night sky photography and trailing.

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