Sky and Telescope - May 2012 - (Page 65)

a cluster of three jacks on one side of the camera. One accepts the included 10-foot (3-meter) USB 2.0 computer cable, and another is for the 12-VDC power input (a 10-foot power cord with a cigarette-lighter plug is included). The third jack is a modular phone connector that the manual says will be used for future features. The Nightscape has a mechanical shutter, making it easy to acquire dark frames for image processing without having to cover the telescope’s aperture. An infraredblocking ﬁlter is mounted ahead of the CCD chip but behind the shutter. More details about the camera’s physical construction appear in the 16-page Nightscape manual, which can be downloaded for free from the Support section of Celestron’s website. Because Nightscape’s TEC system, which cools the CCD chip to as much as 20°C below ambient air temperature, is regulated, you can make a library of stored dark frames for various temperatures. Doing this during twilight or cloudy nights will avoid wasting valuable observing time shooting dark frames when the sky is clear. The TEC’s user-selectable temperature set point is visible on the computer monitor throughout the imaging process, and I found the temperature regulation very precise, varying by no more than 0.03°C on a typical night. The software lets you know when the selected temperature has stabilized so you can begin to make expoWHAT WE LIKE: sures. This took up to 20 Large, one-shot color CCD minutes depending on the Regulated cooling ambient air temperature. Easy-to-use software Nightscape’s CCD array is made up of square WHAT WE DON’T LIKE: 4¾-micron pixels, and Camera body lacks a full-resolution image tripod socket measures 3,760 by 2,840

Nightscape’s one-shot color CCD has 10.7 million pixels in an array measuring 13.5 by 17.9 millimeters. The camera’s mechanical shutter and the optical window in front of the CCD are also visible in this picture.

The camera’s small, 4¾-micron pixels work well with short focal lengths, and the author had excellent results shooting with a 300-mm f/2.8 Nikon telephoto lens. He used a stock lens adapter sold by Orion Telescopes and Binoculars to couple the Nightscape to the lens.

pixels. Binning the pixels 2×2 or 4×4 while shooting, which increases the camera’s sensitivity and speeds the readout of images (at the expense of lower resolution), produces images measuring 1,880 by 1,420 pixels and 940 by 710 pixels, respectively. There’s also a subframe setting that allows imaging at full resolution, but using only the central half or the central quarter of the array. The binning and subframe options allow optimal imaging over a wide range of focal lengths. The small pixels work well with fast, short-focus telescopes, while binning is great for long-focus instruments with slower f/ratios. I tested Nightscape at the f/4 Newtonian focus of my vintage 12½-inch classical Cassegrain reﬂector, using a Baader MPCC coma corrector to improve star images at the edges of the ﬁeld covered by Nightscape’s large chip. I also tested the camera on my 11-inch Celestron Schmidt-Cassegrain telescope and a 300-mm f/2.8 Nikon lens, using a Nikon lens adapter available from Orion Telescopes and Binoculars. The lens performed very well with the Nightscape’s small pixels, and fortunately the tripod socket on the lens permitted me to easily attach the imaging setup to a tracking platform. A tripod socket or optional tripod adapter for Nightscape would be welcomed by astrophotographers looking to use shorter-focallength lenses that lack tripod sockets. Nightscape’s CCD is located 55 mm back from the T threads on the front of the 2-inch nosepiece, which is very convenient if you use the camera with accessories designed for conventional 35-mm camera bodies. With the nosepiece removed, the setback distance to the CCD is 26 mm from the front mounting surface of the camera body, which also has female T threads.
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Table of Contents for the Digital Edition of Sky and Telescope - May 2012

Sky and Telescope - May 2012
Table of Contents
Spectrum
Letters
75, 50 & 25 Years Ago
News Notes
Saturn’s Raging Superstorm
Stars Above, Earth Below: Astronomy in National Parks
The Remarkable Case of Comet Lovejoy
In This Section
May’s Sky at a Glance
Binocular Highlight
Planetary Almanac
Northern Hemisphere’s Sky
Sun, Moon, and Planets
Celestial Calendar
Exploring the Solar System
Deep-Sky Wonders
Going Deep
S&T Test Report
New Product Showcase
Telescope Workshop
Planetary Imaging with Your DSLR Camera
Gallery
Focal Point

Sky and Telescope - May 2012