Designed to Shoot the Sky for Years, I’Ve Wished I Could Walk Into a Camera Store and Buy a Large-Chip, Single-Lens Reflex (SLR) Camera Designed for Astrophotography

equipment review Canon’s EOS 20Da camera sets a new standard for astrophotography. /// BY JACK NEWTON Designed to shoot the sky For years, I’ve wished I could walk into a camera store and buy a large-chip, single-lens reflex (SLR) camera designed for astrophotography. Now I can. In 2005, Canon introduced a modified version of its 20D digital SLR that’s astrophotography-friendly. The latest version, the best-selling EOS 20Da, features a modified The best feature may be the sharp, 1.8- infrared-blocking filter that sits in front of inch liquid-crystal display (LCD) on the an 8.2-megapixel CMOS sensor. The new camera’s back. The exposure control also filter now lets the Hydrogen-alpha (Hα) ranks high. It has two settings past bulb: line of the spectrum, located at the wave- FC1 and FC2. Both lock the mirror and length of 656.28 nanometers, pass through provide instant, real-time focus. and reach the chip. Capturing this wave- At FC1, you gain a magnification of 5x length is a must for high-quality images of on the LCD, and, at FC2, the gain is 10x. many deep-sky objects. Higher magnification allows easier focus- Canon claims this camera captures 2.5 ing of your subject. Be careful using this times the Hα light recorded by older mod- feature the first few times. At FC1, only 4 els. This means better pictures of emission percent of the chip’s center is active, an area nebulae. It also boosts an image’s overall that drops to 1 percent at FC2, so it’s contrast, an important consideration when important to center your target precisely. shooting faint HII regions. The camera comes with an AC adapter Other changes help, too. To improve the — use this in place of the DC battery for quality of long-exposure images, the EOS long-exposure sky photos. Canon 20Da employs advanced noise-reduction indicates a fully charged bat- technology. Digital cameras are sensitive to tery should last 2.5 hours temperature changes, which create optical background noise (seen as white dots) in long exposures. Mindful of the stars THE CANON 20Da digital SLR employs The Canon 20Da ($1,650 street price) has a special filter that the conventional features of the better- passes more recognized 20D — you can use it to take Hydrogen-alpha family photos and landscapes with perfect light than compa- color balance. But, for astrophotogra- rable cameras. This phers, that’s only the beginning. results in more detailed images of Jack Newton is a world-renowned astropho- bright and plane- tographer and manager of Arizona Sky Village, tary nebulae. ASTRONOMY: WILLIAM zuback an astronomy community in Portal, Arizona.

⁄ ⁄ ⁄ © 2009 Kalmbach Publishing Co. This material may not be reproduced in any form 90 astronomy JULwithoutY 06permission from the publisher. www.Astronomy.com ⁄ ⁄ ⁄ s p e c i f i ca t i o n s for this IMAGE of emission nebula Canon 20Da digital SLR IC 1795 in Cassiopeia, the author com- Sensor: High-sensitivity CMOS chip Flash: Built-in, auto pop-up bined fourteen 5-minute exposures at Image size: 8.5 megapixels (total); 8.2 Monitor: 1.8-inch color liquid-crystal ISO 800. The 20Da’s extended trans- megapixels (effective) Live-view mode: 5x or 10x monitor mission of red wavelengths — a result Maximum resolution: 3,504x2,336 pixels magnification of Canon’s modified infrared-blocking Interface: USB 2.0 high speed Dimensions: 5.7" by 4.2" by 2.8" (144mm filter — brings out this object’s deep- Viewfinder: Eye-level pentaprism by 105.5mm by 71.5mm) red color. JACK NEWTON

Shutter speeds: 1⁄8,000-second to Weight: 24.2 ounces (685 grams) 30 seconds, bulb Street price: $1,650

www.astronomy.com 91 N O NEWT JACK

SOLAR IMAGES taken through the 20Da revealed Hα detail in the lower chromo- sphere across the disk and well-defined prominences on the limb. The author set the camera to ISO 200 and shot through a Coronado Maxscope 90 Hα telescope for 1 this ⁄250-second exposure. N O NEWT JACK

THE DUMBBELL NEBULA (M27) in Vulpecula posed no problem for the author. This image shows a single 60- THIS 10-MINUTE EXPOSURE of the Milky Way was the author’s first nighttime shot minute exposure through a 16-inch through the Canon 20Da. He mounted the camera on the side of his 16-inch Meade LX200 Meade LX200 Schmidt-Cassegrain tele- Schmidt-Cassegrain telescope and shot through a 28mm lens set to f/4. JACK NEWTON scope. The author set the 20Da to ISO 800. in the bulb setting. If you’ll be using the exposures at ISO 800 I obtained using the As a focusing test, I chose the great camera for long sessions or in cold weather, self-timer. I used a Coronado Maxscope 90 globular cluster in Hercules, M13. I at- consider purchasing extra batteries. Hα telescope to test the camera’s ability to tached the cable release and set the expo- capture the deep red wavelength of Hα sure to manual (“M”), ISO to 800, and the Skyshooting emission; I set the 20Da at ISO 200 for 1⁄250 shutter speed past B to FC1 to lock the mir- Using instant gratification as my guide, I second. It performed beautifully. Solar ror and activate the LCD monitor. I selec- decided to image the Milky Way for the images revealed Hα detail in the lower ted the corner star in the Keystone of 20Da’s “first light.” I set my Canon 10– chromosphere across the disk and showed Hercules nearest to M13. At 3rd magnitude, 28mm zoom lens at f/4, focused at infinity, well-defined solar prominences on the the star’s brightness worked perfectly. and simply placed the camera on a tripod. limb. I also imaged the Moon at various It took about 5 seconds to focus the That’s when I discovered how well this phases. The camera’s LCD viewfinder made camera. I activated the cable release, lock- camera delivers. The 20Da’s self-timer can sharp focusing seem almost too easy. ing the shutter in the open position. Next, I take a 30-second exposure on the manual For long exposures, I set the custom- released the cable and moved the shutter setting. This allows any vibration resulting functions menu to FN-02 for noise reduc- speed selector to FC2 — 10x. I refocused, from handling the camera to dissipate tion. This setting causes the camera to which took only a few seconds, and pre- before the shutter opens. follow a regular exposure with a “dark pared to take an image. I pointed the tele- I then attached the camera to my 16- frame” taken for an equal time. The camera scope toward M13 and checked the inch Meade LX200 Schmidt-Cassegrain then subtracts the dark frame from the first centering through the camera’s viewfinder. telescope and imaged several objects exposure. This dramatically reduces the A 5-second exposure provided a razor- through it. I combined raw 30-second electronic noise in the final image. sharp image of the cluster. If this camera

92 astronomy ⁄ ⁄ ⁄ JULY 06 N O NEWT JACK

A SINGLE 4-minute exposure of the Andromeda Galaxy (M31) revealed lots of detail. For this image, the author set the Canon 20Da to ISO 400. N O NEWT JACK

THIS COCOON NEBULA (IC 5146) wide-field image combined sev- BECAUSE THE 20Da uses interchangeable lenses, a simple T- enty 30-second exposures through a 4-inch Borg 101 refractor. mount plus a T-adapter allows you to connect it to any telescope. Why so many short exposures? The Canon 20Da has a self-timer Here, the author mounted the camera on the back of his 14-inch and can take a 30-second exposure on the manual setting. Meade RCX400 telescope. JACK NEWTON offered only this feature, it would still have tweaks to produce the image. MaxIm DL ing the needs of astrophotographers. If the been enough to win me over. activates the color matrix to produce a $700 price difference between the 20Da Of course, the real test for the Canon clean, 16-bit color image. and the regular 20D model is an issue for EOS 20Da comes when you use it for color The Canon 20Da is a high-tech digital you, try the relatively inexpensive — but astrophotography. Many imagers operate imager for the amateur astronomer. Canon high quality — 8-megapixel 350XT. At less computer-controlled telescopes with CCD has moved the bar up a notch by recogniz- than $1,000, it presents an attractive option cameras. You can control the 20Da directly for an entry-level digital SLR camera. on such setups (substituting it for the CCD ⁄ ⁄ ⁄ p r o d u c t n o t e Weighing 24.2 oz (685 grams), the 20Da camera) using either a custom RS-232 or outweighs Canon’s Digital Rebel by 7 oz serial cable (not provided) or a standard 20Da discontinued (485g). The higher weight could be a factor USB 2.0 cable provided with the camera. if you use a lightweight mount. On April 10, 2006, Canon announced it Diffraction Limited’s camera-control But the focus-live LCD makes the 20Da would be discontinuing the EOS 20Da software MaxIm DL supports the 20Da worth every nickel. When I added light- as of April 21. The camera debuted in α through a plug-in. This plug-in allows you Japan in February 2005, in Europe in pollution and H filters behind the lens, to control both the exposure time and ISO June 2005, and in the United States in the camera automatically corrected the settings straight from a computer. Raw files July 2005. Astroimagers may still be focus. This feature saved a lot of time. download from the camera as 12-bit RGB able to purchase the 20Da. Check with Astrophotography keeps getting easier, images. At this stage, the image appears reputable dealers, who may have the and Canon has made a substantial contri- black and white, but the software then sub- camera in stock. bution toward this hobby’s enjoyment with tracts the dark frame and performs other the introduction of the EOS 20Da. X

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