Resolution and image size have grown steadily, and media costs are now far below $1 per megapixel of storage. The key though has been in full-manual or scene-mode functionality that allows exposures of several seconds up to minutes in length, combined with built-in noise reduction. Today’s product line represents unequaled opportunity to explore digital imaging without investing heavily in hard-to-use, dedicated equipment.

Tripod astrophotography is by far the easiest, and digital astro-snapshots are no exception. Twilight scenes come out beautifully, using the specially designed exposure mode. Constellations can be taken with the camera mounted on a tripod and pointed up, with no tracking or polar alignment. The image can be checked immediately for trailing or distorted stars, and additional shots cost nothing but battery power.

I’ve learned a couple of things taking these snapshots last December in New Zealand. I set my Olympus 3020 3.2-megapixel camera on full manual mode, forced the ISO speed rating to 400, turned on the noise reduction (a dark frame is taken and subtracted after each exposure), set the manual focus at infinity, and used the longest exposure available, 16 seconds. It’s nearly impossible to see stars through the tiny viewfinder, but the wide field of view ensured that I got something in the shot. Even at full optical zoom, star images were good, though slightly trailed. With successive frames, heat noise increases, so it would be best to turn off the LCD if possible. I shot at high resolution (2048 x 1536 pixels) and minimal compression and recorded stars to 4-5th magnitude in color over a 60º x 45º field of view. In the process, I used a lot of memory media and battery power, so I had plenty of both on hand.

What else can you do? Here’s one for this summer: follow Mars in its retrograde loop through opposition and into the fall. It would be interesting to try an aurora, a space station pass or satellite flare. What about recording the rise and fall of a bright variable star like Mira or Algol?  With my southern sky shots, I’m going to assemble a panorama of the closest and brightest stars. Stay tuned to see if it turns out.

These two resources should get you started. The first is an article, "Deep-Sky Imaging with Digital Cameras" by Edwin L. Aguirre in the October 2002 Sky & Telescope. Note however that product lines change quickly. An online source will yield the most current information: the digital astro yahoo group. They have a "Getting Started Guide" and "FAQ" files, plus an extensive Gallery and monthly challenges. Great planetary images, even deep-sky objects, can be captured by mounting the camera at the telescope eyepiece. Remember that these are the folks who are pushing this field forward, so don’t be intimidated by their high-end cameras (they prefer particular models of Nikon and Cannon brands) and image processing shoptalk. Grab a tripod and start your clicking. Clear skies and keep shooting for the stars.

Moondark is written by Doug Miller, published on the web, and printed in the Delmarva Star Gazers' Star Gazer News. This document was last revised on 21 May 2003. Text and images copyright © 2003 by Douglas C. Miller, All Rights Reserved. This material may not be reproduced in any form without prior permission.