The answer, no surprise, is that it depends. I have one answer based on using all three cameras on the same telescope (10” LX-200 f/10, top photo) at nearly the same time and conditions. The subject of interest was the recent naked-eye sunspot region 10030, and images were taken around midday on July 13th with high cirrus thickening into the afternoon. Setting the scope tracking to a solar rate and taking reasonable care with the power-up alignment (zero altitude, pointed due south) allowed me to image without having to constantly chase the Sun to recenter my sunspot target. 

Daytime imaging has the advantages of easy setup and no mosquitoes. There is no problem finding the Sun, of course, and big optics are not needed, although safety for optics as well as eyesight must always be a concern. Heat causes breezes, turbulence and bad seeing, the effects of which can be minimized by imaging in the morning and away from hot surfaces (roofs and streets). Most important is taking plenty of images to ensure capturing the rare crisp one. Compared to most astro-objects, the Sun is low contrast so dust and vignetting make themselves more than apparent. I used an off-axis 60-mm, Baader solar filter and autoexposure modes on all cameras.

Afocal photography with my Olympus 490 (2 megapixel chip, 3x optical zoom) digicam is easy and with practice requires only a little fussing with the mounting bracket. My standard procedure is to use full optical zoom and shoot several memory cards of pix at high resolution (1600 x 1200). Combined with frequent checks and tweaks of the focus, this seems to catch a least a few shots with good resolution (second photo). The actual image scale depends on the camera zoom and eyepiece focal length (here, 25 mm), and could be increased.

Setup of the video camera (SuperCircuits’ PC164C monochrome, NTSC video output) is not much harder since I have a portable VCR-TV combo unit. Plug in the power, attach a video cable, press a few buttons on the remote, and I’m imaging. The camera's resolution is great for watching on a television screen, and videotaping allows you to pan the whole solar disk even with a narrow camera field of view. Tapes can be later shown almost anywhere with a VCR, and if desired digitized (Dazzle DVC 50 frame grabber, 320 x 240 resolution) for digital enhancement and display (middle photo). Autocontrast features were fooled by the dark spot on a white background: I had to tinker extensively with the digitizer settings to get a useable image.

With a resolution of 640 x 480, my Philips Vesta Pro webcam provides the highest actual resolution of these three systems. Since the webcam requires a computer, this setup is the most extensive (cables, plugs and luggable pieces), and its learning curve is steepest. High-resolution video files take up incredible amounts of hard disk, and I find that I save about one CD-ROM’s worth of avi files per session. A 320 x 240 mode is a space-saving option. Good software like AstroVideo (highly recommended) can save raw video, time-lapse, or just individual frames. Post-processing on a computer is needed to compress the video or automatically select the sharpest frames for enhancement. While this system has the highest overhead factor, the results can be impressive (second photo from bottom).

So for a quick shot of a sunspot, I’ll use my digicam and afocal bracket (bottom photo, full frame of sunspot region 10036 on July 20th). Unless I need greater resolution and feel that the seeing can provide it, the added equipment of the video and webcam is not justified. Especially because of the turbulence, the most difficult part is focusing, and I find it particularly frustrating to see fine detail on the television or computer screen in bright daylight.

Of course, all three of these cameras can be used for bright nighttime objects, and this would surely yield other answers to the question of which camera is best. In comparison to the Sun, imaging the Moon presents very different challenges, including extremely high contrast (shadows and sunlit features) as well as very low contrast at high sun angles, nighttime operation of the equipment, and possibility of very high resolution with modestly sized optics and favorable seeing. Look for the results of a “moon match-up” in a future column. Until then—keep “clicking”  by taking those astroimages!

For comparison, sunspot images at right are reproduced at nearly the same scale. Contrast and brightness have been adjusted and mild sharpening has been applied. Processing was accomplished using CompuPic Pro, AstroVideo and MaxIm DL. Moondark is written by Doug Miller, published on the web, and printed in the Delmarva Star Gazers' Star Gazer News. Please address comments and suggestions to dcmiller@dmv.com. This document was last revised on 23 July 2002. All text and images copyright © 2002 Douglas C. Miller, All Rights Reserved. This material may not be reproduced in any form without prior permission.