A large NASA unmanned helium balloon, part of NASA's Scientific Ballooning Program, imaged from Albuquerque in September, 2003. The balloon was catching the last of the Sun's evening light at an altitude of over 30,000 meters. This balloon was launched by a New Mexico State University's Physical Science Laboratory program from Fort Sumner, New Mexico and carried an experiment to measure cosmic rays. One of these balloons can obtain a maximum diameter of over 175 meters. This is a composite obtained with a 203 mm f/7 newtonian and a Philips ToUcam webcam. 

    My first experiences with imaging through a telescope were with my Edmunds 3" f/11 newtonian. I captured a partial lunar eclipse by shooting through an eyepiece (afocally) with a 35 mm camera and color slide film. Later, I obtained images of the moon and brighter planets with color and black and white film. Now I employ CCD's for digital, video and webcam imaging almost exclusively.

    Remember those advertisements on the back or inside-front-cover of Sky and Telescope showing photographs of various objects taken through premium instruments? These images would be used to show just how well these instruments could perform. Its really amazing how imaging technology has advanced since those days. I am now able to obtain, with my relatively humble equipment, images of the moon and planets that surpass the quality that was obtained just twenty years ago or so with many of the best professional observatories.

    An image of Mars obtained by the Hubble Space Telescoe on August 27, 2003 during Mars' closest approach to Mars in about 60,000 years (left) and an image of Mars obtained with my 8" f/7 newtonian and a Philips ToUcam Pro webcam on August 21, 2003 (right).

    Books of my youth would stress that the eye was able to see much more detail during those fleeting moments of calm than photographic film would ever be able to record. With the advent of the CCD chip, the amateur is now able to digitally capture those details. It is now possible to record features on solar system objects right down to the resolution limit of one's telescope. Want to capture surface features on Ganymede? Would you like to image the Encke Division of Saturn's rings? Want to see how many craterlets you can detect on Plato's floor? These are goals easily accomplished with a quality 6" or larger telescope and an inexpensive CCD-based camera.

    The CCD camera preserves a real record of what is observed. The eye and brain of an observer are notoriously unreliable witnesses when it comes to recording visual phenomena. It is easy for the observer to misinterpret what is seen and no matter how disciplined the observer is, he can not be completely objective. The brain is constructed to recognize patterns and to see order when no real pattern is actually present. The brain is programmed to construct lines and to enhance contrast between adjacent features. Perceiving color is also a highly subjective enterprise. One only has to look at the history of visual observation of Venus and Mars by observers like Percival Lowell to understand how a person's senses can be deceived.

Webcams and Video versus cooled CCD cameras.

    CCD-based Video and Webcams have been my cameras of choice for imaging solar system objects. A good video camera or webcam can be purchased for less than $100. These cameras are best used in conjunction with a computer. Fortunately, much of the software required to capture images and then process them are available for free from the internet. There are many reasons to use a webcam, in particular, for imaging the moon and planets: 

The Philips ToUcam Pro 740K webcam (with lens in place).

    Note that atmospheric conditions rarely allow a telescope to operate at its full potential. My video and webcam imaging increase my chances of capturing views under good conditions. Still, I am usually limited to about 2-4 minute windows where I need to maximize the number of useful frames. The more frames that I can capture, the better the final image. Good seeing allows me to retain about one out of three frames for final stacking.

Frame Rate Versus Picture Quality

    Because of field rotation, I have a limited window in which to capture my images. Therefore, I wish to capture as many usable frames per minute or so as possible. Why not run my Philips ToUcam pro to its maximum of 30 frames per second at 640 x 480 resolution? Because the USB has limited throughput, the video data must be compressed. This compression results in loss of final picture quality. According to tests by Peter Katreniak (http://www.pk3.org/Astro/index.htm?astrophoto_vesta_pro.htm), the best image quality is obtained at a frame rate of 5 per second. Above about 15 frames per second, the 640 x 480 images are probably interpolated to 320 x 240 resolution! I'm still experimenting to find the balance between the seeing (capturing as many of those fleeting images as possible during my window) and degradation caused by compression as I push those frame capture rates higher.

Image Processing

    Digital images can be manipulated with computer software to alter and enhance features. Processing can be used to alter brightness, contrast, and color balance of an image. Special sharpening routines such as wavelets unsharp masking can accentuate the subtle contrast differences between features and make them stand out in stark relief. However, overprocessing will also accentuate noise and produce unwanted image artifacts. There is an art to producing an esthetically pleasing image that also reveals subtle details. I definitely lean to creating a more "natural" appearance versus an "over processed" image. This is highly subjective and a matter of personal taste. Experience and new software tools will hopefully result in increasingly better final images.

Software

Guide by Project Pluto - An excellent and relatively inexpensive planetarium software package. This works well in conjunction with Scope and my computerized goto altazimuth mount. Boasts the highest precision for planetary positions of any planetarium software.

by Software Bisque - An excellent planetarium software package.

Registax for the alignment, stacking, and processing of BMP or AVI image sequences.

Astrostack is freeware by R. J. Stekelenburg. I used this extensively until Registax arrived on the scene.

Iris - An extremely powerful (and free!) program but with a steep learning curve.

  Adobe Photoshop and Illustrator - the premier image processing and composing software

Links

Ron Wodaski's Magic CCD Calculator - Has some freeware to help calculate field and resolution using specifications of your scope and camera.

Digital-Planets list

QCUIAG (QuickCam and Unconventional Imaging Astronomy Group) Web Site - A good site especially if you are interested in modifying your webcamera to take long exposures (Steve Chamber's Modification [SC])

QCUIAG list - An extremely active site with many postings from around the world. This is cutting edge.

Videoastro Web Site - A good place to get started in video imaging.

Videoastro (Video Astrophotography) list - An active list with many helpful individuals who are eager to get the newbie started on the right track.

António Cidadão's Lunar and Planetary Observation and CCD Imaging. Much of this imaging was obtained wtih a Meade 10" SCT and CCD cameras. Dr. Cidadão has also dabbled with webcams. His sites are extremely informative. When does this man sleep?

Ed Graften's CCD Astro-imaging Page - Fantastic high resolution images obtained with a Meade 14" SCT and CCD cameras. Housten, Ed Graften's home, often has excellent seeing.

Gérard Therin

Gy Yu - Fantastic images with a 9.25" Celestron SCT and a ToUcam Pro Webcam.

Articles

"Thoughts on High-Resolution Imaging" Therry Legault, Sky and Telescope, January 2000, p. 148 -152.

"Color Planetary Imaging for Beginners" Maurizio Di Sciullo, Sky and Telescope, November 2000, p. 142 - 148.

"Thoughts on Super-Resolution Planetary Imaging" António Cidadão, Sky and Telescope, December, 2001, p. 127 -134.