One of the main problems with visual planetary observing is that a large, bright object like a planet is very much more affected by atmospheric turbulence than are the more dim deep-sky objects. For example,
many beginning scope users are disappointed with their first view of Jupiter (which is, after all, the largest and most easily observed planet), because atmospheric turbulence prevents it from appearing with the
amazing detail they have seen on astrophotographs taken by other observers.
Experienced planetary observers have learned that planetary observing requires spending some time watching a planet, because periodically the atmospheric turbulence settles down and you get a brief view of the planet in all its glory. (This is a primary reason I note that a good observing chair is a must-have accessory.)
It turns out that planetary astrophotography has the same atmospheric turbulence problem. Regardless of the type of camera you use, most photos will be tend to be rather blurred and indistinct. So
experienced planetary astrophotographers became resigned to taking a lot of photographs and sorting through them to find the good ones. But recently some folks have discovered a new, much easier, and very
inexpensive solution (assuming you already have a computer) to the atmospheric turbulence problem - using a simple Webcam.
A Webcam is a device sold for the purpose of transmitting a digital “television-like” view of something (usually the computer user or a view of a room) across the Internet to someone else. The CCD in a Webcam
is very small and the series of frames Webcams collect are typically fairly slow, so the “television-like” view is small and tends to be “jerky” (or stroboscope-like).
This is due to the need to keep the typical consumer Webcam inexpensive, and also due to the fact that the bandwidth of most consumers’ connection to the Internet is just too slow (even with a broadband connection) to support the transmission (or reception at the other end) of moving images that simultaneously have large frames and high frame-rates.
Nevertheless, a Webcam turns out to be a perfect device for planetary astrophotography. It takes a whole bunch of frames (i.e. photos) in a row, and all that’s needed is software to accumulate the photos,
decide which ones are good, and stack them together to create a good planetary photograph.
During the recent historical Mars opposition, many astrophotographers created amazing photographs of Mars using Webcams. Even though Mars is moving away from Earth, a Webcam can be used for great photos of Jupiter and Saturn, both of which remain large in a telescope from year to year.
One of the most popular Webcams for planetary astrophotography is the Phillips ToUcam Pro, also often referred to as the ToUcam 740. The Pro version has a CCD chip rather
than a CMOS chip (which are to be avoided in this application due to their much lower sensitivity to light), whose size is 640 by 480 pixels (1.3 megapixels), a chip size that is
rather small for most deep-sky imaging but just fine for planetary imaging. It can be purchased for a little over $90US from Pocketscope, one vendor that didn’t jack up the
price of the ToUcam during the recent Mars Mania. (Note: the ToUcam does not like a USB2 (high-speed) connection - plug it into a USB1 port.) Other, similar Webcams that
have been successfully used for planetary astrophotography include the Logitech Quickcam 4000 (also a VGA CCD, and a street price of around $70US) and the 3Com Home Connect (with a smaller 512 by 492 pixel chip).
These Webcams connect to a USB port on a computer and are most easily used for astrophotography at a telescope, with a laptop computer.
None of the above Webcams were designed to be mounted on a telescope, so you’ll
need a special adapter made to screw into them, that allows them to be mounted into a 1.25” eyepiece holder. Such an adapter is made and sold for each of the
above Webcams (at a price of about $20US) by Steven Mogg, at Webcaddy.com.
(It is the black cylinder shown mounted on a ToUcam, in the photo on the left.) Typically you also need to place a Barlow lens between the Webcam and the scope,
to increase the size of the image delivered to the Webcam. All in all, this total investment is far less than any other form of astrophotography! (Aside from the laptop
computer, which you’ll really need for almost any form of digital astrophotography.)
Astrophotography Software for Webcams
The good news here is that some of the best software you need to accumulate and process a stream of Webcam
astrophotos is available free from the software developers. Peter Katreniak’s K3CCDTools is regarded as a good
and easy-to-learn application for acquiring the images from a Webcam. Many Webcam astrophotographers then use Cor Berrevoets' Registax to process the Webcam images; this application can automatically select the
sharp frames and discard the blurred ones. Other popular Webcam imaging applications include Axel Canicio's Astro-Snap, and Christian Buil's Iris.
Note that astrophotographers are starting to use this software to stack a series of short exposures with CCD cameras (rather than the more limited Webcams) and combine them to yield good images of
Deep-Sky Objects (DSOs), and so this software is allowing astrophotographers to take good images of DSOs on Alt-Az-mounted scopes, thereby obviating the need for an equatorial mount for the scope (e.g.
adding a wedge to a fork-mounted scope). Over time I expect that Alt-Az-mounted scopes with CCD
cameras will be capable of astrophotography every bit as good as equatorially-mounted scopes have done in the past (although using film with a fork-mounted scope will still require a wedge).
Webcam Astrophotography Overview Web sites
There is a brief overview of using a ToUcam Pro with Iris software, on Albert van Duin's ToUcam Pro Web page, and Dave Molyneaux has a detailed list of available Webcams and software on his web site. However, I have
not yet found a web site that gets into the details of recommended exposure settings, etc., for Webcam astrophotography. At this time most Webcam astrophotographers recommend that for detailed advice you
should join the Yahoo QuickCam and Unconventional Imaging Astronomy Group. Also, the June 2003 issue of Sky & Telescope has a good overview article - “Shooting the Planets with Webcams”.
Web Sites with Exemplary Webcam Images
If you don’t believe a $100 Webcam can take amazing photographs of planets, here are two web sites you need to study - both of these astrophotographers have really mastered this technology.
From Singapore, Tan Wei Leong's Lunar and Planetary Images site has amazing images. (One of his images of Jupiter
is shown here on the right.)
From Hong Kong, Eric Ng's Webcam High Resolution Imaging site also has amazing images.
These astrophotographers, and many others, have produced many incredible images of Mars during the recent historically close conjunction, but you probably want to concentrate on their
images of Jupiter, Saturn, and the Moon - these solar system bodies will be just as large in the future as they
have been in the past. There’s nothing stopping us from taking great astrophotos of them with Webcams in the future.