Backyard Voyager
Using a flipmirror is far simpler. Any accessory that speeds up the imaging process is worth looking into, but I consider flipmirrors a necessity. Meade makes them for around $150.00. The flip mirror accepts a 1.25" eyepiece at a 90 degree angle. Your webcam adapter screws into the back of the flip mirror. With the mirror in the up position you use the eyepiece to center the object in the eyepiece field of view. Flipping the mirror down allows light to pass through the barrel to the webcam's CCD chip.
Starlight instruments Feathertouch Focuser
For larger image scale on your planetary shots a barlow is necessary. Whether or not you need a high quality barlow is debatable. Some people think it isn't very important, since the ccd chip is so small and the on axis performance of even the cheaper barlows is usually not bad. Because of the fluctuation of seeing conditions I bought a 1.25" 1.5x barlow from Siebert Optics. I use it on nights when the seeing won't quite support 2x magnification.
At left is pictured a dual speed Feathertouch focuser. In the image below you can see how it fits into my scope's optical train. At a little over $315.00 they are the most expensive manual focuser on the market, but are, in the author's opinion, worth every penny. Even so, a high end focuser is not absolutely necessary. In fact, if you plan to put together the best possible system but are working within a limited budget, this item should go to the end of the list. But, if you can somehow work it in, you won't regret it, particularly if you are imaging with an SCT. Even with a dual speed focuser you will spend more time focusing than with any other aspect of the imaging process.
So Which Telesope?
Practically any driven scope can be used for planetary photography, but obviously some will produce better results than others. It is possible to acquire images from a camera and scope mounted without tracking motors, but few have attempted it and I doubt that anyone has ever advised it. The results, in any case, would be less than pleasing.
One fairly common myth is that the larger apo refractors are ideal for planetary imaging. Although untrue, the misconception is
Imaging optical train with C9.25-- Feathertouch Focuser,
Meade flip mirror, barlow, Phillips ToUcam
understandable given the quality of views they produce at the eyepiece. And four to six inch apos really are among the best scopes available for DSO imaging, particularly for wide-field images of large nebulae and open star clusters. But planetary imaging is one of those areas in which aperture is of utmost importance. Bigger really is better. The larger the telescope's aperture, the easier it will be to resolve minute detail at high magnification levels.Remember, an 8 inch apochromatic refractor starts at around $20,000. At 10 inches, the 20k scopes begin to seem inexpensive.
Newtonian reflectors and Maksutov Newtonians are both better suited for this kind of astrophotography, at least in part because larger aperture is more affordable in these designs. But their focal lengths make it difficult to get the kind of image scale you need for planetary work. Where they really excel is in wide-field lunar shots or lunar mosaics.
The ideal telescope for lunar and planetary astrophotography is one of the catadioptric designs, such as a Dall Kirkham, Maksutov Cassegrain or Schmidt Cassegrain (SCT). All of these designs have long focal lengths and easily produce high magnification images. Larger Maksutovs are available through the Telescope Engineering Company, but are beyond the price range of most amateurs. Several Dall Kirkhams are available in Takahashi's Mewlon series at slightly better prices than Maksutov Cassegrains of similar size.
But it isn't necessary to spend a lot of money to get a scope that will produce professional quality images. Most of the world's best astrophotographers, such as Damien Peach and Christopher Go use SCTs. People have called the Schmidt Cassegrain telescope a jack of all trades and master of none. Given the variety of purposes to which one can apply a telescope, that is not at all an unflattering description. But it's not quite true. I don't feel as if I'm going out on a limb to say that an SCT really is a master in the field of planetary photography.
How? Well, first of all, accusations of "soft" images produced by SCTs aren't relevant, since the issues at hand are really of size and resolution. Many of those judgments were based on views though the eyepieces of inadequately collimated and cooled scopes anyway. Everyone knows that an apo will "win" when its views are compared to those of an equally sized SCT. But comparisons of planetary images produced by refractors and SCTs are never fair to the refractor. So few large aperture refractors exist that fair comparisons can't be made. But, if you still believe that a six or seven inch apo can compete, let the pictures speak for themselves. The proof, as they say, is in the pudding, and there are thousands of SCT-generated planetary images available for view online. It might surprise you, but you'll like what you see.