While I've gone through quite a few different telescopes over the past 5 years, I believe I've settled in on a good combination of telescope, mount, camera and guidance system. Back in November of '05 I purchased a 30 year old Takahashi E-160 off of astromart.com (the most comprehensive used astronomy equipment sight out there). The Tak E-160 is an extremely fast telescope at f/3.3, meaning the ratio of its optical mirror to the focal length (the length of the light path) is approximately 3.3. In this instance, the mirror is 160mm wide and the focal length is 530mm. In the attached photo, the E-160 is the big yellow tube.
Coupled to the telescope is an ordinary stock canon 20d DSLR (digital SLR), available at all fine photo shops for around $1200 new. The telescope is mounted to a Losmandy g-11 mount, this is rated for scopes up to 70lbs, my scope probably weighs in around 25lbs with all the accessories mounted to it. The mount will properly guide the scope through the celestial sphere as it rotates around us. Have you ever watched the stars long enough to notice that they rise in the east and continue on a westward path moving about one thumbs width every two minutes? Therein lies the most difficult problem in photographing the heavens, not just having a camera that can do long exposure photography, but also can track an exact position in the sky (for the sake of these discussions, a DSO, deep sky object) for several minutes and even hours at a time. While a mount such as the losmandy g-11 can move the telescope in sync with a DSO moving across the sky, getting the precision necessary for long exposure photography requires one additional step, it's the one that drives us all crazy and is the one most prone to failure, that is, guiding. In this photo, you'll see an additional blue scope mounted on top of the Tak e-160, that's called a guide scope. There's one last component, called a ST-4 guider, that is essentially a 1990's era CCD camera that takes continuous photos through the guidescope and sends back directions to the losmandy mount on how to move the telescope to stay perfectly trained on that D
SO. Sound easy? It's not ;-) Astrophotography is a labor of love, and a byproduct of many sleepless nights. However, in the end, for me it's well worth it. I'll also post on some of the easier and equally rewarding aspects of this hobby.
