Thank you!
Choosing equipment starts with the question what you want to image. If it is planets you need a very long focal length, a decent barlow lens, a camera with a small chip that can capture movies and no cooling is needed. I can't help in this case. If you want to image Deep Sky Objects (DSO) you will probably evolve from easy to more challenging. Easy means the object is large and bright. Examples are the Great Orion Nebula and the Rosette Nebula and the Pleiades. The smaller and the fainter the target the more difficult and the more demanding for the equipment. The most difficult one that comes to my mind is the Cat Eye Nebula. There are some large and relatively faint objects the require special filtering: narrow band. There is no one fits all optics so you will have to start with one and add more later. Re focal length overview, I'm talking about a APS-C sized sensor: for a shot of the whole milky way you would use a 12 or 16mm camera lens, a prime. For large fields like Heart and Soul in one frame or the Spaghetti Nebula or the Cosmic question mark 135 or 200mm lenses. Then comes a transition point where a lens is as expensive as a real telescope, this is roughly from 300 or 400mm up. The above examples (Orion, Rosette, Pleiades) require 300-400mm, the Andromeda Galaxy as well. If you go for the smaller objects, namely the galaxies outside of our local group you need a far longer focal length like 1000+ mm. This needs a far more expensive mount and is in general far more difficult to handle than the smaller ones. So you have to decide if you want the large objects and have technically good images with a moderately priced rig (3 to 4k$). If you want all the galaxies you should add 1k$ to the mount.
The next thing to decide is OSC (one shot color) or mono and filters. OSC can be a DSLR that you perhaps own right now or an astro camera. Mono is more effort, you need a filter wheel, a set of filters and need to dealt with 3-7 sets of date to compose one image. See my video "which camera is best for me". A popular cooled mono with filters is in the 2k$ range. Cooling is not always needed. Noise comes from a warm sensor and noise also comes from a bright sky background. So cooling makes sense under very dark skies or if you image narrowband. Under a city sky with an OSC you might not see much of a difference. For details find 2 videos by Robin Glover, linked in the Media section of my website. OSC and a relatively short focal length below 500mm is the easy route with early success but a limited selection of objects. If you want more of a challenge go for a longer focal length and mono and filters. Only you can tell if you tend to get along well with tasks that consist of many steps and if you can handle tricky situations. Many start simple and by the time sell things and get new stuff to grow. With the mono you have an option for narrowband. The bright stars and the sky background is dimmed down while the nebulae stand out. This works well under light polluted skies. It requires long exposure times and thus a good mount a a long over all exposure time. One narrowband image can easily take you several nights.
Telescopes: a newton gives you most aperture for the money. It is as long as it's focal length, it needs to be collimated (easy) and it need a coma corrector. It must be designed for imaging and even then not all of them work with a DSLR because the sensor is too far away. Refractors do not need collimation, they are also as long as the focal length and they need a flattener. You can attach any camera without problem. If you want a fast refractor with a long focal length it will be expensive. That is where a folded design like a Schmidt-Cassegrain, a Richey-Chretien, a classic Cassegrain, a Dall-Kirkham and so on will be cheaper with the same parameter or offer the desired fastness at all. They all need collimation and this can be difficult. They are short, a bit more than 1/3 of the focal length and some of them come with a flat field, so you need no more correctors. The Celestron Edge is one example, RCs can be used without flattener when cropping a bit of the image. Less common designs like maksutov-newtonian also come with a flat field. If you have damp conditions all scopes with a glass element at the front (corrector plate in case of Schmidt-Cassegrain and Mak-Newt, lenses for refractors) can fog up and need dew heaters. Scopes without a front Element like RC or Newton do not fog up. The mirrors in the tube are protected from the wet air. The idea of using the same telescope for AP and visual is not a good idea. I got myself a pair of binoculars to watch the sky while the scope is taking the image. Some have a cheap large dobson for "family fun". All telescopes have some sort of image errors. For more money you get better corrections. The most important one for refractors is chromatic aberration (CA). In general a triplet lens can correct this better than a doublet, though there are some excellent doublets on the market as well. Mirror scopes don't have CAs. They only occur if the light goes through glass, not when it is reflected on a silver mirror.
Answering your question: my first rig was an RC6 on an AVX and a DSLR. The AVX was the biggest mistake. The RC6 is regarded as a monster by many but mine did not cause much trouble. I invested a few hours in the first collimatiotion and then it was fine. Reasons for choosing it was large aperture for the price, short an compact, light weight and camera at the rear end plus no fogging trouble and no CA. Many here will recommend not to start with an RC and tell you horror stories about collimation. I decided to sell it in order to update to it's larger brother, the RC8 carbon. A carbon tube reacts less to temperature changes. You don't need to refocus that often. There are carbon refractors as well. I decided to get the SW EQ6-R as an intermediate step because right now I don't want to invest in a premium mount but going on with the AVX was an absolute NoGo. I also started with a book of Messier objects. Alas many of them are too large for the RCs and I got the small refractor. I decided to get the quad to save me from trouble with flattners and I decided to get a small one, 65mm aperture only because the faster it is, the more accurate you need to focus. Of course I wanted a triplet front element to avoid CA. My decision was not to use a computer outside because I hate computers and the trouble they cause. That in turn made me invest quite a large sum of money in a mono conversion of a DSLR and a stand alone auto guider. This is really a minority path. I am a multiple minority member anyway, so why not continue here? My biggest mistake was the AVX and my biggest boost was the mono camera.
Hope this helps!
Edited by the Elf, 11 December 2019 - 12:20 PM.
