Most any scope and mount can produce decent, short exposures of planets and the moon. Even a digital camera held to the eyepiece of a Dobsonian scope can yield surprisingly good results. But long exposure work requires a mount that is not only equatorial, but can track the sky with a minimum of errors.
To satisfy the equatorial requirement, German Equatorial mounts (GEMs), fork-mounted scopes with wedges, and even Dobsonians on Equatorial platforms can be used. But it’s the quality of the mount that determines the amount of success you will have. Unfortunately, and to the dismay of many, “quality” costs money!
Until recently, my recommendation for a serious entry level mount for astrophotography would have been either the Losmandy GM-8 German equatorial mount, or one of the many forkmounted Schmidt-Cassegrains (SCTs) when used with a quality wedge. However, the advent of affordable digital SLRs has allowed for even less expensive mounts to be useful. The CG-5 types of mount, such as the newer Orion Skyview, the Celestron ASCD, and the Meade LXD55/75 GEMs fall into this category. These mounts are all quite similar, with very competitive prices in the $300 to $500 range. While they generally do not allow for exposures longer than 3 to 5 minutes, this is not a problem with the newer digital SLRs because of the method used, whereby you take many 3 to 5 minute shots and "stack” them in an image processor. The result is akin to a single, longer exposure. Therefore, the person who wants to dabble a bit in astroimaging might find this level of mount to be quite functional, especially when paired with a shorter focal length scope (for ease of use) and one of the newer digital SLRs like the Canon Digital Rebel or the Nikon D70. However, I would not recommend a mount of less quality than this for deep-sky imaging.
GEMs are my favorite types of mounts for a variety of reasons, but mostly because they allow for interchangeable optical tubes assemblies (OTAs) and because they avoid some of the problems inherent with the fork-designed scopes on a wedge. Therefore, for the serious astrophotographer with a moderate budget, a Losmandy G-11 or Celestron CGE mount will be better performers than the Meade LX200 or Celestron Nexstar scopes. While those scopes can yield fine results, they will not be as refined as GEMs in this price range. Plus, the GEMs will hold payloads much higher than the forkmounted SCTs, meaning that mounting heavier accessories on those scopes is all but impossible.
The Losmandy types of mount represent a price range of between $1500 and $3200 new. There are some mounts in the $1000 range that can be used with quite a bit of success, most notably the Vixen GPDX mount. I would advice caution when purchasing the EQ-6 type of mounts, such as the Orion Atlas (around $800). While these mounts will yield more success than the previously mentioned CG-5 type of mounts, some of these GEMs do not allow for an autoguider input nor do they have smooth or accurate gears for imaging. In other words, mounts like these, and the fork-mounted scopes, will have higher amounts of Periodic Error (PE) and Random error than the more refined mounts. Therefore, if you are wanting to have a platform that you can grow with, one that allows for at least 10 minute exposures with an autoguider, then you’ll have to spend some money. The Losmandy mounts are the affordable entry at this point, and the ability of a mount for imaging simply goes up from there depending on the price that you are willing to pay.
The upper end imaging mounts will be those from Takahashi, AstroPhysics, Software Bisque, Parallax, and Mountain Instruments, to name but a few. Be prepared to spend over $3000 for such a setup, though these mounts will cost typically in the $5000 to $15000 range.
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