Celestron's parent corporation is well known for its light German mount, the CG5 (also known as Skyview Pro and EQ-4). This mount is excellent for visual use and light imaging, but it is really not heavy enough for demanding work with larger OTAs. Recognizing that fact, Synta is now selling a pair of much more robust GEMs, the Sirius EQ-G and the Atlas EQ-G. These mounts, which are sold in the United States by Orion, are also available elsewhere in the world, often under Synta's Skywatcher brand name (as the SkyScan HEQ-5 and SkyScan EQ-6, respectively).
The Sirius ($1,150) is an impressive mount able to easily handle payloads up to 30 pounds, at least 10 pounds more than the CG5. This capacity makes the mount just about perfect for a C8 and very good for a C11 but does not come at a huge weight penalty. The Sirius's equatorial head comes in at less than 30 pounds. Tracking accuracy is very good, the go-to HC features PEC (not PPEC), and the mount is fully capable of supporting a C8 loaded down with guide scopes and cameras.
The Sirius is great for dressed-out C8s and does fine with basic C11 OTAs, but it is not quite enough for the Meade 10-inch or heavily loaded 11-inch OTAs and is inadequate for a even a bare Meade 12-inch. The next step up, the Atlas EQ-G ($1,500) is able to support up to 40 pounds of scope, so 10- to 12-inch OTAs, even those weighted down with accessories and cameras, will do well on this GEM. That does come at the cost of a heavier mount; the Atlas equatorial head weighs 40 pounds (without counterweights), which may be pushing it for lightly built observers. The payload rating of the Atlas makes it seem the mount might even be enough to accommodate a C14, but the mount's counterweight system would be a problem for the large scope. The declination weight shaft is not long enough, and really not heavy-duty enough, to allow sufficient weight to be positioned on the shaft to balance that monster OTA. The Atlas features great tracking and excellent stability.
Both mounts come with respectable, if not perfect, tripods. The Atlas ships with a 2-inch leg diameter steel tripod identical to the one found on the CG5, and the Sirius features a slightly smaller 1%-inch leg tripod that is sufficient, if not much more. Both mounts are available with or without the SynScan go-to controller. Interestingly, even the non-go-to version can be turned into a go-to by use of the innovative freeware computer program EQMOD (Appendix 1). This software driver works in similar fashion to the Celestron NexRemote program, allowing go-tos to be initiated from a laptop without the presence of an HC.
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