What is the difference between the CEM70 versions?
All versions share the same 70 lb (31.8 kg) payload, 30 lb head, iPolar, GPS, counterweight and hard case. The standard CEM70 uses PPEC for a periodic error below ±5 arcseconds. The CEM70EC adds a high-resolution encoder on the RA axis with Real-time PEC for < 0.3 arcsec RMS, and the CEM70EC2 adds encoders on both RA and DEC with the same rating. Within each family, W versions add built-in WiFi and a USB 3.0 hub, NUC versions add DC 19V, LAN and USB ports on the saddle for an onboard mini PC, and the standard CEM70 is also offered with the iGuider guiding system.
What is the main advantage of the iOptron CEM70's center-balanced design?
The primary advantage is a superior payload-to-weight ratio of 2.33. By balancing the payload's center of gravity over the mount's core, every CEM70 can carry a 70 lb (31.8 kg) instrument package on a mount head that weighs only 30 lbs (13.6 kg), making it more stable and portable than traditional German equatorial mounts of similar capacity.
Can the CEM70 handle a Celestron EdgeHD 11" for imaging the Whirlpool Galaxy (M51)?
Yes. An 11" EdgeHD OTA weighs approximately 28 lbs (12.7 kg), well under the CEM70's 70 lb payload capacity, leaving room for a camera, filter wheel and off-axis guider. The included 9.5 kg (20 lbs) counterweight may not balance a fully loaded 11" setup on its own, so plan on an additional counterweight for payloads above roughly 20-25 lbs. With PPEC and autoguiding on the standard CEM70, or < 0.3 arcsec RMS tracking on the EC and EC2, the mount holds the fine spiral arm detail of M51 at SCT focal lengths.
Do I still need to autoguide with the CEM70EC or CEM70EC2?
For many focal lengths, no. The < 0.3 arcsecond RMS periodic error of the encoder versions allows multi-minute unguided exposures with round stars. Autoguiding is still recommended for the longest exposures and highest-resolution work, because it corrects things encoders cannot, such as atmospheric refraction, polar misalignment drift and flexure in your optical tube. The standard CEM70, at < ±5 arcsec with PPEC, is designed to be autoguided for long-exposure imaging.
How does the integrated iPolar work if I can't see Polaris?
The iPolar plate-solves the star field around the celestial pole, so it does not need Polaris itself to be visible and typically delivers a precise alignment in a few minutes from your computer screen. It does need a clear view of the sky near the pole; it cannot see through clouds, trees or buildings. If the pole is completely blocked, use an alternative method such as drift alignment.
Should I choose a W version or a NUC version of the CEM70?
Choose a W version if you control the mount from a laptop or tablet: it adds built-in WiFi and a hub with 3x USB 3.0 ports for fast camera downloads through the mount. Choose a NUC version if you want an onboard computer: dedicated DC 19V, LAN and USB ports on the saddle power and connect an Intel NUC or similar mini PC (sold separately) mounted directly on the CEM70, so no cables wrap or snag as the mount slews.
What kind of power supply do I need to run the CEM70 in the field?
You need a stable DC 12V power supply capable of delivering at least 5 Amps, with a 5.5mm/2.5mm plug. The mount itself draws only about 0.6A when tracking and 0.8A when slewing, but the 5A rating covers motor start-up current and the accessories powered through the mount's cable management ports.
