UMi17X Vs UMi17S: What Should You Get?

A major new feature of the UMI 17X is the pass-through on the saddle. It includes another USB-C port with a screw hole for connecting devices like an ASIair and a 12V DC output capable of supplying up to 10 amps, providing ample power for various equipment. The power button is also conveniently located on the saddle.

The presenter introduces the UMI 17S, which he has owned for over a year, and the new UMI 17X, explaining his decision to upgrade despite the 17X being heavier, having less carrying capacity, and being more expensive. He also mentions that the 17X was initially a loaner for review, but he decided to keep it.

The UMI 17S weighs 3.5 kg with a carrying capacity of 14 kg (without counterweight) and 21 kg (with counterweight). In contrast, the UMI 17X weighs 4.3 kg and carries less at 12 kg (without counterweight) and 18 kg (with counterweight). The 17X is also significantly more expensive. The video reveals that the differences lie in the home positioning and RA limits.

The UMI 17S uses an electronic FRAM home positioning system, which constantly tracks the mount's position. The UMI 17X features a physical home sensor, which is more reliable. Both store information in non-volatile FRAM memory. Similar differences apply to the RA limits, with the 17S using electronic measurements and the 17X employing physical RA limit sensors that can be adjusted in software.

The 17X comes in a hard case with a test report and manual. Key physical features include a non-detachable altitude adjustment knob (unlike the 17S), azimuth bolts that need to be screwed in, and two bubble levels. It also has a thread for an optional counterweight shaft. On the top, there's a 12V DC input, a mounting point for an iPolar or PoleMaster, and two USB-C ports (one for the mount and one for ST4). The mount port features a unique locking screw for secure cable connection. There's also an adapter for traditional hand controllers. A significant new feature is a dedicated 'home' button that returns the mount to its home position without needing app or computer connection.

The 17X has less carrying capacity despite having the same gears and motors as the 17S because its saddle sits further away from the RA axis. This increased distance creates more torque, reducing the overall carrying capacity. This extra space is used for the additional sensors and encoders found in the 17X.

The 17X features two homing sensors, allowing for different home positions depending on whether the mount is used in equatorial or alt-azimuth mode. The presenter demonstrates how to switch between these sensors. Another cool feature is the anti-collision system, which immediately stops slewing and moves back if it detects an obstruction, preventing damage.

Initially, the presenter didn't expect much difference in guiding performance, but the 17X delivered outstanding results. After fine-tuning the settings, the mount achieved guiding performance of 0.3 to 0.4 arc seconds of total RMS, occasionally peaking to 0.5 or 0.8 during wind gusts, which is exceptional for any mount.

If maximum carrying capacity for the lowest price is the priority, the UMI 17S is recommended. However, if convenience and a 'grab-and-go' setup are more important, especially for smaller refractors and wider fields, the UMI 17X is an excellent choice. Its convenience factors include integrated power on the saddle for better cable management and the physical home button for easy packing at the end of a session.