EQ8 - the most powerful of the Sky-Watcher equatorial assemblies. Its 55-millimeter diameter axles made of high-strength steel and 22-centimeter drive gears are able to work with a load of up to 50 kg, thanks to which you can easily hang professional astrographs with a diameter of up to 50 kg on the EQ8 mount. 16 ”with all accessories - and we plan to test with the GSO RC 20” soon.
The head body was made using CNC technology, completely different than before, where various types of castings dominated. The shape of the head is slightly angular, typical for large equatorial mounts. The whole is aesthetically finished, black anodized. The mechanics pay attention to the reliability and perfect fit of the elements.
Dual axis encoder system
Patented by Sky-Watcher, the dual axis encoder system allows the telescope to be electronically or manually redirected to a new object without interrupting automatic object tracking. After setting on a new object, the mount automatically switches to its tracking. The assembly does not require any alignment and is perfect for remote observatories, among others.
High resolution stepper motors
The assembly uses bibolar stepper motors with a resolution of 0.9 degrees / step for high precision. They drive the worm directly in the declination axis without a reduction gear, thus eliminating the periodic error of the gear.
In the right ascension axis between the worm shaft and the motor shaft, a belt transmission with a 1: 1 ratio is used. Such a solution allows to effectively eliminate vibrations that could be transferred from the drive to the axis of the telescope. The PE spectrum of the assembly is regular and clean, so it is possible to very precisely correct it.
The set with a very solid mounting mechanics includes the advanced SynScan controller, known from the top versions of the mount such as the EQ6 or HEQ5, allowing you to use the same advanced tracking, correction and GOTO functions. It can also be controlled by SynScan Tour.
Advanced PE correction
The continuously programmable PEC system corrects periodic errors for each gear and axis of assembly. The simplification of the mechanics of the drive gear reduces the irregularity of the PE and has a positive effect on the PEC effect.
Convenient assembly alignment
Automatic parking of the assembly in the starting position with automatic setting to the start markers.
"Snap" socket - 2.5 mm jack used to release Canon cameras shutter. The set includes a suitable cable that fits all three and four-digit Canon models. There is an option in the SynScan remote control menu that allows you to program the number of exposures, the interval between them and their duration - the same as in the programmable trigger.
Note: due to weight, dimensions and price, this product is usually shipped on a pallet - delivery time may be extended by 1-2 days for this reason.
• mount type: EQ8 class equatorial
• power supply: 12V DC
• head weight: 28.5 kg
• weight of the counterweights: 10 kg
• hand controller: SynScan
• mounting capacity: 50 kg
• RA gear: D = 219.5 mm, 435 teeth, aluminum
• DEC gear: D = 219.5 mm, 435 teeth, aluminum
• RA axis: D = 55 mm, aluminum
• DEC axis: D = 55 mm, aluminum
• Counterweight axle diameter: 31.5 mm
• height adjustment: 15 ° - 65 °
• horizontal adjustment: approx. +/- 10 °
• optional external polar finder
• alignment to the gear axis: program or with the use of a polar finder
• dual encoder system
• PEC: EQ Mode
• starting position: RA and Dec. reset at power on
• limit in the RA axis: mechanically
• motors: high precision DC 12V bipolar stepper motors
• tracking accuracy: 0.1164 seconds of arc
• tracking speeds: stellar, solar, lunar, stellar + PEC
• tracking mode: in one or two axes, EQ Mode
• surface finish: black anode
Note: The photos below show the EQ8 mount with the optional polar scope and field tripod - these items are not included with this product
The base model is the EQ8. Then Sky-Watcher released its corrected versions of EQ8-R and EQ8-RH (let's call them "R" series - they have common manuals).
The "R" series differs from the EQ8 in something that Sky-Watcher describes as the Cable Management System  - that is, the de facto built-in USB hub and power hub, which allowed to run most of the cables in the head housing, and so on. thus avoid their damage and facilitate their replacement .
Further on, the EQ8 had two encoders, in the declination and right ascension axis on which the Freedom Find function was based - a wealthy user of such an assembly could turn the handle and after fastening the couplings, the assembly did not lose its position. Quote the EQ8  manual here: "The EQ8 mount is equipped with auxiliary encoders on both the RA axis and Dec. axis. Therefore, the mount can keep tracking its current position even when a user unlocks the clutches and rotates the mount in RA axis and Dec. axis manually.
With this feature, a user can manually operate the mount anytime without worrying about losing the mount's alignment status. When the user wants to operate the mount with the SynScan hand control again, no alignment is required and all that is needed to be done is to re-lock the clutches. "
In the case of the R series, the differences are as follows. The EQ8-R model does not have any encoder, while the EQ8-RH has a Reinshaw encoder in the right ascension axis, which is responsible not for the Freedom Find function, but for minimizing the mechanical periodic error :
"The EQ8-RH mount is equipped with a Renishaw's high resolution incremental encoder on its RA axis. It helps to reduce / eliminate the influence of mechanical periodic error while the mount is tracking an object for astrophotography"
Another difference - the belt intermediate gear. The EQ8 model had only one, on the axis of right ascension (Belt driven transmission to limit RA backlash)  while the EQ8-R and EQ8-RH have such a solution on both axes (Belt-drive On Both Axes. minimal backlash and significantly reduced periodic error, which mean smoother, more accurate tracking)  .
• EQ8: old version, two encoders, freedom find, only one belt gear
• EQ8-R: improved version, cable management system, no encoders, two intermediate belt transmissions
• EQ8-RH: revised version, cable management system, Reinshaw encoder, two intermediate belt transmissions