Strain wave gearing is a type of gear mechanical transmission, the peculiarity of which is the multi-link engagement. For comparison, in a conventional cylindrical involute gear the torque can be transmitted by two teeth, but wave transmission provides the load transmission by approximately half of the teeth. Another name for strain wave gearing is harmonic.
The main advantages of the strain wave gearing are reliability, compactness, high gear ratio, efficiency, service life, resistance to impact loads, as well as simplicity and maintainability of the design. With regard to astronomical mounts, one of the main advantages of using wave reducers is the refusal to use counterweights even under heavy loads. However, if the mount is heavily loaded, there is a risk of the telescope tipping over, so when using a heavy tube, it is advisable to use a counterweight. Another important advantage of the strain wave gearing is the absence of backlash (significantly increases resistance to wind) and the absence of the need for maintenance and adjustment. The disadvantages of mounts on a srain wave gearing include worse tracking accuracy than mounts on a worm gear, but when shooting with long exposures, this issue is solved by fast autoguiding (exposures of about 1 second), or software and hardware (correction of periodic error, encoders).
Sky-Watcher Wave 100i is an astronomical mount, in the design of which wave reducers are used, and on two axes. Judging by the declared characteristics, a wave reducer of size 17 is used on the AZ (R.A.) axis, and a size 14 on the ALT (DEC) axis. This mount can operate in both alt-azimuth and equatorial modes. At the same time, the mount is distinguished by its small size and moderate weight (4.3 kg) for such a lifting capacity (up to 10 kg without counterweights, up to 15 kg taking into account the counterweight). The manufacturer recommends not to overload the mount and to avoid breakages, the weight of the entire observation structure, INCLUDING THE COUNTERWEIGHT, should not exceed the maximum permissible load on the mount.
Another interesting feature of the Sky-Watcher Wave 100i mount is the ability to place two tubes simultaneously on different sides of the mount (instead of the counterweight axis). Not only the mount head arrived for review, but also an extension column, a tripod, a counterweight with an axis (not included in the kit, purchased separately).
Specifications | |
Mount type | AZ/EQ |
Limit payload, kg | 10 |
Pole finder | no |
Latitude range (in degrees) | 0° to 90° |
Type of motor | Stepper |
Gear | stepper motor + belt drive + Strain-Wave |
Gear ratio | 300:1 |
Gear (dec. axis) | 14-100 |
Gear (Right Ascension Axis R.A.) | 17-100 |
Maximum speed | 2400х (10° per second) |
Speed | sidereal, solar, lunar |
GoTo | yes |
Wi-Fi | yes |
Hand control | SynScan remote control (not included); iOS, Android, Windows and Mac devices |
Ports | USB |
Power supply | external power supply 12V |
Tripod included | No |
Attaching the mount | Vixen, Losmandy |
Mount material | aluminum, stainless steel, plastic |
Mount size, mm | 119 x 183 x 222,5 |
Weight of the mount, kg | 4,3 |
Extras | Red LED backlight of latitude scales; bubble level; Bluetooth module |
PART OF THE CHARACTERISTICS FROM THE RUSSIAN MANUAL | |
Maximum load | 3 kgf·m (15 kg @0,2 m) |
Maximum imbalance in the right ascension axis | 2 kgf·m (10 kg @0,2 m) |
Maximum imbalance in declination/elevation axis | 0,45 kgf·m (15 kg @0,03 m) |
Polar alignment range | 90 degrees latitude, 20 degrees azimuth |
Electric drive | stepper motor (1.8°/step), 256 microsteps/step |
Gear ratio | R.A.: 324:1; DEC: 324:1 |
Power supply | 12-16V (DC), more than 35W |
Maximum pointing speed | 7,5°/s |
Autoguiding speeds | 0,125х, 0,25х, 0,5х, 0,75х, 1х |
MOUNT HEAD
The mount is supplied in a cardboard box with dimensions of 26 x 43 x 37 cm and a weight of 7.8 kg. Inside there is a case with the mount head, an additional mounting platform, a fastening cover, a power cord (from the cigarette lighter), a USB cable, two Allen keys, two M6 screws and two M5 screws, as well as case keys. The mount is a single unit with a polar axis adjustment mechanism (wedge, lift). The measured weight of the mount head is 4.1 kg. The case reliably protects the mount from mechanical damage during transportation.
The mount is quite heavy, but compact. The body consists of two main parts – the polar axis tilt mechanism (wedge) and a cylindrical block with motors, control system and connectors. The mount does not have an optical pole finder and its installation is not provided.
The wedge is completely metal, covered with matte paint, smooth to the touch. The tilt of the polar axis is adjusted using a ribbed flywheel, before which it is necessary to loosen the polar axis clamps on both sides. The tilt adjustment is smooth, without jamming. There is also an azimuth adjustment. There is a backlight for the latitude scale and bubble level, its brightness can be adjusted via the SynScan Pro application.
The motor block is easily soiled, covered with a matte rough paint, fingerprints and smudges easily remain. The body has a mounting platform for Vixen-Losmandi plates with a double spring-loaded clamp. On the opposite side there is a metal plug, under which there is a thread for the counterweight axis, as well as 4 holes for installing a second mounting platform.
At the bottom of the mount there is a hole with a 3:8 inch thread, as well as three additional holes for fixing on the native column and (or) tripod. At the same time, the mount easily fits on the standard tripod from Sky-Watcher AZ-GTi.
Interestingly, the Sky-Watcher Wave 100i mount is comparable in size to the Sky-Watcher AZ-GTi on a wedge. Yes, the AZ-GTi is much lighter, but at the same time it is more flimsy and its lifting capacity is much less.
The only on/off button and all connectors are located at the top of the mount:
USB – port for connecting to a computer
HAND CNTRL – port for connecting a wired SynScan remote control
GUIDE – autoguide port
PWR – power port.
The manufacturer recommends powering the mount with a power supply unit with a capacity of 35 W (12V>3A, or >2.2A 16V). However, I tried powering the mount with an external battery Romoss SW10PF (12V, up to 1.67A), as well as a trigger adapter (Type-C->5.5×2.1 mm) 12 Volts. Measurements were taken with a USB tester FNIRSI FNB58. Idle (without tracking): 0.37A (4.4 W)
Tracking in alt-azimuth mode: 0.5A (6.3 W)
Tracking in equatorial mode: 0.4A (5 W)
Turn in azimuth at maximum speed: 1.1A (12.14 W)
Turn in altitude at maximum speed: 1A (12.6 W)
Turn in two axes simultaneously at maximum speed: 1.67A (20 W).
I did not notice any problems with power supply in this way, except that the charge of the battery with a capacity of 10,000 mAh literally melts before your eyes. I recommend stocking up on a capacious battery in case of use away from a socket, but when traveling by plane, keep in mind that airlines have restrictions on the energy capacity of external batteries.
Be careful when using the mount. The distance between the mounting platform and the mount body is very small, so when aiming, the mount can easily chew the power cord or camera cable. Make sure that the telescope tube does not rest against the tripod, wall or other obstacle. If a collision is inevitable, immediately turn off the power to the mount.
The mount does not have manual axis rotation, all control is carried out only through the SynScan Pro application or the SynScan remote control (purchased separately). I tested the mount by connecting via the Wi-Fi interface through a smartphone. When connecting to the mount, the application offers to select the operating mode – AZ (alt-azimuth) or EQ (equatorial). The correct direction of installation of the telescope tube is indicated on the mounting platform. When turning on for the first time, I recommend starting the mount with a light short tube or without a tube at all to understand the operating algorithm.
Below I will tell you about my experience using the Sky-Watcher Wave 100i mount. It is not exactly “according to the instructions”, but it should work.
By default, the wedge is in the alt-azimuth position (latitude +90 degrees), but the mounting plate faces up. This created some confusion when I first tested the mount. The Sky-Watcher alt-azimuth auto-guided mounts usually start with the mounting plate with the tube horizontal and facing north. In the case of the Sky-Watcher Wave 100i mount, the main mounting plate should be on the right, when facing north, the mount is in front of you.
In equatorial mode, with the wedge tilted according to the latitude of the observation site, the mounting platform should be located at the top and facing the celestial pole. This can lead to confusion when choosing the mounting mode.
The Sky-Watcher Wave 100i mount has Home Position sensors – in other words, both before and after use, the mount can automatically return to the original position of the axes in accordance with the selected mode.
For example, when transporting in a suitcase, the mounting platform is in the starting position for the EQ mode, but for the mount to fit into the case, the wedge must be set to latitude +90 degrees. If the mount is to be used in alt-azimuth mode when turned on, then the wedge does not need to be tilted (latitude +90 degrees), and after turning on the mount and connecting via the SynScan Pro application, you must select the AZ mode, then go to Utility>Advanced>Auto Home. After this, the mount must turn so that the mounting platform faces north and is horizontal. After this, we install the telescope tube, align it with the stars, use the telescope and the mount.
Now comes the most interesting part. Let’s say we’ve finished the observation or shooting session, then we return the mount to the starting position (Utility>Advanced>Auto Home.). The tube should turn horizontally and to the north. We remove the tube. Then there are several options:
a) If after this the mount is not sent for storage and transportation in a case, then everything can be left as is.
If you still need to put the mount in the case, then…
b) Using the app, turn the mounting plate so that it faces up and is located above the latitude adjustment wheel. Turn off the mount (disconnect it from the tripod and put it in the case)
c) … or after turning off the mount, close the app (don’t minimize it, just close it!), turn on the mount, connect to the mount, select EQ mode, select “Auto Home” in the app, the mount turns with the mounting plate facing up to the transport position. Turn off the mount, unscrew it, put it in the case.
I repeat that if the mount is used in EQ mode, then in order for it to fit into the case, you need to set the latitude to 90 degrees on the wedge. And so every time. In this regard, there is some inconvenience, the solution to which may be to use another case with a different shape inside.
ACCESSORIES
In this section I will tell you about Sky-Watcher accessories that can be purchased for the Sky-Watcher Wave 100i mount.
Sky-Watcher Counterweight Kit for Wave 100i150i Mounts, 5 kg
And although the use of a counterweight is not necessary for wave transmission mounts, if the tube is massive and (or) long, it is still advisable to use a counterweight. This will improve the stability of the entire structure and prevent the telescope from tipping over together with the mount and tripod. The kit includes a 5 kg counterweight and two rods – the main and extension. The weight of the box is approximately 7 kg, dimensions are 36 x 17 x 19 cm.
Main bar:
– total length 32 cm (with thread and safety screw)
– length 29.5 cm (without thread and safety screw)
– thread diameter M15.5 (male) for connection to the mount.
– at the end there is a hole with M12 thread for a safety screw or for a rod extension
– weight 0.73 kg
Extension bar:
– total length 16.4 cm
– added length 15 cm (without thread)
– at the ends there is a thread M12 male and M12 female (for connection to the main axis and installation of a safety screw).
Counterweight:
-measured weight 5.1 kg
-diameter 100 mm, height 85.4 mm.
-inside hole with a diameter of 20 mm.
Since there are no friction clutches or manual rotation of the mount axes, balancing the mount is difficult. In the instructions, the manufacturer recommends selecting the counterweight position using the formula:
Skywatcher Wave Carbon tripod for 100i and 150i
A very light, but strong carbon fiber tripod can be purchased for the mount. The tripod is supplied in a box weighing 3 kg and measuring 58 x 22 x 22 cm.
The measured weight of the tripod without the spacer is only 1.9 kg, with the spacer 2.13 kg. At the same time, the declared load capacity is up to 20 kg.
The tripod is two-section (two tubes, one in the other), the measured diameter of the legs is 40 mm and 34.8 mm, the length of the legs from the base is 50-86 cm.
The spacer rests against the carbon body of the tripod – I do not recommend tightening the bottom screw too much.
The inner base of the platform has a diameter of 85 mm and is recessed by approximately 22 mm.
To use the mount without a column-lift, the tripod comes with a special adapter ring with an outer diameter of 84.97 mm and an inner diameter of 71.56 mm, and a thickness of 22.22 mm.
Wave Tripod Extension Tube for Wave 100i/150i
It raises the mount about 18 centimeters relative to the tripod. This is necessary to prevent the telescope from hitting the tripod with its tube. However, a long tube or protruding accessories can still catch the tripod. Be careful!
The weight of the tube is 0.9 kg, the total length is 19 cm, the rise is 17.5 cm. The kit includes a ring with an external diameter of 84.9 mm, an internal diameter of 71.7 mm for installing the Sky-Watcher Wave 100i mount on the extension tube.
TEST
I tested the Sky-Watcher Wave 100i mount in visual and photographic modes with various tubes – 203 mm Schmidt-Cassegrain (weight 6 kg), 127 mm Schmidt-Cassegrain (weight 2.5 kg), Sky-Watcher BKP150750 Newtonian telescope (weight about 6.5 kg), 102 mm refractor (weight about 3 kg). When pointing even at the highest speed, the mount works very quietly. At the same time, it confidently holds and rotates the above-mentioned telescopes without any strange sounds or signs of overload even without counterweights. I was very surprised and pleased by the complete absence of backlash – an instant response of the mount when pressing the buttons of the virtual remote control in the SynScan Pro application. GoTo is fast and very accurate – after tying in by two stars, the desired object almost always appeared in the center of the telescope’s field of view with a magnification of 20x. In this regard, the pointing accuracy is significantly higher than that of the Sky-Watcher AZ-GTi mount. When observing and photographing Jupiter in the equatorial mode of the mount, no periodicity or rocking of the planet was noticeable – the planet was simply held in the field of view, very slowly crawling away due to the not quite accurately set polar axis. I set the polar axis “by eye” using a laser pointer – the mount in the home EQ position is directed by the mounting plate in approximately the same direction as the polar axis of the mount. Therefore, for quick installation of the “polar axis” it is quite possible to use a laser. In the alt-azimuth mode, setting the polar axis is, of course, not required, but you need to know the direction to the north.
Wi-Fi connection works stably, no glitches or crashes were noticed in the SynScanPro application (smartphone Xiaomi 13 Ultra). Stellarium Mobile immediately identified the mount, also pointing it at the selected object without problems. Please note that SynScanPro and Stellarium Mobile work correctly only on Android devices. On iOS, unfortunately, one of the applications closes – this is a feature of iOS.
Yes, sometimes the optical pole finder was missing – I got used to it and usually use it for quick polar alignment. Although, many amateur astronomers now use electronic finders or use software polar alignment, but in some cases I personally need an optical pole finder.
Autoguiding was tested using the PHD2 program, Sky-Watcher Evoguide 50ED guide and QHY5III178m monochrome astronomical camera with IR-cut filter. Guiding was performed without the ST4 cable, via Wi-Fi connection, with preliminary installation of the ASCOM platform, ASCOM driver and SynScanPro app (Windows version). The polar axis was set approximately using a laser pointer. Payload – Schmidt-Cassegrain 127 mm weighing about 2.5 kg + autoguide (about 1 kg). The calibration and guiding process can be seen below. Due to the inaccurately set polar axis, the results may not be entirely reliable.
GENERAL IMPRESSIONS
I liked the mount – compact, load-bearing, stable, without backlash, with two modes (AZ and EQ), quiet, accurately pointed, and there is the ability to install two tubes simultaneously. Of the minuses for me personally – there is not enough optical pole finder or at least a mount for it, but this issue is quite solvable. Also, there is no way to rotate the mount axes manually, but this seems to be a feature of the strainwave gear and you just need to get used to it. Also, there is no way to balance the telescope, but balancing couplings are available in the higher version of the mount – Sky-Watcher Wave 150i. There are also questions about the moisture protection of the ports and connectors – they are located on top of the mount, some plugs would not hurt. Also, personally, I did not like the easily soiled rough body of the mount – perhaps a lighter color of the body would be preferable, especially for daytime shooting of the Sun. But this is just nitpicking. Otherwise – I definitely recommend buying.
I also recommend watching my short video review of the Sky-Watcher Wave 100i mount (at Russian language).