The Avalon LINEAR is a German Equatorial Mount driven by the Fast Reverse Technology, a system of pulleys and toothed belts for high guiding accuracy and zero backlash.
No gears for high guiding performance
This mount ranks in the medium-size mount range with a payload capacity of 20kg for astrophotography and 25kg for visual observations. Differently from other mounts with a similar payload, the Avalon Linear has such a low guiding RMS error that it makes astrophotography possible with long focal length optics.
The majority of telescope mounts employ a worm drive gear system. However, this system may produce a poor guiding performance due to mechanical errors in gears such as: periodic error, rough gear surfaces and a play between gears (backlash).
- Periodic error: it is caused by the eccentricity of the worm gear in right ascension which has to turn constantly in order to compensate the Earth's rotation. While the guiding system tries to reduce the periodic error, it will never disappear completely due to its short period and its high amplitude. As a result, the tracking accuracy in right ascension will be always poorer than in declination. The Avalon fully belt driven system produces a periodic error with such a long period that your guiding system will always be capable to correct it and therefore delivering high performance guiging results.
- Gears roughness: gears are made of metal and while the grease reduces friction and wear, rough spots on the gear surfaces generate sudden tracking movements (spikes). When a guiding graph shows a sudden spike, your photo is most likely ruined or the stars in your photo will look ovalized. The effect is similar to wind gusts that do ruin your shots. Avalon does not use gears so the guiding performance is strikingly high!
- Backlash: in mounts driven by gears, backlash is caused by a gap between the gear teeth and it causes a play and consequently a delay in the guiding responsiveness. Some mounts allow a backlash compensation, producing a quick acceleration of the gears until the gear teeth touch and then transmit the rotation. However, the backlash varies along different points of the worm drive and generally also increases overtime. Avalon and its fast reverse technology produce an immediate guiding response as the system employs pulleys that do not suffer of backlash.
Pulleys and toothed belts, zero backlash!
This choice has allowed to obtain several advantages: a very steady motion without play (no backlash) or sudden peaks, which are factors of paramount relevance for long guided exposures and during high magnification visual observations. These features are of particular relevance especially for the declination axis motor which can now quickly reverse the motion without breaks to recover the plays: hence the mount name FAST REVERSE. The toothed belts used in the M-uno have the structure made of special material with steel strands to avoid any deformation, elongation and stress, much better than those used in the automotive engine distribution system (which are generally made of rubber with nylon strands). Comparing the service time for the automotive toothed belts, which is around 100.000 km, assuming a medium regime of 2.000 rpm and thermal stress from 0 to 90°C in a few minutes, we can assure that the life cycle of the Linear toothed belts will be extremely long!
It is important to point out that in the gear-worm systems the motion transmission has only one tangent point of contact; any error on each of the two components will sooner or later result in a tracking error.
In the pulley-toothed belt system, no direct contact occurs and the motion is transmitted by the belt, engaging from 50% to 90% of the girth surface. Consequently, any eventual error present is averaged among the cogs and greatly reduces the tracking error.
These features allow the Linear mount to perform guided exposures up to 20-30 minutes with pinpoint stars even with optics of 2-3 meters of focal length (see our suggested PHD2 guide parameters table).
No wear, no friction!
No wear since no relevant friction occurs. In fact, all the pulleys and the axes rotate on roller bearings; 13 for the RA axis and 13 for the DEC axis allow to reduce the total friction almost to zero.
Another significant advantage of very low friction is that the risks of motor slipping during GOTO operation is virtually nil.
On the contrary, it is well known how difficult it is to regulate the coupling between gear and worm in conventional mounts. If the coupling is tight, the motors can get stuck with consequent loss of the position, if the coupling is too loose the play increases.
On the other hand, the absence of significant play in the M-uno makes the initial calibration quick and easy.
No lubrication, no maintenance!
Since there are no gears, there is no need for periodical lubrication of the internal components and therefore the maintenance is much reduced and limited to the external cleaning.
20 kg for imaging, 25 kg in visual mode
12 kg, without counterweight and bar
Four stages belts drive system
CNC anodized aluminum
|Heavy duty steel, Ø 35mm; 1 x dual ball bearings, Ø 62mm + 1 x roller bearing Ø 72mm + 2 x roller bearing Ø 45mm – On bearings clutch system|
|Heavy duty steel, Ø 35mm; 1 x dual ball bearings Ø 62mm + 1 x roller bearing Ø 72mm + 1 x roller bearing Ø 45mm – On bearings clutch system|
|StarGO GoTo Control System (WiFi or Bluetooth) + USB|
|SkyWatcher polar scope (optionally Losmandy model)|
|Quick release, Ø 30mm, stainless steel bar|
|Losmandy 3" (75mm) saddle, single knob with 2 tightening points|
|2 years (5 years for the belts)|
- German equatorial mount wi-fi or bluetooth,
- Losmandy style dovetail saddle
- Counterweight bar
- AC power supply 15V 4Ah
- 6 kg counterweight
- Stargo hand controller
- USB drive with softwares and instruction manuals
- Tripod is not included
The StarGO is a Computerized GoTo Control System is based on stepper motor technology. It has been manly design for the M-Zero, M-Uno and Linear mounts but thanks to the programmable Gear Ratio and the special motor kit, it can be easily used with mounts of other brands.
Its design follows the most recent technological development in this field, consisting in realising a very simple hardware characterized by a large field of applications such as the management of focusers, filter wheels, DSLR cameras and so on. It is controllable by a PC, smartphones and tablets.
The StarGo features:
- The Control Box that can be embedded in the mount as for the Avalon Linear and M-Uno, or in a separate control box for the M-Zero (and for its use with all other compatible third party mounts). It performs all the communications with specific components (Focuser, DSRL camera, and other auxiliary devices) using direct connections with Windows and Mac computers via USB. The wireless Wi-Fi and Bluetooth capability is also integrated in the control box to interact with intelligent devices such smartphones, tablets and, again with Windows and Mac computers.
- The StarGo Keypad allows the control of the mount, perform almost all the available and most needed operations.
- The StarGO software, entirely developed by Avalon Instruments, uses a computer to perform all the setup and management operations, including the control of various external equipment that can be connected to the control box.
The X-Solver is an application based on the Plate Solve solution. With X-Solver it is possible to build Sky Model till 24 stars that can be saved and used later even during other night sessions.
With X-Solver application comes two very useful tools: the Sky Model and Polar alignment.
The Sky Model allows to easily build a sky model with up to 24 stars. The tool provide an intuitive GUI that shows a 2D representation of the sky that can be designed from the user simply by the mouse double click.
The modelling function is particularly useful in fixed observatory installations, however for the speed of its execution, it may be used also for mobile installations, especially for visual observation (after a short period of CCD use at the very beginning of the session).
The Polar Align is a tool for a fast and easy Polar Alignment by using the Plate Solve function.
- The StarGO-BT application for Android devices that allows to interface them with the StarGO control box via Bluetooth connection. With this application the Android devices become like a control pad. This application, as well as the PC StarGO, is under continuous development to add new functionalities. Only for Bluetooth mounts.
- The AvalonStargo ASCOM driver that makes possible the interaction between the StarGO Control Box and the most used astronomical software applications such as Phd2, TheSkyX, SNPP7, Maxim, SGP, CartduCiel, Stellarium, etc.
In this video it is possible to watch how the StarGO Ascom Driver is able to manage several astronomical softwares connected at the same time: