The M-Uno Fast Reverse mount is a parallactic single-arm mount designed specifically for astrophotography with Schmidt-Cassegrains, Maksutovs and other compact telescopes with rear viewing.
The M-Uno Fast Reverse offers the technical solution to an old problem in the design of conventional German-style parallactic mounts, namely the swivelling of the telescope when the object being observed reaches the meridian. When the object passes the meridian, observation (exposure) must be interrupted with classic parallactic mounts in order to swivel the telescope to the opposite position. This costs valuable observation time, especially when the object is at its highest point above the horizon (the AutoGuider may even need to be recalibrated).
The classic parallactic fork mount is used successfully with compact telescopes such as Schmidt-Cassegrains. Its stability, compact dimensions and the possibility of meridian passage are among the reasons for its popularity. The Avalon M-Uno complements these features with outstanding stability, modern technology and exceptional drive technology.
The special construction and design guarantee exceptional stability, and the pole base, which has been designed with particular attention to detail, dampens any kind of vibration. The arm that carries the optics can be adjusted according to the polar height to mount telescopes of different diameters while facilitating the balancing of the tube. The latter is particularly easy, as the axes run smoothly, allowing for perfect balancing. This eliminates load changes and pendulum effects during meridian passage.
Conclusion: The M-Uno allows very long observations and exposures without the typical interruption near the meridian. This is not only a huge advantage for astrophotography, but also for scientific work where an object needs to be observed for a long time without interruption.
The advantages of the toothed belt drive in Avalon mounts:
- A toothed belt drive, which by design has no backlash, is superior to other mechanical drive designs due to its operating principle. When worm gears are used, the moving parts only touch at one contact point. This causes the lever forces and tensions in the mount drive to result in small, non-linear inaccuracies in the drive. In addition, manufacturing tolerances can cause irregular rotational errors in the worm and worm wheel. The result is a pendulum motion of the drive, superimposed by peaks, known as periodic error (PE). This pendulum error is proportional to the focal length of the camera; the longer the focal length, the more significant the error.
- Thanks to the four-stage reduction gear, Avalon mounts also have a periodic error of typically +/- 5 to 7 arc seconds. However, unlike a worm gear drive, this pendulum motion is absolutely uniform and linear and can therefore be easily corrected by any autoguiding system.
- The reason for the smooth linear error lies in the belt drive, as there is no direct contact between the drive wheels and the movements are transmitted completely without play by the belt. The toothed belt lies on a large area of the wheel, so that movements are transmitted very finely and evenly – without the peaks, braking and acceleration phases that are typical of systems with worm gear drives and can also cause problems with autoguiders. Autoguiders usually react too slowly to compensate for such sudden fluctuations in the drive.
Further advantages of the special drive system from Avalon:
- A side effect of the toothed belts is that they do not require any lubricants – so there is no grease in the mount. Thanks to the belt drive, there is no gear play regardless of load, wear or temperature. No materials susceptible to wear or corrosion have been used in the M·Uno.
- Once it is perfectly balanced, no further adjustments are necessary during operation. Traditional mounts with worm gear drives must be rebalanced before and after meridian passage to minimise the "pendulum effect". Once the M ·Uno has been balanced, it has perfect mass balance – ideal for permanent installation or remote-controlled observatories.
- The drive belts of the M-Uno are made of polyurethane with a steel core. Polyurethane is a highly dimensionally stable polymer with a high modulus of elasticity, so it does not change over time – even under heavy loads and large temperature fluctuations. In addition, a preload element is used on each axis to eliminate any play. The drive gears, which Avalon Instruments manufactures itself, are made of glass fibre-filled cast polyamide and have remarkable stability. Avalon's engineers designed special smoothed teeth to minimise or even eliminate irregularities in tracking speed (a source of tracking errors) that can otherwise occur due to the interaction of the toothed belt and drive wheel.
The Avalon M-Uno Fast Reverse mount offers solutions that simplify life for amateur astronomers and eliminate many technical problems.
