The LINEAR FAST REVERSE is an innovative mount designed for astronomical imaging and manufactured in Italy by the DAL SASSO Srl, a company with more than 30 years of experience in the field of high precision mechanics. Marketed with the AVALON INSTRUMENTS trademark, this mount falls in the medium-size mount range with a weight capacity around 20-25 kg (44 – 55 lb), imaging and visual observing, respectively.
The LINEAR FAST REVERSE project arose from a passion for astronomy and mechanics, taking advantage of more than 15 years of experience and testing, attending many star parties and spending countless hours under starry skies, with different types of instrumentation. Since the great majority of the problems in amateur astonomy involve the mount, both design and manufacture have been focused on developing a mount to overcome the common technical problems.
With the Linear Fast Reverse mount, Avalon Instruments achieves a professional portable German equatorial mount devoted to deep sky imaging in the capacity range up to 20 kg (44 lbs.) or 25 kg (55 lbs) for visual use.
Advanced Mount Control
Several options exist for controlling the LINEAR mount including the proprietary STAR-GO system included with the mount as well as many commercially available and free ASCOM compliant planetarium programs. The mount can be controlled through the built-in Bluetooth interface, USB2 connection or serial connection. The wireless Bluetooth interface allows you to control the mount using programs like SkySafari through your smart phone or tablet. The LINEAR has been specifically designed as a guided imaging platform and relies on a standard polar alignment (using the polar scope and/or drift alignment), a rough goto, and synchronization on a star located near your imaging target. The STAR-GO software is actively being improved to include additional goto, slewing and alignment routine capabilities that can be easily downloaded to the mount. In addition, the LINEAR may be controlled using Software Bisque's The Sky and Tpoint programs to control all functions of the mount and develop pointing models for high precision goto accuracy.
The choice of pulleys and toothed belts allows Avalon Instrument's FAST REVERSE drive system to have very steady motion without play (no backlash) or sudden peaks, factors that are critical for long guided exposures and during high magnification visual observations. These features are of particular importance for the declination axis since they allow the axis to quickly reverse the motion without breaks to recover the backlash. It is from that ability that the drive system name FAST REVERSE was born. The toothed belts used in the LINEAR are made of special material with steel strands incorporated to avoid any deformation, elongation and stress, and are much better than those used in the automotive engine drive systems (which are generally made of rubber with nylon strands). Similar belts are used in high precision CNC machining equipment.
It is important to note that in gear-worm systems the motion transmission has only one tangent point of contact and any errors on each of the two components will, sooner or later, result into a tracking errors. On the contrary, in the pulley-toothed belt system, no direct contact occurs between the pulleys and the motion is transmitted by the belt engaging from 50% to 90% of the girth surface. Consequently any error present, is averaged among the cogs and is very smooth, greatly reducing any tracking error.
These features allow the LINEAR to perform guided exposures of 20-30 minutes with round stars even with optics of 2-3 meters of focal length.
No Wear, No Friction, No Lubrication, No Maintenance
The affects of wearing common in most mounts is greatly reduced or completely eliminated in the LINEAR mount since no relevant friction occurs. All the pulleys and the axes rotate on roller bearings, 13 for the RA axis and 13 for the DEC axis, that reduce the total friction almost to zero. In addition to reducing wear, the very low system friction reduces any potential of motor slippage during GOTO operation to essentially zero. In conventional gear-driven mounts, on the contrary, it is well known that the difficulty regulating the coupling between gear and worm causes the loss of position if the spacing is too tight and the drive slips or in increase in play or axis slop is the spacing is too loose. The absence of significant play in the LINEAR combined with the almost instantaneous movement of the axes with no drive slippage makes the initial calibration of the guiding CCD and program quick and easy.
Besides the performance advantages of the FAST-REVERSE system another substantial benefit is the substantial reduction in necessary maintenance. Unlike conventional geared mounts, the FAST-REVERSE system allows the mount to be constructed and operated without significant, and often troublesome, lubrication (most lubricants in the mount are contained inside sealed bearings). In addition, self-adjusting tensioning systems require no user adjustment. As a result of the elimination of lubricants and greases and the self-adjusting mechanisms of the mount virtually not mount maintenance is necessary. This has been proven by observing mounts that have seen significant field use while displaying not need for maintenance or adjustment over time.
The LINEAR mount may be mounted on a variety of tripods including the Hercules wood tripod, the Avalon aluminum tripods, the Berlebach UNI and PLANET wood tripods, or one of two Avalon Instruments portable piers (Berlebach PLANET is available in different colors and with different options here). The LINEAR will also fit on tripods from Baader, Geoptik and Skywatcher. The heavy duty Hercules tripods are available in three different minimum heights, 37 inch (95 cm), 27 inch (70 cm) and 18 inch (47 cm). The Avalon portable piers are available in 39 x 7 inch (100 x 18 cm) and 39 x 10 inch (100 x 25 cm) models with cast aluminum legs on the 7 inch model and all solid machined aluminum on the 10 inch model.
The LINEAR FAST REVERSE mount is ideal for those traveling astroimagers seeking long deep sky exposures, even with high focal lengths, and excellent value for the money. The unique characteristics of the LINEAR make it ideal even for use in a permanent location, especially with remote control.
The LINEAR Complete Kit Option includes the following:
The LINEAR A la Carte Option begins with the following: