Below is summary information about a number of RoboFocus installations on a variety of scopes/focusers.
|The Meade LX200 was used as the design basis for the general SCT RoboFocus application. The concept was to use the primary focus knob on the backplane of the scope and drive the focus movement with a set of timing sprockets and a timing belt. The motor support bracket sits directly on the rear scope cover and is held into place with a double-sided Very High Bond, (VHB), tape designed for powder coat finished surfaces. The sprocket (two different sizes, as the GPS model, has a slightly larger diameter knob), simply slides over the existing knob, is adjusted for the proper height, and tightened into place with three set screws. The bracket is positioned in a manner to allow the 8-inch timing belt to be secured between the motor and the focus knob. The motor can slide approximately one-half-inch to adjust the tension on the belt.
A special bracket has been designed for mounting the RoboFocus system onto the Meade 8-inch GPS model. With the mirror lock knob and handle both mounted on the rear plate, there is no available surface space next to the focus knob to directly mount the motor bracket. This special bracket supports the motor above the rear handle and attaches to the timing sprocket mounted on the upper portion of the focus knob.
RoboFocus has been successfully attached directly to the Meade Micro focuser on the GPS models. This allows the mirror to be locked while focusing. Contact us for complete plans/instructions
Many people question the use of the primary focus knob overusing the mirror lock and adding a secondary third-party focuser. The stability and precision of the RoboFocus system provide extraordinary results with this setup. In fact, a study conducted with RoboFocus units mounted first directly to the primary focus knob on the LX200, then onto a JMI NGF-S focuser added to the same scope, resulted in nearly identical results. This LX200 Study can be downloaded and viewed or printed.
|The most common Takahashi RoboFocus install is the Rack & Pinion setup, mounted directly onto the focus shaft, after removing one wheel knob. Takahashi has standardized with an 8mm diameter shaft on both the 2.7-inch and 4-inch focusers. A small brass coupler (with a built-in “clutch” on the motor side), attaches the motor directly to this shaft and is held into place with two set screws on each end. The system comes with a set of “generic” motor support brackets, as well as a new optional finished “Takahashi Bracket”, (see Accessories Tab for Brackets)
There are some Takahashi models, (probably the most common being the Sky90), with short tapered focus shafts. For these models, we make a special, shorter, coupler with the set screws very close to the end. Many users of this scope have found this solution workable with all features and functions of the RoboFocus then available.
Takahashi also makes a line of Newtonian/Cassegrain telescopes, (the CN-212 a common RoboFocus install). The RoboFocus solution for these scopes is built around the SCT motor bracket and a timing sprocket/timing belt.
|The Celestron line of SCT telescopes typically utilizes the standard SCT motor mounting brackets and timing sprockets/timing belts. There are several attachment approaches based on the scope model and focus knob assembly. The “classic” line of Celestron scopes (C8 and C11 for example) have either a 1/2 or 3/4 focus knob (after removal of the rubber finger grip). A couple of models have gnarled metal focus knobs that cannot be easily removed. We have a larger timing sprocket that slides over this knob.
The Nexstar GPS models, CGE1100 and CGE1400 have a unique install. Once the grip is lifted off, what remains is a short, stepped tube assembly on a raised housing. We include both a special timing sprocket and an elevation block attached to the motor bracket. The CGE1400 elevation block includes a cut-out to straddle the ribs that radiate out.
The C9.25 uses a sprocket directly over the existing focus knob (0.87 inches in diameter), without removal.
JMI NGF-S and NGF-C
|The NGF-S has a small tear-drop motor that is removed by loosening the set screws applying pressure on the shaft and removing the single screw that holds the motor onto the housing. The RoboFocus NGF-S motor has an identical shaft and motor mounting hole. This allows the RoboFocus motor to simply slide into the housing and attach exactly the same as the JMI motor. We also supply an additional sleeve bearing for the inside slot to provide a smoother and more stable operation. This motor also works for the NGF-SE (model without the JMI motor).
In 2005, the NGF-S was replaced with the NGF-C model. This focuser is small and operates with a small gear motor under a center housing plate. This motor is removed, along with the Crayford style shaft, and the RoboFocus motor is mounted nearly the same as the NGF-S. The housing on the NGF-C does not have a motor mounting screw hole, so a special mounting plate is provided. This plate uses our double-sided VHB (Very High Bond) tape to adhere the motor to the flat surface on the side of the housing.
JMI DX1 and DX2
|A standard Rack & Pinion RoboFocus setup is used on the DX1 and DX2, with the motor mounted directly onto the 1/8 inch diameter shaft under one of the focus knob wheels. The motor can be supported with the “generic” brackets that come with the system, or an optional mounting bracket, (see Accessories Tab for Brackets), can be purchased. The optional bracket does require the drilling and taping of two mounting holes on one of the side flanges. We will drill and mount the RoboFocus motor at no additional cost if the focuser is sent into Technical Innovations.|
|All Astro-Physics focusers are Rack & Pinion style and have a standard 1/4 inch diameter shaft. Installation is very straightforward, with the motor attached to the shaft via a small brass coupler with a clutch piece next to the motor shaft. The motor can be supported with the “generic” brackets that come with the system, or an optional mounting bracket, (see Accessories Tab for Brackets), can be purchased. These brackets attach to the bottom of the housing, using existing screws/holes.|
|The Feathertouch focuser from Starlight Instruments comes in both Rack & Pinion and SCT models, both of which can be fitted with the RoboFocus System. Discussions with Starlight and tests run by current users show that extremely good results are obtained with the RoboFocus motor mounted on either the “coarse” or 10:1 “fine” focus knob. As a result, most owners tend to mount on the coarse. With the Rack & Pinion model, the motor is mounted directly onto the shaft (1/4 inch on coarse and 3/32 inch on fine) under the focus knob. The motor is supported with generic brackets provided by the system.
The SCT model rises 2.5 inches above the backplane of the Telescope. The RoboFocus attachment is standard “SCT”, with timing sprockets and belts connecting to either the fine knob (0.928 inches in diameter) or coarse focus (1.238 inches in diameter. Because of the height, an adjustable mounting bracket is included in the package. This bracket allows the positioning of the motor at either focus knob level.
|The Orion 80ED has a Crayford-type focuser with a unique attachment design. The knob wheel itself has an attached shaft that slides over another shaft and under a sleeve before being held into place with a set screw. The shaft attached to the focus knob wheel actually screws into the wheel, which allows the wheel to be removed (a set crew holds the shaft firm), leaving the rest of the assembly in place. The motor coupler can then match up with the treads at the end of the in-place shaft.|
|All TeleVue focusers are Rack & Pinion style and most have a standard 9mm diameter shaft. Installation is very straightforward, with the motor attached to the shaft via a small brass coupler with a clutch piece next to the motor shaft. The motor can be supported with the “generic” brackets that come with the system.
The exceptions identified are the Pronto and Genesis, (0.43 inch), and the Stellarvue with a shaft diameter of 0.338. The RoboFocus system has been installed on all of these.
|The timing sprocket/timing belt approach can be adapted to nearly any SCT telescope with a primary mirror focus attachment. You will need to check for an available surface mounting area near the focus knob, (approximately 1.5 inches wide by 3 inches long), and get a diameter measurement of the focus knob, or shaft under the knob. If you do not have a caliper, the “paper method” can be used. Wrap a small piece of paper around the knob, mark and measure the circumference, then divide by 3.1416 to calculate the diameter.
The Clement focuser uses a timing sprocket/belt setup. Either have Clement attach the motor prior to shipment of the focuser, or obtain the proper mounting bracket directly from them.
Other Rack and Pinion
|Below are listed several focusers that we have successfully mounted the Rack & Pinion style RoboFocus units onto. For these units, we have all the information needed to provide the proper setup directly to the buyer:
Meade LXD55 – Shaft size 1/4 inch.
Vixen Models – Shafts of either 6mm or 9mm, please confirm prior to order
Williams Optical – Shaft size 7mm
TEC140 – Uses Feathertouch focuser – shaft size 1/4 inch
MAK 67 – Shaft size 5/32 inch
Megrez 80 – Shaft size 4mm. Special coupler due to tube design and shaft length
Nearly any Rack & Pinion or Crayford style focuser can be equipped with RoboFocus. We will need information, such as shaft diameter, available mounting options, and other characteristics (for example protruding parts), that may cause special installation concerns.
Email or call to discuss your equipment.
RF3 RoboFocus System Add-On
|RoboFocus can be adapted to nearly any device requiring precise and repeatable focus movements. We are happy to work with you and your application to assure success. RoboFocus has been used on electronic research microscopes, radar tracking and response devices, and range sights.
For additional ideas or input into your application design call or email us today!