Frequently Asked Questions


Q: How do I determine the motor size?

A: The size of the motor for each axis is a function of the weight of the telescope, the friction associated with the gear reductions, and the acceleration during a slew. For example, the SC-2438 24" telescope with roller drives uses 470 oz-in motors on each axis. Whereas the mount for the C14 with worm gearing uses 210 oz-in motors.

Q: Can I use DriveScope with a German Equatorial mount?
A: DriveScope has been designed to work with fork-type equatorial mounts. The German Equatorial mount requires that as the telescope crosses the meridian it be "flipped" to the other side of the mount. Most GE mounts are not made accurately enough to maintain correct pointing after being flipped.
Q: Can I reverse the motor rotation direction?
A: Yes. By exchanging two wires in the Power Supply/Driver the motor direction can be reversed.
Q: How do I determine the number of "microsteps per full rotation" for each motor?
A: The number of microsteps per full rotation is a product of the drive gear ratio x the number of full steps per revolution of the motor x the number of microsteps per full step. For example, most precision stepper motors have 200 steps per revolution. Typical microstepping is set at 64 microsteps per full step. Common gear ratios are 360:1. Thus, the microsteps per full rotation is 360 x 200 x 64 = 4,608,000 microsteps per full rotation. This represents 0.28 arc seconds per microstep.
Q: Does DriveScope work with TheSky™?
A: The DriveScope system can be configured to recognize Meade LX-200™ command set. This command set is used by many third party telescope pointing programs such as TheSky, MPO Connections, and others.
Q: Why use the optional Serial TC Card?
A: The Serial TC Card can be connected to any computer with a serial communications port. Additionally, the cable length between the computer and the Serial TC Card can be up to 25 feet allowing flexibility in placing the computer near the telescope. The internal TC Card requires an ISA BUS connector in the computer. In order to install this card, the operator must have a working knowledge of internal computer hardware.
Q: Can I get a copy of the DriveScope Manual?

A: Yes. A .pdf version of the manual is available online. Download Manual

Q: How far from the TC Card can I have the Power Supply/Driver?
A: The normal distance is 10 feet. However, by using special cabling that distance can be increased to 50 feet.
Q: How long can the motor cables be?
A: As these cables carry large currents and voltages, they must be kept as short as possible. The maximum cable length should be less than 12 feet.
Q: What CCD camera is best with the SC-2438?
A: The first consideration is the desired field of view. At prime focus of the SC-2438, using a coma corrector, the plate scale is 0.125 arc seconds per micron. If the seeing is one ar second or better, then the pixel size should be nine microns. If the seeing is two arc seconds then a camera using 18 micron pixels (or 2 x 2 binned 9 micron). The second consideration is the size of the coma corrector. The Paracorr® corrector will provide a 33 arc minute field of view. The custom corrector will provide over one degree and can accommodate a CCD chip over one inch square.
Q: Since the CCD Camera is in the light path, will the heat effect the images?
A: The quantity of heat given off by the cooling system of the camera is relatively minor. The temperature differential of the air blowing from the cooling fan is very near ambient temperature and thus does not effect the image quality.
Q: Is water cooling of the CCD camera available?
A: This is available and is dependent upon the type of CCD camera. The addition of water circulating tubing along the camera support veins represents a slight, but minor increase in the light blocked by those veins.
Q: Why carbon fiber truss members?
A: The truss members control the spacing between the primary mirror and the CCD camera. Most materials change their length with changing temperature, therefore as the temperature changes the camera will move out of focus. Carbon fiber filament wound truss members can be designed to not change their length with temperature and thus keep the camera at focus over a wide temperature range. Carbon Fiber Truss System
Q: Why three support piers?
A: The SC-2438 is a large telescope. To try and balance this much size and weight over a single pier would make the telescope very unstable. Three piers even distribute the load of the telescope over a large footprint and thus maintain stability as the telescope moves.
Q: Is there a shroud for the truss system to exclude external light?
A: A shroud is available, however, it should only be used when the air is calm as it presents a large surface area for wind buffeting.
Q: Can I move the telescope by hand?

A: The telescope maintains its pointing reference through the computer system. If the telescope were to be moved by hand this pointing reference would be lost. Additionally, there are no clutches on either of the drives.

Q: Does dirt on the roller discs cause problems?
A: Although the discs themselves are exposed, there are wipers on all rolling surfaces just prior to their contact that keeps dirt off of the discs. After three years of operation the prototype SC-2438 exhibits minimal wear on these surfaces.
Q: Do I need a finder scope?
A: During initial set up of the telescope it is helpful to have a pointing reference. A device such as a Telrad or other illuminated reflex sight is adequate to place a reference star on the CCD camera.
Q: Why roller drives and not worm gears?
A: Roller drives are enharently smooth and without periodic error. They are easily aligned and have no back lash. Since the SC-2438 uses computer control for pointing, the necessity of a precise drive ratio is eliminated. Roller Drives
Q: How much does the telescope weigh?
A: The telescope weight is a function of the necessary counter balancing required for the CCD camera and corrector. The basic weight is 600 lbs.
Q: If I use WinScope do I need to buy any other pointing software?
A: WinScope will completely control the pointing of the telescope and provides nine catalogs of object data. No other software is required to operate the telescope.
Q: Does WinScope control the CCD camera?

A: WinScope controls the pointing of the telescope only. The camera is be controlled by the software from the camera manufacturer. As WinScope does not require a dedicated computer, the camera control software can also run on the same computer.

Q: Is there a demo version of WinScope?

A: A demo version of WinScope is available that does not require a TC Card or Power Supply/Driver unit. This demo version is fully functional but will not control a telescope. Download WinScope Demo Version
Q: What corrections to pointing does WinScope apply?
A: The only pointing correction applied is precession. The other corrections amount to less than 1/2 arc minute. The exception is refraction which typically amounts to less than two arc minutes if the zenith distance is less than 60 degrees.
Q: Do I need a special version of WinScope to operate the optional Serial TC Card?
A: WinScope will operate with both the internal and external Serial TC Card.