A double arm mount offers much greater accuracy than conventional designs.
Double arm barn door tracker.
His paper a mathematical analysis of the double arm barn door drive appears on pages 155 160 of the december 1988 monthly notices of the astronomical society of south africa.
The base board is the bottom board and hopefully doesn t move around during the course of the exposure.
The base board the drive arm and the camera platform.
One end is connected to the base board with a hinge that allows the drive arm to.
Double arm drives have three main platforms.
The hinge is aligned with a celestial pole and the boards are then driven apart or together at a constant rate.
Smits notes that all of dave trott s drives including the single arm version have the drive screw mounted as the expanding base of an isosceles triangle.
Both ends of the drive arm are connected to the base board.
Calculation of drive arm length.
An inexpensive route to astrophotography has long been the scotch mount also known as the barn door drive after its appearance or the haig mount after its inventor.
First cut the 500mm length in half and mount the hinge.
Make sure everything is square and moves freely clap the 2 hinged boards together and shout action a few times like they do when making movies if it makes a nice clack sound it should work well for a star tracker now measure 228 55mm from the center of the hinge pin down the middle of the board and mark the drive rod holes do this on.
To use it the tracker is set up in the field so that the hinges are aligned with the earth s axis of rotation.
For some of my longer exposures i use this device which can track the motion of the stars across the sky while the image is being made.
A camera is mounted on the top board usually with some sort of ball joint to allow the camera to be pointed in any direction.
Signal frequencies on cmos 4024 pins.