Now it's time to sum up. The typical modern DSLR astrophotographer uses a laptop computer for control, a webcam for autoguiding, and a computerized telescope. Here are all the connections that have to be taken care of:
ELECTRICAL CABLE RELEASE FOR CAMERA
SERIAL OR PARALLEL CABLE CIRCUIT
Figure 10.7. Strategy for adapting a serial or parallel port cable to a non-Canon DSLR. Use a voltmeter to identify the + and — sides of switch.
• Power for the telescope, the computer, and the camera (preferably all separate).
• USB or serial connection from the computer to the telescope for guiding, and possibly also for telescope control (finding objects) and electric focusing.
• USB connection from the computer to the webcam for autoguiding (this also supplies power to the webcam).
• USB connection from the computer to the DSLR to control settings and download images.
• Serial- or parallel-port cable from the computer to the DSLR cable release socket to control long exposures.
If the telescope is an older one with a six-pin modular autoguider port, you can use cables available from www.shoestringastronomy.com that interface it to the computer's parallel or USB port. And if you need serial or parallel ports that you don't have, use USB-to-serial or USB-to-parallel converters.
Now count the connections. You may need as many as five USB ports, in which case a USB hub enters the picture. Small USB hubs, powered from the USB port itself, are to be preferred if they work adequately.
In a few years, we will be using short-range wireless communication instead of a rat's nest of USB cables. Then the only cables that we have to deal with will be for power, and the case for running each device off its own battery will be compelling.
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