When it comes to making sharp images with medium- to long- shutter speeds, there are 4 fundamental things that are necessary; a sturdy tripod, a good tripod head, a camera with mirror lockup, and a cable release. The RS-80N3 is Canon’s cable release for their mid- and high-end cameras including the X0D, 7D, 5D, and 1D lines.
What is a cable release? Fundamentally, a cable release is a button on the end of a cord that connects to the camera’s shutter release so that vibrations aren’t transited to the camera when pressing the shutter release. In the early days, with manual camera’s this was accomplished with a Bowden cable that connected an external push button directly to the the camera’s shutter release. Modern camera’s with electronic release systems use an electrical cable release instead.
The Canon RS-80N3 is an electronic cable release that provides the same functionality as the electronic shutter built into the camera. That is, half pressing the shutter button on the cable release is equivalent to half pressing the shutter release on the camera—both the autofocus and image stabilization systems will be engaged if enabled. Fully depressing the shutter release on the cable releases the shutter mechanism.
Additionally the RS-80N3 provides a mechanical lock to hold the shutter release fully depressed. This can be used in conjunction with a camera’s bulb exposure setting to produce extremely long exposures or keep the camera firing when set in continuous drive without being operated directly.
The RS-80N3’s release functionality is completely passive and requires no battery power to operate.
The cable on the RS-80N3 is flexible, though doesn’t feel easy to break or wear out. Additionally, the proprietary N3 connector provides a positive lock when attached so the release won’t accidentally fall out that’s released when the housing is pulled on to remove the connector. Fortunately, the N3’s locking mechanism isn’t nearly as cumbersome as Nikon’s 10-pin screw in connector is.
Canon makes and sells two versions of their cable releases using their proprietary N3 connector, the RS-80N3 is just a basic cable release with no advanced features, and its bigger brother the TS-80N3, which provides intervalometer functionality in addition to being a basic cable release. The decision between the RS-80N3 and the TC-80N3 ultimately comes down to whether there’s a foreseeable need to have intervalometer functionality. Personally, I have and use both depending on the situation, though if I’m only going to carry one, I take the TC-80N3 just in case.