Using Capture with an L-bracket is possible. It doesn't work for everybody, but it certainly works for some folks.
In order to use your camera with Capture, you must have Capture’s quick release plate attached somewhere on your camera. Most L-brackets have auxiliary tripod mounts that allow you to attach Capture’s quick release plate and still keep your L-bracket handy. Depending on the size and weight of your camera and L-bracket, this may be workable solution for you.
Our ultimate goal is to partner with a manufacturer of high-end L-brackets to eventually provide an L-bracket that is directly compatible with Capture. A Capture compatible L-Bracket is available from Legged Thing.