[uglyduck]

Which output should I use to power a micro FPV camera?  I assume the AUX but it appears that intended for lighting.

[LukeZ]

The Aux can be used for anything, it would be fine for a small (5 volt) FPV camera. For that matter any of the light outputs would work equally as well, if you aren't already using them, they all use the same mosfet switch, the only difference is that the Aux output has a flyback diode protection so it can also drive a very small motor. But to switch on/off a camera any of them will work the same.

Imex Erik used the Aux output to power an FPV camera and he reported it worked quite well.

If you don't need to switch the camera on/off, and are happy to just leave it on all the time, you could also plug it into one of the General Purpose A or B pins. The signal pin won't be needed and will do nothing, but the GND and +5V pins are always powered so they can provide voltage to your camera.

[uglyduck]

Thanks Luke, I assumed as much but wanted to confirm. 

One more related question, is it possible to reduce voltage to one of those outputs through OP Config?  I see a "default low" option for the I/O outputs.  After testing the camera on the OP board I noticed it got pretty warm.  The camera came off a 1s micro drone that runs at 3.7v.  I still need to measure the output voltage off the drones flight controller.

[LukeZ]

No, no way to change the output voltage, it is fixed at 5 volts. You can read more about the "default low" option for the I/O ports in the Wiki but it refers to the state of the signal pin, not the voltage level generally. In fact if you are using one of the I/O ports for source voltage I would set the Port Direction to "Input" just so there is no chance you are using the signal pin to power your camera (it can not handle the current). For the purposes we are talking about here, you only want to use the fixed positive and negative pins of the I/O port to power your camera. It might be better to use one of the light outputs or the Aux if you are confused about any of this.

It is quite common for the FPV transmitters (which in you case is apparently built in to the camera) to become hot to the touch in normal operation, so that doesn't necessarily concern me. However, you do certainly need to check your camera can handle 5 volts.