We (the team) are trying to get an LED light onto or near the camera, in order to illuminate the vision target: Some questions:
Not very bright at all would be plenty. Think small flashlight, not 747 landing lights. Try a Radio Shack yellow LED, as long as it’s mounted right at the camera, the retro-reflective tape will live up to its name.
I suggest using a spike, but there are other legal methods. Using the Pneumatic Solenoid bumper is NOT a legal method. The Digital Sidecar might not have sufficient current available to drive even a small LED.
We’re currently using four red LEDs around the camera lens, each at roughly 3 candela. It is subject to change, yet, depending on what the programmers decide they need, but my understanding is that it’s working relatively well so far
Using the Pneumatic Solenoid bumper IS a legal method as of update 8.
As others have said, don’t use too bright a light, unless you want to blind your alliance drivers.
Er, what part of the Robot Manual dictates which methods can be used?
Also, can I get a measurement of how bright it should be?
That is incorrect.
<R42> that was changed in update 8 refers to Spike relay modules, not solenoid modules. <R60> still says exactly what can connect to solenoid modules:
<R60> Solenoid Breakout outputs shall be connected to pneumatic valve solenoids or photoelectric
sensors, PN 42EF-D1MNAK-A2, only. No other devices shall be connected to these
outputs.
I assume you’re talking about the modification to in team update 8? No where in the rules, FIRST documentation, or NI documentation is the solenoid breakout module or digital sourcing module referred to as a relay. I believe refers to a spike relay only and not the solenoid breakout, so it is not legal to hook a light up to the solenoid breakout.
Thanks for correcting me!
It seemed reasonable to me to have a low-current light on an output where you can draw up to 3A. Re-reading R42, the intent is actually to allow multiple lights, or multiple solenoids, to be powered in parallel by a Spike relay.
Okay then, use a Spike relay to connect the LED to the robot.
Are there any other methods available?
If you’re into making electronics, you can make a “custom circuit” and hook it up to a digital output.
Wicked,
Remember that the light will be too bright when you or your alliance cannot see the field with the light shining in their eyes.
Does not everyone know that the camera can be adjusted for varying light levels?
I think we’ll stick with the Spike relay. 
Last question: what specific brightness range should the light be in?
Someone pointed out to me the other day that the blue plastic housing associated with the Solenoid Breakout actually is prominently marked “RELAY”. However, that’s the only place I know of where that word is used for that module.