So how do you know when your IR light is bright enough?
This is easy to answer if you know exactly what your subject is and exactly where it is. You have sufficient light if the entire subject is visible and details are clearly seen. It is harder to answer if you're not sure what or how many things you're looking at. One of the problems with inadequate lighting is you don't realize how much you are missing until you compare the scene using better lighting (as illustrated below).
When your job is to count bats exiting from a roost, you need to be able to see the entire area, and you need enough light to clearly see and distinguish each and every individual bat. For larger entrances or other applications, the Sony light is insufficient. You will fail to see all the bats that are there, and your count will be inaccurate. The only way to ensure sufficient lighting is to keep adding brighter light until you no longer see an improvement in image quality.
IR Lamp Kit - Light for consumer DV cameras
Our infra-red lamp kit is an incredibly bright IR source for field use. It offers 40 high performance IR LEDs in a specially designed heat sink case. At less than three inches in diameter, the lamp takes up very little room in a backpack.
With a totally machined case to improve both the ruggedness of the lights as well as better heat sinking capability, making it brighter than the original design.
Tried and tested kit, especially for illuminating bats as they emerge from their roosts and exclusively imported and sold in the UK and Europe by me.