How to Perform a Black Balance

 

Black balance is an operation similar to white balance. As white balance gives the camera a reference to "true white", black balance gives a reference to "true black". This function is normally available only in professional cameras — home video users don't need to worry about it.

When to Black balance

There seems to be a lot of debate around the subject of black balance, and when it's necessary to perform one. Some people say you should do it every time you white balance, but we also know camera operators who hardly ever do it. Our advice is that it can't hurt to black-balance, and you should definitely do it at the beginning of a shoot, whenever you change filters or gain level, and whenever the lighting conditions change significantly.
A poor black balance usually shows as unnatural or incorrect colours in the dark areas of the picture. If you notice this happening, try performing a black balance.
You will need:

• A camera with a manual black-balance function. The "black-balance" switch should be located with the "white balance" switch.

How to Black Balance

A black balance is usually done in conjunction with a white balance. The exact sequence varies between operators but this is a common routine:

1. Perform a white balance first.
2. Throw the black-balance switch. This should shut the iris down and perform a black balance in much the same way as the white balance. Some cameras may require you to close the iris manually first, and you may need to open the iris again when the operation is complete.
3. If you like, perform the white balance again, making a sequence of "white - black - white".