Moving on from the last 'Light Test' post that explained why I do it, here we have a prime example of a test photo to check the exposure.
With the Lumedyne flashes I use, the Hasselblad 120 film camera can sync up to 500th of a second, which is a perfect speed to freeze the action. The canon 5Dii can only sync at 200th, which isn't usually fast enough, especially in the daylight. It does however give me a good indication of where the flash is hitting and if the exposure will be right once I change over the cameras.
You can see here that after I changed cameras I stopped down from 200th to 500th of a second, and as a result the background gets darker but the flash exposure is still correct and a little sharper.