How to Measure Flash Exposure

If you have no light meter, Mark Warren can help you by giving advice on how to measure your flash exposure. Since e-TTL is not very consistent, while the manual mode ensures a very stable exposure. This is especially useful in a studio environment. First set your external flash to a wireless mode. It will be triggered by your on-camera flash unit. You need to configure your camera's settings for the wireless flash control. Set your on-camera flash to behave as a trigger only which means that it does not contribute to the overall exposure. Change the flash mode from E-TTL to manual and start off with full power (1/1). Then you are ready to begin your exposure measuring. Have a white towel placed on a chair and make a shot at 100 ISO, 1/200 shutter speed and 2.8 exposure to begin with. If your towel is blown out, you need to adjust your flash power. You may need several iterations to achieve the right flash power of your external flash unit. By the way, you are controlling your external flash power from your camera and in order to do that you have to use a camera that supports that mode as well as the brand external flash. Always consult your histogram and make sure you have no lights clipping.

This method allows you to get very consistent results but just make sure you place the white towel at the same distance where your subject will later be located, otherwise the exposure will not be right.

No comments :

Post a Comment