After you’ve gotten used to metering using your camera’s in built light meter, and you’ve tried your hand at the studio lights as well, its time to start experimenting with studio lights working hand in hand with ambient light(s). This can create some amazing results if you use the right judgement, or it can ruin an otherwise great image if you meter wrongly!
The first step is to take 2 different readings, one for the studio flash and one for the ambient. Check out this image of Kajal Aggarwal photographed by KAPA mentor Karthik Srinivasan (SONY a7 MarkII with 70-200mm, 1/160sec, ISO-100, f/7.1). There are three light sources involved here – the chandelier, the lamps, and of course the studio lighting. To get it all into your exposure latitude, the first thing to understand is that you can control ambient light with your shutter speed, and flash with your aperture. To put it simpler, the shutter speed will not make a big impact on flash exposure unless it is by many stops.
So, lets say the ambient light, in this case the lamps, are giving you an exposure of f/8 at 1/125 sec. All you need to do is to vary the intensity of the flash to give an output of f/8, and you are all set! You can play a little with varying the shutter speed a little to adjust the effect of the ambient light on your photograph. This technique also works great outdoors against a sunset background. All that you need is quick metering abilities!