I was going through a set of images for a recent shoot for a salon and though it would be a good way to explain to the those not used to using flash how you can control ambient light and change the feeling of a photograph. The two pictures above are taken with the same camera, same flash, same shutter speed and the same processing done to them in lightroom - no photoshop trickery pockery. All is identical apart from settings. The scene To camera right, we have a flash pushed into a silver umbrella to bounce onto the subject, the white wall to camera left is acting as a fill source. The camera is set the same ISO 100, Shutter speed at 160/second. The only two differences here in this picture is the F-stop and the flash power. The first picture has an F-stop of f.6.3 so the flash is acting as a fill flash and was at around 1/16th power, but because so much ambient is coming in, the sky has no colour or definition. By changing the f-stop to from f6.3 to f.11 the camera aperture closes allowing less light to enter the camera and so can capture the sky and ambient light becomes darker. But what of the model? Well, she too would get darker as well. I don't have picture to illustrate this but it would just be a darker picture in general. So the only option is to increase flash power. Seeing we went roughly 2 1/2 stops up, we can we need to push the flash power up by the same amount. Thus, the power on the flash went from 1/16th power to 1/4th power. I found that it was still a little dark, so I pushed the flash to one more stop at 1/2 power. Which is what you see above. The flash used here was the powerful Godox flash I wrote about here. Many standard flashes may not be able to produce the above effect unless using a high-speed sync.