We often talk about how to kill the ambient light in a shot so you can fully control the lighting with flash, but sometimes, you actually want to use both natural and artificial light in a shot. This great video will show you how to balance both flash and ambient light for a balanced result.
Coming to you from Robert Hall Photography, this excellent video discusses how to balance both flash and ambient light in the same image. A lot of the time, you will want to completely eliminate the ambient light in an image with flash so you can avoid contamination and take total control. However, there are other times in which you will want to have both contribute to an image. For example, you frequently see this scenario when shooting something like a backlit sunset portrait, where you need to expose for the sky to avoid blowing out the highlights, which consequently leaves your subject underexposed. This is where putting a bit of flash on your subject can balance out the overall exposure and give you the best possible image. It is a great technique to have in your bag of tricks; check out the video above for the full rundown from Hall.
To me the flash need a colour temperature correction gel, the ambient light was a warmer colour than the flash, a pack of correction gels is a must have for any mix lighting shoots. A leaf shutter with a much higher sync speed is a massive godsend when flash balancing, changing multiple pack and iso to control ambient light can be a nightmare as it lacks simple fine tuning..
Agree with you on both points but his approach of changing ISO within the range he did was easy and efficient. Better than staying at ISO 100 and going for longer shutter speed when he wanted lighter background (could have resulted in camera or subject movement). In his particular situation, a leaf shutter would not have helped him as he didn't need to sync at faster that 1/250s (his darkest background image was at his base ISO and his max sync speed and he said that was already too dark). Useful video for people learning to work with flash, most of whom do not use cameras with leaf shutter lenses. Those who do typically don't need to watch this video.