Turning up to a photo shoot location blind can be daunting, especially if you need to use flash on some level, preferably with a touch of creativity.
In my very short tenure as a working flash photographer (0.000001% of my total photographic life), I have gained enough knowledge to work in a “lets see what we get”, rather than a “Oh sh#t, oh sh#t, oh sh#t” frame of mind.
The basics.
Use Manual.
Manual flash has four active exposure controls and one passive one.
The active controls are; Power (1/1 to 1/128th power), Distance (subject to flash-not camera), Aperture and ISO chosen. The passive control is Shutter Speed, which does have an effect on ambient exposure, but not flash.
The more of these you can control from the get-go the better.
Working for only a month with my rig, I am now comfortable setting up a 1-2 flash outfit and shooting nearly straight away, but I need to control the environment.
I know that if my flash to subject distance is about 3 metres, zoom on the flash at 28mm, my aperture at F2.8* and my ISO set to 400, then 1/32 +.3/.7 to 1/16th power through a shoot through brolly, or 1/16th from a silver reflector brolly are going to be in the ball park. Note that where I stand is basically irrelevant. The flash to subject distance is critical, the photographer to subject distance is not.
Similarly, most ceilings in modern event halls will work with a flagged flash at about 1/8th power at 2.8* and ISO 800 and the flash zoom set to 105mm. This gives me even coverage This is also a good starting point for bouncing flagged flash.
If shooting for fill light outdoors, I will often start at 1/1 power and work for balance. This one is still a work in progress, but a test or two and I am good to go.
These known values (with my flashes), are a starting point I can rely on.
To change these I have a wireless controller on camera that can run three groups separately and is a dream to use (choose the group and increase or reduce the power). If this fails, any one of my 560 IV flash units can step in as a controller.
Shutter speed is chosen based on how much ambient light there is and whether I want to add it in for atmosphere or cut it out to capture movement. At slow camera shutter speeds, you will still capture subject movement sharply as long as you overpower the ambient light , because the flash effectively becomes your shutter. If there is too much ambient light though, you will get subject ghosting as the flash’s fast light and the ambient slow shutter speed light share the exposure giving you one sharp and many blurred versions of your subject. Using a higher shutter speed is not going to capture the movement, but it will cut out ambient light allowing the flash (possibly shooting at up to 1/20,000 of a second), to effectively be your shutter.
As I add more modifiers and make up more complicated flash configurations, I record them in a note book. This allows me to go to an idea with a workable base, then modify as I need.
The reason I do not use TTL is simply because I prefer to control things as shown above. It sits in my head better. TTL uses a totally different set of controls.
The basic strength of TTL is it’s ability to set most of the above for you. It’s weakness is that it bases it’s choices on subject reflectance. Shoot a dark subject without flash and you will usually need to set “-” exposure compensation on your camera. Flash needs the same compensation. It rarely falls outside of a workable-fixable range, but it cannot be relied on to be consistent.
Even though I shoot this way normally (Aperture priority with exposure comp), TTL flash often confuses me and works against my wishes, trying too hard to make flash invisible, then jumping to being too overpowering. It also makes judging battery drain harder. You can control the camera with manual mode, but the flash will still react to it’s environment.
No flash used, just enjoying a great spring.
*One huge advantage of M43 is f2.8 aperture gives me plenty of flash power (the wider aperture reduces the amount of power needed), but still provides a decent amount of depth of field (equal to f5.6 in full frame). A full frame camera at f5.6 would need either more flash power or a higher ISO setting. Flash on M43 is effectively two stops stronger.