This is something I do a lot on my magazine shoots and it helps to not only helps get around poor ambient light conditions, but it also helps create images that have impact, a key consideration when you hope your image is going to make it onto the front cover!
Firstly, a little about why I use this very simple style of lighting:
On-camera flash, whether bare or diffused, is a useful tool but it's not the most dynamic of light, basically hitting the buject and bouncing straight back to the lens. It's flat, boring and because it's on-axis to the lens, it kills directional shadow, shadow being massively important in giving an image depth. This is where off-camera flash (OCF) comes into play.
These days, the '
strobist' movement has made off-camera flash both one of the coolest things in photography (even though it's not a new concept), but also one of the easiest to master because there are so many resources available. I myself learned a lot of my OCF technique through this useful website. Anyway, many exponents of OCF get into multiple light shooting but a single light is a very important tool to give additional 'fill' that can help control the shadows and produce a better looking shot. I love using one light, especially combining it with natural side-lighting to mix white balances and it's the easiest (and cheapest) OCF technique to master.
First off, I use both bare (undiffused) flash and diffused flash, the latter usually through a portable 12x12" softbox. Most of my work utilises the softbox, because I just prefer softer light and it's kinder on reflective surfaces, especially fish, which are one of the things I shoot a lot of. Bare flash usually comes out when I have diffused ambient on overcast days and I want to create some harder shadows that are associated with a small, bare light source. It's all about knowing what you want on the day and what you think looks best when combined with the ambient conditions.
Before I get onto sample images, I'll point out that there is no right (or wrong) way to do this in terms of light position, light distance, and the way you fire the flash. On the latter point, I use a basic Yongnuo TTL cord or a wireless trigger system (currently the Phottix Strato system), although I'm now finding that a wireless system is far more versatile because you can place the light source anywhere and still fire it. With a TTL cord you're limited by the length of the cord, although I do think it's best to have a wired option with you at all times because one day there will be a time when you're out of batteries and and wireless system is rendered useless.
I use my flash in M (manual) mode so I can adjust the power in increments, plus it's easier to know the effect when it says 1/16th, 1/32th etc, as opposed to +1 etc when it's in TTL mode. Anyway, TTL flash is rendered useless by my trigger system because it's a dumb system; I.e. It doesn't transmit TTL info from camera to flash. You'll need something like an expensive PocketWizard setup to do wireless TTL.
I do a lot of close-up work showing anglers doing things like holding fish, mixing bait, holding equipment so it's all fairly close-quater stuff - a lot of torso shots basically - that doesn't require a massive light source, hence why I only use a 12x12" softbox. It's not a great tool for wide shots because the light is essentially still small in relation to a wide scene, and its quite hard (hard: it creates hard-edged shadows). However, for rig-tying sequences and macro, this softbox produces a very soft light. For larger subjects - full body shots for example - then you're going to need a much bigger softbox. When using bare flash I just place the flash at the distance I feel the fall-off (how the light power decreases over distance) will benefit the shot.
Remember that using a diffuser like a softbox will reduce the overall power if the light when compared to bare flash. I'll hazard a guess and say that my softbox, which has a single diffuser sheet inside, cuts the light output by around 1.5 stops so if I'm getting f/13 with bare flash I'll have to open up to f/8 to get the same exposure with the softbox fitted.
The whole idea of adding flash into a shot is to control the shadows but not totally kill them off - remember, you need shadow to create depth - and use them to your advantage to create an image that looks three-dimensional, or at least doesn't look flat and boring. Look at the natural light and look at where it falls and what shadows it casts and then you can see where you need to add fill light into and where you need to retain full shadow. It's effectively
cross-lighting just using a mix of natural light and flash.
These two shots show just how dramatic a difference adding flash into the shot can make:
You'll notice that in both shots the background is underexposed. Aside from underexposure helping you retain detail in seemingly lifeless skies (although don't overdo it because noise will be a problem, even in RAW), it will make the use of flash appear more dramatic. Also, in this case, I'm shooting at ISO 800 so you can see by the settings (1/100th @ f/8) I have little leeway to get a steady, sharp shot at lower ISOs, so poor were the light conditions. By underexposing I get a fast enough shutter speed and enough DoF and with the additional flash light, the shot looks fine. It didn't make the cover BTW - that's life
In terms of how you meter a scene it's up to you; you can meter to get the flash setting right (using the aperture) and then change the shutter speed to lighten or darken the ambient exposure. This is pretty fail-safe method because the subject is always lit by the flash at a constant light level so if you happen to not quite nail the ambient exposure - for example, if you're working under time constraints - you still have a useable shot. The other way is to get the ambient exposure to how you want and then add flash in until you have what you want, but this isn't as instant a technique, taking several test shots to get the result. Plus, it's not great for failing light conditions. I generally use the latter when I am up against it in terms of getting a useable exposure (like in the images above) because I know where I stand with the ambient exposure and my shutter speeds and DoF. Again though, there are or right or wrong ways to do this and in full daylight I use the former method....
Actual metering for me is done in M (manual) mode on the camera so I have full control over shutter speed and aperture, and I refer to the camera's LCD, firstly using blinkies to check for any burnt highlights, then using the histogram to check overall tonal range. I just go with my gut mostly though, knowing what will look good when I process the image. I'm a recent convert to raw, and this gives a bit of processing leeway.
I do use light stands in calm weather but when it's windy I tend to hold the flash/softbox in my left hand, holding the camera and shooting with my right. It takes getting used to but isn't that uncomfortable. The main disadvantage with this though is EVERY shot ends up with the artificial light coming from the left of the frame. I've learned to shoot cack-handed, holding the flash in my right hand but it's uncomfortable and not for continuous shooting. This is where a heavy-duty tripod with the light on comes into play.
Another piece of equipment that may come in handy is an ND (neutral density) filter. Here's the scenario; you want to shoot using off camera flash on a cheap trigger system but at f/2.8. Thing is, you're camera's sync speed is 1/250th and the exposure reading is actually 1/2000th so in reality the flash isn't going to show properly on the exposure. Put an ND filter on though (say, an ND4) and the exposure is now reduced by four stops so now you can shoot at 1/125th, well below your camera's maximum flash sync speed, AND still use a very wide aperture. I carry screw-in Hoya filters in ND4 and ND8 strengths. Just prefer screw-in filters because they're less liable than drop-in filters to get knocked off and damaged.
Before I leave you with a few of my shots done using what I've described, please remember that this is just a very basic guide to utilising your flash to create something different and of course, multiple flashes can take this theory to several new levels. This isn't a definitive guide, just an insight into how I shoot day-to-day. Check out the strobist
website or
flickr group for more information that i can ever give and in particular, check out the Lighting: 101 section.
I used an on-camera fill flash to kill some of the shadows AND rigger the additional flash because I didn't have a wired/wireless triggering system at this time.
Just a standard editorial shot. This was bare flash from camera left to kill any shadows created by the strong daylight of mid-summer, and to pick out the outline of the smoothound's Jaws-esque dorsal fin against the angler's shirt. Heavily processed I will add, to make the most of the sky and add even more drama.
This is shot cack-handed, holding the camera in my left hand using the vertical grip, and the softbox in my right. Notice how the colour temperatures are wildly different on each side of his face - this is how i like to shoot.
Shot using two lights, one to create the main fill (softbox) from camera left, and the other to create a strong highlight from camera right. As with just about every shot I do using fill, the light hits the subject the way they are facing to fill all the shadow, hence the term 'fill flash'.
