This is the third and last post in a series on Photographing People while you are traveling. The first article provided general guidelines on setting up the shot and the second provided guidelines on working with the light. This post discusses tips on using a flash.
Know the Difference Between Fill Flash and Main Light
As photographer’s we all have “ah-ha” moments when the lightbulb goes off in our head. I still remember mine when I realized how I used my flash depended on whether I was using it as a fill light, filing in shadows on a face, or as a main light. If my flash is the main source of illumination of my subject, because it is more powerful than the ambient light, it is my main light.
When I use my flash as fill flash, I typically set my exposure settings on my camera as I normally would without a flash. I put my flash on TTL mode, and as a starting point, dial down the power to -2. I then adjust the power as necessary once I check my image in the LCD and look at the histogram.
If I am using my flash as a main light, the power level of the flash and the distance of the flash from the subject determine the amount of light hitting my subject. Because the flash of light from my flash is so quick, shutter speed does not affect the exposure for my subject. The shutter speed will affect the exposure for that part of my image not lit by my flash. I can light my subject with my flash and use a slow shutter speed to bring in the background. Using a slower shutter speed is called dragging the shutter.
When your flash is your main light, you don’t usually have to worry about how camera shake affects the sharpness of your main subject lit by your flash. Your flash is so quick it should stop any movement. Your background, however, may be softer due to camera shake. You may want to experiment with moving your camera on purpose, or zooming it in and out, keeping your subject sharp but using your movement to create a more interesting, artistic background.
I usually shoot fully manual when I use a flash as my main light (both camera and flash in manual mode). That way I can control both the aperture and shutter speed to get the end result I want. When I am using flash, my initial settings are based on the ambient light. I measure the light with my in-camera light meter and set my camera for the recommended exposure. I usually set my aperture at f/5.6 to start and determine the shutter speed based upon that aperture. I typically keep my initial ISO between 200 and 800, depending on how dark it is. I then set my flash to 1/4 power. After I have my initial settings, I take a test shot and review the results to determine how to change my settings. It is a balancing act. If the scene overall needs more light, I might change the ISO. If the subject needs more or less light or if I want greater depth of field, I adjust the aperture. If the background is too bright or dark, I adjust the shutter speed. I prefer keeping my flash power down and so will increase the ISO before I increase flash power. If I use more flash power I will eat up my battery more quickly plus it will take longer for my flash to recycle between photos. Having said that, I prefer not going over ISO 800, so will increase flash power once I reach IS0 800, and not increase the ISO unless I find I have to, to get the proper exposure.
Natural Light is the Best.
Unless your artistic vision dictates otherwise, natural light is the best. I am not referring to light without a flash. I am referring to light that makes your subject look natural even if you are using a flash.
Don’t overdue flash power for fill in flash. Remember, the flash is just filling in shadows on a face, not adding light to the rest of the face.
If your flash is the main light, keep the ambient light in balance with the light on the subject. The rule of thumb is the exposure for your subject is about two stops more than the ambient light. (Remember, rules of thumb can be broken.)
Even if you get your exposure right, your lighting may not look natural. Bounce or diffuse your light to soften it up. Get a bigger diffuser than the one that came with your flash. I use the MadMod MagSphere. I have tried many other diffusers and have found this to be the best. It travels well and isn’t too heavy to carry. Learn to use gels over your flash so the color of the light from the flash blends with the ambient light. I often use a 1/4 CTO gel on my flash. It keeps the color of the flash more like the daylight around me. Learn to use a grid. Grids focus the light on your subject, keeping it from spilling over. The MagMod system make it very easy to use gels and grids. Levi has written an excellent article on the system, discussing the use of gels and grids, which I highly recommend reading.
Using a flash off-camera gives great results when shooting a portrait. When I travel my flash is usually on-camera as I don’t travel with a light stand or assistants. I have put my camera on a tripod and hand-held my flash, when making portraits of bugs and butterflies, and have gotten great results. I am sure it would equally work well when photographing people, but I typically don’t walk around carrying a tripod when I am in the city photographing people and so have never tried it.
High Speed Sync
Flashes typically sync with your camera’s shutter at speeds of 1/250 or less. Some flashes have a high speed sync feature. High speed sync allows you to use your flash with a wide open aperture on a very bright day. A wide aperture means less depth of field and a blurrier, out-of-focus background. By setting your flash to high speed sync you can set your shutter to a really fast speed–possibly at 1/2000 or higher so that you don’t overexpose your background on a very bright day. It does eat up your battery, so use it sparingly, keeping your aperture wide open. Levi has also written a good article on shutter sync speed, if you are interested in more information.
Experiment, Experiment, Experiment
Practice, Practice, Practice
Lighting is tricky, and not always intuitive. Experiment and practice before you leave on your trip. It will lead to a lot less frustration and to many more successful images.