flash tips: in the blink of an eye

Remember: that itty-bitty flash will not light up the Grand Canyon.

Unlike with natural light, it is difficult to see the effects of flash before the picture is taken.  You can't meter it the same way with natural light. It seems to have a mind of its own sometimes. It's just, in a word, frustrating! I hope this short article will shed some, ahem, you know what...

Contrary to the beliefs of many a tourist, that tiny flash on the camera will not light up the Grand Canyon.  No, Sir.  So when you take a photo with flash, there's the portion in the scene that's lit by the flash, and the rest comes from ambient light. Balancing the two is the fun part.



Imagine you have a spotlight in your living room on a dimmer switch, and it's shining on a flower vase from the Ming Dynasty. The rest of the room lights are on another dimmer switch, so you can control them independently. For drama, you could turn up the spotlight on the vase, and turn the rest off completely.  Or you can 2/3 spot, and 1/3 ambient.  Or you can match them.

Here's an illustration with my priceless Ming Vase.

Both 1/200 sec @ f/4. One of them with flash.

This is an experiment you can try. Take one image without flash, then take another with flash. See the part that's lit by flash?  Good :)

Place your vase in the shade against some bright background. Take an image without flash (just turn the flash off). Remember to meter the background. But the vase is underexposed, you say? Precisely. If we expose for the subject, the background will blow out, and when we add flash the subject too will blow out. Not what we want.

Now turn on the flash. Take another picture. Best to do this in manual exposure mode and leave the aperture and shutter speed settings the same for both images. The image without flash shows the ambient exposure. We simply add flash to bring the subject to good exposure. We've just matched the subject exposure with ambient exposure.

The next question, naturally, is how to control the flash power. If you're using a TTL flash, it talks to the camera and automatically sets the correct power for you. Or you could put your flash in manual mode, and dial in the power by hand (typically they go from full power, 1/2 power, 1/4 power, etc.)

Here are some tips:

• When using TTL flash, accurate focus is important. For best results, set your camera in One-Shot (Canon) or AF-S (Single Servo, Nikon) mode.
• TTL works in manual exposure mode (something I didn't know for the longest time).  
• Shoot at a higher ISO setting will make those batteries in the flash last a lot longer (higher ISO setting requires less light, thus less drain on the batteries). Latest cameras should do well at ISO 800.
• Turn your flash head to bounce the light off the ceiling or wall to soften the light and create more interesting lighting direction.  Note the nearest wall may be behind you.

Next time we'll look at how to control that ambient exposure.  Stay tuned.

 Better Background

1/250 sec @ f/2.8, Nikon D200, 50mm

If "I'm a natural light photographer." means "Flash scares the *** out of me." We can help.