Q&A: What kind of flash should I use for my SLR?

Recently, a friend asked me what kind of flash accessory is best for an advanced camera such as a Nikon D7100 or a Canon Rebel T5i SLR to light up photo subjects. (He owns a Canon SLR.) He'd seen ads for LED lights, which were cheaper than external strobes, and wondered whether they were a better bargain.

First, you might be wondering why you'd even need a flash accessory. If you've bought an SLR or advanced camera, chances are you've used the camera's on-board popup flash. For many types of shots, this type of flash provides decent illumination. In fact, it's also the strobe we use when we calculate our flash-photos score in our camera Ratings.

For more advice and information, check our buying guide and Ratings for digital cameras.

If you want to expand your lighting options, avoid red-eye, and improve your flash photos, though, you'll want to buy an external flash, which is larger and more powerful than the on-board flash and fits into the hot shoe on top of your advanced camera. You can increase or decrease the flash output on these units, and set when and how the flash is triggered. These external strobes are also more flexible: You can adjust the head of the flash to bounce the light off walls and ceilings, which can give you more natural-looking light.

As to my friend's question: An LED light is not an adequate substitute for an external strobe, although it may give you some additional light if you shoot video. Several professional photographers I've talked to agree that it's hard to beat the versatility and flexibility of a dedicated external flash. Although LED lights are used in photography, they're most often found in professional photo studios or indoor-portrait settings. So I recommend buying an external strobe, not an LED light.

Another tip: Buy a flash that's the same brand as your SLR or advanced camera. The flash and camera body communicate back and forth with each other to set the optimum exposure settings, and this communication works best within a brand. So, for example, if you have a Canon SLR, you might consider one of several Canon external flash units:

• Canon Speedlite 600EX RT, $550: Canon's top-of-the-line strobe and offers the most options, including wireless features.
• Canon Speedlite 430EX II, $300: offers lots of features, but is less expensive than the 600EX RT.
• Canon Speedlite 320EX, $250: includes a built-in LED for use when shooting video.
• Canon Speedlite 270EX II, $170 and Speedlight 90EX, $150: Canon's most inexpensive and lightweight flash units.

If you're considering buying a third-party external flash, try Metz or Sunpak. But do some research to make sure it's compatible with your camera.

—Terry Sullivan