I like to shoot nature subjects with my Nikon D7000 and AF-S 85 mm f/3.5G VR II macro lens and I’m thinking of buying a macro flash kit. What is best in terms of lighting? Should I use a shoe-mounted SB-910 flash unit with a downward tilt, a ring flash or a twin flash unit with two flash tubes?
On-camera flash is not suitable for extreme close-up photography, Helen, because the flash is unlikely to illuminate the bottom part of the subject. It’s simply not possible to tilt the flash head far enough down. If you do want to use a conventional flash unit, move it off-camera using a TTL extension cable or wireless off-camera flash. (Your camera, like most current DSLRs, supports the latter feature.) For softer lighting, add a large diffuser accessory such as the Lumiquest Softbox ($47).
The high-tech ring light flash units—like the Sigma EM-140 DG ($529)—are very versatile and easy to use. They typically consist of a circular mechanism that’s mounted on the front of a macro lens with an adapter ring. The “ring”—with two individual flash tubes—can be rotated so you can place the two light sources at the desired position. Some of these special flash units also include a diffuser accessory. A ring light provides somewhat flat lighting when both tubes are illuminated. I recommend the more directional light that’s possible with the ratio control feature: set so that one tube produces most or all of the light.
The twin flash accessory systems—with articulated arms that hold two flash units—are even more versatile in terms of the exact placement of the light source(s). Some photographers definitely prefer this type for maximum control of flash placement. As a Nikon D7000 owner, you would want the Nikon R1 (for cameras with a built-in flash that support wireless off-camera flash). It sells for $530, including two SB-R200 wireless macro flash heads.
For anyone whose budget is very tight, the off-camera flash technique described in the first paragraph would be a suitable alternative. All that is required is a versatile external flash unit, a diffuser accessory ($30 and up) and perhaps a TTL extension cord that sells for about $80.