The Metz shoe mount does offer something lacking in the Canon unit: a secondary flash head. While you could always use the bounce (kicker) panel to kick back some light and create catchlights in the eyes, this is a fairly weak form of light. As an alternative, the unit can be directed to shunt power from the main flash head to the secondary, or sub-flash, when the flash head is swiveled or tilted (even with a downward tilt for close-ups, where you may not want it because of parallax problems). The flash can be set to split output equally or to reduce output on the secondary head to 1/2 or 1/4 so as not to overwhelm the main light (the primary flash head). When the main head is seated normally, the secondary head is deactivated.

You do, however, have to be careful with subjects standing too close to the background: the secondary head on the Metz can cast its own shadows. And one more important observation about this sub-head: when using a wide angle lens, I discovered that the secondary head produces a noticeable band of vignetting along the bottom of the frame--more pronounced the wider you go. Both the Canon and Metz units produce typical vignetting at the corners at 24mm--despite what the tech specs might lead you to believe in terms of flash coverage. But the corner vignetting is only readily apparent on a uniformly toned surface and can easily be corrected in Photoshop (not a practical solution for that dark band).

For this shot, I positioned the camera on a tripod in one corner of the store. Again both flash units did an equally nice job of filling in while retaining the ambiance of the store. In this case, the Canon 580EX II was used.

Remote Flash Usage
I often find it necessary to shoot with the flash off-camera. We'd expect the 580EX II to work flawlessly with the Canon Off-Camera Shoe Cord 2 (although there is a new 580EX II dedicated off-camera module with similar improvements, but I did not have it for testing). The Metz 58 AF-1C had no problem either. The other cable-based Canon adapters do not support E-TTL/E-TTL II, so I didn't test these units with either flash.

But if you hate cables, then you'll be glad to know that both flash units support wireless control as master or slave. In fact, the 58 AF-1C was able to trigger the 580EX II when slaved, and the 580EX II triggered the Metz unit in turn. And both were slave-synced successfully to my 550EX that was seated in the camera's hot shoe.

I also tested the two flash units slave-synced to a Canon ST-E2 remote transmitter. The Canon flash worked fine, regardless of which direction the slave cell on the front of the unit was facing. The Metz, however, needed to have a clear line of sight with the transmitter. That prompted me to take a second look at the Metz. Upon further investigation, this was also true when triggering the Metz flash using the 580EX II from the hot shoe. In short, this is a disappointing find for anyone who plans to use the Metz slave-synced alone or in multi-flash wireless operations.

More interesting still, I set both flash units to operate as slave units. I seated each in turn in the camera's hot shoe. Only the Canon flash responded appropriately, reverting to normal operation and disabling the slave-sync setting automatically after recognizing the direct sync connection with the camera. The Metz unit, however, failed to revert to Normal mode. I had to manually disable the remote trigger setting on the 58 AF-1C so that the camera would trigger the Metz strobe seated in the hot shoe. Oddly enough, setting Wireless mode was more intuitive on the Metz than on the Canon flash. The 580EX II, I should add, replaced the mechanical master/slave switch found on earlier Canon strobes with digital control, to my chagrin.

I bounced the Metz flash off the reflector sitting atop the Sunpak light tent, but did so by hand holding the flash (aimed upward) just inside the top edge. I then took the same picture but with one change: I enabled the secondary flash head, which drew power from the main head, hence the darker background tone and change in the depth of background shadows. The off-camera flash was triggered via the E-TTL hot-shoe adapter cable connection. For the setup shot, I used direct on-camera flash.

Final Thoughts
I came away from my experiences with a positive feeling about both flash units after using both in E-TTL II mode. On the one hand, there is that comfort factor in sticking with the manufacturer's own dedicated system tools--a Canon strobe matched to your Canon D-SLR and lenses. However, the 580EX II was developed more for the new EOS-1D Mark III, which extends the flash unit's functionality. For instance, auto external metering works only on this camera. Manual external metering (not to be confused with Manual mode) is supported on other EOS models, my 5D among them.

The Metz only offers one Automatic (Auto-Thyristor) mode, so there's no confusion. And it appears to provide the full array of bells and whistles, although it doesn't necessarily do things the same way. In some respects, this flash exceeds the 580EX II; in others, it falls a bit short. The Metz 58 AF-1C does offer that secondary flash, something I've always treasured as a fill source when using bounce flash, although the sub-head does draw power away from the main head. To counter that, the Canon 580EX II touts that weatherproof design, something I would feel more comfortable with when shooting out in the rain.

To capture the ballerina in motion, I employed slow-sync flash, with the camera in Aperture-Priority mode. The setup shot shows how I positioned the Canon flash on the left (on a tabletop tripod for the optimum angle) and the Metz flash on the right, as fill to bring out that pattern on the right side of the piano jewelry box (with bounce flash plus the secondary head). The two strobes were triggered by the ST-E2 remote transmitter seated in the camera's hot shoe. I used black velvet as a backdrop.

In the end, most people look at price, but I wouldn't let that be the deciding factor. Both flash units are highly capable and reliable tools. In the past, the choices were not that tough. Now they are. I guess we can thank technology for the current dilemma. But what a wonderful dilemma it is!

My thanks to my friends at Lorimer Market (Brooklyn, New York) for letting me shoot some of the pictures used in this report.

For More Information...
Canon Speedlite 580EX II: Canon U.S.A., Inc., One Canon Plaza, Lake Success, NY 11042; (800) 652-2666, (516) 328-5000; www.canonusa.com.

Metz Mecablitz 58 AF-1C: Bogen Imaging Inc., 565 East Crescent Ave., Ramsey, NJ 07446; (201) 818-9500; www.bogenimaging.com.