The newest canon speedlight......but there may be a better choice

I've been into digital slr photography for almost two years. My first near professional camera was the Canon Digital Rebel (original not the newer one out these days). That camera has built in flash but it's just not good enough to keep up with fast action sports, which is what I tend to shoot most. The 580 was out at the time I bought my flash but at that time it was nearly five hundred dollars. The 550EX and the 580EX are quite close in terms of the functions they offer and the flash speed, for the money difference I got the 550.

Recently I've gotten into some more creative shooting and I wanted a second flash unit, the 580 has come down to around the same price I paid for my 550 so I went with it this time around.

550EX vs. 580EX:
Both flash units are very powerful for their size and offer full integration into Canon film and digital bodies and their professional quality snap and shoot cameras that have a hot shoe. So that means this flash will work with a Canon G2, a 10D, 20D, or anything newer including the new full 35mm frame digital, the 5D.

The 580 offers marginally faster cycle times over the 550EX and has the port on the side for the external battery pack. I've read that the 580, unlike the 550, powers everything--including the lcd control panel from the external battery pack. On the 550 you needed batteries in the head to power the lcd panel or the flash didn't work--I'm under the impression you might not need to have batteries in the 580 if you're using an external pack. Unlike the 550, the 580 offers the round sync port style of flash unit cable so that it can be used off the camera (flash units on top of the lens create issues like red eye at times--most pros use flash to the side of the lens for that and other reasons).

The 580 supports the relatively new flash exposure bracketing function that isn't supported by the 550EX.

If you ask me, the 580 is a good bit lighter than the 550EX.

Both flash units fully support zoned wireless multi-flash operation, both can function as master or slave units.

The 550 has more buttons on it, the 580 has the multifunction dial like the 20D and is a little easier to deal with if you ask me. The Master/Slave settings for wireless mode are in the same spot at the base of the flash.

What I think of it?
Like most flash units, buy yourself a diffuser first thing, it makes for much better exposures and fewer hotspots. Sto-fen makes a plastic diffuser that fits over the front, they are made in white (diffuser), green (corrects for flourescent light), gold (warmer skin tones in daylight). With my 550EX on top of my metal bodied 20D with a battery grip the camera is almost too heavy to hand hold for long periods, the 580 is enough lighter than the 550 that it's not as bad.

Personally I don't think it cycles that much faster than the 550 does but I do seem to have fewer shots where the flash didn't fire at all even when shooting a lot of frames continuously. Now that I have two units with wireless capabilities I could come up with a tandem setup and should never have any more black pictures because both units would share the load---the weight of handholding such a beast is what scares me.

Watch the bounce adjustment. Just like my old 550 it'll put a flashing icon on the lcd panel if it detects the bounce head is in a strange position. Most photographers tell you to aim the head up a few degrees so the flash isn't head on but when you've got the omni-bounce installed on the front it's already preventing that issue. Like the 550, it comes with a stand in the vinyl case (but no belt loop or strap rings on the case at all).

Exposure:
Maybe it's just me but I'm never happy with flash exposure when left to automatic. On my old rebel I would set 2/3 stop extra exposure on the flash. On my 20D I set 1/3 extra exposure overall and 1/3 extra exposure for flash too so it works out about the same. With the sto-fen omni-bounce installed the pictures are very pleasant and well lit as long as the subject is not too awfully close to the camera--this flash can get a little hot with nearby subjects--it's one of those things that takes a little getting used to. When shooting human subjects supposedly one of the ways to avoid overexposed flash pictures is to be sure the camera is reading a patch of skin when focusing and setting auto exposures.

I've used this flash with the 17-55 kit lens that came with my 20D, I've also got 28-135 IS lens that I use a great deal but I haven't used it with this flash yet. If you get an ST-E2 unit you can use two flashes in full auto mode since that device mounts on the camera shoe and transmits exposure information to the flash unit(s).

External battery packages:
While you get a fair amount of flashes off 4 batteries you might want to invest in some high capacity lithium ion or nickel metal hydride batteries. Alkalines will give you faster cycle times but will be really expensive to keep your flash fed. Canon makes a couple of external battery packages that improve cycle time. The ones that hold extra batteries are ok but really don't give you that much improvement in cycle time. I haven't tried their rechargeable units but if you need top speed cycle times look into one of the professional units made by jackrabbit, sunpak, metz, leitz etc. Canon is constantly at battle with third party accessory makers, they don't want you to be able to buy a third party battery pack--they want it bought from them. Because of this, be careful of third party stuff, just because it works with your 550 you can't expect the 580 is the same internally--I've read of battery packages for a 550 melting the capacitor in a 580 because Canon apparently made some minute changes to the 580.

Conclusion:
If you need the flash bracketing functions of the 580 then spend the extra on it, for most folks the 550 is enough. Also be aware the 580 is a good bit lighter than the 550 when perched on top of an already heavy 20D (metal) camera body with battery grip. I think the 580 is a teeny bit faster but not enough to justify the extra cost if you're just looking for cycle speed. The canon speedlights offer full integration with their cameras but there are cheaper alternatives from manufacturers such as Sigma and Sunpak. The third party units might not offer as much functionality with the electronics (or external power plugs) in your camera but you may get more power.

update 02-2007: Well here I am 14 months into owning this flash unit and I seem to be having issues with it. On a shoot this past weekend the unit kept shutting down (i.e. no lcd display, like it was going to sleep) I keep like 8 sets of nimh batteries in my bag tried every set (two of which just came off the charger) and none of them would keep the flash going for more than a few shots. I was also using a high voltage pack plugged into the high voltage port at the same time so all the AA's were doing was running the display and electronics in the flash. Fortunately I had a set of alkalines in the car and popping those in the flash let me get through the shoot...good thing...I would not have been a happy camper if I'd lost out for an equipment failure; I shot 900+ pictures that day and used the flash on every shot. Any pro will tell you to carry backups for as much gear as you can...so now the 550EX goes in the bag just in case the 580 starts up this garbage again. Had a problem with it the last time I used it too, wouldn't charge up with just AA's installed in it; changing batteries fixed it up that time.

The flash only has about 20000 frames on it, really not much...haven't yet found any statistics on how long this dude should last but I guess the big lesson here is to buy the extended warranty if it's reasonable...would have been worth it in this instance. Canon is about to release the 580EX II in April, but it will probably be months before the regular joe can buy one. Metz/Bogen has been making flash units at least as long as Sunpak and has long held the reputation of making excellent flash units. The new shoe mounted 58 AF-1C is supposed to be at least the equal of the 580, integrates with the Canon camera, and has the advantage of user upgradeable flash firmware via a built in mini usb port, it also has a high voltage port (but of course they recommend only their high voltage pack). I Need the speed of this flash, don't want another 580 that won't last more than a year again so I ordered the Metz and the p76 power pack since at least so far I can't find a cable for the sunpak power pak I've been using.

Most sales people will try to sell you on the idea that any third party flash will never work as well as the Canon unit because Canon doesn't release their firmware specs for the use of competitors (competitors must reverse engineer and guess at protocals). So far most real world tests from folks on photo forums say the Metz 58 unit does a better job than the 580 ever could as far as picking proper exposure using ETTL mode. In short, there may now be some better choices out there than the Canon flashes, take a long look before laying out nearly four hundred for this unit because there may be something better out there for only a little bit more.