Now that I'm building up my studio / location lighting kit, I can no longer rely on my trusty Canon 580EX's built in E-TTL system to do the dirty work of exposure calculation for me on the fly. E-TTL is great, don't get me wrong, but it only works when the flash is either on camera, off camera with the off camera flash cord or triggered with Canon's IR remote, which only works if your flash is facing you and you were within a fairly distance from your flash and within a fairly narrow angle. I logically decided that I needed a flash meter.
There are plenty of flash meters out there, from the trusty analog flash meter to high end digital meters with built in radio slave transmitters. I thought of it, like many folks think of tripods, that you can start out with the cheapest you can get, but in the long run you'll most likely end up spending more on upgrades until you get to where you want to be, than if you just shell out the money for the good stuff up front. So I decided on the latter, and shelled out the roughly half grand on the Sekonic L-558R.
The Sekonic L-558R is an easy to use (once you've read the manual) and sturdy flash meter, that also functions as an incident and reflected spot meter. The meter will read your flash in both incident and reflective modes, I think it is pretty cool that you can take a spot meter flash reading, but I'm sure there are other units that can do the same thing. As I mentioned before, the meter has a PocketWizard module that is built into the L-558R which allows you to trigger your flashes directly from the meter without using a sync cord.
One of the features that I find most useful is the ability to meter you key light, and then meter your fill light, and the meter will give you the difference between the two in EVs. This is an easy way to figure out the ration between your key and fill. You can also fire a series of flashes, storing each one in memory, and then get either a cumulative or average reading.
The meter itself is very compact, fits nicely in your hand and feels solid and well built. I would prefer the device didn't require the expensive 3V lithium battery that could be tough to procure in a bind, but I guess they decided they could make it a tiny bit more compact if they used the 3V lithium as opposed to using 2 AAs or AAAs. The only other issue I have with the meter isn't actually related to the meter, but to an older spot meter that I've been borrowing from my mother to use with my Mamiya RB67 setup, which was "modified" by Zone VI to have a nice little movable zone scale on the side, which makes ensuring that my exposure contains the data I want much easier. I know that I can just take an EV reading and put that into either my mental Zone chart, or I can put it on my handy Zone worksheet, but the little paper ring on the manual scale was really nice.
Before I bought the L-558R I found out that Sekonic is coming out with a new meter, specifically tailored to digital cameras, called the L-758DR. The 758DR allows you to load 4 custom profiles into the meter via a USB cable so that the meter will "respond to light exactly like your digital camera or type of film." Another very cool and helpful feature is the ability of the meter to warn you if you are outside the dynamic range of your medium. The 758DR is also extremely sensitive, down to f-2.0! I may or may not upgrade when it comes out. The 558 has all the features I really need and many more.