Three ETTL Hot Shoe Flashes Compared

Canon 580EX II, Metz mecablitz 58 AF-1
and Sigma EF-530 DG Super
and a quick overview of hot shoe flash photography

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Note: I’ve watched Joe McNally work with his Nikon SB900 flashes, and they are ahead of Canon’s ETTL flash system (Nikon calls it iTTL). The SB900 isn’t compatible with Canon cameras (which I use) so it isn’t in this comparison. Metz and Sigma offer Nikon versions of the two flashes tested which are intended to compete with and be compatible with the Nikon SB900 as well as versions for other brands.
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There’s a nearly bewildering array of hot shoe flashes available, and some of the third party flashes are much less expensive than their Canon or Nikon “equivalents,” so I decided to compare a few of them and see how equivalent they are, if at all.

Each of the three flashes I tested has Manual and Auto modes, their flash heads will swivel & tilt and they will permit high speed sync, allowing you to use the flash at shutter speeds higher than your camera’s sync speed. They do this by putting out multiple blinks of light which have the effect of a constant light during the time the shutter is open, say 1/500th or 1/1,000th of a second. This permits you to use wide apertures in outdoor situations.

They’ll each operate in stroboscopic mode, too, flashing your desired number to times per second during a long exposure. I’ve never had the need for this, but it’s another bell/whistle they all have. They’re all capable of emitting a one-second modeling light, too, but I’ve never had occasion to use this feature either. It would’ve been very handy back when we didn’t have a Liquid Crystal Display (LCD) image review on the back of the camera.

All three flashes permit “second curtain sync.” If you’re using a very long shutter speed (say, at night) and you have the flash fire the instant the shutter is open (called “first curtain”), the open shutter will continue to allow the scene to be recorded until the end of the exposure. Let’s say you have moving cars in the night scene behind your subjects. The entire scene will be lit with your flash, and then their motion will be recorded as (an available light) streak out in FRONT of the frozen part of the image. This looks strange, as if the cars are moving backwards. Using Second Curtain Sync, the shutter will open, exposing the moving cars as a blur and just before the shutter closes, the flash will fire, “freezing” the cars, leaving the blur BEHIND the cars. Strangely, second curtain sync is disabled when you’re using wireless (multiple) flashes (sigh!)

Each is capable of operating beeplessly (a Custom Function on the Canon or a Parameter on the Metz has to be set). You can change the default distance scale from meters to feet on the Canon and the Metz (another Custom Function or Parameter); The Sigma shows both at once by using smaller numbers in the display.

The Metz also has a secondary, fixed flash tube designed for use as a fill light. To me, this isn’t a very useful feature. Each of the flashes has a pop-up card to act as a fill light when the flash head is swiveled towards a wall or ceiling. The Metz is the only one of these flashes to have a battery level indicator. I’d like to see this on everything that’s battery powered.

Why use an ETTL flash?

If I simply wanted a pretty powerful flash to stick on my camera (or at the end of an off-camera cord), I might be willing to settle for the old Vivitar 283 I used years ago with film. It has a light sensor on the front of the flash which “reads” the amount of light bouncing back from the subject and shuts the flash off when it figures there’s enough light. I was even able to stick that light sensor on my camera’s hot shoe and run a cord from it to the flash which I could position anywhere (within reach of the cord). That was pretty miraculous in its day, but I had to change a setting on the flash each time I decided to change f-stops. That got to be kind of a pain. (Vivitar has updated their 283 to include TTL, but it wasn’t among the flashes I tested.)

Today’s modern flashes are controlled by the camera instead of that removable sensor. Using Through The Lens (TTL) technologies, the camera is able to “read” the amount of light reaching the camera’s sensor (the “film”) and shut off the flash when the exposure is sufficient. Since it reads right off the camera’s sensor (the light has already travelled through the lens), I can change f-stops between shots and this automation still works. Canon calls their latest TTL technology Evaluative Through The Lens (ETTL). The current version is ETTL II.

For available light photos in semi-automatic modes, my camera has an Exposure Compensation dial. If I think the picture should be darker than my LCD shows, I can darken it using this dial, or lighten it if I want.

For flash photos, the camera has a similar Flash Compensation dial. To increase or decrease the amount of flash output, I can adjust that dial. These adjustments will vary depending upon your camera. Your camera manual or a Magic Lantern Guide for your camera model will show you how to operate Exposure Compensation and Flash Compensation. Each of the tested flashes is compatible with Canon’s Flash Compensation feature.

The most important things I want in a flash

For me, the most important aspects of a hot shoe flash are Guide Number and recycle time. I use my hot shoe flashes off-camera whenever possible, using Canon’s ETTL flash metering and I use PocketWizard radio remotes, too, so my hot shoe flashes have to communicate with each other in Canon’s wireless language. In this article I’ll compare each of these features on the three flashes.

I’m really comparing five flashes

I use Canon cameras and I have a couple of Canon 580EX flash units, the predecessors of the current 580EX II flash. I also have a couple of 430EX flashes which are the earlier version of today’s 430EX II flash. Since I’m comparing three of the flashes currently on the market, I also compared them to my older equipment. It stands to reason that today’s 430EX II flash will be at least a slight improvement over the models which I own, so you’re actually getting a comparison of four current ETTL flashes which will work with Canon cameras.

I don’t like paying more money than I have to for a product, and seeing that there were a couple of competitors to Canon’s 580EX II flash, I thought I’d put them through their paces. If I could find a flash nearly as good as my 580EX for a hundred dollars less, I’d like to know about it and pass the information along to you. Likewise, this comparison could prevent you or me from having to return an incompatible product if we’re better informed about them.

Guide Number made simple

A few words about Guide Number (GN): That’s a measure of the amount of light a hot shoe flash is putting out (at full manual power). A Guide Number is ten times the f-stop you’d use to get a good exposure of a subject ten feet from the flash. The assumption is that the person testing the GN is using ISO 100. If he’s using ISO 200, of course this will double the GN; this would give a deceptively high GN.

Modern flash units have Fresnel (pronounced “Fray-nel”) lenses on the front of them which focus the beam of light. If your zoom lens is set at 100mm, for instance, the flash on the camera will automatically focus its light in a more narrow beam than when your lens is set for 50mm. That prevents wasting light (battery power) on an area not “seen” by the lens. When comparing flash GN’s, therefore, we have to be sure each flash is set at the same zoom setting when testing the GN. Since each of the flashes were capable of a 105mm setting, I compared them all at this setting.

A note about that flash zoom in relation to the camera you’re using: In ETTL mode, Canon’s 580EXII detects whether your camera has a “crop sensor” or a full sensor, so the area covered by the flash is appropriate to the field of view of that lens’ zoom on whatever Canon camera it’s on. The Metz can be adjusted for use on crop sensor cameras, but you can’t just put it on another camera and expect it to “know.” Since the Sigma automatically adjusted to light the entire scene as I zoomed (as the other two did) with my full-sensor Canon 5D Mk II, and has it no provision for adjusting to a camera with a smaller sensor, I can only conclude that it’s wasting light (battery power) by lighting an unnecessarily wide area when used on a crop-sensor camera in ETTL mode. Guide Number tests are done in Manual mode at a specific zoom setting, however, to be sure each flash is putting out its maximum amount of light.

Here’s how they compared in light output

I set each flash to Manual mode and set the flash’s zoom to 105mm. I placed my Sekonic L-308S flash meter exactly ten feet from the flash (incident reading) and fired the flash. I read what the flash meter said and then moved the decimal one place to the right to get the guide number of each flash.

Flash              GN Tested                  Mfr. GN
580EXII              116                              190
Metz                     110                             192
Sigma                   80                              174
580EX                114
430EX                  80

In my tests the flashes each had less than half the output advertised by the manufacturers. Their conditions must’ve been quite different from mine. Nonetheless, the results show a valid comparison between the tested flashes in the same situation. These tests showed me that the 580EX, 580EXII and the Metz are twice as powerful as the Sigma or the 430EX. Incidentally the more powerful flashes cost about twice the price of the lower powered flashes. Another example of getting what you pay for.

We have to be careful not to think in simple math terms when comparing guide numbers. Remember, they’re based on f-stops! At a glance you might think that a flash with a GN of 110 is only about a third more powerful than another flash which has a GN of 80. (80 x 1.33 = 106.4). What’s the difference between the light at f/11 and f/8? Right! F/11 lets in HALF the amount of light as f/8. Therefore a flash with a GN of 110 is exactly TWICE as powerful (a full “stop”) as one with a GN of 80, not just a third more powerful. Put another way, a flash with a GN of 110 will light a subject who is twice as far away as a subject properly lit with a flash with a GN of 80.

A more powerful flash gives me a broader choice of apertures and is able to light more distant subjects. This can often mean the difference between getting the shot and missing it.

The importance of recycle time

The best photo gear is that which gets in your way the least. We’re capturing fleeting moments in time and if a flash hasn’t recovered from its last burst, it’s not ready for use. No flash recovers instantaneously; that delay is called recycle time. I try to capture spontaneity, even in posed photos, but if a subject has to wait for my flash to recycle, the spontaneity of their expression is lost. When I’m watching for that perfect candid moment, sometimes I see something even better in my viewfinder almost immediately after I’ve taken that shot. My flash has to be ready for those moments.

How their recycle time compared

To test recycle time I used a freshly charged set of Sanyo Eneloop batteries in each flash. With the flash in Manual mode, I pressed the flash test button and a stopwatch button at the same moment and hit the stopwatch’s Stop button when the flash’s Ready light came on. I did this repeatedly with each flash to eliminate as much error as I could.

580EXII                3.0 seconds
580EX                  3.4 seconds
430EX                  2.2 seconds
Metz                      4.5 seconds
Sigma                  4.5 seconds

Rechargeable AA batteries v. alkalines

A lot of tests have been done by various people and they all show that the nickel metal hydride (NiMh) batteries used in our test have about half the recycle time of Alkaline batteries. NiMh batteries continue to have this fast recycle time until they’re exhausted, unlike alkalines which take longer and longer to recycle as they get weaker. Most NiMh batteries gradually lose power even when they’re not being used, but using a new hybrid technology, Sanyo Eneloop batteries don’t have this flaw. This gives me the best of alkalines and the best of NiMh batteries.

You don’t have to be a tree-hugger to use Eneloops

Of course recyclable batteries are more kind to the environment than the ones you use once and then put in the landfill, but there are also selfish reasons to use these NiMh batteries instead of alkalines. The initial purchase price of a set of four Sanyo Eneloop AA’s is about twice the price of four Duracells I can buy at my local grocery store. Then there’s the one time cost of a 4-battery charger and shipping, but by the time I’ve charged that set of four Eneloops six times, I’ve spent less than if I’d bought six sets of alkalines and from there on it’s like putting money in my pocket every time I charge them! Eneloops are rated at 1000 charges (I didn’t test this). Unlike other NiMh batteries, Sanyo Eneloop batteries are very slow to self-discharge, so the experience of using them is more like using alkalines except they recycle so much faster. Frankly, I’d pay more money just to get batteries which recycle this fast!

External battery packs

As I mentioned, recycle time is a very important factor. An external battery pack gives a faster flow of the same power to your flash. It can be a gamble, though, because using an external battery pack not made by the flash’s manufacturer will void your flash’s warranty. For that reason, I’ve stuck with Canon’s CP-E4 battery pack. It’s simply a sturdy plastic holder for eight AA batteries in a convenient nylon pack. When using eight Eneloop batteries in the Canon external pack, the recycle time was about three times as fast: 1.1 seconds!

Although you can jury rig many kinds of batteries into a DIY external battery pack, Sigma doesn’t offer an external pack (nor is there a receptacle for attaching one). Metz offers a battery pack which I didn’t test, but it costs more thatn the Metz flash itself, doesn’t come with a cord and doesn’t take the readily available AA batteries. Strangely, Canon’s 430EX II doesn’t have a receptacle for the CP-E4. Canon, you’re missing a good bet here! Maybe on the next version.

I have a couple of CP-E4 battery packs and I find it convenient to keep a charged set of eight Eneloops in a spare CPM-E4 magazine ready to replace a dead set of batteries. When the discharged battery magazine is emptied, it’s easily filled with recharged batteries and at the ready again for when the other pack’s batteries are discharged. I have a designated pocket in my camera bag for discharged batteries so they can’t be confused for charged ones.

Single flash attached to the camera

I prefer to work with my flash(es) off camera anytime I can, but there are many situations where you’re working alone and can’t set up off-camera flashes. When I’m in a room with white walls and ceiling, I put a Stoffen Omni-Bounce diffuser on my flash and swivel/tilt my flash to bounce light off a nearby surface. There’s an Omni-Bounce available for the 580EXII, another for the Metz and one for the Sigma I tested.

I take the Omni-Bounce off the flash if I’m not near reflective surfaces, though, because it won’t make the light source larger (as a softbox will), it’ll only reduce the output of light. In those no-bounce, by myself, on the move situations, I have to use direct flash. If my flash is in my hot shoe, I’ll get a very flat photo with no feeling of the depths of the shapes I’m photographing. That’s the nature of on-camera flash. When I turn the camera into a vertical, “portrait” orientation, though, the shadows of my subjects go sideways. Those dark shadows are very distracting, and sometimes the shadow of one subject can fall on another subject. The solution to this is a flash flip bracket. I have a few of these, and my favorite is the Stroboframe VH 2000 Stroboflip Bracket. It’s very compact, placing the flash atop the lens rather than over the flash bracket. To use any bracket, you’ll need a Canon Off-Camera Cord. With the bracket, you can just flip the flash into position over the lens, regardless of whether the camera is vertical or horizontal and the shadows will fall down behind your subjects and be hidden. You can even hook a couple of these cords together and put the flash on a light stand some distance from the camera.

For the photo above, I used a PocketWizard radio remote, but it could have been done with a couple of off-camera cords, or shot manually using a long sync cord. There’s a 580EX in a Lastolite EZYBOX Softbox just out of sight in the upper left corner. It’s the main light on the subject’s face. I used ETTL to control the flash output with the camera on Aperture Priority. The sun is acting as both hair/kicker light and background light. Below you can see how poorly the picture would’ve turned out without that flash!

Wireless multiple flashes

When you take a flash off the camera and put it above or to the side of your subject, it shows the textures and shapes of your subject by the shadows which are cast. This gives your subject a much more 3-D effect. You can do this by simply running a wire from the camera to a remote hot shoe, but wires are inconvenient and can pose a safety hazard, so I prefer a wireless connection to a remote flash.

Any flash which you can somehow hook up with a wire or an optical slave unit can be used as a Manual off-camera slave flash. This is how studio flashes work. You hook the various flashes to the camera and you manually adjust the output of each flash to your liking. Each time you want to increase or decrease the output of one of your off-camera flashes, you have to walk over to it and make the adjustment (hopefully the slave flash has adjustable output!).

Higher end Canon and Nikon flashes will each communicate wirelessly with their own brand of flash units off-camera. I can have a 580EXII on my camera (the A group) and another on a light stand (the B group) and adjust the ETTL light ratio between the two flashes (the groups they’re in) directly from the on-camera flash. Then I can walk around and shoot ETTL and maintain that ratio of main light to fill light (or change it as desired with by turning a thumb wheel on the back of the camera’s flash), even if I get closer to my subject. I don’t have to touch the Slave flash(es) – I can adjust them from the flash on the camera. Canon also offers a non-flash Master unit, the ST-E2 transmitter. I very rarely want a flash in my camera’s hot shoe, so this allows me to control two or three groups of flashes directly from the Master unit in my hotshoe. An important part of my testing these flashes was to determine how well they communicated with the Canon flashes.

For my test series, I put each of the test flashes (in turn) on a light stand in Slave mode, adjusted to be in the B group, off to the left of a folded white card I’d prepared. The test flash was wirelessly controlled by a Canon 580EX which was the Master on the camera. By adjusting the flash ratio on the Master flash on the camera, I should be able to achieve anything from the flat light of the on-camera Master to lighting dominated by the brighter Slave flash at the left.

Primarily on-camera flash                   Primarily Slave at camera left

As you can see by the pairs of photos above, each of the Slave flashes was able to fire in response to the signal from the Master flash, but the Canon achieved a far better ratio control, yielding the most and the least contrast between the sides of the test card. If you’re doing wireless multiple flash, this puts the Canon 580EXII at the top of the list.

I also did this test in reverse, using the non-Canon brands as a Master (A group) flash to control the other flashes as Slave (B group) flashes. Both the Metz and the Sigma were able to fire the slave flashes, but I wasn’t able to control flash ratios with either of them as Masters. This means that if you want to control ratios to any extent, these two flashes have to be Slaves, not Masters. The 480EX and 480EXII will also only work as Slaves, not as Masters.

The limitations of line of sight wireless slaves

Canon’s wireless flash communication is only line of sight, though, regardless of the brand of the flash unit. When I put a slave flash in an umbrella behind me for fill, for instance, it can’t “see” my on-camera master flash, so it doesn’t fire. I’ve found there are many situations where this line of sight communication breaks down, specifically when using softboxes.

In a white room, “line of sight,” is pretty generous because the light bounces around the room, but in a non-reflective space or outdoors, “line of sight” has to be taken literally.

The PocketWizard MiniTT1 and FlexTT5

PocketWizard’s latest radio units, the ControlTL system, are just incredible. I can understand how a radio transmitter can convey a signal given to it through a hot shoe, but I’m completely baffled to explain how, when I put a 580EXII (or the flash-less Canon ST-E2) on TOP of that transmitter, it can tell a slave flash what adjustments I’ve made! It’s the closest thing I’ve ever seen to magic.

Anyway, that’s how it works, and since they’re radio waves (not the light waves which operate the Canon system), the slave flashes don’t have to be able to “see” the master flash on the camera! This makes it perfect for me, since I use softboxes and bare flashes well out of the line of sight of my on-camera flash. I’ve even written another article here about how I use my RayFlash ringlight with these PocketWizards.

The system consists of a FlexTT5 transceiver under each of my slave flashes (they have a hot shoe atop each unit and a flash foot underneath) and either another FlexTT5 or a MiniTT1 transmitter in my camera’s hot shoe. I can have all of my flashes off camera if I want. I can also put a 580EXII or ST-E2 atop the transmitter on the camera and tell two groups of flashes how much light I want from them proportionately, without ever touching any of the slaved flashes.

For the portrait above, I used two 580EX flashes and I put each one on a FlexTT5. I put one of these units in a small softbox above and behind her head as a hair light and I put the other in a larger softbox about parallel to her ear, camera left. The room we were in was lit by incandescant light bulbs, so I put a CTO gel filter on each of the flashes so the color temperature would more closely match the light coming from those bulbs. Beyond the subject, camera right, sky light was coming in a window, acting as a “kicker” light. I could’ve put a sheet of gel material over the window, but I didn’t mind the blue tint of that light as it skimmed across her cheek.

I tested all three flashes with the PocketWizards and the results were exactly the same as if I’d been using Canon’s line of sight system, except the Slave flash didn’t have to be on a line of sight with the Master flash (or ST-E2).

Using the 430EXII as a slave to the 580EXII

As I mentioned, the 430EXII can’t be a Master. In any situation I can think of, I’d want my off-camera flash to be more powerful than my on-camera flash. The off-camera flash is the main light and the on-camera flash is only to put in enough light to prevent my losing detail in the shadows, right? The problem with having the 430EXII as the main light is that it’s not as powerful as the Master (fill) light on the camera, so from the start you’re telling the 580EXII not to put out as much light as it’s capable of. A far better solution is to have a second 580EXII as your slave as well as your main light. Where the 430EXII excels off-camera is if it’s bare and the 580EXII is also off camera, but in a softbox. This makes the two flashes of more equal output. The main 580EXII light can be very soft and the 430EXII can act as a hair light or a kicker light, coming from beyond your subject. For fill light in this situation, I can use available light or my other 580EXII also in a softbox, umbrella or ring flash on the lens’ axis. (You CAN use the 430EX as an on-camera Master with the PocketWizard system, but it has no provision for varying flash ratios.)

Using this gear under pressure, alone

Last year I was assigned to photograph each of the 13 employees of the Rutherford Hill Winery tasting room in 90 minutes (before they opened for the day). The tasting room manager specified she did not want the portaits to look like “school pictures” with each person against the same background. I’d have to light each person separately in a different area in the room. That’s less than seven minutes per portrait sitting.

Naturally, I prefer to work at a much slower pace. I like to have time to pay attention to all of the details in a portrait, including taking a few moments to chat with the subject so they can relax and enjoy the sitting. I’m employed by that company, though, and don’t always get to schedule things my way. Who does?

I put two 580EX’s on FlexTT5’s in softboxes on lightstands, and put a MiniTT1 on my camera with an ST- E2 on top of that. This setup enabled me to quickly move the lightstands around for a change of background (and lighting) for each shot. I adjusted the light ratio of main light to fill light using the ST-E2 on the MiniTT1 on the camera. External battery packs on each flash recycled them in just over a second. If I’d been setting the output of the flashes manually, I wouldn’t have been able to do even half those portraits within the alloted time. Multiple, wireless ETTL flashes saved the day!

The portraits don’t look like flash pictures, and I was able to achieve near studio-quality lighting on each subject.

Conclusions

I didn’t start these tests to prove that the Canon 580EXII was the best flash using any of my criteria. In fact, I was hoping that (at half the price) the Sigma would be a worthy substitute for the Canon. Either the Metz or the Sigma would make a fine on-camera flash and you could use it off-camera as a Manual mode slave, but in looking for a slave flash on which I can control light ratios wirelessly, I have to stick with the Canon 580EXII. It outdid the Metz and the Sigma in light output (GN) and recycle time and it’s compatible with a lightweight external battery pack which holds commonly available AA batteries. Since Canon invented their wireless flash technology, it’s not surprising that (so far) no other brand of flash “speaks” this language as well. The 580EXII provided the best flash ratio control and it does so with a convenient wheel on the back of the flash. I find that much easier to control than a menu with up/down arrows.

My thanks to B&H Photo-Video for loaning the Photozo the three flashes for this review.
Canon 580EX II
Metz mecablitz 58 AF-1
Sigma EF-530 DG Super

Photos copyright Bruce Philpott and Terlato Wine Group

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