average plant [deleted] 6:46pm, 7 January 2010
After playing with things last night and doing a little more research this is what I have found as the main differences between the flash systems.

Full TTL
In a full TTL situation the two systems are very different. With Nikon you control the flash exposure compensation of each flash group independently. You have up to four groups that you can control if you include the on-camera flash (A, B, C, on-camera). You can set the ratios between any of the four groups by changing the compensation on each separately such as A = 0.0, B = -1.0, C = -2.0 (3:2:1).

With Canon you control the overall flash exposure and then the ratio between the A/B groups. The C group is intended to be used for background lighting and it is always ignored in the A/B exposure compensation. This means that if you have it hitting anything that A/B hit you will probably be over exposed by the C group. Also the on camera flash gets put in group A by default, this has confused more than a few people.

Differences
Canon you are locked into only being able to do a ratio between A and B, and C is really designed for just background lighting. Nikon gives you much more flexibility in this regard (and more groups) but you would need to change two settings (A comp, B comp) to change the ratio from A to B whereas on Canon you just spin the dial.

Mixed TTL/Manual
Nikon's CLS system lets you set each group to any of the flash modes, for instance put group A in TTL, and group B in manual. The most common usage scenario for this would be to use manual flash to light a stationary background object, and TTL for the moving subject. If you want you can even use the repeating flash (stroboscopic mode) wirelessly and mix it in, however, the pulse rate and duration for the strobe has to be the same for all groups in that mode.

With Canon the nearest you can get is to use group C for the background. This group fires under ETTL independently of the A:B ratio, however since it’s ETTL it may change slightly between shots.

Full Manual
With full manual control both systems just act as wireless commanders that tell the flashes how much power and sync the firing. Neither system behaves much differently in this regard.

Other differences
There are a couple of other small things that arguably swing in Nikon’s favor. The most obvious one is the ability to use the pop-up flash as a commander on many models.

The Canon wireless commander (ST-E2) can only control A, B, or A:B combination. If you want the C group you need to use a 550EX, 580EX or 580EX II. I have also heard that it's range is about half of the flashes as commanders. The Nikon wireless commander (SU-800) has full control capabilities and seems to have excellent distance in my experience.

Another plus for Nikon could be the simplicity that all models of flash that are CLS compatible behave the same and have identical abilities since the introduction of iTTL. I am always confused when Canon people are explaining the different versions of flashes and how some can do some things and others can't. For instances, the ability to do A:B ratio lighting seems dependent on the camera body and not the flashes themselves.

Flash sealing seems different between Nikon and Canon as well. I seem to recall being told that the 580 EX and 580 EX II both have sealed bodies while Nikon only has the new SB-900 that is fully sealed. That said, I have used SB-800s frequently in light rain with no issue but this could maybe be a bigger deal for people doing sports or journalism in a downpour.

Metering of the flashes seems different when using the flashes wirelessly. Canon lets you choose evaluative metering but it seems to be more center weighted. I found notes that Nikon seems to still be able to use any of the three metering modes (spot, center weighted, matrix).

Again, I don't use the Canon system and have only worked with others using it, so if I have things incorrect for either system please leave a comment to let us know.

Here are some sites I used for reference:
photonotes.org/articles/eos-flash/index3.html
www.timothyarmes.com/blog/2009/03/canon-vs-nikon-flash-sy...
photonotes.org/articles/eos-flash/
njl-photolog PRO 8 years ago
Full TTL
The C group is intended to be used for background lighting and it is always ignored in the A/B exposure compensation. This means that if you have it hitting anything that A/B hit you will probably be over exposed by the C group.


No probably about it, it will be over-exposed by 1 stop. I tried this and can confirm that this is the case.

Also the on camera flash gets put in group A by default, this has confused more than a few people.

This is due to the odd Canon manual writing style that I refer to as "learning via telepathic osmosis from the Canon engineers". :-S
Canon manuals are terse almost to the point of being beyond comprehension. Having said this I have downloaded and read a couple of Nikon manuals and unfortunately I didn't consider them to be that much better.


Full Manual
With full manual control both systems just act as wireless commanders that tell the flashes how much power and sync the firing. Neither system behaves much differently in this regard.


This is my understanding of how Canon Speedlites work, but I've not had the opportunity to test and verify this. As I mentioned last night the 420EX Speedlites are an oddity as they can only be used on-camera or in full E-TTL. If you set the transmitter to manual they will fire once and then lock-up until they are turned off and back on again.

Other Differences
For instances, the ability to do A:B ratio lighting seems dependent on the camera body and not the flashes themselves.


I think you are referring to what Canon calls Type-A and Type-B camera bodies. Type-B cameras are the film SLR cameras that appear to have been designed & manufacturer before 1995, but support TTL.

For example, the Canon EOS 650 (wikipedia) [1987 to 1991] is a Type-B camera.

To my knowledge ALL Canon DSLR cameras support the flash ratio A:B system and full E-TTL II.

Just to clarify Canon has three flash metering systems, E-TTL II, E-TTL and TTL (from the Canon 580EX manual):
E-TTL II : evaluative flash metering with pre-flash reading & lens distance information
E-TTL: Evaluative flash metering with pre-flash reading
TTL: off-the-film metering for real-time flash metering
average plant [deleted] Posted 8 years ago. Edited by average plant (member) 8 years ago
Niel I think you are right most modern digital SLRs seem to support the ratio mode. Here is the list I found online for film and digital:

Type A bodies
Support for E-TTL flash, FEL and FP mode:

EOS Elan II(E), EOS 50(E)/55
EOS D2000, D6000 (digital)
EOS IX, IX 7, IX Lite, IX 50 (APS)
EOS Rebel G/500N/New EOS Kiss, Rebel G II
EOS Rebel 2000/EOS 300/Kiss III, Kiss IIIL
EOS 300V/Rebel Ti/Kiss 5
EOS 3000N/Rebel XS N/EOS 66
EOS 3000V/Rebel K2/Kiss Lite
EOS EOS 300X/Rebel T2/EOS Kiss 7 (no TTL support)

As above plus support for wireless E-TTL flash ratios and modelling flash:

EOS 3
EOS Elan 7(E)/EOS 30/33/7
EOS 1V
EOS D30, D60, 10D (digital; no TTL support)
EOS 1D, 1Ds (digital; no TTL support)
EOS 300D/Digital Rebel/Kiss Digital (digital; no TTL support)

And the support for E-TTL vs E-TTL II is definitely a camera body thing just like D-TTL vs i-TTL was for Nikon. There is way more information about all the little details in my handout from last night too.
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ShutterCraze (NUEL) Posted 8 years ago. Edited by ShutterCraze (NUEL) (admin) 8 years ago
@NXTFoto said: "There are a couple of other small things that arguably swing in Nikon’s favor. The most obvious one is the ability to use the pop-up flash as a commander on many models."

From my new Canon 7D user's manual page 119: "The camera's built-in flash can work as a master unit with Canon Speedlites having a wireless slave feature and wirelessly trigger the Speedlite to fire."

Of course hardly any reason to sway back people to Canon. Funny thing is I read way more technical manuals at work for installing and servicing my $2- $3 million MRI's at the hospital and none make my head spin more than trying to read my Canon manuals. I'm dead serious! Going full manual and using remote triggers just seems more intuitive for my brain and less work with consistent results. Thanks for the good info though guys. Maybe someday I'll give Wireless TTL a go.
average plant [deleted] 8 years ago
Wait... ShutterCraze you went back to a crop sensor? No, seriously, it is good to see Canon is now doing the same in the most recent camera with the built in commander.
Maybe this got covered above but I just found out that on my Canon 7D if you switch to Manual Flash mode on the camera menu but leave the flashes on E-TTL, you can control the A,B & C groups independently with the usual manual flash power settings of 1/1 - 1/128 from the camera. Just shot a test and, sure enough, it worked with camera shutter/aperture in full manual, as well.

Of course, you still have a small on-camera flash pop and have to be within the specified range - and mostly line-of-site - but for smaller home/studio work this could save me a lot of walkin' back & forth to my flashes - especially when I have something up on a boom.

Did everyone know this already??
Aaron Audio 8 years ago
With that being the case, you should be able to disable the speed light on top of the camera and still have it control the others.
njl-photolog PRO 8 years ago
Thanks for verifying that point. I suspected that this was the case, but I hadn't tried it myself.

I can disable the 580EX flash, though I have noticed that I have to flag it with the "black form thingie" to prevent a shadow being cast on the background. Even if the 580EX is told not to fire it still flashes, either as part of the pre-flashes or to transmit commands to the remote flashes. Either way you can still get a shadow being cast because of it. Unless you can use a long TTL extension cord to get it off the camera, but that kind of defeats the wireless concept a little. ;-)
Yeah, but you don't have to have the 580 as a master on the camera - just the built-in pop-up flash does the trick as the master and then all your speedlites operate as slaves in the different groups. It's suh-weet. Gonna try it this weekend on a shoot (and have my cybersyncs ready just in case!).
njl-photolog PRO 8 years ago
Sorry, I should have clarified that neither the Canon 1D Mk III (which doesn't have a pop-up flash :-( ), nor the Canon 20D, both of which I use, can control remote Speedlites. That's why I need to use the 580EX.

The Canon 7D is the unique exception in the Canon line-up. Yes, it is sweet. Have fun shooting on the weekend. ;-)
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