Trying to get 6 stops of EV comp in ETTL with the ST-E2

[musicaleCA]

Okay, this is a question for those who have used Canon gear pretty extensively. Hope someone on here might know the answer.

I've been fiddling with using my various pieces of gear to command an off-camera flash unit in ETTL. The important thing here is that I can control the EV comp on the off-camera flash by adjusting controls on-camera (if I put the camera outside a window, I bloody well don't want to have to run outside just to dial the flash up or down, just to run back in, take another shot, and realize I should've dialed in less or more; I'm sure you know what I'm talking about). I've messed with using one of my 580's to command another 580, and quickly figured out that if I left the commander 580 on-camera so that it didn't fire, and set the EV comp there, it would also be applied to the off-camera flash. So far so good, that gives me a wonderful exposure latitude of EV -3 to +3 stops.

But when using the ST-E2, there's no ETTL EV comp on the commander unit itself. A little more futzing and I figured out that I could use the flash exposure comp in my 450D's menu to set the EV comp between -2 and +2 stops. Thing is, that's two stops at the extreme ends that I lose if I need to use the ST-E2 transmitter. When I'm backpacking and running around, I'd much rather use that baby commander unit to trigger off-camera flash over carrying my second 580.

So, here's the question: Does anyone know how to finagle another stop of flash exposure comp in ETTL while using the ST-E2 and setting the comp from the camera's menus? Or do I need to sacrifice one of my other flashes to get that extra bit of control?

 

[JerryPH]

Not a Canon guy, as you know... but if you needed an extra stop, would not raising the ISO do just that for you at the camera end?

 

[musicaleCA]

Er...yes. Yes it would...um...um...trying to sound not silly here...

Well that'd also increase ambient, but I could just speed up the shutter a stop too. Still, it'd be nice to know if I can finagle it or not. Good point though; I'm getting a little caught up in the specifics, but at least I know how to trigger my flashes...lesse...four different ways! Yay!

 

[JerryPH]

I think that the reason Canon placed the limitations in there are the same reasons that Nikon placed similar restrictions in their own CLS setup... the limited power output of the speedlights themselves. Three stops is a heck of a big difference and up against the wall in terms of what these small lights can put out. Especially when you don't have another 580EXII or SB-800 at the far end or the distances that greater flexibility would demand of the system.

 

[musicaleCA]

Well you see, you can get a three stop EV comp in either direction if you dial it in at the flash, just not on the camera. On-camera it's only two. *scratches head*

It's possible that it's just carry-over in the programming, in that the flash EV comp on the 450D was only really intended for the pop-up, given that the target market for Canon's Rebel series is...well it isn't me, that's for sure. :lmao: (I didn't know I'd get so madly into photography as I have when I bought it. If I had known, I would've bought a 50D. >.< )

And thinking on the ISO change, er, the ETTL would just play right along with it and keep the exposure the same. Unless one goes on full manual, adjusting ISO, aperture, or shutter speed won't affect the flash exposure. D'oh!

 

[Big Mike]

I think the three stop (+ & -) range is considered a higher end option. So you need the 580 as a Master or a high end body. With just the ST-E2 and/or a regular body, you are limited to 2 stops.