Paul C. Buff, Inc. Technical Forum

Technical Support/Luap,
I understand that currently the PowerMC2 doesn't support the ability to allow a PocketWizard Mini/Flex to do TTL-style exposure control on an Einstein via ControlTL channels (i.e. allowing a Canon camera to do TTL-controlled exposures w/Einstein via having the radio shut off the IGBT at quench time).

I'm wondering if the reason for this is a technical limitation or is it something that's just not currently implemented in the PowerMC2 firmware. In other words, is there ever a chance of seeing this feature in the future? This would be a totally kick-ass (i.e. using Einsteins as TTL-controlled strobes) if it were possible.

Thanks as always,
Tim Henrion
Boston, MA

If they can make an einstein look like a big flash to the nikon/canon bodies, maybe. As long as the einstein can do the preflash, my guess is it'd work...

TTL with Einstein or other studio flash isn't practical. I've discussed this at length with Jim Clark (PW) and there are too many technical issues.

Thanks, Luap. I appreciate the insight.

I just recently received my Einstein 640. I shoot with a Nikon D700 and I was experimenting with some flash setups. My setup is as follows; Einstein flash sensor turned off; Using Cyber Commander to trigger the Einstein with sync cord into my D700. I've found if I use the Nikon Flash system to trigger other remote flash units (SB600 and SB700), the iTTL controls the output of my Einstein regardless of how what I've set on the Cyber Commander. If I'm not using the Nikon flash as a commander then the Einstein unit output is what I have set on the Cyber Commander. Is this how it is supposed to work? Thanks for any advice.

It is impossible for Nikon TTL flashes to alter power on an Einstein. There is no method of communication that a camera of any brand can adjust power on any of our lights (some Pocket Wizards would be an exception to a degree, but even then, this would not be the case here).

What happens is the speedlites have a preflash of known amount that the camera uses to determine how much power it will need for the exposure. The camera does not know when a studio light is attached, so it does not take it into consideration. This makes manual and TTL flash difficult at best. There are two results that can come from this miscalculation.

First, if the slave eye is active (this needs to be set in the Commander, not just on the flash head, as it will revert to CC settings), the preflash will trigger the light. The camera sees all of the light the speedlites put out, plus the light from the studio light. The camera thinks all of that light comes from the speedlites, and compensates by telling the speedlites to underexpose. Also, by the time the studio light has to fire again (fractions of a second later), it most likely has not completely recycled, and is therefore putting out less power. This results in a very under exposed image.

Conversely, if the slave eye is in fact locked out, the camera and flashes do the preflash thing, and the camera calculates a "proper" exposure. Then during the exposure, the light form the speedlites fire, plus the light from studio lights fire, resulting in over exposure.

If the studio light is the only light, the camera is not tricked in to any calculations, and the light fires only when it is supposed to at the power it is supposed to.