Z330 FEC problem

Hi Everyone, 

I've just been having a play around with my RX100VA, and 7d, along with my Z330 strobes (via optical connection), and have come across a puzzling problem. 

In STTL mode, no matter what I do, I can't get any FEC control via the EV control knob on the back of the strobe! All exposures come out identical! 

It would seem that in EV comp, the Z330s are cutting or adding output on the preflash pulse as well as the main pulse. So, the camera gets less return from preflash pulse, aims for +-0EV flash compensation (where the camera is set), then compensates for the Z330s diminished output - thereby nullifying the FEC set on the back of the strobe. This is confirmed if I put a sekonic light meter in front of the strobe, and hit the flash exposure lock on the 7d to produce a preflash. The Z330 EV control knob is 100% having an effect on preflash strength. 

I've tried the strobes with both the preflash magnet in and out. No difference. 

Any ideas?! I'm starting to wonder if my strobes have a bug. I've only ever used them in manual mode before now. I know they were from pretty early off the production line. 

Bevan

Gah.... talk about embarrassing. Use quality fiber optic cables - not chunks of cutup toslink for ETTL.

Compensation out of the dial on the Z330 is minimal though. At a stab it appears to be ~1/6 stop per click.

Lesson learned. 

In reality the exposure compensation in STTL mode on all Inon strobes is practically non-existent. I have tested multiple scenarios on Z-240's and Z-330's, also without any FO cables to get in the way of signal transmission, and the result is always the same: no real change in exposure.

You can change flash exposure compensation in your camera settings. Although not all cameras have this option and it would be nice to actually have it working on the strobe. Btw, that's not the only feature that's not working as advertised on Inon strobes. But hey, they work most of the time so it's fine!

Save yourself some trouble and get comfortable using manual strobe power.  TTL is more trouble than it's worth and will end up limiting your creative potential.  It doesn't work well at all for wide angle, and your macro shots will be uniformly bright with less shadow and definition than you might achieve with manual control.

Cheers guys, 

Yep, very much aware of the benefits of manual flash- it is what I usually use. I was simply playing around and came across the above and thought it odd.

Bevan

This is truth, Inon FEC algorithm via Z240 / Z330 right dial switch is effective not for all cases. Synching by pop-up flash, the effect sometimes is small or invisible.

But, if you use any Optoelectronic TTL-Converter for Z240 / Z330 synchronization, you see that Inon FEC (right dial switch) really adjusts +/- lighting. This is because of LED's clear square signal shape, Inon FEC algorithm process it much better than analog flash signal.