THE RETEST IN BALI
After South Africa’s failure, I went to Bali with more experience. Average metering was good if the subject is close and the brightest subject filled the majority of the metering zone or frame. I decided to stick with it and use FEC to control the light from the SeaFlash.
Shooting with ETTL
Shooting wide angle at the Liberty wreck, the Seaflash suddenly became another strobe, one that metered and lit subjects beautifully. Setting my Drive Mode to One Shot and FEC to -1/3 - 0, the shots of the coral came out very nicely.
The gorgeously warmish wide beam filled the subjects with a soft edge. Using the diffuser, the beam is even softer and more even but also very wide. With the turbidity of the water not being so good, backscatter was a problem with the diffuser on.
With Average metering, the camera evens out all points of the metering zone to come up with exposure for the strobe. This was a bit problematic with backlit shots where the sun was in big part of the picture. Average metering would choose to underexpose. FEC control of +2/3 to 1 stop was necessary to make up for this metering, pretty much like it was topside. This would require a lot more chimping and take second shots with different FEC settings to get things right.
Switching to Evaluative mode, the tendency to underexpose was less. More accurately, it chose to ignore the strong back lights or any other subjects in the metering zone that it considered “shiny objects” and metered everything else. I decided to stay with
Evaluative and then use FEC at -1/3 or 2/3 to control overexposure for shiny fish.
I found ETTL to be very effective with dynamic and shiny subjects like Trevally, even with strong backlit shots. It overexposes slightly but doesn’t blow out the silvery fish and considers the ambient background. I know I don’t have the ability to switch as fast as the ETTL chip and certainly it works better than my eye, leaving me to concentrate on composure and subject choice. It isn’t perfect though (otherwise, there’d be no need for manual mode!).
When 2 (or more) strobes are used, ETTL doesn’t differentiate metering from each strobe to control exposure at each strobe. Basically, it fires both strobes at the same power. Thus depending on how the subject is composed in the picture, one can get the classic one sided over-exposure problem of the subject. To prevent this, one either shoots one strobe in manual or pull the closer strobe back to compensate.
The Sea Flash is the only strobe that supports 2nd curtain sync for Canon. Just sent the strobe to SL mode and the strobe will fire 2nd curtain so long as the shutter speed is slower than 1/50, otherwise it will just shoot in 1st curtain. It does allow very interesting creative opportunity but my review time was limited so I only tried it on a couple of dives. I’ll include a hyper-exaggerated example to illustrate what is possible:
There was a downside with leaving the 150 in SL mode for 2nd curtain. The slave sensor on the strobe is very sensitive. If someone nearby fires a flash, it would fire as well. That won’t endear you to your fellow photographer or your battery life as it fires to the power setting you leave it at.