2nd try: overexposure problem w TTL (Olympus E-M1)

I posted this question yesterday, but the photos didn't come thru. Here's a second try.

On my first dive trip with the Olympus E-M1 and the Nauticam housing, I had a problem using TTL. I think it showed up the most with medium distances using the 60mm macro lens. I was using two YS-01 strobes.

I have some examples of the problem. All of these are shot with the mode dial on manual. The metering was center-weighted.

Here’s a pair of flamingo tongues that were overexposed when shot at 1/320^th and f6.3.

My reaction was to drastically change the f stop, so exposure on the next shot was OK 1/320^th at f 14.0:

Same dive, here’s a toadfish overexposed when shot at 1/320^th and f 8.0:

Again, I stopped the camera down, and the next shot was OK at 1/320^th and f 14.0:

Here’s a shot that had OK exposure at 1/160^th at f 6.3:

But then the very next shot (different subject), is way over-exposed when also shot at 1/160^th at f 6.3:

The same scene is better exposed after drastic changes to the shutter speed and aperture, this time 1/320^th at f13.0:

Any ideas what I was doing wrong? Could I have had the flash setting on “full” rather than “fill”? Would that explain this?

What make/model strobes are you using? If they are Inon this will help explain the correct settings:

http://reefphoto.com/kb.php?id=7

In short for your camera and Inon Z240 strobe(s):

Camera flash set to fill.

Left hand dial on strobe set to sTTL

Right hand dial on strobe set so it is putting up to B

ACC switch enabled (out)

it's two YS-01 strobes.

Have you tried manual flash instead?

Or tried s-TTL low?

it's two YS-01 strobes.

In that case:

Camera flash set to Fill

Set the strobe mode switch to [TTL]

Set the strobe light level control dial to [FULL]

Should do the trick.

There has been some trouble with the EM-1 and getting S&S strobes to work well in STTL. In my hands, I can get it to work for a shot or two then not work. Trying to figure it out without a lot of luck. That being said, something is wrong with the OP photos.

Bill