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


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#1 msilver2

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Posted 25 August 2014 - 06:47 PM

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 1/320th and f6.3.

 

8v1gFhz.jpg

 

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

 

0YLz5pA.jpg

 

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

 

tzsmQdn.jpg

 

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

 

DoTl4qP.jpg

 

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

 

PQIVz4i.jpg

 

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

 

9Qpd1YN.jpg

 

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

 

VGnh5Bk.jpg

 

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

 

 

 

 



#2 Gudge

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Posted 25 August 2014 - 07:12 PM

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)


Canon 7D, Nauticam NA-7D housing, 2 x Inon Z240, 1 x Inon S2000, Tokina 10-17 & 12-24, Sigma 17-70 Macro, Tokina 35 macro, Canon 60 & 100 macro, Tamron 2X & Kenko 1.X Teleconverters.

#3 msilver2

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Posted 25 August 2014 - 08:28 PM

it's two YS-01 strobes.



#4 Aliens

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Posted 25 August 2014 - 08:48 PM

Have you tried manual flash instead?


Or tried s-TTL low?



#5 Gudge

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Posted 25 August 2014 - 09:30 PM

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.


Canon 7D, Nauticam NA-7D housing, 2 x Inon Z240, 1 x Inon S2000, Tokina 10-17 & 12-24, Sigma 17-70 Macro, Tokina 35 macro, Canon 60 & 100 macro, Tamron 2X & Kenko 1.X Teleconverters.

#6 bvanant

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Posted 26 August 2014 - 08:42 AM

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


Edited by bvanant, 26 August 2014 - 08:47 AM.

Bill
Canon 7d, Nauticam, Lots of glass, Olympus OMD-EM5, Nauticam, 60 macro, 45 macro, 8 mm fisheye, Inon, S&S, Athena Strobes plus lots of fiddly bits.
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