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Mysterious Inon Z-240 behavior


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#1 Bentoni

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Posted 16 April 2012 - 02:16 PM

I have two Inon Z-240s (type 2) that are frustrating me. They are both being triggered optically from a Sea&Sea MDX-D700 housing. I have very carefully set the camera and its built-in strobe, and all the settings on the Inons according to their respective factory owners manuals for TTL operation. When I test the system topside the resulting images are perfectly exposed, consistent, and predictable. As soon as I get into the water, the images are inconsistent, and mostly underexposed by the flash. For a long time I thought I was just not being careful enough with my light placement, or not getting close enough. On my latest trip I did some controlled experimentation and got mostly the same disappointing results. Meanwhile, my wife's ultra-simple P&S camera w/ off-camera Intova strobe was delivering colorful correct exposures. My shots should look at least as good as hers. I like to think I understand photography very well, and underwater photography reasonably well, and have addressed all the obvious oversights which could produce these results. But still 90% of my shots are just blue. I am desperate for some help, or advice.
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#2 bvanant

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Posted 16 April 2012 - 03:08 PM

I have two Inon Z-240s (type 2) that are frustrating me. They are both being triggered optically from a Sea&Sea MDX-D700 housing. I have very carefully set the camera and its built-in strobe, and all the settings on the Inons according to their respective factory owners manuals for TTL operation. When I test the system topside the resulting images are perfectly exposed, consistent, and predictable. As soon as I get into the water, the images are inconsistent, and mostly underexposed by the flash. For a long time I thought I was just not being careful enough with my light placement, or not getting close enough. On my latest trip I did some controlled experimentation and got mostly the same disappointing results. Meanwhile, my wife's ultra-simple P&S camera w/ off-camera Intova strobe was delivering colorful correct exposures. My shots should look at least as good as hers. I like to think I understand photography very well, and underwater photography reasonably well, and have addressed all the obvious oversights which could produce these results. But still 90% of my shots are just blue. I am desperate for some help, or advice.

One quick question (or a few). Next time in the water see if you can get reliable exposures from a single strobe. Also (I don't know about Nikon) but be sure that the strobe is not being used to help with focus. On Canons at least that can lead to underexposed pictures since the strobe needs to recharge and doesn't often have time. The reason that i suggest trying one strobe is that sometimes if the strobes are pointed at each other the TTL pulses can lead to the strobes firing inappropriately. Also what happens if you try the strobes in manual mode.
Bill

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#3 diver dave1

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Posted 16 April 2012 - 07:05 PM

You do not mention the lens(lenses) being used. Do you have the same problem with macro photo's as with wide angle?
Perhaps if you posted some photo's with settings and lens used, someone with more knowledge could provide some clues or suggestions.
One simple above water test is to take a photo in a dark room with the setup facing a mirror. If TTL is working, you should see both strobes lit in the photo.
Whenever I get something new or planning a trip after a long time between dives, I test it all in a local pool until I get results that are satisfactory. This at least allows me to do some of the learning before I go on a trip. Whatever you learn at this site, you might consider some pool testing so you do not have to learn it on a trip.

I also have type 2 Z240's and use a Nikon camera (D90). When I am diving, sometimes my hand/fingers bump the button for pre-flash on the strobe. Then I have a degree of uncertainty as to which strobe is set correctly since they are now different...button in or out? To make certain I have it set correctly, I set both buttons one way, take a photo and see the results, then move both buttons the other way and test again. I get underexposure with the wrong setting. I found this test to work much better underwater than on land as the differences on land were not so great.
I am no expert...just trying to provide some food for thought.

dave

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