First dives with Ike eTTL housing - my Review

I think my little test, which is very easy to reproduce btw., disproves the non-spot metering. If you call it center weight or SPOT. What't the difference? 8,5% instead of 2,4%. Not noticeable in UW situations.

Possible reason: I don't know how much light is send during the preflash. When it comes to wideangle shots to much light might be absorbed by the water. This could be the case when the preflash is very weak which could be necassary in order to match E-TTL system's criteria.

Just a loud guess as E-TTL works reliable for similar lightning scenarios topside.

 

By the way, manual strobe control rocks! :-)

 

Julian

Sounds logical, however if you take a picture with the lens cap on, the flash gives a full dump, so if all the preflash was absorbed by the water - the camera would over-expose rather than under-expose. Right??

But then I did have the diffusers on so if that was the problem it may be partially aleaved by taking them off next time. Will try....

Also, wouldnt the preflash be equally diffused by the water in macro?? You are looking at a smaller portion of the area, but the flash heads arent zooming so the flash is no stronger.

By the way. Yes manual strobe control works. But if eTTL worked, that would rock....

RE: macro

Well if all the macros are over exposed by 1/2 a stop, that is very easy to deal with: fec= -1/2 I can live with that as long as it is consistant.

RE: Sync cord flood

I dont know what a flood would do, but it seems like to me that a flood in the cord would have to effect manual powers set on the eTTL converter just as much as eTTL signals and would effect macro as well as wide angle. But hey, if next week it majically starts working this may be the best explination.

I will do a pool test sometime - though I could do that in the ocean as well...

Thanks for sharing your experiences William. I'm baffled. The macros look over exposed to me by about 1/2 a stop. And the wide angle is very wrong.  

 

Like Peter I have used Ikelite TTL with the Olympus and found it worked very well.  

 

The land shot looks perfect. one difference might be a minor flood in the cable/synch sockets that could be shorting out the strobe connections when it is underwater? Very small - so you wouldn't notice it - and it would dry after the dive - so the strobe would work on land.  

 

What I suggest is to do a TTL test - shoot a range of test shots in the pool of a macro subject with different aperures (all at a fast shutter speed - so that the lighting isl flash dominated). If TTL is working they will have the same exposure. Here is an old example I did more than 2 years ago now on the D100:

 

The performance there might tell us a bit more about what is going on.

 

Alex

William, another problem might be the settings you used for your wide angle pics i.e. "both shots 1/40th sec, f/7.1, ISO 100"

 

With that much natural light exposure in shallow, clear water, the camera may not have asked for much help from the strobes.

 

Thus, my suggestion would be to shoot manual with 1/100th sec. and f/9 to f/11 if you want more light from your strobes for shallow  clear water shots.

That picture was in 70ft of water so it wasnt that shallow. I dont think that the exposures look like the background is much too light - I underexposed it by 1 stop acording the the incamera meter. But yes I did try larger aperatures and shorter shutter speeds but that didnt help.

William- Did you ever resolve this issue and work out why TTL was working differently underwater than on land?

Lanier

To be honest, I'm not sure if I ever figured out what was going on that day.

I have found that the eTTL system is very sensitive to water/moisture.

So far, on every multi day dive trip I've gone on, by the end of 2nd day the eTTL system will Crash.

It took me a while to figure out what was going on but here is what I found out.

• I'm not sure what part of the rig is getting wet.
  It causes a full dump in eTTL mode. No matter how much FEC was dialed in.
  After the first shot is fired, the eTTL module crashes. You cannot change FEC or put it into manual mode.
  You must turn off strobes to reboot system.
  Problem will continue if you leave it in eTTL mode, but if you put it into Manual mode (before you take another picture), everything will work fine in Manual.
  The system can be revived by disassembling the rig and allowing it to air out (with all caps left off) in a dry location overnight.
  

But this is not what was happening that dive, I was getting under exposure, the module didnt crash, and the next dive it worked fine with no time to dry out.

I think that eTTL just doesnt work well underwater when used for fill. I have had sucess with WA eTTL on only 1 dive. I was in deeper water (80ft).

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