I recently bought an Ikalite Ds50, TTL slave with arm and tray kit to use with my Oly c4000z in an Oly housing. I am constantly under exposing my shots. I have tried various solutions including blanking off the diffuser on the housing, increasing the internal strobe power by 1 and facing the slave to the rear but I have the same problem. Does anyone have any step by step suggestions. I am shooting in programme and TTL. As I am going to the Red Sea in July I need help and fairly quickly!
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Exposure
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Can you provide some examples with specifics?
Am I understanding correctly that you are planning to use the DS50, as a secondary strobe and you internal strobe as the primary?
I am not familiar with the oly system, but normally with Ike's DS series strobes, you completley block off the forward firing of the strobe and point the sensor to where the internal strobe is firing. (You want all the internal strobe lighting to be bounced back)
Then, the sensor in your IKE TTL sensor will mimic the internal strobe, fire a prelash and then the full flash.
Try narrowing the problem down. Take some test shots with just your internal flash. If it is working, than add the IKE, block of the internal strobe, and repeat the same test. They should in theory match.
One other thing to be careful of, I no nothing about your particular camera, but some cameras have an external flash sensor that tells the camera when to quench the flash. If yours has one, make sure not to block it.
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Normalise (0) your flash intensity and exposure compensation values. Take a photo of the scene with your camera's internal flash only for an exposure reference. Now try the following suggestions:
DISTANCE
Make sure the scene you're trying to light is not out of the strobe's effective range.
THE AIM
facing the slave to the rearOk, it looks like you've tried this. This usually solves most of the issues. Have a look at this thread here. The member has a similar setup. You'll find pictures of my rig and others on how our slave sensors are positioned.
THE MIN-MAX DIAL
On the TTL slave sensor make sure it's turned to MAX so it doesn't miss the pre-flash.
THE SWITCH SETTING
The TTL sensor has a pre-flash duration switch in the battery compartment. Use a coin to open the compartment and try the other position. When looking at the back of the sensor and the min/max dial on top of the compartment if the switch is to right then it's giving a longer pre-flash. This is telling your camera that it doesn't need so much light and shortens your main flash - giving you an underexposed picture. Switched to the left will give you a shorter pre-flash and subsequently a longer main flash. The switch seems to get 'flicked' easily - I use a piece of pencil eraser to keep it in place. You can read all about it here. DON'T FORGET to close the compartment and make sure it's water proof when you've finished.
If none of this improves your exposures then as a test try completely isolating your camera and sensor from the rest of the equation like covering the camera (not the lens of course) and sensor with a thick black cloth or plastic sheet.
You also mention that 'I am shooting in programme and TTL'. Try a few in manual (M) with the ISO at 100, shutter speed of 1/125 and aperture at f5.6
Also, you'll want to block the camera's flash UW - only so you don't get back scatter
HTH and let us know how you go.
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Following URL from the Photo Tips and Help of the web site FAQ section explains basic problems and suggestions:
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I have tried shooting with only the internal strobe as a guide and have found that the most improvement is with the control in the slave to the left and the diffuser on the housing blanked off. It is a big improvement but I will have to go diving to see if it really works. I have also tried shooting in manual, at the settings suggested, but it wasn't as good. Any further suggestions? I am unable for some reason to be able to point the slave back very far. Is it possible to change the way it is orientated to its clamp?
