Canon ettl Help Please

The environment:

I placed a tarp over the deep end of our pool, so that I would not have a stark white environment. With it, the light was not bad, but not great. Obviously the water was clear and no particulate matter.

The Camera Setup:

Canon 40D, with 100mm macro f2.8 lens, dual DS-125 Ikelite strobes in an Ikelite housing, with dual sync cord. Strobes were set to ttl.

The subject:

I placed small plastic fish on the bottom of the pool to shoot pictures. My intent was to work on depth of filed underwater.

The Problem:

Shooting at a distance of three feet or less I got the following problems.

Set to a shutter speed of 1/160, the camera determined an f stop of between 2.8 and 3.5. Obviously too open for good depth of field.

Set to an aperture of f9, the camera determined a shutter speed of 1/60 or less. At f11, it was down to as low as 1/15. Too slow for hand held.

Set to manual at 1/125 and f/11, the camera read underexpose by at least two stops. But, the pictures were perfectly exposed, good histogram. Good depth of field.

It was the same answer with all metering settings.

With the M settings, I was even getting the camera attempting to reset the shutter speed in some instances and the strobes were short firing.

I could not get the camera to read the light correctly.

The Solution:

Beats the heck out of me. Any suggestions would be greatly appreciated.

How do I trick the camera while it is trying to trick me?

What am I doing wrong?

Thanks for the help.

PS: (Any pros in the Tampa Bay area?)

The environment:

I placed a tarp over the deep end of our pool, so that I would not have a stark white environment. With it, the light was not bad, but not great. Obviously the water was clear and no particulate matter.

 

The Camera Setup:

Canon 40D, with 100mm macro f2.8 lens, dual DS-125 Ikelite strobes in an Ikelite housing, with dual sync cord. Strobes were set to ttl.

 

The subject:

I placed small plastic fish on the bottom of the pool to shoot pictures. My intent was to work on depth of filed underwater.

 

The Problem:

Shooting at a distance of three feet or less I got the following problems.

Set to a shutter speed of 1/160, the camera determined an f stop of between 2.8 and 3.5. Obviously too open for good depth of field.

Set to an aperture of f9, the camera determined a shutter speed of 1/60 or less. At f11, it was down to as low as 1/15. Too slow for hand held.

Set to manual at 1/125 and f/11, the camera read underexpose by at least two stops. But, the pictures were perfectly exposed, good histogram. Good depth of field.

It was the same answer with all metering settings.

With the M settings, I was even getting the camera attempting to reset the shutter speed in some instances and the strobes were short firing.

I could not get the camera to read the light correctly.

 

I think at least part of the difference is that the camera doesn't know that the strobes are connected. The 40D meters the scene and says the light is too low for 125/f11 and that is probably true. The IKE ttl meters the scene and says fire the strobes at whatever power makes sense based on the f stop the camera is set at. I am not sure how or even if, the IKE ttl is communicating back to the camera, but if your exposures are right on, why worry?

I think at least part of the difference is that the camera doesn't know that the strobes are connected. The 40D meters the scene and says the light is too low for 125/f11 and that is probably true. The IKE ttl meters the scene and says fire the strobes at whatever power makes sense based on the f stop the camera is set at. I am not sure how or even if, the IKE ttl is communicating back to the camera, but if your exposures are right on, why worry?

Thanks for the reply.

The issue to me would be that if it meters wrong in that setting it will meter wrong in most if not all settings. I am trying to get it right most of the time, not wrong most of the time.

I need to try and trick the camera while it is trying to trick me.

I think at least part of the difference is that the camera doesn't know that the strobes are connected. The 40D meters the scene and says the light is too low for 125/f11 and that is probably true. The IKE ttl meters the scene and says fire the strobes at whatever power makes sense based on the f stop the camera is set at. I am not sure how or even if, the IKE ttl is communicating back to the camera, but if your exposures are right on, why worry?

 

 

 

Thanks for the reply.

 

The issue to me would be that if it meters wrong in that setting it will meter wrong in most if not all settings. I am trying to get it right most of the time, not wrong most of the time.

 

I need to try and trick the camera while it is trying to trick me.

To the camera's point of view it is getting it correct, if it doesn't know the strobes are attached, then it will meter what it sees not what will really happen. Same as if you had an external studio strobe set up. tHat is why you shoot in manual mode, not in program mode. Just set up for 1/160 sec and f16 and then let the sttrobes do their thing