how much difference does a strobe make??

[ReyeR]

By your reasoning, the best strobe would be situated as far as possible away from the camera with an enormous angle of dispersion to produce a cone shape that just barely touched the subject.

I woke up this morning thinking about this. What you have there is a pretty accurate description of the sun as a light source....

 

[segal3]

So of the three possibilities, which one is optimum for lighting up the most without backscatter. I'm placing my bets on #3...

This is what I'm talking about...

~Matt Segal

 

[Meddler]

Yeah I would say 3 is the best because it has the least light in front of the subject.

 

[segal3]

Meddler once bubbled...
Yeah I would say 3 is the best because it has the least light in front of the subject.

...with the most light behind, and the least direct reflection...more of a "lit" scene, yes?

~Matt Segal

 

[Meddler]

And longer shadows

But I expect thats why two strobes are good.

 

[ReyeR]

TBH I think both 2 and 3 will work. A lot depends on the angle of coverage of the camera lens as well. Also, notice in fig. 3, to light up minimum area in front of the subject you've had to move the light source further away from the camera lens.

 

[diverdeb001]

I can sort of see how the strobe works better at an angle now. The light travels to the subject and most goes straight back to the strobe or is reflected off the subject to the camera. Instead of lighting up the particles on the way to the subject, making all those white spots, the light hits the particles on the way back to the camera, essentially lighting up the back of the particles which doesn't show in the pic. Actually in theory, there should be little dark spots where the light can't get back to the camera???? db

 

[g8trdiver]

That's true - you could expect some image quality degradation compared to clear water just because the particles exist between you and your subject. The viz is just bad. Probably too small to make THAT much of a difference if they're not illuminated.

But the problem is also one of exposure - the light reflecting back to the camera from the particles will throw off the exposure readings. You have all this bright stuff coming back, confusing the meter - so your actual subject is under-exposed.... and all you get on your picture is brightly lit scatter, and a shadow of the actual subject you were going for.

Getting the flash away from the camera reduces that - so that you can at least properly expose the subject.... (assuming you're using automatic exposure).