question wrt YS-D2 on manual

[aviator8]

Here is the starting point recipe:
Everything -- camera and strobe -- are on manual.
1. Use as low an ISO as conditions allow. This likely will be 100-400.
2. Use f/5.6 for point and shoots, f/8 for m43, f/11 for 1-inch sensors, f/16 for full frame. Smaller f-stops risk diffraction effects. Go one f-stop smaller if you must, for depth-of-field.
3. Use a shutter speed that exposes the water for your desired background color...light blue, dark blue, black, your choice. You may be limited in how fast your shutter will sync with your strobe.
4. Adjust the strobe power and position so your foreground is exposed correctly.

This is not hard, and for different subjects at similar depths requires only adjusting the strobe power.

Why not use some automatic mode on your camera, like A or P or whatever your system calls it? Because that mode is not designed for underwater shooting, and will attempt to expose the scene using ambient light, which causes two undesirable things to happen: (1) the camera will likely choose a slow shutter speed and/or a high ISO, because it is pretty dark own there. The former gives you motion blur, the latter gives you a noisy picture (today's equivalent of the old grainy pictures). (2) When your stobe fires, it adds light on top of the ambient-light exposure, so you get an oveexposed result, all blown out.

Nice summary.

 

[Chris Ross]

I actually have a question about metering -- I have a film background (as in "motion picture film" rather than "still photography") so most often I used a spot meter, then moved/scrimmed/diffused the lights to taste.

So when I started doing photography, I kept it on spot metering. It's what I'm used to.

But underwater..... I'm really not getting great results. It's almost like it's way more contrasty underwater. I was told I shouldn't use spot-metering, just "center weighted" metering. What are your thoughts?

When you say "not great" what is not great about them and what are you spot metering? If you are going to meter anything it needs to be the water column - the meter knows nothing about what your flash will do in the way of exposure. If you meter your subject it will try to get the right exposure on that with ambient light. You can't just meter the water either - the camera will try to make the water tonality equivalent to 18% grey, depending where in the water column you meter the exposure will jump around a lot. Even centre weighted is fraught with problems - it is going to try to provide the correct ambient light exposure on your subject.

This is why I suggest you consider the image as two separate exposures. Get you flash exposure right at your chosen aperture and ISO. Then adjust your shutter speed to get your water exposed nicely. I find that it's something like 1/125 f11 ISO200 at moderate depth maybe 10m or so. I would suggest giving away metering and just review your histogram for exposure.

When you start out set your aperture and ISO. Shoot a subject from around 300m-500 mm away and adjust flash power till exposure looks good - this will ensure you have enough flash it will probably be something like half power. Next subject light have water in the BG, use your same flash expsoure from about the same distance - adjust shutter speed up or down from around 1/125 till it looks right and histogram looks good.

If shutter speed is too low you might need to increase ISO go up half to one stop and bring flash power by same number of steps. If it's too high (above sync speed) reduce ISO and increase flash power by same number of steps- then do your test shot again to confirm shutter speed.

Once you have that dialled in leave ISO and f stop alone and adjust subject exposure with flash power while you get the hang of things - the advantage of this is it's only one thing to think about. If you stay at the same depth your shutter speed won't vary much, unless you start doing sun balls. Take one step at a time and get used to that before starting to adjust more parameters. If you maintain same distance from your subject flash exposure should not move around a lot.

 

[M DeM]

When you say "not great" what is not great about them and what are you spot metering? If you are going to meter anything it needs to be the water column - the meter knows nothing about what your flash will do in the way of exposure. If you meter your subject it will try to get the right exposure on that with ambient light. You can't just meter the water either - the camera will try to make the water tonality equivalent to 18% grey, depending where in the water column you meter the exposure will jump around a lot. Even centre weighted is fraught with problems - it is going to try to provide the correct ambient light exposure on your subject.

This is why I suggest you consider the image as two separate exposures. Get you flash exposure right at your chosen aperture and ISO. Then adjust your shutter speed to get your water exposed nicely. I find that it's something like 1/125 f11 ISO200 at moderate depth maybe 10m or so. I would suggest giving away metering and just review your histogram for exposure.

When you start out set your aperture and ISO. Shoot a subject from around 300m-500 mm away and adjust flash power till exposure looks good - this will ensure you have enough flash it will probably be something like half power. Next subject light have water in the BG, use your same flash expsoure from about the same distance - adjust shutter speed up or down from around 1/125 till it looks right and histogram looks good.

If shutter speed is too low you might need to increase ISO go up half to one stop and bring flash power by same number of steps. If it's too high (above sync speed) reduce ISO and increase flash power by same number of steps- then do your test shot again to confirm shutter speed.

Once you have that dialled in leave ISO and f stop alone and adjust subject exposure with flash power while you get the hang of things - the advantage of this is it's only one thing to think about. If you stay at the same depth your shutter speed won't vary much, unless you start doing sun balls. Take one step at a time and get used to that before starting to adjust more parameters. If you maintain same distance from your subject flash exposure should not move around a lot.

And I'm guessing that the f-stops on the strobe (the adjustment knob when you're in manual) work the same as with a lens? i.e., putting the setting on f2.8 will produce more light than f5.6?

 

[outofofficebrb]

And I'm guessing that the f-stops on the strobe (the adjustment knob when you're in manual) work the same as with a lens? i.e., putting the setting on f2.8 will produce more light than f5.6?

On manual mode on the D2's, the larger the number, the brighter the strobe light will be. So 5.6 will be brighter than 2.8 on that knob. 32 will be the brightest.

 

[bvanant]

"And I'm guessing that the f-stops on the strobe (the adjustment knob when you're in manual) work the same as with a lens? i.e., putting the setting on f2.8 will produce more light than f5.6?"
I think it is the opposite. The strobe is set up to produce enough light for the fstop on the label. Since f 5.6 needs 4 x as much light as f 2.8 the strobe indeed puts out 4 x as much light on the 5.6 setting as on the 2.8 setting. It does this by changing the timing of the strobe flash, shorter flashes for less light.
Bill

 

[M DeM]

"And I'm guessing that the f-stops on the strobe (the adjustment knob when you're in manual) work the same as with a lens? i.e., putting the setting on f2.8 will produce more light than f5.6?"
I think it is the opposite. The strobe is set up to produce enough light for the fstop on the label. Since f 5.6 needs 4 x as much light as f 2.8 the strobe indeed puts out 4 x as much light on the 5.6 setting as on the 2.8 setting. It does this by changing the timing of the strobe flash, shorter flashes for less light.
Bill

A-ha! Thanks!

 

[Chris Ross]

The manual says they are approximately guide numbers so 32 is the brighest. There is a half stop click between each guide number. So each click is approximately half a stop.

 

[bvanant]

In the pool at least the clicks are fairly close to what you expect. In the lab if you look at pulse times they are quite close but I can’t measure pulse times in the water

 

[divergal80]

What is "full power" in manual mode for the S&S D2 strobes? Is it the setting for 1 or for 32, obviously mid-output will be 8?

 

[divergal80]

Sorry, I now see the earlier reply that 32 is the highest output...