Wide Angle Exposures

[Clay Coleman]

Cameras have come a long way from the old Nikonos that I've been using for the past 30 years for wide angle shots, and the new cameras are far more consistent in TTL mode with their wide angle exposures. However, (and this is a purely subjective opinion) I've found that "auto" exposures generally make a background (ambient light) exposure that is too light for my taste. Fortunately, nobody has to live with exposures that are unpleasing to them. There are two easy ways to customize your wide angle exposures:

1. Manual camera, TTL strobes. Many cameras will work with TTL strobes even if the camera is set in manual mode. There's an old expression among underwater shooters which sums up capturing that magical moment or unusual subject--"f8 and be there". A lens set at f8, ISO 100, will give a shooter a nice variety of background exposures with different shutter speeds. In blue water, try shutter speeds of 1/80-1/100 when shooting at an angle toward the surface; 1/30-1/60 when shooting horizontally (there is no problem with camera shake shooting at 1/30 underwater). Once you have a shutter speed that renders a nice background at f8, set your strobes to TTL and shoot away.

2. Manual camera, manual strobes. If the TTL setting on your strobes is inconsistent, set the strobe to manual and experiment for a good exposure from a distance of 3 apparent feet and for 1 apparent foot at f8. 90% of my wide angle shots are from a distance of 3 apparent feet from my subject. I guess about 5% are close-focus-wide-angle from 1 apparent foot. The remaining 5% are very wide shots focused at infinity and without strobe light.

This is stuff you can experiment with in a pool, so get out and figure out what works best with your rig. Remember, even if your camera has a Cray supercomputer inside, there are only three exposure decisions it can make once an ISO setting has been selected: aperature, shutter speed, and strobe power. That ain't so hard, is it? -Clay

[Jonathan Bird]

Cathy Church used to teach that she always liked to see the blue water background about 2 stops darker than the subject. (She may still teach this, not sure!) I always found that was a little dark for my taste. I prefer about 1 stop underexposed. With digital cameras, this is very easy to accomplish, because you can see on the LCD when you get it right. The way I always did it with film was:

1. Take a light meter reading on the background and adjust the aperture until the shutter speed was reading at the flash sync speed (about 1/60).

2. Now close the aperture 1 stop.

Now, from this point, depending on how you are shooting (manual or TTL) the next steps are different.

In TTL:

3. Shoot. TTL will adjust the strobes to the foreground based on the distance to the subject, reflectance, and the power of the strobes. This is assuming your subject is close enough to be properly exposed by your strobes.

In Manual:

3. Look at the f stop you have selected, and the distance to the foreground subject, then look at your flash table, and select a strobe power that is right for that distance and aperture. The manual technique almost ALWAYS comes out better.

Of course, you would bracket a little to be sure you nailed it. But you didn't bracket too much because you only had 36 frames. With digital I use the same procedure, except I can bracket a lot more, and I use the TTL compensation knob to tweak the exposure instead of doing it with the strobe power.

Birdman

[peterplantman]

I agree in general with this. However, if you´re shooting towards the surface and include the image of the sun rays, like a "star" on the surface, I´ve always thought this fools the metering in my camera. By following the camera metering the water becomes WAY too underexposed for my taste. So, unless I bother switching to spot metering, I generally measure at approx 45 degrees upward angle. That way the water becomes nice when the camera turns upward.

Another trick I like is to expose for background light in ambient water. Then I let the flash be underexposed, so as to just dash a bit of colour on my main subject. This works especially well for sceneries where there is a lot going on in the background, e.g. a coral garden stretching from my main subject and further away into the void. As a general rule my exposure would be equivalent to setting exposure for ambient light and tweak the strobes to between 2/3 to 1 1/3 f-stop underexposure.

If you allow me to break the theme of subject, then this technique also works for macro with large aperture and long shutter speeds. A blue background with blurry blue details of out-of-focus details of your subject and then the in-focus parts (usually the closest parts...) are sprinkled with colour from my flash that is underexposed between one third to two thirds of an f-stop. It´s not a recipe for immediate success, but when I do succeed, these images become among my best!

/Peter

[Jonathan Bird]

If you allow me to break the theme of subject, then this technique also works for macro with large aperture and long shutter speeds. A blue background with blurry blue details of out-of-focus details of your subject and then the in-focus parts (usually the closest parts...) are sprinkled with colour from my flash that is underexposed between one third to two thirds of an f-stop. It´s not a recipe for immediate success, but when I do succeed, these images become among my best!

/Peter

Show an example Peter!

[Jonathan Bird]

One trick for wide angle exposures that I picked up uses the different color histograms to distinguish between ambient and strobe light. Because there is no red worth talking about in the ambient light below about 20 feet, you can use the blue histogram as a guide to your ambient light exposure and the red histogram is pretty much entirely strobe light. So in a wide angle exposure where there should be a mix of strobe light (typically, the close stuff) and ambient light (the background) you can view the histograms and look at the blue and red channels. If the blue histogram is low and the red is high, you are underexposing the background and overexposing with the strobes. So open up the aperture and turn down the strobe power. If both are low, you can try just opening the aperture (because that affects both). If the ambient is too high but the strobe looks fine, just increase the shutter speed (which only affects the ambient, not the strobe). It's a very cool trick that provide at-a-glance instant feedback on the relationship between the ambient and strobe light. It's not 100% perfect because every scene is different, but you would be surprised how well it works.

Jonathan

[tarczy]

One trick for wide angle exposures that I picked up uses the different color histograms to distinguish between ambient and strobe light. Because there is no red worth talking about in the ambient light below about 20 feet, you can use the blue histogram as a guide to your ambient light exposure and the red histogram is pretty much entirely strobe light. So in a wide angle exposure where there should be a mix of strobe light (typically, the close stuff) and ambient light (the background) you can view the histograms and look at the blue and red channels. If the blue histogram is low and the red is high, you are underexposing the background and overexposing with the strobes. So open up the aperture and turn down the strobe power. If both are low, you can try just opening the aperture (because that affects both). If the ambient is too high but the strobe looks fine, just increase the shutter speed (which only affects the ambient, not the strobe). It's a very cool trick that provide at-a-glance instant feedback on the relationship between the ambient and strobe light. It's not 100% perfect because every scene is different, but you would be surprised how well it works.

Jonathan

WOW!!

Now, why didn't I think of that??

DOH!!

Very cool, Jonanthan. That's why your the pro!! :)

Thanks

[Jonathan Bird]

I didn't think of it either. I read it somewhere ages ago before I was even shooting digital and filed it in my brain waaaay in the back.:) Someone cleverer than me thought it up. I actually did my first couple of trips shooting digital before that little gem "came back" to me.:o It's extremely helpful for shooting wide angle. (And of course completely useless for macro).

Jonathan