Keeping our expose to the right rule in mind, how about those deep, dark canyons and rain fed rivers. Sometimes they have the most epic scenery but can be hard to photograph well. Let's tackle the second most common issue in whitewater photography, motion blurred photographs.


     When there is not enough light to shoot our ideal settings, it's time to play a game of balance with our three previously mentioned controls, Shutter Speed, Aperture and ISO. 

   First we can adjust our shutter speed, because the slower the shutter the more light we let in. The problem with this is that rarely do you want motion blur in a kayaking shot. I consider my slowest acceptable shutter speed to be 1/500 to 1/800 depending on the situation. You will have to judge this based on the speed of the paddler and water. If you are freezing motion at the top of a waterfall, both the paddler and water will be going slow enough that 1/500 might work (although paddle blades can blur).

Here the paddler is nice and crisp both the paddle blade and splashes make it feel soft overall.
Nikon D200. Nikkor 18-200 @ 70mm. Shutter: 1/500 Aperture: F5 ISO: 500


    On the other hand, if you are trying to freeze action at the bottom of a waterfall,, it's will be moving much faster and harder to freeze, and thus will blur. Shutter speed is the weakest of the three methods for adjusting exposure on dark days, because you only gain one stop of light going from 1/1000 to 1/500. 

 ISO, the equivalent of film speed, will play a role on dark days but has some serious drawbacks. Noise, the digital equivalent to film grain (often looking worse) is the most well known drawback. Outside of noise, using a high ISO also drops your dynamic range and the sensors ability to correctly capture color and texture. But there are occasions where there is no other option than to pump the ISO up. This is where they amount of money you spend on a camera can make a big difference. Whatever you do, do not, I repeat, do not, under-expose a high ISO shot. If you are shooting at your camera's base ISO you have quite a bit of flexibility to adjust the exposure while post-processing. (Which will be it's own tutorial) At high ISO's any noise is greatly magnified if you adjust the exposure, and this can ruin a great shot, making it even worse than too slow of a shutter speed.

 Example One: Shutter: 1/1000. Aperture: F4.8. ISO: 800. Post production +2.5 exposure.
 

Example Two: Shutter: 1/640. Aperture: F2.8. ISO: 800 Post production +.25 exposure.


While the difference is pretty obvious, it's even more obvious when the images are cropped at 100%:

ISO: 800, Post production +2.5 exposure
 

 ISO: 800, Post production +.25 exposure.


   Although a little bit of the sharpness loss is due to lens choice,the first illustrates the dangers of underexposing a high ISO image. 

   Aperture is by and far the most powerful of the three choices. Opening your aperture from 8 to 2.8 is a full three stops. This is the same as going from ISO 200 to 1600, or 1/1000 to 1/125. There are some downsides to large apertures. Large aperture zoom lenses are expensive and heavy, because it takes a lot more glass to let in all the light. Another downside is that on many lenses the largest apertures are not as sharp and lose contrast. As a rule of thumb you can't shoot low light kayaking with a cheap zooms and get great results.

Option #1 is to lower your standards and shoot high ISO speeds with cheap light zooms. 

Option #2 is to buy expensive fast zooms, but  they run around $1,500 and weight as much as 3lbs.  Plus 2.8 isn't really that fast. 

Option #3 is the route I have gone. Trade away the convenience of a zoom for the light weight and (often) cheap cost of a "prime" lens. Prime lenses have generally been in production a long time and are light and simple since they don't zoom. The $120 50mm 1.8 is a great example. Over one full stop faster than the $1,700 24-70mm 2.8, 1.7lbs lighter and $1,600 less! The downside of shooting primes is the hassle of changing lenses on a regular basis, and more hiking to get the shot you want. Sometimes you just can't get where you'd like to be too. They are especially tough in a rainy environment, where you don't want to expose the inside of your camera body while changing lenses. 

Nikon D200, Nikkor 50mm 1.8 @ 1/500 F1.8 ISO 250. 
 

   The final problem with low light kayaking shots is white balance. Ever notice how most dark weather kayaking shots look "cold"? That's because they have too much blue in them, even the best of cameras' Auto White Balance (AWB) is not perfect. As always we have a few option to remedy the problem. The first is to use a preset white balance that is built in. Shooting on a cloudy day? Hold down the WB button and rotate the command dial until you get to the cloud symbol. The downside to this method is that it's not completely accurate as not every cloudy day is the same. 

White Balance set to cloudy on a Nikon D50.


   The second is to leave the camera on AWB and adjust while post-processing. This works well with high end cameras that gets it right 90% of the time, but with a camera like the D50 I found myself adjusting nearly every shot, way too much work. 

   Third is setting manual white balance with a gray card. Judging from my love of doing things the hard way (manual exposure and prime lenses) it seems like this would be right up my alley, but it's not for two reasons. 

A. It's simply too much work to set manually for every shot.
B. It's impossible to stand in the location of the actual shot to get a true white balance, and the lighting on shore is often different. 

With the D50 I used the camera presets. With the D200/700 I use the AWB and adjust in post processing. You'll have to judge based off of your camera's AWB abilities.



To sum it up with a few rules of thumb:  Adjust to your slowest acceptable shutter speed & largest aperture before raising the ISO. There is a fine line between lens performance at maximum aperture and ISO degredation. For example on the Nikon D200 I'll bump ISO from 100 to 200 before taking the 50mm from 2.8 to 1.8, because the ISO boost effects quality less than the limited depth of field and loss of contrast seen in the lens at 1.8.




Next Up: Locking Focus.

Whitewater Photography Tutorial  #1: Intro.

Whitewater Photography Tutorial  #2: What is the right exposure?

Whitewater Photography Tutorial  #3: Getting the right exposure. 

Whitewater Photography Tutorial #4: Low Light Action

Whitewater Photography Tutorial #5: Focus

Whitewater Photography Tutorial #6: Basic Lighting

Whitewater Photography Tutorial #7: Composition 

Whitewater Photography Tutorial #8: Wide Angles

Whitewater Photography Tutorial #9: Panning

Whitewater Photography Tutorial #10: Post-processing

Whitewater Photography Tutorial #11: Sequencing