Friday, July 31, 2009

Capturing the mist that isn't really there is no longer a mystery

Landscape photographer Colin Southern is based in Nelson, New Zealand. "Every serious photographer," says Colin, "knows there will be times when their best laid plans for a great image will fall through. That's when I find myself having to switch to 'Plan B' at the last moment. ('Plan B' being essentially 'The lights fading - think of a plan quickly!') This first image falls squarely into that category.

"Not wanting to come away empty handed, I instinctively set up a composition that I'd used before. Later, when I shared this image with some friends, most found the misty effect quite stunning, which came as somewhat of a surprise as this type of shot is actually quite easy to achieve by following a few simple guidelines. Here's what I mean.

Step One: Choose a wide-angle composition
"Wide-angle lenses make things look smaller and further away -- so to make the rocks in the foreground look more significant, I know I must get the camera really close to them. For this shot I had the centre of the lens approximately 50 cm (20 inches) above the ground with the tripod legs in the water. I like to place the horizon line about 1/3 of the way down from the top on the frame. I then lower the camera until the foreground takes on a meaningful size. It really helps if you have a camera with LiveView or attach a right-angle finder to your camera. Wide angle lenses make this kind of agressive composition possible -- and ensuring an image with a dramatic perspective. I also set the focus on a point a few feet away and then switch the lens to manual focus because depth of field is seldom an issue at smaller apertures with a wide-angle lenses.

Step Two: Control the wide dynamic range
"Shooting into the light like this means that the detail in the rocks facing the camera are buried deep in the shadows - so shooting RAW is necessary, but it's still not enough. The very best way to reduce the extreme dynamic range of scenes like this is to use either a Singh-Ray Graduated Neutral Density filter or Reverse GND filter. I think that the common thought with many is that you install the filter so that it reduces the intensity of the light coming in from above the horizon, but in my opinion, with this kind of shot it's better to lower it even more so that it covers everything except the rocks in the immediate foreground -- the camera needs all the help it can get to record those foreground shadow details!

Step Three; Expose for minutes, not seconds, with multiple exposures
"The 'mist effect' is generated by waves surging over and around the foreground rocks. To get this effect you need a long exposure (ideally 2 to 4 minutes). But long exposures with falling light levels are tricky things to calculate (if you get it wrong you may not have time to reshoot). With the tide coming in, there's every chance that you'll get water splashes on your camera and filter. The trick here is to leave the camera on Aperture Priority mode (adding or subtracting exposure compensation so that highlight detail is retained) -- and then taking a series of shots. For a more extensive explanation of this step, refer to my post of September 26, 2008.

"The next question is usually, 'but how many?' Enough so that the total exposure time of all images adds up to the 2 to 4 minute target that we're aiming for. This shot consisted of 9 frames of 10 to 13 seconds each. The joy of this technique is that the camera will automatically compensate with longer exposures as the light levels drop -- you also can use a higher/noisier ISO setting than you normally would as the combining of the images in post-processing averages out the noise -- and if you get water splashed on the filter at some point you may already have enough images to still get a worthwhile result.

Step four: Combine the images in Photoshop
"First step is dealing with the RAW converter. If you're using a later edition of Photoshop (CS3 or CS4), then you'll probably need to use the fill light control quite agressively -- and be sure to adjust the colour temperature and saturation for whatever looks good.

"To combine the images, just open them all up, and then use the move tool to drag the remaining images into the first one (this stacks them as layers), and then change the opacity of each layer --100% for the lowest, 50% for the 2nd to lowest, 33% for the 3rd to lowest, 25% for the 4th etc. If you have too many images to do all at once, just combine them in, say, groups of 8, and then combine the resultant images in exactly the same way.

"I took this next image, 'Bar Code,' shortly after the one above. An initial composition meant walking quite some distance over mud flats -- but the further out I went, the deeper each step started to sink into the soft mud. I quickly realized a hasty retreat was the better strategy! After moving further around the coast, I spotted a better place, but the ideal composition meant standing in about 2 feet of mid-winter seawater well over the tops of the gumboots. I used a Singh-Ray 3-stop hard-step Graduated Neutral Density filter for knocking back the power of the lights above the waterline to balance them perfectly with their reflections. It also meant that I could expose for 2 minutes instead of 15 seconds.

"For shots like these, the size of the "stars" is inversely proportional to the size of the aperture used -- so these lights were shot at f/32 to emphasise the star patterns. Correctly exposing scenes like this can be tricky as cameras will often try to protect highlight areas to the point where the majority of the image (the mid-tones) are severely under-exposed. I find that it's usually best to simply choose an exposure that "looks about right" on the review screen (the highlights are going to blow anyway). It's often easier to start with a wide aperture - work out the correct exposure - and then double the exposure time for each f-stop you close down the lens. Post-processing is fairly straight forward - don't be afraid to raise the black clipping point to give the image more contrast - and adjust saturation and sharpening to suit."

To see many more scenes of Colin's New Zealand countryside visit his gallery images now posted at www.pbase.com/cjsouthern. You can also contact Colin at the Cambridge in Colour Forum if you have any questions or comments.

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