Tuesday, May 03, 2011

Step-by-step, Darwin Wiggett and Samantha Chrysanthou outline their technique for Painting with Time

The following is a modified excerpt from Darwin and Samantha’s latest eBook entitled Advanced Filters for Digital Nature Photography. You can purchase the entire eBook from Visual Wilderness.

As landscape shooters, we love capturing light in the “magic hour” just after sunrise and just before sunset. But beautiful as this low, skimming, warm light is, we often create our most ethereal photos during the darker hours of dawn and dusk when exposures go from several seconds to many minutes.

Long exposures capture the light passing over the land to create effects you can’t see with an unaided eye. Anything that moves -- rushing water, swaying grass, flitting clouds -- takes on a surreal, painterly look. Over the past few years, we have been capturing long exposures even in bright daylight using various combinations of filters. Here are some examples of how we paint with time.

Darwin captured the above photo of the old barn on Niagara Peninsula in Ontario with his Canon 1ds Mark II with the 24-70mm f2.8L lens set at a focal length of 37mm. He used a Singh-Ray LB Warming Polarizer and 4-stop Solid ND filter to achieve a 1-second exposure at f/16 in the middle of a sunny day.

The Right Tools
The key to such long exposures in bright light is to reduce the light coming into the lens, and the easiest way to do this is with neutral-density (ND) filters. These come in various strengths from 1 f-stop up to 10 f-stops. Most can either be screwed to the front of the lens or placed in a filter holder attached to the lens. The two ND filters we use the most are the Singh-Ray Vari-N-Duo and Singh-Ray’s George Lepp 4-stop Solid ND filter. The former is a screw-mount filter that allows you to dial in from 2 to 8 f-stops of variable density plus have the benefits of a polarizer. The latter is a drop-in filter available for P, Z, or X-series sized holders.

Samantha took this second image of Abraham Lake and Mount Michener in Alberta with her Nikon D300s fitted with her Nikon 17-55 f2.8 lens set at a focal length of 18mm. She used a Singh-Ray LB Warming Polarizer, a Singh-Ray 4-stop Solid ND filter and a 2-stop hard-step ND Grad to get a 4-second exposure at f/14. In our landscape photography, we almost always use a polarizer. In fact, we can’t imagine doing serious landscape photography without one. A polarizer reduces glare for more saturated colour and richer blue skies and adds about 1 to 2 stops of neutral density on its own (to learn the other benefits of a polarizer be sure to see our eBook Essential Filters for Digital Nature Photography).

By using a filter holder with a drop-in 4-stop Solid ND filter plus a polarizer, we get a total of 5 to 6 f-stops of light reduction. This one-two punch is hard to beat. We often add an ND grad to this duo to subdue the light in bright skies without further darkening the foreground.

This image of the Crocus in spring at Bow Valley Provincial Park in Alberta was captured by Samantha using a Nikon D200 with a 17-55 f2.8 lens set at 17mm. She chose a Singh-Ray LB Warming Polarizer, Singh-Ray 4-stop ND filter, Singh-Ray 2-stop hard-step ND Grad to get a shutter speed of 13 seconds at f/16. Which ND filter we use depends on the lens and whether we want to combine it with other filters.

With our 70-200 or 300mm lenses we’ll often use the Vari-N-Duo filter because it simply screws onto the lens and gives us the benefits of both polarization and ND effects. With wide angle zoom lenses, the thick profile of the Vari-N-Duo (or any of the variable density filters) will often cause vignetting with zoom settings of 35mm or wider on full-frame cameras and settings of 24mm or wider on cameras with smaller sensors. Stacking other filters with it only adds to the problem. Our preferred solution for our wide-angle lenses is simple. We use the Z-Pro sized filter holder which is designed for larger, 4x6-inch filters. This big holder coupled with the larger filters prevents most problems with vignetting. Our favorite combination for painting with time is the Singh-Ray LB Warming Polarizer in the Z-Pro sprocket mount combined with a George Lepp 4-stop 4x6-inch ND filter.

Besides filters, other essential gear you need includes a solid tripod with a sturdy head that won’t sag or shift during long exposures. We also use an electronic cable release to trip the shutter along with mirror lock-up or live view to prevent camera shake from mirror slap. If your tripod is light, hang a bag of rocks or sand from the center column to stabilize it.


The Right Technique

We look for scenes that have moving elements -- flowing water, surging surf, blowing grass, or clouds floating across the sky -- combined with other elements that are immovable, such as a fence, solid tree trunks, or rocks. We compose the scene and focus as we would for any landscape, most often using manual focus in live view for precise focus (note: we do this before any filters are in place). If we do use AF, we let the camera focus and then we switch the camera to manual because, once we drop the heavy filtration into place, the scene will often be too dark for the camera to autofocus properly.

We start with the LB Warming Polarizer in the rear slot our filter holders, rotated for maximum effect. We then drop the 4-stop Solid ND filter in the next closest slot to the polarizer to prevent extraneous light from bouncing between the two filters. To determine exposure, we set our camera to aperture-priority mode and pick a small aperture for maximum depth-of-field and longer exposure times. Darwin's image of Abraham Lake was taken with a Canon 1ds Mark III and his Canon TS-E 24-mm tilt-shift lens at f/3.5. He chose the Singh-Ray LB Warming Polarizer, the 4-stop Solid ND and the 2-stop hard-step ND Grad filter for a 30-second exposure at f/14. We tend to use lens openings around f/16 instead of f/22 because lens performance often suffers at the smallest apertures due to diffraction. Bright light entering the viewfinder can cause the camera’s meter to underexpose, so we use the eyepiece shutter to block light before exposure. You can also just block the eyepiece with your hand.

Most digital SLRs can time exposures only up to 30 seconds. In bright daylight, at ISO 100, exposures run about 1 seconds at f/16 with a polarizer and a 4-stop ND filter in place, so the camera will have no problem calculating the exposure (be sure to block the camera’s eyepiece to get proper exposure!). On cloudy days, or at the magic hour, exposures may run from 4 to 30 seconds at f/16. Any darker, and we need to figure out the exposure ourselves.

Here’s how: we simply open up our aperture until we get a shutter speed reading of 30 seconds. For example, say we get an exposure indication of 30 seconds at f/5.6. Now, for every stop we close down the aperture, we have to double the time the shutter is open to get the same exposure. So at f/8, our shutter speed would be 60 seconds; at f/11, it would be 120 seconds; and at f/16, it would be 240 seconds (4 minutes).

For a 4-minute exposure, we switch our camera to Bulb mode and use a locking cable release to hold open the shutter. A watch is handy, but many newer digital cameras display the time elapsed on the LCD while the camera is exposing.

We have never had a problem with noise except in exposures longer than 15-30 minutes. We always use a low ISO and, in our experience with both Canon and Nikon digital cameras, noise is only an issue if the images are underexposed and then heavily manipulated in post-processing. Keep the histogram slightly biased to the right but still showing good shadow detail. We turn off in-camera noise reduction which we find has little benefit and eats up critical shooting time in processing. Here's Darwin's image of Waterfowl Lake in Banff National Park in Alberta which he captured with his Canon TS-E 24 f3.5L fitted with a Singh-Ray LB Warming Polarizer, a 4-stop Solid ND filter and a 2-stop hard-step ND Grad filter. The exposure was 59 seconds at f/14.

Long-exposure photography is like any other photography -- good light, stellar composition, and solid technique make for success. The difference is that when painting with time, exposures will open up a new way to record the natural world -- a world dominated by movement and rhythm.

Darwin Wiggett and Samantha Chrysanthou have authored many instructional eBooks at Visual Wilderness where you can download their helpful eBooks on a variety of topics in mastering the art of photography. To learn more about their workshops and tours, you can also visit Darwin's website and Facebook or Samantha's blog and Facebook.

1 comment:

Craig Brown said...

Great shots as always!

Darwin I remember that barn! I was with you that day!