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Archive for November, 2010

Photographing the obedience and protection routines at the United Schutzhund Dog Clubs of America’s (USA) German Shepherd Dog National Championship in Carson City, Nevada (the Nationals) this year was real challenge, complicated by an eight-foot fence surrounding the trial field and bleachers that pretty much faced the sun all day. And, with the sun being fairly low in the sky, it was difficult not to photograph directly into the sun from the spectators’ side of the field.

On the last day, Louise Jollyman was able to take pictures from the competitors’ side and stand in one of two entries onto the field, which meant no fence. With the sun over her shoulder, and the sun’s rays at a very advantageous angle, she was able to get off some really nice shots of the dog / handler teams (see slideshow below of her photos of Peter Spanos and Leroy v. Rietnisse). As the day wore on, she was able to continue taking great photos in some very changeable weather conditions, including sun, clouds, driving rain and wind, courtesy of a winter storm blowing in off the Sierra’s. Thanks, Lou!

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These conditions and seeing Lou’s photos prompted me to investigate the relationship between f-stops (aperture), film speed (ISO), shutter speed and lighting conditions. Even though, like me, you may be using automatic or semi-automatic modes, understanding the relationship of these four elements is the key for taking properly exposed photographs and will be very helpful in dealing with rapidly changing lighting conditions. The next series of posts will look at each of these elements in more detail.

First up: A general explanation of the relationship between aperture, shutter speed, ISO and light, including the Sunny 16 Rule.

Dee Clark, another very talented Schutzhund photographer, referred me to Dummies.com for a pretty simple explanation of exposure settings. Don’t laugh. The article was very helpful. According to this article, how the aperture (f-stops), film speed (ISO) and shutter speed settings work together may be likened to filling a bucket:

  • A full bucket = a good exposure
  • The size of the bucket = the ISO
  • The size of the garden hose = the lens aperture
  • The amount of time it takes to fill the bucket = the shutter speed

Think of the camera’s digital sensor as a light bucket. Larger (wider or open) apertures (lower f-stop settings, such as f/1.4, f/2, f/2.8 and f/4) fill the sensor bucket with light faster than smaller (narrow or closed) apertures (higher f-stop settings, such as f/8, f/11, f/16 or f/22). With a faster or higher ISO, the light sensor bucket will fill up with light faster than with a slower or lower ISO setting. Faster or higher shutter speeds also fill the light sensor bucket faster than slower or lower shutter speeds. Larger (wider or open) apertures, as well as higher ISOs, require faster shutter speeds. Smaller (narrow or closed) apertures, as well as lower ISOs, require slower shutter speeds. Clear as mud, right? The trick is to get these elements in the right proportion.

Many photographers rely on the Sunny 16 Rule, which according to Bryan Peterson, author of another very helpful resource, Understanding Photography Field Guide: “The Sunny 16 Rule posits that from one (1) hour after sunrise to one (1) hour before sunset, on any given sunny day and when one uses f/16…the correct exposure would be exactly the same as the ISO.” If, for example, the aperture is set at f/16 and the ISO is set at 100, then the shutter speed should be set at 1/100 or 1 over the ISO setting. If the scene is photographed at an ISO of 400, the shutter speed would be 1/400.

Christopher Dodds in his January 12, 2010 blog post offered some helpful charts (www.NaturePhotographyBlog.com). Chart 1 illustrates the equivalent exposures for ISO 100 and 200, using the Sunny 16 Rule. Each setting allows the same amount of light to fall on the digital camera’s sensor. The selection of the f-stop allows for faster or slower shutter speeds (to freeze or blur action) or a change in the depth of field (very narrow to blur the background or very large to capture an entire grand landscape sharp). Chart 2 adapts the Sunny 16 Rule for different lighting conditions.

Chart 1. Equivalent Exposures for a Sunny Day (Sharp, Distinct Shadows)

f/2.8

f/4 f/5.6 f/8 f/11 f/16 ISO

1/3200

1/1600 1/800 1/400 1/200 1/100

100

1/6400 1/3200 1/1600 1/800 1/400 1/200

200

Chart 2. Equivalent Exposures for Different Lighting Conditions

Sunny

Sunny Cloudy Bright Cloudy Overcast

Bright Sand / Snow

Distinct Shadow Soft Shadow Barely Visible Shadow No Shadow

f-Stop

f/22 f/16 f/11 f/8

f/5.6

ISO 100

1/100 1/100 1/100 1/100

1/100

ISO 200

1/200 1/200 1/200 1/200

1/200

ISO 400

1/400 1/400 1/400 1/400

1/400

ISO 800 1/800 1/800 1/800 1/800

1/800

Both Christopher Dodds and Bryan Peterson warn photographers about backlit and sidelight conditions, which require adjustments to get the right exposure. Christopher advises that with very light subjects in very bright conditions to subtract light (narrower or higher f-stop setting) so as not to clip the highlights. With very dark or black subjects, he advises adding light (wider or lower f-stop setting) to maximize the recorded detail. Bryan points out that the Sunny f/16 Rule will not work if a polarizer or other colored filters are used, because these filters change the amount of light that is let into the light sensor. He notes that photographers will lose two (2) stops of light with a polarizing filter, so again adjustments will be needed.

As a starting point for Schutzhund photography, I set the ISO at 640 and the shutter speed of 640 and let the camera adjust the aperture setting. I do use a polarizer filter to block out glare on very bright sunny days, especially early in the morning when there is a lot of dew on the field, so either I or the camera would need to adjust accordingly. Next post will cover aperture settings in more detail, in particular f/stops and how they work.

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