Tuesday, September 22, 2009

When choosing the right lens for your landscapes, is wider always the answer?

From his vantage point in Nelson, New Zealand, landscape photographer Colin Southern has evolved his own rationale for making equipment choices. "I like to think of myself as a typical photographer," he says, "a perfectionist bordering on obsessive/compulsive.

"People often ask me about the suitability of a particular lens for landscape photography. In many cases the lens in question has a minimum focal length around 24mm -- and often it's for use with a smaller-than-full-frame camera. This makes the field-of-view approximately equal to that of a 36 to 40mm lens on a full-frame camera. Often their question is along the lines of, 'Is that really wide enough for landscape shooting?'

Let's look into the question
"Before advising the purchase of a new, wider-angle lens, however, I suggest we first discuss if and when wider is really better. If I use a truly wide-angle lens -- with a focal length anywhere from 10 to 24mm -- and then simply place the horizon somewhere around the middle of the frame and take the shot, with nothing in particular in the foreground, I nearly always end up with a pretty boring shot. That's because the lens pulls visual information from such a large field of view (both horizontally and vertically) that anything farther than just a few feet away becomes tiny -- REALLY tiny -- and the shot lacks any significant detail or visual 'anchors.'

"When we're using wide-angle lenses, we also capture light from a much larger field-of-view. That often produces quite a variation in light levels reaching the sensor. Although we may have good light levels and exposure in the centre of the image, we may face a significant degree of under-exposure at the edges -- to the point where the image just isn't appealing.

"Vignetting is the result of under-exposure of the image at the corners and outer-edges due to optical limitations of the wider-angle lens design. Most high-quality wide-angle lenses suffer from only minor vignetting when used without filters -- or with only a single thin-mount filter -- but shooting world-class landscape images is synonymous with filter use. That includes graduated ND filters, solid and variable ND filters, polarizers and color intensifiers. And often we need to use more than one filter at any given time. Unfortunately these additional filters often -- on a good day -- increase vignetting to the point where it needs extra attention in post-processing. However -- on a bad day -- it can progress from vignetting to outright obstruction where the filters are visible in the shot and need to be cropped out. And finally -- if you're a perfectionist like me -- you find that the wider the field-of-view, the harder it is to get a perfect composition without distracting and unwanted elements appearing in the background.

"So, am I saying that all wide-angle lenses are a waste of money? Not at all. But in some situations they can create more problems than they solve, and those problems have to be worked through -- perhaps by zooming to a longer focal length or by severely cropping the image. These issues can often be avoided entirely by using a longer focal length lens in the first place.

Here's a quick test
Look closely at the image at the top of this story and the next two images below, and then try to guess what focal was used for each -- you'll find the answer at the end of the story.

"Lone Tree Vista (above) was a night shot taken from the perimeter walkway of the Nelson Airport. Initially it may look like a sunset shot, but in reality my Singh-Ray 3-stop, hard-step Reverse ND Grad filter allowed me to balance the brighter sky with the reflections in the foreground pools and to extend the exposure to a full 12 minutes (not seconds). This image was shot approximately 1-1/2 hours after sunset to allow for a gentle smoothing of the slow-moving clouds.

"The Cut gets its name from a man-made cut in the 13-km boulder bank to facilitate the entry by ships into Nelson Harbour. When this particular image was made, the water was quite choppy. So I used my trusty Singh-Ray Vari-ND to reduce lighting levels to achieve a much longer exposure which helped smooth out the water.

"Haulashore Island was formed when the Cut (photo above) was dredged. In the earlier parts of the last century the island was used to haul ships ashore for maintenance. For this shot I've again used my Vari-ND to lower the light levels and allow me to capture a gentle smoothness of the ripples.

And the answer is...
"For any of you still wondering what the focal lengths were for these three images above, you might be surprised to learn that ALL THREE images were shot using a 70-200mm lens on a full-frame camera -- with focal lengths set between 70 and 78mm. As a comparison, the image below is an ultra wide-angle shot straight out of the camera (warts and all) of the same scene - shot at the same time as the first two images. If you look carefully you can see the portions of the scene captured by the 70-200mm lens.

"So the point of my story is that although wide-angle and ultra wide-angle lenses certainly have their place in landscape photography -- I love mine dearly! -- wider isn't always better. And the lack of a wide-angle lens doesn't have to limit our creativity."

With some 12 years to go before retirement, Colin continues to focus on the many photo opportunities to be found in his New Zealand homeland. You can enjoy more of Colin's insights and images by visiting his gallery of images. You can also contact Colin at the Cambridge in Colour Forum if you have any questions or comments.

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