Friday, September 25, 2009

Combining the Vari-N-Duo with a bit of software magic opened up the shadows

During his most recent workshop in Great Smoky Mountain National Park, fine-art nature photographer (and former magician) Tony Sweet made this image by slowing his exposure down to 10 seconds. "By using my Singh-Ray Vari-N-Duo," says Tony, "I was able to convey the surging action of the mountain stream while I also controlled the specular highlights reflecting off the stones and moss to fully reveal their true colors. That's because the Vari-N-Duo filter combines the classic Vari-ND variable neutral density filter to slow my shutter speeds anywhere from about two to eight f-stops with the LB Warming Polarizer which lets me control the glare from the water and wet rocks.

"I could see that this scene presented an interesting opportunity to merge two different techniques -- one hardware and one software. In mountain streams, where there are large boulders, the undersides of the boulders are very dark. If the water is running well, it is very bright, even on overcast days. So, therein lies our conundrum. Expose correctly for the water and the rock undersides become black holes or expose to bring out some detail under the boulders and the water loses all detail in the white areas.

"This is when my HDR software comes in handy. But now, with the moving water, we have another problem: when the short exposures (-2ev) and long exposures (+2ev) are captured in an HDR series, the water can often look unreal, almost abstract, and even visually distracting (especially in this type of quiet stream scene). In order to get sufficiently long exposures on every image in my HDR series, the Vari-N-Duo was the obvious tool to be used. The polarizer also helped tone down the glare from the rocks.

"My base exposure in the 5-image HDR series was 1 second @f/22. That would give me a 1/4 second @ -2ev, which wasn’t slow enough to keep the water smooth on all 5 exposures. I figured out that if my base exposure could actually be 4 seconds, my longest exposure would be 15 seconds, no problem there, but more importantly my shortest exposure would be 1 second. Adding the Singh-Ray Vari-N-Duo slowed the exposure sequence so that my shortest exposure of one second easily blended with the other longer exposures to get the same smooth feel as in the natural image above. The blending of all five HDR images and some tone mapping in post-production resulted in this final 'super-real' HDR image, where the undersides of the boulders are well exposed and the water is practically identical. The scene was captured in the Tremont area in the Great Smoky Mountains with my Nikon D3X and 24-70mm f/2.8 lens.

"Contrary to some in this age of digital imaging who assume their computers erase the need for using filters in the field," says Tony, "I continue to rely on all my Singh-Ray filters to help achieve the images I see in my imagination." To explore the wide range of Tony's photographic pursuits, including his books, workshops and fine art images, you'll want to visit his website and blog.

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.