Sunday, March 29, 2009

HDR - a leap in the evolution of tools for high contrast scenes

The problem of dealing with high-contrast situations has been with photographers for ages.  The human eye can see a much wider range of light than can be recorded by film or digital cameras, or that can be displayed on prints.  In many lighting situations, this leads to photographs that are missing much of the shadow or highlight detail that you see out in the field, and disappointing results when you process the image.

Over the years, the solutions for this problem have evolved.  Ansel Adams was a master at recording as much dynamic range as possible with his Zone system and knowledge of processing chemistry, and printing techniques.  The earliest technique that I learned about was dodging and burning an image in the darkroom to get more detail on the print -- more texture in the clouds or in the shadows.

Later when I was using colour slide film, the technique changed to using split-density filters.  These filters would typically lower the amount of light from the sky, and allow the film to capture more detail and colour in both the sky and foreground.  I also used (and still use) a polaroid filter to tone down the highlights and darken the sky.

 Mill of Kintail, March 2009.  
Simple Raw processing only.

Now with digital photography, I have often used the same technique as split-density filters, but now I make more than one exposure of an image -- one to capture the highlights, and one to capture the shadows. I combine them, often with considerable amount of time and effort, to produce an image that comes close to what I saw while taking the photograph.

I have also used a tool from Kodak, called Digital SHO Professional, a plugin for Photoshop that also works nicely with Corel Paint Shop Pro.  This plugin expands the detail in shadows and highlights of an image, and can significantly improve many high contrast images.  This tool was a big improvement over other manual methods, but it sometimes gives quite unrealistic images, especially with the the amount it boosts saturation.  I often have to reduce the saturation considerable over the default values in the tool, and sometimes I blend the resulting image with the original to mute the effects, and make the final image look more authentic.

Mill of Kintail, March 2009.  
Processed with Kodak Digital SHO Professional plugin.

Also available in the recent releases of Raw image processing software such as Capture One, there are tools that can expand the detail in highlights and shadows.  I have also been using these tools increasingly often to deal with high contrast scenes.  With tools that operate on a single image, it helps to photograph using the lowest ISO possible, to avoid noise in the shadows that these tools make much more apparent.

Over the last year or two, HDR (High Dynamic Range) software has been developed that makes a huge leap in the tools available for managing high contrast scenes.  The big difference is that these tools take a series of images that represent the range of tones in the scene, and combine them to produce an image that represents the whole range of tones.  Typically, you would use three or more images ranging from +2 or +3EV to -2 or -3EV, giving you a wide range of tones to work with.  Then, the HDR tool essentially compresses the wide range of tones in the scene into a representative range in the image file.  It automates the technique that had been done earlier by hand, but does so with a much higher level of precision than could be achieved before.  The results can be spectacular.

Mill of Kintail, March 2009.  
Four images (+2, 0, -2 and -4EV), processed with Photomatix Pro.

Last week I tested out a couple of different tools, but by far the best was Photomatix from HDRSoft.  Photomatix is a bit on the expensive side ($99 US for the standalone program), but it produced the best results of the programs I tried, and gives you lots of control over the look of the final image.  There are two steps to the process: first, you read in all of the images and align them into a single "HDR" image, and second, you map the tones in the image into a final image.  The tone mapping stage allows you to control the intensity of the HDR process, saturation, luminosity, colour temperature, and other options to let you get the effect that you want.

After processing the final image, Photomatix allows you to save the image as a 8-bit or 16-bit tiff file, or as a jpeg.  I have found that I still want to process the image afterwards, to fine tune the brightness and contrast. Even with the various controls available, I haven't found the right combination to produce the final image (although I haven't spent enough time yet to try out all the options).

One caution:  in browsing the HDR images on the web, there are lots of spectacular examples of HDR images.  However, there are also examples where the HDR effect is overdone to the extent that it dominates the photograph, and produces a highly unrealistic result.  This may have been the intention of the photographer, and that's okay.  This technique can produce some fascinating results, but not necessarily good photographs.

Personally, I prefer more subtle results that look good, but where the technique does not overpower the subject matter of the photograph.  As with any tool, you have to understand it's strengths, and know when and how to use it to benefit the image.  HDR tools are a valuable step in the evolution of techniques to manage high contrast scenes.  Although Photomatix is expensive for a stand-alone tool, in reality, it only costs a third of the cost of a single split ND filter that I used to use for film (and I needed several with different grades).  I look forward to taking advantage of it in the future.

. . . Rob Williams

Monday, March 23, 2009

Expect the Unexpected

One thing I really enjoy about getting out with my camera is that I never really know what to expect.  I always make a plan, deciding where to go and I try to envision what kind of photographs I want to make.  More often than not, though, I end up discovering something new, or getting distracted by something that catches my eye.

This weekend was prime Maple Syrup weather around here (temperatures are below freezing at night, and above freezing during the day), so I decided to visit a local pioneer farm where they have original farm buildings and demonstrations of how sap was collected and processed in the past.  I was planning on photographing the old buildings and maple syrup production.

Log Farm Buildings 
I really like the textures of the old buildings and log fences.  I'm really glad that these buildings have been preserved to show us what kind of life the area's settlers had to live.
Original Barns at the Log Farm
I ventured inside the barn shown above, where it was completely unlit except for the light from the door.  It took my eyes a moment to adjust to the light, but then I really got a feeling of what it must have been like back when the farm was running in the mid 19th century.  The interior was not as weather-worn as the outside, so it gave a feeling like you had been thrown back in time seeing the barn as it may have been all that time ago.  I made a few photographs there -- using only natural light and exposures in the 10's of seconds.  
Riding equipment

Ropes hanging in the barn 
I know that the materials and colours are not quite the same as 150 years ago, but the feeling inside was quite unique.  I think these two photographs are my favourites of the day, even though this kind of photograph wase the furthest from my mind when I started the day.

. . . Rob Williams

Saturday, March 7, 2009

Photography in Winter: Light painting

Asiatic Lilies

In the winter, the weather often doesn't cooperate, and I resort to learning how to photograph in the studio.  I have a section of the basement sectioned off as a makeshift studio, basically making use of a plywood table I made when I was a student, and other material that I've scrounged from around the house.

I started off buying two used SB-26's from EBay to use with my SB-28, but this year I have started using just a flashlight, and painting the light onto the subject.   Right now, I am primarily using a very small LED flashlight that is on a flexible arm.  It cost me about $10 at a local hardware store.  To give me some protection from the glare of the light, I taped a 2cm black cardboard tube to the end of the arm where the LED sits.  The tube just stops stray light from leaking out.

The flashlight gives me a huge amount of control over what the final image looks like -- it makes using flash with all of the gadgets to control the light seem crude by comparison.  The light of the LED makes a circle of only an inch or two in diameter when the flash is close to the flower, so I can light individual petals if I want.

However, all of that control comes with a price.  It takes a great deal of time and effort to make each exposure, and I have to get all parts of the image correctly exposed for the final image to be good.  Each image takes at least 30 seconds to expose -- sometimes up to a couple of minutes.   If I get the background done well in one image but not the foreground subject, I have to remember how I exposed the background for the next image.  It's actually quite a bit like making a print using an enlarger.  Often  you have to dodge and burn parts of the image.

Another downside is that the LED light is not exactly "white".  It's quite blue, and I have to adjust the final image's colour balance to compensate.  I found a good balance while I was photographing a white flower (see below) and I've saved the setting in my raw image processor.

White Flower

In the end, I really like the results.  The flower seems to glow with light.  Each image is unique, so sometimes it's a matter of opinion about which image is the best of the bunch.

. . . Rob Williams