Ferns in French Canyon

The weather did not fully cooperate on the day I went to Starved Rock to lead a landscape photography workshop.  It rained in the morning, was sunny in late morning but began to cloud up after Noon, just the time we were going out to shoot.  Sure, you say, shooting landscapes at Noon is crazy but as an experience in composition for workshop participants it has a world of value.  Anyhow, back to the subject at hand.  I chose to explore in French Canyon, a canyon in the sandstone carved by flowing water fed by snowmelt and rainfall alone.  Even with an evening and morning rain, the “river bed” was dry with the exception of a few remaining puddles here and there.

As I walked along the dry river bed I saw this bunch of ferns growing from the sandstone wall of the canyon.  Surrounded by fallen leaves, the green of the ferns just popped out at me.  The pattern of the fern leaves and the random scatter of the fallen leaves that surrounded the ferns implies an unresolved tension.  I simply couldn’t walk away from this image.

I decided to shoot using HDR technique.  By exposing for highlights, shadows and midtones in three separate exposures I knew I could overcome the gloomy gray skies and the soft, shadowless light and have an image that reflected the saturation I saw in nature.  I was right.  The green makes a statement among all of the fallen leaves.

French Canyon Foot Bridge

Near the fern patch this foot bridge crosses the river bed just above a small falloff that, in the wet season, sports a small waterfall.  Because of the rain there was a wet streak in the center of the falloff that, from this view is covered by the fallen leaves.  I saw entropy in the colors of the bridge and the fallen leaves carpeting the river bed.  The foot bridge caps the curve of the riverbed as it falls off into deeper recesses of this inspiring canyon.  Of course, the way I framed  the image a viewer is not privy to specifics about where the bridge comes from or goes to.  The bridge is just there, much like the landscape, only it is placed by some organizing purpose while the landscape simply is, a random occurrence peculiar to the geology of the area and the erosive forces of water and ice.

Here are some shots of participants applying some of the ideas discussed in the workshop.  The day was a mixture of sort of dull light with some interruptions of bright sunlight.  There was a threat of rain, mostly in the morning when we were inside talking.  No one seemed to mind the weather and all went out shooting up a storm.  I was out there with a gray card and my light meter which gave me an opportunity to talk about how one uses the gray card to control white balance along with manual metering to assure a proper exposure in the camera.  One might want to rely on the in camera meter for some shooting but for greater control a manual meter and manual adjustments is needed.  I even had a chance to explain what I was doing to a group of hikers walking through French Canyon where we were shooting at the time.

When we returned to the conference room to look at the work we did it turned out that because I shot in RAW format, my computer would not read the .cr2 files on my card.  What a bummer, I thought.  We looked at a number of images made by participants, looking at them through the critical perspective of composition.  But I didn’t get to show any of mine.  Well, I can now correct the error and show off four images that I shot while out in the woods.  These images, all of them HDR conversions, were shot using 5 exposures in a range from 2 stops under to 2 stops over at one EV intervals.  The first image is a ferns and leaves that I though presented interesting visual patterns.  The second image is made from an overturned tree root structure.  One can see the embedded dirt throughout the entire frame.  I shot this fairly close with a long lens (I was using a Tameron 70-200mm f2.8 lens wide open) looking to capture the irregular patterns of the roots as they spread out from the center.  The next image is of a hollowed out log at the base of an intermittently flowing waterfall.  I was struck by the contrasting shapes as they contributed to the almost surreal nature of this scene.  Finally, a fence line leading along the path at the top of a canyon.  To the left of the fence is a several hundred foot drop to the canyon floor.  I was taken by the almost strange leaning of the fence as it serves to protect hikers from doom.

Our next workshop is tentatively scheduled for late January, although we do not have firm dates as of this moment.  We will be exploring lighting for portraits using simple light setups as well as available light sources.  Sign up for our email list and I’ll be sure to keep you updated as to the details of the workshop.

The highlight I wanted to emphasize was the haze hovering just above the water.  In the original tone mapped image made from 5 exposures, the line of fog turned a muddy gray.  Unacceptable.  I decided to bias the highlights without sacrificing the midtones so I merged a second hdr file in which I chose the +2, +1 and -1 exposures.  By biasing the highlights I was able to create an image that held the midtones well and allowed the fog to appear as a separator between the tree line and the reflection of the trees on the water.

5-Exposure Merged HDR Image

The merged image to the left is the first merger of the full 5-shot bracket.  Notice the gray-blue tone of the fog line as opposed to the whiter line in the image above.  When working in low contrast conditions it is important to remain flexible in one’s approach in the preparation of the final image.  By shooting a 5-stop bracket I had the flexibility to choose from the exposures to create an image that I found satisfying.  I experimented using other exposure combinations as well but finally decided that the +2, +1, -1 combination produced the image I felt most comfortable with.

Low contrast scenes present one with a series of decisions.  Do I shoot a single image?  After all, my D-SLR is fully capable of recording up to a 5-stop dynamic range with no significant falloff from the scene I was photographing.  On the other hand, should I shoot a 5-stop bracket in order to be able to bias the highlights or shadows without much image manipulation?  Or should I shoot a 3EV bracket to merge into an HDR file?  My personal bias pushes me toward the most expansive choice.  In the end, this choice affords me the greatest freedom available.  I could choose to use a single exposure, probably the one exposed normally.  But I may wish to explore some HDR combinations and so I have the widest possible choices to make in creating merged files.

Single Normal Exposure

The image to the left is a single shot normal exposure, the central exposure used in making the two HDR images above.  For most purposes this image is acceptable but there are areas that would take a great deal of manipulation to bring out.  The area in the right lower corner is lost in the shadows, appearing mostly without detail as the darkest area of the shot.  The HDR images both allow for the green seaweed to show through and the detail on the stern of the boat is not lost.

Here is the point.  There is more to photography than just reading exposure meters, histograms and getting the gamma right, much more.  The most important aspect of photography is not technical, it is visual.  Being aware of the scene you are photographing, the light, the conditions, the dynamic range and so on must become second nature in order to produce a condition in which seeing the scene and composing an image are the most important aspect of your time.

Let’s begin by looking at a few scenes, the EV range likely to be found in any of the given conditions, and the dynamic range/contrast conditions likely to be found in the scene.  Each bullet point below describes a scene, states the EV range and the dynamic range found in the scene.  These conditions are worth committing to memory as they impact how you approach any of the scenes when shooting HDR.

• Interior with bright window light ~ 14-15 EV ~ HDR/high contrast
• Bright sun backlit subjects ~ 15-17 EV ~ HDR/high contrast
• Night scene with street lights ~ 12-13 EV ~ HDR/high contrast
• 100 watt bulb in small interior ~ 11-12 EV ~ HDR/high contrast
• Overhead sun (11:00 AM – 1:00 PM) with some shade ~ 7-9 EV ~ MDR/medium contrast
• Sunny day, side lit subject with some shade ~ 7-9 EV ~ MDR/medium contrast
• Overcast sky and shade ~ 5-7 EV ~ LDR/low contrast
• Overcast sky with sky excluded ~ 3 EV ~ LDR/low contrast

Let’s generate some general ideas from the list above:

1. High contrast scenes all have significant separation of light source and shadow.
2. Point based light such as a bare light bulb or street lights create contrast.
3. Point your camera directly at a light source and you have a high contrast condition
4. If your light source is to the side of your subject you and there is some reflection bouncing back into the scene from a direction opposite your light source, you are in a medium contrast condition.
5. In conditions where shadows are limited or non-existent, you are in a low contrast situation.
6. Dynamic range is correlated with contrast.

It is also important to understand that the human eye sees two kinds of contrast: brightness and color.  Brightness, however, is the only factor in determining the dynamic range of any given scene.  If you want to be more or less certain about the dynamic range of any given scene and you have access to a spot meter or you have a spot meter setting in your camera, meter the brightest and the darkest area of any given scene and subtract the dark value from the bright value.  The difference is the dynamic range of the scene.  The higher the dynamic range number the higher the dynamic range.  High dynamic range values are always greater than 11 stops.  Medium dynamic range (MDR) falls between 7 and 11 stops.  Low dynamic range (LDR) is always below 7 stops.  Some judgment is required at the transition points.

Center exposure in 5-shot bracket compressed from RAW to JPEG

The image to the right was shot as the center image of a 5-shot 5-stop bracket used to prepare the HDR image at the beginning of this post.  The sun is positioned behind the building and the sky was somewhat overcast creating a condition of flat light.  When comparing the histograms of the original proper exposure and the HDR image, one can see the even spread of midtones across nearly the entire histogram of the single exposure and the concentration of the midtones clustered in the center of the HDR image.  The top histogram indicates to me a flatter, medium contrast or MDR condition.  The HDR corrects that condition.  In the processing of the HDR tone mapped image I pushed the saturation to capture the rust on the pipe at the front of the building draining into the sewer grate near the door.

Variation in Dynamic Range as seen in the distribution of Mid-Tones (Top spreads mid-tones flatly across the entire range while bottom shows a normal distribution of shadow, mid-tone and highlight)

Some things to think about when considering the dynamic range of a scene.

1. Treat reflective sources as a light source.  Reflective surfaces dramatically increase the brightness of a scene.  Ignore small reflections but big ones cannot be ignored.
2. A dimly lit scene may be low contrast if you do not include the light source in the image
3. A brightly lit scene may be low contrast if the light source is not included in the scene.  Consider a cloudy sky.  Shoot the sky without including the sun in the shot and you likely have a low to medium contrast scene.
4. During the 20-30 minutes prior to sunrise or after sunset contrast is relatively low unless you are shooting directly into the rising or setting sun.  The same is true for the golden hours after and prior to sunrise and sunset.
5. Do not try to expose for the sun’s disk.  Expose for the scene and allow the sun to be blown out.

Tone mapping software, especially Photomatix Pro, offers one a wide range of creative control.  One may use controls to keep the image looking more natural, more realistic look, much like a single image shot or one may use controls to achieve what some have described as painterly, cartoonish, or surrealistic.  In my own work, I tend toward creating the more surreal look which often prompts people to ask if I enhanced the colors.  In fact, the rich saturation I achieve is the result of the HDR process and nothing more than that.

That being said, one must also realize that  tone mapped images are rarely perfect, hence the need for a powerful image processor such as Photoshop.

S-Curve for Enhancing Contrast

Tone mapped images may look flat, may lack overall contrast, and often suffer from ghosting, halos and other artifacts.  Depending on the amount of a surreal look one wants to achieve, the first step in adjusting the final image file is to use curves to enhance contrast.  The S-curve to the right is a simple adjustment that adds contrast to a flat image.  One must be careful to not go overboard in making curve adjustments.  I like to do curves adjustments on a separate layer so I can also take advantage of masking, blending and opacity adjustments separately.  The object of the curve adjustment is to preserve highlights and shadow detail while boosting the contrast of the midtones.  You will notice a significant improvement in the appearance of your tone mapped image with the application of just a slight S-curve adjustment.
There are other ways to creatively approach your hdr imagery.  But I will save some of those for a later post.

What struck me about this scene near Galena, Illinois was the juxtaposition of the bright red farm buildings in the upper left set in a corner opposition to the grazing cows at the bottom right.  The colors of the mature corn fields as well as the deep green of the pasture near the buildings helps hold this image together for me.  The scene presents an idyllic view of farm life without acknowledging the hard labor that is farming.  There is no sweat in the scene from a distance.  There is no hardship from afar.  The image presents a delightful surface view of a life that, while ideal, is no representation of the underlying reality that produces the external picture.

Not 5 miles from the scene above, the remains of this truck rusts in a field, internal  parts removed.  Shot with a Canon 5D with a Tameron 28-105mm lens set at 28mm f/2.8 lens with the focal length set at 28mm and the aperture set at f/16 on aperture priority mode.  This image was merged from a 5-shot bracketed exposure with 1EV between each exposure.

The rusting carcass of this abandoned farm truck asks the viewer to contemplate how one removes that which is no longer wanted from close contact.  It asks one to think about how we remember or want to remember things past.  It begs the question of waste, pollution, nature and responsibility.  It litters the very land it once served becoming an object of art for passing photographers.

These two images shown together ask one to step into the image and peel back the layers that are unspoken, unseen, so as to explore one’s relationship to the world in which we live.

I was recently asked, “Can I shoot hdr with by PHD (push here dummy) camera?”  The short answer is a qualified yes.  As long as your camera has a setting that allows you to control the exposure settings you will be able to shoot hdr.  You need a bit more than a camera to do so.  In order to merge your images into a 32-bit hdr file you also require an inexpensive piece of software that handles both the merging itself and the ability to then tone map the image and compress the hdr file into a usable 16-bit TIFF file.  This software is inexpensive, available for both iMac and Windows and is generally easy to learn and use.  I use Photomatix Pro for my work but there are others available for both platforms.  FDRTools is available for both platforms.  If you work on a Windows platform then you might look into Dynamic Photo HDR or Artizen HDR as alternatives.

After my discovery that a 7-shot bracket is far superior to a 5-shot bracket over the same 5EV range, I decided to try a 9-shot bracket at the next available opportunity.  I wasn’t planning on doing this the very next day but, while driving to deliver some prints to a client, I saw this tractor in a hayfield that just screamed, “Photograph ME!!!”  On my way back I took out my camera and tripod, parked the car and shot away.

If a 7-shot bracket over a 5-stop range is fantastic, how can I describe the 9-shot bracket over the same range?  I am not certain there are enough superlatives in the language to describe anything like what I have in front of me.  The richness of the shadow detail along side the sharpness of the highlight detail is quite striking.  I printed the image on Moab Entrada Rag Bright matte paper and the image simply jumps off the page.  The luminance value of matte paper is far less than a glossy finish so I also printed the image on Photopaper Glossy Professional paper from Office Max (I use this paper for proofs and presentations) and the image nearly jumped off the page.

I want to say a bit about when to use more exposures in a bracketed shot.  The scene with the tractor was a high contrast scent, bright sunlight, dark shadows.  While in the days of film one might refer to such a day as a 5-stop day, the truth is it is more like a 17-stop day.  In a high contrast situation, in order to cover the totality of the dynamic range, one must make more exposures over the 5-stop range.  As one overexposes one really is exposing for the brightest part of the dynamic range while the opposite is true for the under exposed shots in the bracket.  While a 5-shot bracket is better than a 3 shot bracket, so a 7- or 9-shot bracket will capture incrementally more of the dynamic range and, therefore, provide an hdr image that captures more of that range.

In low contrast situations, what one might call a 3-stop day, say, for example, in overcast skies or in foggy conditions, or just in shadow, a 3- to 5-shot bracket across 3-stops will be adequate to capture a vivid hdr image.  Indoors, in normal tungsten light, I shoot as I would in low contrast conditions.

A couple of other thoughts.  I have written about the need for a sturdy tripod when shooting for hdr images.  I use a carbon fiber tripod because it is lightweight yet incredibly sturdy.  The problem with carbon fiber is the expense.  My tripod cost a bit under $900.00, and when I bought it that was a bargain.  Today, however, the story is different.  Induro carbon fiber tripods start at around $300 and provide the same light weight and sturdy features that my tripod does.  Trying to shoot hdr without a sturdy tripod is something like balancing on a tightrope in a 30 mile per hour wind.  The results won’t be so good.  By the way, a sturdy tripod on soft ground is not sturdy.  When setting my tripod on soft or spongy ground I generally wiggle it around until it settles on a firm surface.  In another situation, you may set your tripod on a smooth polished surface, tile or marble flooring, which may cause your tripod to slip.  Again, a remote trigger is advisable in a situation like this.  When you are out in the field you must do everything you can to get the shot right the first time because you may never again have the chance to re-shoot.

Another thought, if you are shooting at 1/15th of a second or faster and your camera has a mirror lock up feature you might want to use it.  The movement of the mirror causes some camera shake and that shake is likely to place stress on the merger of your bracketed images.  You might try shooting the same image with and without mirror lock up and compare the difference.  If you do use a mirror lock up it is a good idea to have a remote firing device, either an electronic device or, if your camera allows, an old fashioned cable release. Shutter speeds less than 1/15th of a second don’t really require mirror lock up simply because the vibrations caused by the mirror are long over before the pixels begin to saturate across the digital sensor.

Technical stuff aside, I became enamored by the tall grass prairies of my native state around 2 years ago when I began making macro images of wild flowers growing on the prairie.  The more I looked, the more I saw and what I saw seemed to be in constant flux, changing every day.  As we move from Summer into Autumn, the tall grass prairies are beginning to display more rust and yellow colors.  Grasses are preparing for Winter, marigolds are in full bloom; the prairie smells lush and musty.

These glacier cut lands with their trees and grasses do not give up their beauty easily.  It is easy to pass by unimpressed with the endless sea of grasses waving in the wind.  Where, one asks, is the scenery among these flat lands.  No mountains rising majestically above the plains, no great bodies of water creating insurmountable barriers.  Just rolling hills and creeks and rivers cutting through natural depressions.  But look closely and one finds a richness beyond compare.  Every plant, every insect, every snake, every living thing lives in harmony, each playing a part selected over millions of evolutionary years.  The apparent randomness weaves itself into a space worthy of preservation, worthy of conservation.

JPEG 5-shot Bracket

JPEG 3 shot Bracket +2, 0 , -2

RAW 5-shot Bracket

The four images to the left represent one each of one of the JPEG hdr mergers and the RAW hdr mergers.  My initial impression of simply looking at the images was clear.  The 5-stop bracket in either the JPEG or RAW versions provides superior quality than does the 5-st0p 3 image bracket.  In short, both images in the pairing were merged from the same exposures.  In the 5 shot image the bracket I used was a 5-exposure bracket with 1-stop between exposures.  In the 3-shot bracket I used 3 of the 5 exposures with a 2-stop differential between exposures.  Selecting only the extremes, it seems, leaves out much subtlety that otherwise could be in the images.  In fact, though not readily apparent in the 3-shot bracket JPEG, there is much clipping in the clouds that is simply not present in the 5-shot bracket.  My next experiment must be to compare a 5 shot with a 7 or maybe even a 9 shot bracket using 1/2 stops or, perhaps 1/3 stops, rather than full stops.

The 5-shot brackets produced a richer, more realistic rendering of the scene.  While I am not displeased with the 3-shot brackets, I believe that I have missed out on some wonderful opportunities in not shooting this way.

Now for the RAW mergers.  To my eye, the RAW mergers were far and away the richer, more satisfying images overall.  They tended to be a bit darker, even with the tone mapping presets exactly the same.  They also tended to be more subtle in both versions.

RAW 3 shot Bracket +2, 0 , -2

Interestingly, when one compares histograms of the two sets of images one sees very little difference between the JPEG and the RAW images.  The top pair are for the 5-exposure bracket while the bottom pair are for the 3-exposure bracket.  I did not do a fancy test of significance but I suspect that if I were to do so there would simply be no significant difference in the luminance between the JPEG or RAW merged images.  For all intents and purposes, the histograms are equivalent.  So the difference I see must be qualitative, my subjective interpretation.

Compare Histograms JPEG-RAW_2_16-bit_TIFF

So here is what I now think.  First, I continue to suggest that if you want to shoot hdr and your camera only is capable of shooting JPEG that’s fine.  I wouldn’t run out to buy a camera that is capable of capturing RAW images unless, of course, you have some other reason for wanting to capture RAW.  For hdr purposes, it is simply not necessary.  Secondly, if you have the capacity to shoot RAW then do so for hdr images.  Your results will be far richer and pleasing than if you shoot JPEG.

Compare Histograms JPEG-RAW_2a_16-bit_TIFF

The jury remains out for me regarding the efficacy of the 3 image bracket.  I am now leaning toward the 5 image bracket and perhaps even more that that.  I will have to test that possibility soon.  For my work, however, it is clear that I will shoot my hdr images in RAW and expose a 5 exposure bracket with 1EV between exposures.  This seems to be a reasonable approach to this otherwise subjective problem.  I am sure I will have more to say in the future that will revise much of what I said here.  But, like everyone else, I am still learning how to apply the craft of photography to the photographic arts.

In HDR photography, RAW does provide one with a possible advantage.  RAW exposures create a digital file (not an image) that captures all that the camera’s sensor is capable of capturing.  The RAW image displayed is prioritized to the camera settings but all of the other image data is present in the file as well.  In single image shooting, RAW offers one a wide range of fixes for shots that simply got away, that are over or under exposed or the white balance is way off.  Because all of the data is already there, poor RAW images can be salvaged.  In HDR the RAW file allows one to create a faux HDR image in a number of conversion/merger software solutions.  Photomatix Pro, the software I use allows one to create a good HDR image from a single RAW formatted file.  The image to the left is one I captured recently while visiting the Volo Bog in Northeast Illinois.  I was on a walk with my wife (it was a slow day at the studio) and, of course, I had my camera along because I intended to take some macro prairie flower images.  This shot presented itself; I shot it hand-held in RAW with the intent of creating the faux HDR image.  In this case, I made a good choice.

Other post-processing software have presets that selectively adjust the highlights and shadows of a single image to produce something that appears to have the full dynamic range of a merged HDR image but don’t be fooled!  Adjusting the shadows and highlights is something like putting 10 peaches in a small basket and then transferring them to a bigger basket.  The fact still remains that one still only has 10 peaches.  While these adjusting techniques produce interesting images, they are not what they pretend to be.

One more thing to keep in mind.  RAW files are quite large and slow.  Recall that they record simply everything that can be recorded and store that information in a digital file.  To display the RAW file on your camera’s display or on your monitor the prioritized image is converted to a JPEG prior to display.  JPEG captures are smaller and load much quicker in both the camera and monitor.  Shooting JPEG will speed processing time.  If this is important to you than JPEG may be the format of choice.

Making the choice between shooting HDR bracketed images in RAW or JPEG is a matter of choosing the best solution for the task at hand.  Let me give you an example.  When I am going out to capture an HDR landscape I normally lug my Canon 5D and a carbon fiber tripod (its both sturdy and lightweight but quite expensive).  That way I can take my time, compose the image to my liking and manually control my bracketing.  When I am in full control I capture HDR brackets in high quality JPEG.  But there are times when I am taken by surprise.  I see a scene that would make a perfect HDR image but I don’t have an adequate tripod with me.  I then take a single image shot in RAW and let Photomatix Pro create a faux HDR tone mapped image.  While not perfect, it is a perfectly good solution in a pinch.