Chromatic Aberration

Foiling the Fringe in the Camera and in the Digital Darkroom

The Fringe

You know the old saying, "There is nothing that is certain except death, taxes and Chromatic Aberration". Chromatic Aberration (CA) is a physical property of light when focused by a lens and the result is varying degrees of color fringing which you may have noticed, especially on the edges of your images. 





From Wikipedia

The Physics
Ever since Newton passed sunlight through a prism, we have known that different wave lengths of light are bent to different angles as they pass through a lens. This is called dispersion and because a simple lens cannot focus all colors of light on the same plane (your camera's sensor), colored halos or fringing is created. This effect is seen most prominently on the edges of images and in areas of high contrast. Red and green bands are most common, but blue, yellow and purple may also be seen. This is all called Chromatic Aberration and although saying "Chromatic Aberration" may make you sound intelligent at the photo club meeting, the color banding can contaminate your images. Fortunately there is much that can be done to minimize or eliminate the fringe, both in the camera and in post processing.


In the Camera
Throw Money

As expected, more expensive lens typically do better with CA. 

From Wikipedia

special coatings and combinations of multiple lens elements can reduce and compensate for light dispersion. Achromatic and apochromatic lens also use special materials, such as fluorite, that have properties of low dispersion. Think of this when you are pondering how a lens could cost several thousand dollars. 


 

Avoid High Contrast Situations.
Creatively it is not always possible or desirable to limit high contrast in your images, but, especially on the edges, contrast control can make a big difference.

Stop Down
CA is more apparent at the widest apertures. Stopping down just a step or two from wide open may limit your beautiful bokeh, but it can reduce the CA contamination dramatically .

Avoid the Extremes of Zoom Lens
It is hard to engineer zoom lens that can offset dispersion across the full range of the zoom. You will usually get the best results somewhere in the middle of the range. Extreme wide angle lens may be especially susceptible to this effect.

Get Ready for the Digital Darkroom
There are a couple of things that can be done to get the image in the camera ready for the work that can be done in the digital darkroom. First, this another situation where shooting in RAW can make a big difference. The great flexibility of RAW images makes it easier to correct for CA in post processing programs such as Camera RAW. Also, one simple approach is to frame images with extra room around the edges which will then allow cropping of the worst areas of CA without sacrificing the composition.

In the Digital Darkroom 
 

Fading Crimson

You've done what you could in the field, but you still notice ugly fringing at the edges of your images. Fortunately, with every new version of Photoshop, the tools to control CA have become more effective and easier to use. Here I will be speaking specifically of Photoshop and the newest version of Camera RAW, although Lightroom approaches the problem in a similar manner. Other image editing software, such as Paintshop, have their own solutions to this problem. 

Lens Correction in Camera Raw

Fringed

In newer versions of Photoshop's Camera RAW correction of CA is largely automatic. Within the Lens Correction menu, the "Color" tab features a simple radio button for Chromatic Aberration control. It is almost magic. The program can reads the image meta data to determine the camera and lens used and in most circumstances applies the correct adjustment without further input. This is much easier than in earlier version in

Aberration Control

which individual red/green and blue/yellow sliders required careful manual adjustment. After the automatic adjustment, some fringing may still remain, especially the more difficult axial CA in the purple/green range. Below the automatic button, purple and green sliders allow fine tuning of the adjustment. In addition to controlling the amount of adjustment, the Hue slider can precisely target the color affected. 

Facing the Dawn, Rockport, Maine

Fringed Rungs

De-Fringed

Dealing with Chromatic Aberration can be frustrating, but, with awareness of the problem, adjustments in the camera and in the digital darkroom can be effective in foiling the fringe.
 

Solstice, Spofford, NH

Dumb Luck and Backing Up Your Images

Do as I Say, Not as I Did

Golden Corridor, Almost Lost

You have heard it many times before, but it can never be repeated too often. Back up your work! This week I will describe how I have attempted to back up my photographs, not as an example of best practice, but as a cautionary tale about what can go disastrously wrong and how dumb luck saved me. 

Several weeks ago I received an order for a copy of one of my favorite recent images. I had printed this image before so I knew that the file was in my edited images directory, ready to print. I found the file, but when I attempted to open it in Photoshop the computer whired for long minutes and then froze. My heart sank as the same thing happen on every file I tried to open from this directory. Nothing worked, and I realized that I had lost thousands of hours of work on more than 4000 of my best images, collected over more than a decade.




During over ten years of more serious New England photography

CD Backup

and especially since digital imagery has come to dominate my work, I have taken various approaches to backing up my photographs. In the early years, the image files were so small that I could fit several months on a single CD. From 2001 until early 2008, I felt secure keeping one set of CDs at home and a second copy in my Keene, New Hampshire office, but as my cameras went from 2 to 6 to 12 and then 21 mega pixels, this solution was no longer practical. Today I would require several DVDs to backup each month's work. This October I captured over 1500 autumn images totaling 32 Meg's, which would fill 7 DVDs. With my ballooning backup requirements I have become shamefully sloppy in my "strategy", with files scattered across several hard drives both on internal and external drives. My first PC had a single 120meg hard drive which at the time seemed liked “more storage than I would ever need”. Now I have a total of 32 Terabytes of capacity spread over 15 drives, and yet it seems I am constantly running out of space. I still organize the images by month, but I had some directories backed up on multiple drives and others hanging precariously on just one fallible drive. I was having nightmares about the fact that EVERY physical drive fails eventually. I knew it was an inevitability NOT a possibility. I had to do something and I knew that the best protection was in redundancy.

Tiers of Redundancy

Save the Drobos First
The first measure was to improve the reliability of the storage.

Desktop Backup

Redundancy is the key. One part of my approach was to move my critical data to Drobos. Drobos are redundant, pooled backup drives which contain multiple drives, making it possible for a drive to fail without losing the data. When failures occur, the system automatically compensates and distributes the data across the remaining drives. I now have two Drobo units each with four hard drives adding up to a total of 20 terabytes, but no matter how reliable, any drive or array of drives can fail. The second tier of protective redundancy is to backup to more than one physical drive.

My current backup workflow starts with translating my camera's Canon proprietary raw files to Adobe’s open source DNG format. I like DNG format since it is nonproprietary and because the image meta data is stored within the image file and not on those annoying sidecar XMP files. I use the DNGs for editing and archiving, but before I do anything else, I save the original Canon raw files to a separate drive as a backup. As I work on my edited files, they are stored in a separate drive as well. This leaves me with two copies of all of my raw images, but only one full copy of my finished, edited images. I figured that if I lost my edited images, I would still have the original raw files. I didn’t allow myself to think about the potential loss of my massive investment in photo editing. Stupid! And deep down I knew it.

I also knew that a fire, flood or tornado could still wipe out all of

partridgebrookreflections.com : archive

my images. In case of fire my evacuation priorities are: 1) Drobos, 2) Dog, 3) Wife, but it is still dangerous to have all my images in one location. Recently I have been investigating approaches to “off-site” backup as my third tier of protection. There are a number
of good “cloud based” services (eg Back Blaze, Carbonite and Crash Plan) available to archive my files, but given my massive amount of data, it would take months to upload all my images over the Internet. I thought that If I could backup my current archive, I could then consider using a automatic cloud solution for my future work. In the meantime, I have started backing up my new, full resolution, edited images to my new Zenfolio Website.








I eventually decided to start by creating my own off-site backup

Bob's Closet Archive

and here is where my dumb luck kicked in. After stalling for months, I copied my RAW directories and my precious collection of edited images to a 3TB external drive. My plan was to store this archive drive in my neighbor’s house, protecting me from fire but not necessarily from tornado or nuclear blast. It took more than a day to copy over the files. As planned I squirreled away the drive in Bob’s closet. I slept better that night, but I had no idea how soon that backup would become critical. 


Disaster
Just two weeks later, as if it knew it was safe to retire, my edited
image drive failed. Suddenly I could see the images in the directory but, despite all efforts at repair, I couldn’t get them to open. If I had not created that backup drive I would have lost years of work on all my most popular images. I still had all the original RAW files, but

4000 files, 21 hours, priceless

the number of hours of lost image editing would have been incalculable and devastating. After all my sloppy delay in creating a backup, I definitely did not deserved to be saved, but saved I was. I retrieved my drive and reloaded the 1.8 TB of irreplaceable images. All I can say is that there are a lot worse ways to learn a few lessons. The lesions are nothing that we don’t already know but they are worth repeating, endlessly.

Lesions

• Every machine fails eventually, and that includes the best hard drive or array of drives.
• Images stored only on one drive will eventually be lost.
• Memory is cheap and getting cheaper all the time.
  
• An image does not exist until it is in two places, preferably three, with one off site.
• An automatic solution is better than one that requires regular thought.
  
• Regular thought NEVER happens.

My backup strategy is not perfect. I'm still working on the cloud solution, and the automation of my backup process, but the important thing is to have a plan and follow through. Many of you must have better solutions, but for those who haven't established a redundant backup plan, do it today.  It takes time, but no amount of time or effort can retrieve your precious lost images. You can't always rely on dumb luck. 

Oh, and the correct order is 1) Drobos, 2) Dog, 3) iPad and then 4) Wife.

A Photographic Meander Along the Back Roads of Vermont

Grafton Wreath

Boldly Going Where No Lens Has Gone Before

The other day, it suddenly occurred to me that I hadn't gone out on a significant photo shoot in several weeks. First it was dealing with the Christmas orders, then the joy of having the kids home for the holidays and finally going through the extended process of moving to a great new web site. There are always distractions, even work gets in the way occasionally, but whatever the excuses I decided I had to get out at least for a few hours of photographic treasure hunting.  

When planning a shoot I often set a defined goal, a specific location at a precise time. It may be a lake at dawn or the moon rising over the mountains, but my greatest joy comes from heading out for visual adventures with no agenda. My simple goal is to wander the back roads looking for new locations and letting the light be my guide. It is a bit "Star Treky", "Boldly going where no lens has gone before".



On this day, I decided to explore in Vermont. We still have snow

cover and although the snow is no longer fluffy and coating the trees, it is still a blessing that we are firmly out of stick season. As is typical, I got out a little later than I had planned, but in the dead of winter, the sun is persistently low in the sky making the soft morning light linger until it is replaced, early in the afternoon, by the equally soft evening light. In January, the days are short, but we never get the stark, flat overhead illumination of summer. My plan was to head north through Putney and Townsend and then wander off onto every obscure back road I could find. I often talk about the

Stranded Rake

value of getting lost in country side, but it is hard to get truly lost these day when I have my GPS, iPhone and a dog eared but detailed Vermont Atlas. Of course the GPS is not infallible, especially in the country. It is surprising how often it has directed me to a road which turned out to be an impossibly narrow cow path, but the great thing about confronting a dead end is that you get to turn around and go back . Country roads often appear completely different when traveled in the opposite direction. Never assume you know a road until you have traveled it both ways.


On this day I had a lovely, relaxed exploration and, along the way, I was reminded of a number of challenges and opportunities that are unique to winter photography

Wanderings

Mill Brook

Most of my wanderings on this day were in Townsend and Grafton Vermont. I first came across Mill Brook weaving around the ice encrusted rocks in Townsend. When photographing a stream, I often rotate the framing to favor one side, changing the banks from monotonously centered parallel lines to a more dynamic diagonal path. A little change that can make a surprising difference in the energy of the composition. Nearby was a lovely farm with attractive foregrounds and framing provided by trees, farm equipment and stone walls. I spent about 45 minutes working through the various options, but my exploration had only started. The nice thing about back roads is that you can slowly inch along
looking for attractive scenes without having to deal with as many impatient drivers roaring up from behind. As I did my meander along the forested roads I was on the lookout for interesting arrangements of trees and light. The dense and chaotic New England forest provides few of these opportunities, but at times the foreground and background elements come into alignment with an almost audible snap. I find it relaxing to scan the forest for the "snaps", but I have to occasionally remind myself to check to see if I am going off the road.

Challenges of Forest Lighting
The day was consistently sunny, making capturing the high contrast between brilliantly illuminated snow and forest shadows a constant

Snap

challenge. As always the histogram was a critical aid. Watching the graph, I was able to avoid muddy shadows by exposing to the right, while also guarding against going too far and blowing out the highlights. As I often say, the key was to get the best image data that would provide the raw material for the best post-processing results. Back in the digital darkroom, Photoshop’s “Shadow/Highlight” tool is especially helpful in maintaining texture in the snow without making it look gray. It is remarkable how precise exposure control and the expanded dynamic range provided by shooting RAW can tame previously impossibly contrasty scenes and can be superior to HDR and tone mapping techniques for all but the most extreme situations. The result is images that look like what I actually saw on site.

Brooks

Simpson Brook

I came across several lovely little brooks in the forest. Winter
waterfalls are often more challenging to capture without the contrast of sparkling water cascading next to dark, rocky ledges.  In fact, in winter, the relationship between the water and the surroundings is reversed, with the water best seen dark against the white banks. When flowing water is surrounded by soft snow, I tend to use shorter exposures to provide more texture to contrast with the flat, homogenous appearing snow. I love to shoot flowing water with long exposures, but the velvet streams can become lost in the surrounding white. 

Grafton Inn

Grafton
After wandering for a few hours I made it to the Townsend Road. Sadly I was back on pavement, but it led me to the classic New England Village of Grafton Vermont. The town is known for the traditional warmth of the Grafton Inn, but I was drawn to the Grafton Village Store where the Chili was outstanding. 

Great Chili, Car Needs a Wash!

 
From Grafton I discovered a few more back roads and old farms. By the time I got to Saxton River, I had been out for about six hours and 80 miles. I was ready to head home to see what I had on the memory card. I find I get a bit hazy after 6-7 hours of head swiveling. On the way back, I got a chance to revisit Westminster West and it's famous sign post. It is always interesting to be reminded that London and the North Pole are both about 3000 miles away. 

Add caption

Back in Spofford I resisted the strong urge to dive right into the images and instead, went through my usual post-shoot workflow. I downloaded the 97 images, applied the GPS coordinates, inserted appropriate meta data and renamed the collection with the date and successive numbers. Then I FINALLY got to actual look at the images. I always feel that a shoot has succeeded if I get even one true “keeper” and although I didn’t find any “breath takers” there were several definite “keepers”. This was as expected with the nice, but not spectacular, light and the somewhat settled snow. Nevertheless the pictures are interesting and quintessentially New England. They may be just what someone is looking for. I have learned that it is impossible fully anticipate someone else’s taste, especially from those who don't have the good fortune of living in the midst of all this beauty.

Most importantly I explored some interesting terrain that I have filed away for future visits when the conditions may be different - they are always different. Learning more about your local country-side is never a waste of time and can be exciting even without a camera in hand.

Photographic Preservation of New England's Visual Heritage

Market Basket's Memorial to the Bardwell Farm

Some years ago, I was picking up my tractor (sounds more manly than "lawn tractor") , at a shop on route 12 in Swanzey New Hampshire, and noticed a classic run down red barn across the street. The barn was massive with lots of interesting and seemingly superfluous additions, sprouting off in all directions , like an unruly shrub. The place was long deserted and seemed ready to collapse at any moment. The perfect photographic opportunity. Of course the light wasn't great and besides, I only had my old camera phone. I vowed to return on a better day with a better camera. I would love to show you images of this historic icon of our New England agrarian tradition, but, before I could get back to the site, the barn was sacrificed to modern commercialism and replaced by a sprawling and sterile Market Basket grocery store. You can find pictures of barn, by other photographer, scattered on the Internet, but I still have a sense of irrevocable loss. It all serves as strong reminder of the role photographers have in preserving the fleeting visual heritage of our unique corner of the world.

 



Whether we realize it at the time, our photographs are a treasure chest of traditional New England scenes that are slipping away, day by day. We have all seen the "Then and Now" features in newspapers and magazine using old photographs to show how things have changed. It is important to realize that our photographs today may soon become the "Then" images used to compare to some sadly diminished "Now" of the future.

Before we get hopelessly depressed by our dull, traditionless,

Harrisville, NH

future, it is important to remember that there is much we can do to protect our irreplaceable heritage. A great example is the work of the Harrisville Historic District. The residents of Harrisville, New Hampshire have done a remarkable job preserving their classic New England mill town. As photographers, our support of historical preservation protects the very fiber of what makes New England such a great place to live and to practice our art.


In the short time that I have been engaged more seriously in New England photography, I have seen many examples of the loss of our visual heritage. The causes are varied and often not as a result of the wrecking ball. Precious vistas have been lost due to natural decay, surrounding development, or overgrowth of natural and introduced vegetation. Often the intrusions seem small, but enough to disrupt a delicately balanced scene. We have all seen this, but it is important to remember that the photographer has a special opportunity and responsibility to capture these scenes before they slip away forever.

Then and Now

Decay
For years I had intended to capture a classic sugar shack along side Route 9 in Stoddard, New Hampshire. It never seemed to be the right time until one misty autumn morning in 2006, when I found myself stopped for road construction right in front of the shack. The Gods were obviously speaking to me and I had just enough time to leap from the car and grab a 4 image panorama. I love the shot, but since that time, the shack has fallen to neglect and now seems poised to crumble to the ground. Buildings in decay can be interesting subjects, but it is the sense of loss that is fundamental to their power.

 


Development
My parents lived in a condominium over-looking Paugus Bay on Lake Winnipesaukee. On the hill above their place was a lovely isolated pasture which featured a stately lone Sugar Maple standing

Encroaching Development, Laconia, NH

defiantly in the middle of the field. The tree and surrounding woods was a hidden treasure of peace and photographic opportunities, but a few years ago development invaded the pasture. The beautiful clean forest backgrounds were bulldozed and my noble Maple was made to stand against rows of monotonous gray buildings and a sprawling parking lot. I could still find a few angles on my tree, especially when morning fog obscured the development, but the sense of quiet solitude was lost. 





Ridge line development is a growing issue in New England. It is

Storms First Light

understandable that people want to build their houses on the slopes, where they can command broad views of the surrounding country, but these structures scar the beautiful forested hillsides. Stonewall Farm is nestled among low hills in Keene, New Hampshire. A few years ago I caught the first light after a storm, breaking above the mist on these hills. Now the same 
location is a warren of lovely but incongruous homes, lawns and steep driveways. It is a difficult 

Lost Ridge

problem not only esthetically, but also because these developments create erosion issues.
Happily, towns are beginning to recognize this problem and are creating "steep slope" ordinances to limit development in the most fragile areas.



 


Overgrowth
The Jenne Farm in Reading, Vermont is a world famous example of

Jenne Farm 2005

the classic New England farmstead. It is justly recognized as one of the most photographed farms in the country. On a perfect autumn morning it is a challenge to find an open piece of ground to set your tripod. It is amazing that the owners of this working farm deal with the crowds of
photographers with such patience and good humor. I have been visiting the farm for only a few years but have noticed the growth of bushes and small trees which are progressively obscuring the best

Growing Cover, September 2012

angles on the farm house and out building. The plantings are perfectly understandable as an attempt by the beleaguered residence to protect a little privacy, but for photographers it is a lesson in the constantly evolving nature of our landscape and in the importance of capturing it when we can.





Another example of the natural encroachment on our scenic

Weathersfield Birches

treasures is the "Weathersfield Birches". I had read about this lovely collection of birches in this central Vermont town, but by the time I found the grove it had become engulfed and smothered with young sapling. The good news was that during my search for this famous collection, I came across another grove of unobstructed birches nearby. 

My New Birches

Little Things
It isn't always dramatic changes that can diminish a classic composition. When I first captured one of my favorite red barns in Keene, New Hampshire, I was able to incorporate a classic pasture fence into the foreground. Today the fence is gone and the open gate leaves a hole in the composition. The owners of the property are friends and do a marvelous job maintaining their magnificent farm, but I will have to talk to them about that gate. I will be glad to provide the railing. 

Lost Rail

Enough depressing detail. The goal of this article is not to whine about lost opportunities, really. Rather, I wanted to drawn attention to the special role photographers play in preserving the visual history of our unique region. New England's great attraction is that development has been slower to sweep away our beautiful rural heritage than in most other parts of the country, but the forces are out there and we must continue to work to protect what we can. Sadly protection is not always possible and we as photographer's have the great responsibility and honor to, at least, preserve a visual record of our rural treasures. Shoot as if it matters, because it does.