About Me

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Spofford, New Hampshire, United States
Jeff Newcomer has been a physician practicing in New Hampshire and Vermont for over 30 years. Over that time, as a member of the Conservation Commission in his home of Chesterfield New Hampshire, he has used his photography to promote the protection and appreciation of the town's wild lands. In recent years he has been transitioning his focus from medicine to photography, writing and teaching. Jeff enjoys photographing throughout New England, but has concentrated on the Monadnock Region and southern Vermont and has had a long term artistic relationship with Mount Monadnock. He is a featured artist in a number of local galleries and his work is often seen in regional print, web publications and in business installations throughout the country. For years Jeff has published a calendar celebrating the beauty of The New England country-side in all seasons. All of the proceeds from his New England Reflections Calendar have gone to support the Pulmonary Rehabilitation Program at the Cheshire Medical Center. Jeff has a strong commitment to sharing his excitement about the special beauty of our region and publishes a weekly blog about photography in New England.

Sunday, November 18, 2018

Lens Correction


The Curved Door

The bad news is that every photographic lens induces some degree of distortion to the image that it sends to the sensor.  Some lenses cause more warping than others, but the amount and type of distortion is dependent on the focal length and the proximity of the subject. 

Types of Distortion
There are two types of distortion.  Wide angle lenses can cause the appearance of swelling out from the middle of the image, called Barrel Distortion.  This warping is often associated vignetting, a darkening at the corners.  Conversely, looking at more distant subjects with a telephoto lens can result in an inward bending of lines on the edges, called pincushion distortion.


The good new is that tools in both Lightroom and Photoshop can correct much of these problems and most of the adjustments are essentially automatic.  In Lightroom the magic all happens with the Lens Correction Tool.

The Curved Door
Recently, I was shooting along the waterfront in Rockport Massachusetts. I was especially attracted by the interesting detail in many of the Lobster shacks; colorful buoys, ropes and weathered doors.  I loved my angle on this shack, but I noticed that by using a 67mm focal length the lines of the distant door showed considerable pin cushioning.  The result was some post-processing correction and an excuse for another blog article





Lightroom’s Lens Correction Panel
Recent versions of Lightroom have a few nifty tools for correcting Lens distortion in the “Lens Corrections Panel”.  In Lightroom CC Classic, the first choice is between “Profile” and “Manual”.  In most cases you will not need to venture into the Manual options. 











Chromatic Aberration
The first option under “Profile” is to remove Chromatic Aberration.  I discussed the cause and treatment of Chromatic Aberration in an article six years ago.   Since then the causes have not changed, but many new lenses have become better at reducing the problem and the software has made its correction easier.  Just click on the button and most of the color banding will disappear. To fine tune the results you may need to dive into the Manual Options, but that will a subject for a future article.


Profile Correction
Profile Adjustment
I love automatic stuff.  Adobe has assembled a large and expanding data base on the characteristics of most of the lenses that are available on the market and many legacy lenses that you may still be using.  This means that it is very likely that Lightroom can identify the lens in your metadata and automatically make the necessary adjustments to compensate for the distortion and vignetting.  Click “Enable Profile Corrections” and chances are your; Make, Model and Profile will pop up and the image distortion will be corrected. 





If the meta data does not contain the lens information, then you can look for it in the Lens Profile drop-downs.  If you can’t find your lens, most likely because it is new, you can wait for the next update which always includes a bunch of new profiles.  When all “automatic stuff” fails you can drop down to the “Amount” sliders and adjust both Distortion and Vignetting manually.





Fine-tuning the Door
The automatic profile adjustment made a marked improvement in the pin cushioning of the door, but it wasn’t quite perfect. The door edge still had a definite curve.  I went to the Distortion slider and found that a full +200 correction led to a better result.  For Lightroom and Photoshop automatic adjustments can work great, particularly for lens profiles, but sometimes they are just a good place to start.




Brick Wall Barrel Distortion
A wide-angle close-up of a plain brick wall gives a nice view of Barrel Distortion and for this I must thank the imposing fa├žade of Dick’s Sporting Goods in Keene New Hampshire.  A straight-on view with my 16mm lens clearly shows barrel distortion and edge vignetting.  In this case the built-in Profile Correction nicely fixes the problems without any need for further adjustments.






Maple Trunk
Often lens distortions are not immediately obvious until they are corrected.  It is always helpful to compare a corrected image with the original, especially when using telephoto or wide-angle shots and it is nice that the process is so quick and easy.  My original shot of a Maple trunk in my yard looks reasonable, but when compared to the corrected version it is easy to see the bloated barreling in the center of the image.







Needs Work


The Lens Correction in Lightroom is one of the program’s simplest and most magical tools.  It is a worthy stop every time you travel through the Develop Module’s workflow.

Jeff Newcomer, NEPG
www.partridgebrookreflections.com

























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