In both cases multiple parameters aka sliders are utilized. We really need two sliders: one near the center to correct barrel distortion and one near the corners to correct pincushion distortion. This resulted in excessive pincushion distortion near the corners. In our first attempt to fix distortion we adjusted the single slider in the Adobe's old Lens Correction filter to correct barrel distortion. This type of complex distortion is often called moustache distortion as it resembles a handlebar moustache such as the one found on Sir Arthur Conan Doyle.
#PTLENS REVIEW FULL#
The distortion at full wide angle, or 24mm, consists of barrel distortion near the center and pincushion distortion at the corners. Complex distortion can be a challenge to correct. Starting with CS5 the Lens Correction filter can automatically correct distortion based on several pre-calibrated parameters. Wide-angle lenses typically require more than one parameter for accurate correction.
#PTLENS REVIEW FREE#
Original Photoshop's Free Transform tool warp Final version.One parameter often does a fine job on standard and telephoto lenses. Barrel distortion Pincushion distortion Complex distortion. Notice the extra long hands in the following image. However it is easily corrected in recent editions of Photoshop using the Free Transform tool.
Sometimes referred to as volume anamorphosis, this type of distortion cannot be corrected by PTLens. In this case you may find that individuals near the edge of an image in a group shot may have large odd-shaped heads! This is especially true when using ultra wide-angle lenses. While this is desirable when photographing buildings, it's less desirable when taking pictures of people. To maintain parallel lines in the image rectilinear lenses warp the image to expand it near the edges. In actual fact, when you look at the building directly with your eyes, the vertical lines converge due to perspective. These parameters are used to lookup the coefficients and automatically correct the image.Īll you do is press the OK button! A photograph of a tall building taken with the sensor parallel to the target will yield an image with parallel vertical lines. Camera make, model, lens, and focal length are sensed in EXIF information. However instead of two sliders there are two coefficients stored in a database. To correct this image we need two sliders: one to correct barrel distortion near the center and another to correct pincushion distortion near the edges. This is because Photoshop has only one slider for distortion correction that controls the amount of curvature. Correcting barrel distortion in the center increases pincushion distortion near the edges. Attempts to correct the image in Photoshop's Lens Correction filter are unsatisfactory. Wide angle lenses are prone to complex distortion. Moderately wide angle lenses often have barrel distortion while telephoto lenses have pincushion distortion. This type of distortion is sometimes referred to as moustache distortion as its shape resembles a handlebar moustache such as the one on Sir Arthur Conan Doyle. Complex distortion is often a combination of barrel and pincushion distortion with barrel distortion near the center and pincushion distortion near the edges. Distortion Explainedįor pincushion distortion the edges curve away from the center. In barrel distortion the edges of the image curve toward the center. The three types of distortion are illustrated below. Values below only tested on camera with crop factor of 1.6.Distortion for rectilinear lenses comes in three flavors: barrel distortion, pincushion distortion, and complex distortion. I just ended up manually selecting values for first order correction, producing a much better result than I could get from tca_correct. Most of the values were far off the scale that ufraw could deal with (ufraw/lensfun wants +/- 0.01 but I was geting +/- 0.5 or more). Unfortunately, following the lens calibration guide, I was unable to get tca_correct to output anything meaningful. The distortion values listed are the default values that are included with the library.