#Corel aftershot 3 lens profiles how to

Make sure that you mark 20 points along each line. The middle line is more or less straight, so its contribution to the correction parameters will be very small - and can thus be omitted. In Example1.jpg, see later in this thread, one can use the three first lines at the top, and the three bottom ones. * Click carefully along a number, say at least five, of calibration lines in the photo, the whole width, in the upper and/or lower half of the photo, depending on how the calibration target looks like. * Start the docal.sh script with the jpg file name given, such as. If you have several photos, which will be the case if you are calibrating a zoom lens, name them uniquely without reusing the filenames. * Take your (first) calibration photo, in jpg format, and put in an empty folder. Collection and calculation of data points: Please see his posting below, where also an attached file with the scripts and instructions is present.Ĥ. Try to work with high-quality photos that eventually will be saved in a jpg format.Īfx has made some scripts that will make the entire data point collecting procedure much easier.

If needed and if possible, enhance the taken photos in order to emphasise the lines - maybe a higher contrast, black and white, etc, will show the lines even clearer. The difference in focal length in each step for a zoom lens should be maximum 15%, and, according to a posting by former Bibble Labs employee Colleen, 10% at the end points.ģ. long-focusing extreme telephoto lenses, this distance will have to be longer than 3 meters. A proper minimum distance would be 3 meters, possibly a bit more. Take photos at an appropriate number of focal lengths at a proper distance from the reference object. Please see the examples of used calibration photos below in this thread.Ģ. If the intention is to calibrate a wide angle lens, you probably will have to find a good building somewhere, as the size of the print-out needed will be very, very large. Find, or possibly make, a good object to perform the calibration against.Ī wall with straight lines, not brick or wood but rather glass/metal frames, plates, etc, or a huge paper print-out, will do. In Windows, you can use the Cygwin package in order to achieve a linux-like environment with command line tools.ġ. This guide assumes a working linux or MacOSX environment, with bash, awk, scilab-cli, g3data and exiftool.

#Corel aftershot 3 lens profiles how to

For me, it was the lack of calibration data for the Nikkor AF-S 28-300mm f/3.5-5.6G ED VR, a very useful lens with severe distortion, that pushed me into learning how to make a proper lens calibration.

I hope this guide will be of help for those, like myself, that need to have a particular non-calibrated lens calibrated but can't wait forever for 'someone else' to do the work. Bibble Labs recommended me to use the SciLab method for the actual correction parameter calculations, and my workflow is based on the SciLab method. I also had problems to get Hugin to do the work for me, so instead I developed the method I describe below.