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Thursday, September 9, 2010

Make Custom Lens Profiles—10/11/10

DPMag Published in Tip Of The Week
Make Custom Lens Profiles—10/11/10

This Article Features Photo Zoom


Along with Photoshop CS5, this year Adobe has also released a fancy new plug-in for making custom lens profiles of your own equipment. Adobe’s Lens Profile Creator is a free program that allows you to automatically and precisely correct for the unique chromatic and optical aberrations that exist in each one of your lenses. More than simply correcting for a general type or size of lens, the profile creator allows you to customize the fixes for the very lenses in your own kit—and every nick, scratch and aberration unique to them. Here’s how to make the most of the freeware.

1. Download the Adobe Lens Profile Creator software from the Adobe Labs web site. http://labs.adobe.com/technologies/lensprofile_creator/

2. In the download package is a folder of calibration charts. Print, on matte or plain paper, the largest calibration chart your printer can handle.

3. Place the calibration chart flat, as if you were going to copy it in camera. Pinned or held by magnets to a wall works quite well, as does framing or mounting to any surface you can easily photograph. If framing, remove the glass to prevent reflections.

4. Light the chart evenly with two lights placed more than 45 degrees to the side of the camera. If lighting equipment isn't available, use any even natural or ambient light that will remain constant during your shooting session.

5. Every change in camera position, focal length and aperture also changes the performance of a lens, so ideally you would make a profile for every conceivable situation. This probably isn't practical for most of us, though, so Adobe recommends hitting a few key points:

5a. For wide angle and ultrawide zoom lenses, shoot at the nominal focal length positions marked on the ring of the lens, each at a fixed ƒ/11 aperture.
5b. For telephoto zooms, shoot at the minimum, maximum and middle focal lengths with a fixed ƒ/11 aperture.
5c. For prime lenses, shoot at the minimum focus distance and five times the minimum focus distance with a fixed ƒ/11 aperture.

6. Position the chart so that it fits entirely within the frame, taking up one quarter or half of the image frame.

7. Zero out camera settings, shoot highest quality RAW if possible, and be sure to use manual mode to maintain consistent exposures.

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