From great to crap, I just want to learn and have fun. I have drawn the following char to print and shoot to measure lens distortion:
http://guillermoluijk.com/lens/lens_distortion_chart.pngI start from two assumptions:
- The lens distortion has radial symmetry (so visible de-centred lenses would be an issue)
- It requires shooting precision to locate the end of the arrows (mainly the two arrows with the stripped blocks) exactly at the end of the frame (needs a 100% coverage viewfinder)
The idea is to measure the size all those blocks (I plan to use RAW's G data) get along the sensor diagonal after shooting which will be the distortion profile. Both hemi-diagonal values will be averaged to reduce measurement errors. Then undo the distortion profile and interpolate is with a smooth curve (spline) that can be applied to correct the distorted lens. Checking if it works will be easy by shooting any checkered or linear subject.
The inner circle serves to make shooting easier since a tiny piece of it will be visible on four corners. I think it cal help locate the arrows in the extreme corners before shooting.
Regards