In article
>In article <1996Jul18.100735@tueel1>,
>ersicmaz@el1.er.ele.tue.nl wrote:
>>Can somebody tell me how to evaluate pincushion and barrel distortions of
>>the lens? I took pictures of a grid and enlarged to 13x18 cm. How do
>>I come up now with some figures quantizing this effect.
>How about measuring the most distorted line's maximum deviation from
>straightness, and expressing this as a percentage of the line's length?
>E.G., a 36mm line that's bowed outward by 3.6mm would be +10% distortion. I
>don't know whether or not that's how the photo magazines do it, but it
>would provide a readily comprehensible measure that you could use to
>predict how much effect the distortion would have on your pictures.
Sounds good! Just don't try to estimate/evaluate lens distortion using
most camera viewfinders - their distortion (pincushion) is generally high.
Hope This Helps