Does the lens correction profile for the Canon 24-70 eliminate all distortion?

Question

The new Camera Raw seems excellent in the Lens Correction...I will be photographing dancers and will have only 9 feet to work with. I would like to use the widest lens I can with lens correction. The question is whether this new program will flatten out the 24mm lens or if I should use the 35.
Roger Minkow

Answer 1

To add to Eric's great explanation, the corrections here are for barrel and pincushion distortion. That can be present in a lens of any focal length.
What isn't corrected is the effect in wide angle lenses where there is spreading of the image of three dimensional objects away from the center of the field. It happens at any distance, not just close up. It is caused by the extreme angle of projection from the back of the lens to the flat film/sensor plane. Think of a straight on photo of a building that has equal size columns across the facade with a wide angle lens. The columns at either end of the image appear wider than the (same width) columns in the middle. Retrofocus design wide angle lenses help a little bit (the rear of the lens is further from the focal plane than in a standard wide angle), but the distortion is usually there.
There is also distortion from being too close to the subject. Focal length doesn't really matter in that, except that longer lenses don't have the field of view to take in the close subject and can't usually focus that close. So we associate this distortion with wide angle lenses. This sort of distortion would be that where a person's nose in the middle of the frame looks very large and there is quick falloff in size to the eyes, ears, background. I think of this as more an issue of perspective, and this is controlled by camera placement, not by focal length or lens design.
Another good page on Paul Van Walree's site is http://toothwalker.org/optics/misconceptions.html
John