Barrel and pincushion distortion

[RyanLilly]

Am I correct in thinking that barrel and pincushion distortion are only created by zoom lenses because of their variable optics? So, should a well designed prime lens be completely free of both? That makes sense I think.

 

[Alex_B]

every lens can show distortion, and even prime lenses consist of more than one lens element, and they move around when you focus.

But you are right, that clearly visible barrel and pincushion distortions you get easily with zoom lenses at their longest and shortest focal length (usually).

 

[(Ghastly) Krueger]

Just as an example, a fishe eye lens is prime and has a LOT of barrel distortion.

 

[patrickt]

My lenses run from 16mm to 200mm. As a practical matter, they're free from the two distortions mentioned. I know that if I shoot a piece of graph paper at 16mm I can find some distortion but when I shoot a parade or a street dance or the interior of an old church, there is no noticeable distortion. I don't think I'd want to pay for the lens that was technically free from all distortion and, for me, it isn't necessary.

Keep in mind, too, that distortion is introduced by orientation. If I shoot at 16mm with the lens perfectly horizontal there isn't any noticeable distortion. If I angle the lens up, that's another matter and lens design wouldn't have any effect on that. That's why they have lenses with adjustments to the front element to compensate. I don't own one though.

Caveat: I'm not an optical engineer. I just take pictures.

Edward Weston took a famous portrait of Jose Orozco. The picture is slightly blurred because it was late in the day, the light was going, and his widest aperture was f/6.3 so the shutter speed was a little slow for a portrait. The picture is famous and Edward Weston described it as "practically satisfactory". I find that concept far more valuable than absolute technical perfection.