Time to be with your loved ones

Time to be with loved ones

by sat

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Take the 2-minute tour ×
Photography Stack Exchange is a question and answer site for professional, enthusiast and amateur photographers. It's 100% free, no registration required.

In the standard model for a lens straight lines in the subject of a photograph will always end up straight. However I have seen a variety of photographs in which straight lines end up being curved, e.g. the horizon tapers down at the edges, or a fence near the photo border is mildly curved.

What could cause straight edges to come out curved in a photograph? I have no idea what cameras were used in these cases, but I am certain they are standard consumer grade cameras (so they aren't fisheye type lenses such as equisolid angle lenses). Believe it or not I have to make computations based around objects in photographs and have no way of accounting for why straight things turn out curved in some photographs. From what I know about optics, this shouldn't happen, but it does, so I am missing something. What is it?

Can anyone give authoritative information about this?

share|improve this question
    
It is barrel and pincushion distortion. Wide angle lenses also have perspective distortion. I believe you can find a great deal of information on this site on these topics already. –  dpollitt Jan 18 '12 at 20:39
2  
    
Signpost! (filler text) –  dpollitt Jan 18 '12 at 20:45
    
Thank you very much. I will look into those. Don't know what to do about an official question answer. –  John Robertson Jan 18 '12 at 20:59
    
You can leave it unanswered, it can be closed as a duplicate, or you can read the other topics, and answer your own question, if no one else does in the meantime. –  MikeW Jan 19 '12 at 4:36
add comment

1 Answer

up vote 1 down vote accepted

You only get completely straight lines using a pinhole camera. As soon as you put a lens element in the path of the light, you get the fisheye-like distortion to some degree.

Modern lenses contain several lens elements which compensate for each other to give straight lines, but you usually get a slight distortion anyway. For really expensive lenses you have a very small distortion, but it's still there.

share|improve this answer
    
Didn't know that. By fisheye like distortion do you mean that a single parabolic lens has barrel distortion? –  John Robertson Jan 31 '12 at 0:39
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.