Barrel distortion ?

neonpollen

neonpollen

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587
Name
Andy
Edit My Images
Yes
Hi,

I took this image earlier today and I know that the verticals are converging due to me having to angle the camera up to get everything in frame, but is there some barrel distortion here too? or am I imagining it ?

Abbey_problem.jpg
 
I'm not sure your verticals are converging noticeably Andy, the pic seems to be leaning to the right more than anything?

I couldn't begin to pass an opinion on barrel distortion from that shot. You really need some geometric shapes, eg rectangles or horizontal lines to show up barrel distortion. A brick wall is a good subject.
 
Your right the images is leaning and I was going to correct that but then I thougth there was some barrel distortion too, but I wasn't sure. I've just been through some of the others I took today and found this one:

Gatehouse-back.jpg


To my eyes it looks like the right hand of the two centre columns is bent banana style, again the image is leaning a little (I must try harder to stop doing that :) ). There are some other images from today which I think are suffering and they all seem to be when the lens is wide open (28mm) and when there are verticals close-ish to the edge of the frame.
 
That does look like a bit of BD. What lens is it? :)
 
It's a 28-105 F/3.5-4.5, I've checked the reviews on Fred Miranda's site but none of them mention BD, could it be the cheap UV filter I put on it ?
 
It's unlikely to be the filter, but do the brick wall test from about 3 or 4 feet - with and without it. :)

FWIW, my 17-40L exhibits barrel distortion with this test although less than the 17-80EF-S which I sold. The 50mm 1.4 (which I love) is also very guilty of it, particularly in close. It does become more apparent towards the frame edges, and portrait orientation (as in your shot) will show it up more with straight lines.

I wouldn't part with either lens although it's as well to be aware of how they behave under certain conditions. ;)
 
Thanks for the help I'll do the brick wall test tomorrow with all my lenses, with and without filters. I don't think it'll be the filter but I thought I'd mention it anyway.
 
No probs. :) I didn't sell the 17-80EFS because of the BD btw, I only sold it because it didn't fit the 1D.

All sorts of distortion are a fact of life with more extreme wide angles, in fact it's how they work. Mind you, 28mm isn't exactly extreme, so it's something you'll want to check out perhaps?
 
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