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Photography Question 
Shridhar Upadhyaya

member since: 7/24/2003
 

What is Barrel Distortion?


Hello!

I have read lots of reviews related to the Canon EF 50mm f/1.4 complaining about the "Barrel Distortion". What does it mean? And are there any precautions against it?

Thanks a lot for answering my previous question, it did help clear up lots of issues.

8/27/2003 9:57:41 AM

 
doug Nelson
DougNelsonPhoto.com

member since: 6/14/2001
  Some lenses show a bowed outward effect at the edges of the frame. It is unusual to me that a 50 would show this noticeably. Many excellent lenses probably have a touch of it. Wide-angles or the wide end of zooms are usually worse in this regard. As a long term Canon fan, it bothers me that a $300 lens would have this problem. If I used this lens for weddings, I would not worry too much about this, but I would be careful posing people too close to the edge of the frame. Strangely, 20 year old Minolta 50-mm f1.7s costing 1/6 as much have tested as having NO distortion, as well as exemplary resolution and contrast characteristics. I would trust a Leica 50-mm lens to have no or nearly no barrel distortion. As for Canon, try to find out if the 50-mm macro shows any significant distortion. I would think that you could use a 50 macro exactly as you would your other 50's. Look also at the f1.8 50.

8/27/2003 12:59:59 PM

 
Jon Close
BetterPhoto Member

member since: 5/18/2000
  On a related note, "pincushion" distortion is the opposite, straight lines at the edges of the frame bending inwards, like ) (. Barrel distortion = ( ).

Virtually all 35mm lenses will exhibit some amount of barrel or pincushion distortion. It is very well controlled in most prime lenses and more noticable in wide angle zooms.

Re - EF 50 f/1.4 USM, I've never seen a review of this lens that rated it as anything less than excellent on all counts. If you're referring to the mention of barrel distortion in the 50 f/1.4 from this source - http://www.photo.net/equipment/canon/ef50/ then it should be noted that (a) the "test" was not scientific. The brick wall pic was taken at full aperture, where the distortion would be most apparent, the conditions are a little sloppy in that the camera does not appear to have been perfectly level and (more importantly in this test) perpendicular to the wall, and there is no normalization (ie, no comparison as to whether it's better or worse than 50 f/1.4 lenses by Nikon, Pentax, Minolta, etc.).

8/27/2003 6:29:40 PM

 
doug Nelson
DougNelsonPhoto.com

member since: 6/14/2001
  Sample of the same lens from the same manufacturer can show differing characteristics. See http://medfmt.8k.com/third/variations.html for information on this. Your lens may not have the degree of distortion shown by other samples. Shoot through a doorway, placing the edges of the frame close to the door edges. Then scan the image, and go into photoshop or some imaging program. Grab lines from the ruler side of the screen and place them over the door edges in the image. You'll likely see some degree of barrel distortion. Alternatively, use a straightedge on the print.
Don't despair if you see some distortion. My Canon FD 85 1.8 has noticeable pincusion distortion in certain architectural shots. It's still my favorite lens.

8/28/2003 7:04:34 AM

 
Shridhar Upadhyaya

member since: 8/5/2004
  Hi again!

I found my apprehensions regarding this lens unnecessary. I have shot almost 40 rolls through my Elan II/ Canon 50mm f/1.4 and I found what I really expected: People look like they actually ARE.

A excellent lens for indoors/outdoors, with people as the subject.

8/5/2004 8:15:54 AM

 

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