Digital Cameras and Barrel Distortion

[shaun_miller]

I am trying to take a lot of pictures of Building floorplans for

templating purposes, but keep getting beveling(barrel-distortion) of

the edges. Is there a digital camera or/and lens that would allow me

to get an accurate image. I'm usually 5ft from floorplan(34"x 46").

This would be a communal camera with most people being between noob

to novice user, so simplicity is an issue.

[todd frederick]

The above photo was taken recently in a very dark chapel at the Sonoma Mission with an Olympus C5050 handheld without flash. I was amazed at the ability of this camera to provide a fine exposure under these horrid conditions, but the horizontal beams and gate show distortion. I can live with that, but it may not fit you perameters. The camera was at it's widest focal length of 35mm. I do not know if this is barrel distortion or not.<div></div>

[giuseppe_malaspina1]

The barrel distorsion is typical of zoom lens. So you have to search a digital camera with non-zoom lens. Usually (on 35mm lens, but is the same with digital) a 35-70 lens presents barrel distorsion at 35mm, this problem decrease at 50mm and then increase at 70mm.

 

Best regards Giuseppe

[chip l.]

It sounds as if you are referring to the "consumer" digital cameras. The issue there is that the sensors are so small you need a 10 or 11mm focal length for a "normal" 50mm view from 35mm film. This leads to distortion in the corners.

 

You can see the effect of what I am talking about by looking a a fisheye image. If you take the very center portion of that image, the lines are relatively straight.

 

To get away from this effect you need to move to a larger sensor. A DSLR with a good quality lens should work out for you.

[gib]

I've noticed barrel distortion at the wide end of the zoom lenses in the Canon G1, G2, and the Nikon CP 5700.

 

I havent tested thoroughly if the acc wa lens for the 5700 (approximates 28mm in 35mm terms) is as bad.

[craig_gillette]

Most of the reviews comment on the amount of barrel or pincushion distortion you can expect on a given camera. Some have much more than others. However, the easiest method on the more distorted cameras is to avoid wide-angles by shooting from further out (not much of a solution). I've never gotten into it but believe there are various approaches to cope with it in post processing.

[leonard_richmond7]

All lenses have some distortion (that may not be literally true, but the small handful that come that close to 0% distortion cost enough that the above answer will suffice for me).

 

No, full frame sensor does not make it any easier to approach 0 distortion. Keeping up with test reports for full frame lenses and consumer digital camera lenses, it appears that the OPPOSITE is true - the small consumer digital cameras as a whole do excellently in comparison to the full frames coverage lenses.

 

The best answer I've found is correcting the distortion in post-processing. I use the Correct plugin for Photoshop from Panotools, available at http://www.path.unimelb.edu.au/~dersch/ . Under "Download PanoTools 2.6:" select "Windows Version 2.6b1, includes Gimp plug-in" which will download the file PanoTools.zip.

Place the file correct.8bf in the Photoshop\Plug-Ins directory (on my pc it�s the Photoshop 7.0 \Plug-Ins directory).

 

To use it, click on Filter -> Panotools -> Correct.

 

Erik Krause has written good and simple instructions at http://www.erik-krause.de/verzeichnung/distort_en.htm on how to do it using PTGui, a graphical front end to Panorama Tools. If you have

PTAssembler instead of PTGui, the same procedure applies. I was lucky - someone posted the table for corrections for my camera's lens. The results are spectacular! The distortion is corrected down to subpixel accuracy, and choosing the most computationally intensive algorith (sinc 256) gives results that show no degradation of the image. I am extremely pleased.