wide angle distortion

[vikramdmello]

i'm trying to understand why a wide angle picture i made has the edges

distorted, sort of leaning outwards.

 

see: http://www.photo.net/photodb/photo?photo_id=5715153

 

i used an 18-70mm zoom at 18mm on my maxxum 5d. the building landscape was

far, far away. my understanding is this is barrel distortion at the edges,

where the corner buildings seem to lean back and away. i thought this

distortion occurred only if you take a wide angle picture of an up-close

subject, not something at a distance.

 

please correct/advise.

 

thank you - vikram.<div></div>

[dave_powell2]

Hi Vikram,

 

Many super-wides from many manufacturers create this distortion when the lens is set to full-wide. You can eliminate it in two ways:

 

(1) Using Photoshop's distortion-removal filters or plug-ins.

 

(2) By shooting such images at slightly less than full-wide (such as at 20-25mm, which I know runs against the principle of the thing)!

 

Sincerely,

 

Dave

[andrew robertson]

You can also minimize this effect by making sure that the camera is dead level (by using a

bubble level) with the horizon aligned exactly with the invisible line that divides the frame in

half horizontally.

[vikramdmello]

thanks both of you for replying.

 

dave: my attempt at photoshop's lens distortion correction features didn't quite correct things - perhaps i'm not using it well enough. i think shooting at slightly less than wide might be my best bet.

 

my confusion is that, i've shot wide angle before, but not of a row of architecture such as this. i wonder if the corner distortion is more apparent in images such as this?

 

andrew: i think i will try your suggestion - i do have one of those tiny bubbles in my tool kit.

 

v.

[dave_powell2]

Yes, Andrew's is a great add! The buildings on the two sides may still bow out a bit. And this too can be somewhat corrected using plug-ins.

 

Good luck!

 

Sincerely,

 

Dave

[robert_martin5]

If you still have problems with lens distortion when you level the camera, try one of the plug-ins that correct lens distortion. DXO and PTLens are two that will correct lens distortion automatically if the lens you use is characterized for the plug-in. I use PTLens and it works great.

[andrew robertson]

If the camera is dead level buildings will not bow out. They will exhibit wide angle

distortion, but vertical walls will be parallel.