Sign Up Now
Twitter Facebook Flickr Buzz
PhotoshopSociety.org
 
Search:   
 
Social Networks

LOGIN     

Go
Forgot Password? Go Join Now
Sign Up for Starter's Pack (Free)
Call (800) 223-8720
Email custserv@photoshopsociety.org
 
Need Web Solutions? Get Free Sample Issue

Inside Photoshop: Search Articles

  Search Library:  
 
2018 |  2017 |  2016 |  2015 |  2014 |  2013 |  2012 |  2011 |  2010 |  2009 |  2008 |  2007 |  2006 |  2005 | 
 

Put your images into perspective: Part 2

Added on Sunday 27th of December 2009 09:21 am EST
 

Application:
Adobe Photoshop CS2/CS3/CS4

Operating Systems:
Microsoft Windows, Macintosh

 

Lens distortion happens, but it doesn’t have to bring you down. By being aware of the characteristics of your digital camera lens and planning your shots intelligently, you can avoid severe distortion of your shots. We’ll show you how to understand and correct two types of lens distortion.

To help you understand what lens distortion is and how you can avoid it, we’ll:

 

  • Describe the two main types of lens distortion: pincushion distortion and barrel distortion.
  • Select appropriate camera settings to avoid the slings and arrows of lens distortion.
  • Correct both types of distortion in Photoshop manually.

In the October 2009 issue of Inside Photoshop, we discussed perspective distortion. But that’s not the only trick your camera will play on you. There are two other primary types of image distortion caused by lenses: barrel distortion and pincushion distortion. These effects can range from dramatic to almost unperceivable, depending on the position of the lens and the content of your scene. Let’s explore why this occurs and how Photoshop can help you fix these perspective problems.

 

Why lenses do what they do

 

Most consumer digital cameras are quite small, requiring their lenses to be relatively small as well. Due to their size, manufacturers must design lenses that can be susceptible to causing distortions in a digital image. This lens distortion is most noticeable when using a zoom lens at its widest setting or “zoomed in” to maximum telephoto. Since the distortion results from a physical property of the lens, you may think there’s nothing you can do about it. But by simply being aware of when and why the problem occurs, you can frame your shot to minimize lens distortion or eliminate it altogether.

 

Not a barrel of monkeys 

Barrel distortion is most visible when you set your lens to its widest angle. This causes the image to appear bloated at the center with the most noticeable distortion visible at the edge of the frame. Barrel distortion is a result of the design of the digital camera lens, but usually the wider the lens, the more obvious any barrel distortion appears.

Take a look at your lens—it isn’t flat (neither is your eye, for that matter); it curves slightly outward to provide you with that nice field of view and accurate focusing. Add a fish-eye lens or wide-angle adapter to your lens and the barrel distortion gets even more obvious. It’s certainly a cool effect if you want it, but one that can look distracting if it wasn’t your intention.

Barrel distortion is a common occurrence when you shoot using a digital camera at a wide-angle in a closed space, as shown in Figure A.

A

 

Pincushion pain 

Pincushion distortion causes images to appear pinched at the center. This occurs when using a lens at its maximum telephoto setting, or “zoomed in” on a subject. Pincushion distortion is less common and less noticeable than barrel distortion because the objects in the center of the frame are unaffected while lines on the edges of the frame appear to bend inward.

Keep in mind that all camera lenses produce some level of lens distortion in the capture process. More expensive lenses tend to distort less, but even the most expensive lens will display these distortions to some degree.

Architectural shots that contain strong vertical lines, such as the ones shown in Figure B, display pincushion distortion more readily if taken with a high zoom factor or with a telephoto adapter attached.

B

 

Reduce lens distortion 

One of the great assets of most digital cameras is the ability to preview your images on the built-in LCD screen. However, a lens distortion that’s unnoticeable on a 3-inch LCD screen can be painfully apparent on ...