Photography Tips: Lens Distortion
Here are a few photography tips to handle the problem of lens distortion, which is quite common while using zoom lenses having a wide-range or wide-angle lenses. The main effect of lens distortion is straight lines in the image are either bent inwards or outwards. Simple lens distortion is usually of two kinds:
Barrel distortion causes all straight lines to bend inwards. A straight line in the very center of the image will not be distorted, but straight lines that are at the edges will tend to curve inwards from the corners.
In Pincushion distortion, you will find that all straight lines in the center of your image will be unaffected, while the ones near the two edges will tend to bend outwards towards the corners.
These distortions are optical aberrations and cannot dissolve with any camera settings; hence, you need a photo editing software like Photoshop to correct the distorting effect. The following steps will show you how to correct barrel and pincushion distortion by using Photoshop.
Step 1: Open Image in Photoshop
Select your image which has the barrel or pincushion distortion, and open it in Photoshop.
Step 2: Go To Lens Correction
After you have opened your image in Photoshop, click on "Filter" in the very top menu on your screen. In the drop down list, bring your mouse pointer on "Distort," which will open up another drop down menu. Click on "Lens Correction" from this list.
Step 3: Start Correcting the Distortion
On clicking "Lens Correction," you will find the respective window on your screen which has your image in a preview window on the left and a number of sliders on the right. You will start working with the top slider which says "Remove Distortion". The pointer in this slider will be in the middle, and the small window on top of the slider will read 0.
Sliding the pointer to the right will correct barrel distortion and sliding it to the left will correct pincushion distortion. As you drag the pointer, you will notice the number changing to a negative or positive value depending on the direction of the slide. As you slide the pointer, you will also see your image changing in the preview window.
Step 4: Correct Perspective Angle
When you have corrected the distortions, you might find your perspective angle a bit askew and you can correct this by adjusting the "Vertical Perspective" and "Marginal Perspective" sliders.
Step 5: Adjust Scale
The very last slider in the window is "Scale," and you need to adjust this so that your image fills up the entire Preview window.
Step 6: Click OK to Save the Changes
After you have got your image free of all distortions, click on OK on top of the window to save the changes you have just made to your image.