Lesson from the Shot: Got Filters?

by Gary Fong

 

Oops!

Photo courtesy of John Haslam (foxypar4)
http://www.flickr.com/photos/foxypar4/2301992319/ 

 

 
Are filters recommended for lenses? The answer - maybe.
 
 
Protection
A couple schools of thought…for protection. Using a filter for protecting the front element is not a bad ideal.  It not only protects the main element from scratches, but a few minor dings from impact damage as well. If the filter develops a fog of scratches, for the cost of another filter, the problem is corrected.
 
Dents and dings will happen…it’s just apart of life.  But when the dent is more than a dent, it won’t matter….an expensive repair is looking at the pocketbook no matter how one looks at it.
 
 
Dirt
For dirty environments. It’s better cleaning dust and dirt off a filter, rather than “sand” the dirt off the front element of the lens. We’re not talking about a small scratch, but a progression of many scratches, where over time the image would become diffused while looking through the lens.
 
Saltwater spray is always bothersome.  Cleaning it off a filter is a bit more tolerable, than trying to clean the primary element.
 
Cameras lenses have a coating that wear or scratch off with constant cleaning. The coating helps reduce lens flair, much like a lens hood. Having the manufacture recoat a lens is not a common request. It may cost the price of a new lens.
 
 
What about optical quality?

A contingent of photographers feel putting a filter over the lens changes the optical formula, thus reducing the sharpness of the element package. That’s a valid point. It’s even more valid, if the optical quality of the filter is poor.
 
The easiest way to settle the optical quality issue is to run a test with and without the filter.  Check the image side by side for any difference.  If there’s a difference, choose to use a filter or not.  Or…try a different filter, perhaps one that is specifically designed to work with the optical formula of the lens….then test again.
 
Back to original question…should one use a filter to protect your lens investment?  Think of if this way; if money were no object, don't use a filter; buy a new lens whenever it gets dirty.