Filters

The following is for DSLR users

So it's been more than a month that many of you have had your DSLRs. A question I keep getting asked is "What filter should I have on my lens?" or "Do I need a filter"? Here's the 514 on that. Firstly, a filter will do two things for your lens. It will protect the lens and, depending on what type of filter, affect the image itself. Before I talk about different filters, let me answer if you really do need one or not.

With or Without Protection?
If ever you dropped the camera and it hits the ground lens first, having a filter will take the brunt of the impact (hopefully taking most of the damage) and leave the lens glass intact. This way, you'll just replace the damaged filter. Comparing this to the cost of having to repair the lens itself and you'll be wishing you spent that $20-70!

However, there is a downside. A filter can reduce the exposure anywhere from 1-2 stops and sometimes cause lens flare (like a ball or streak of light). As well, having a non coated filter vs. single or multi-coated filter can affect the quality of the colour and exposure.

In my personal experience, I have lens hoods on most of my lenses. So that in itself provides protection. So I do not use filters. BUT this is solely depending upon the user. Each person knows how they hold the camera and their personal habbits. So it really depends on how they use the camera. I do however recommend to new users to use filters for protection.


Different Types
Many filters today had stronger applications to film use than they do with DSLRs. This was because film was more sensitive to how light affected the quality of the photo since film was chemical based. Because cameras today are electronic in nature, some materials used for lens glass fabrication already reduce flare and because we can do many adjustments with photo software, many filters to be listed mostly serve to protect the lens rather than affect the photo itself.

UV - Absorbs the ultraviolet rays which often makes outdoor photographs hazy and indistinct. A muliti-purpose fine-weather filter for color as well as black and white films. Also serves as a permanent lens protector.
Note: In digital, mostly serves to protect the lens.

1A - Reduces the excessive bluishness that frequently occurs in outdoor color photography, especially in open shade under a clear, blue sky. The absorption peak is in the range which corresponds to the film's green spectrum. This means outstanding outdoor shots with superb color balance and clarity under all conditions. Also keeps skin tones free of colored reflections from nearby objects such as the shade of trees.
Note: In digital, mostly serves to protect the lens. Similar to UV with additional above mentioned function.

Circular Polarizer - They allow you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. meaning you can shoot through windows. They also enable colors to become more saturated and appear clearer, with better contrast. This effect is often used to increase the contrast and saturation in blue skies and white clouds.
Note: Make sure the lens does not focus externally. Because the circular polarizer depends on how you rotate the filter, external focused lenses will rotate your filter altering the desired effect.


Here are some useful websites with further details on filters.
http://www.hoyafilter.com/products/hoya/gf-01.html
http://photo.net/equipment/filters/
http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/filter/filter-UV.html