Originally posted by wings I used to use various filters on my Spotmatic and had some favorites.
I was curious about the use of filters today especially since you have so much control in taking a photo using a DSLR and it is somewhat easy now to manipulate a photo in post processing?
I was also wondering about how they might affect some functions of DSLRs such as auto focusing and white balance?
Are there advantages in using a filter in certain circumstances instead of relying on post processing?
Finally, what filters do you regularly use if you do use them?
Note: This is somewhat related and probably old school, but when I was searching filters, I ran across something that I never used before and it is a white balance lens cap. I was just curious if it worked or useful.
There are reasons why one would want to use a WB filter with digital, this relates to how the sensor captures color and more specifically how the 3 color channels saturate during the exposure.
For normal daylight shots you will find that the green channel will saturate much quicker than the red channel would, to combat this you can use magenta filter so that how the sensor saturates is more evenly.
So when a magenta filter is used in daylight you can block about a stop of light in the green and blue channels and allow you to use a 1stop longer shutter speed, this can be handy for use when photographing when blurring movement is needed
This also comes in handy when you are shooting scenes with a lot of red and greens so that you can reduce the amount of noise found in the red channel that in turn give you better detail in those reds.
You can also WB filters for artificial light where often times you have a very strong light source that can cause you to clip that light's color way before any of the other colors. Again this will help you and aid in reducing noise for in the colors that have not received as much light. in the shadows and or night sky.
I also light to use both ND grad filters for times that I don't want to bracket a scene for HDR most of the time I use a 1 stop. I also like ND filters to increase the duration of my shutter speed for blurring motion.