Three basic must-have types of filters for digital photography

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I just paste-bombed this from here to make it easier to find.

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Different filters do different things. If you're looking for a basic set of filters, the first must-have is a Circular Polarizer for deepening blue skies (increases contrast between clouds and clear sky) and reducing surface reflections. These are rotatable filters; you rotate them until they create the desired effect.



The sky would have been washed out and dull had I not used a polarizer. Do please forgive the lousy cloning job on the bottom-left, I have to redo it ;)


Neutral Density filters are probably the next thing you want. They are used simply to darken the entire frame. The result is that you can use wide apertures in bright light or use slow shutter speeds in bright movement to display movement. These come in varying levels of darkness from slight to very heavy.



Using an ND filter is the only way I was able to get a shutter speed low enough in mid-day light to be able to smooth out the smoke and show spinning tires. As I recall, I also used a polarizer stacked beneath it to darken the sky and reduce reflections on the truck itself.


I also have a Graduated Neutral Density filter. This is an ND for half (or more, or less) of the frame, while the rest of the frame is clear. They can also differ in the hardness or softness of the transition between dark and light. This is useful mainly for landscapes. I currently have a basic circular one, but it's usefullness is quite limited. If you are getting one (or more) of these, I suggest something like a Cokin rig, which lets you shift filters up and down to change the point of transition. I'm looking into getting one soon.



My grad ND filter allowed me to show the unique character of the sky within the exposure, while avoiding underexposing everything else (or, conversely, without overexposing the sky)


As far as how much to spend? Eh... I can't bring myself to spend more than $10-$15 on a little piece of glass. Some people claim that it robs sharpness, contrast or colour rendition, and that may be the case, but it's nothing that can't be corrected in post by sacrificing a tiny bit of cleanliness (vs. noise) and I doubt my D40 is capable of even resolving high enough to see any sharpness discrepancy anyway.

EDIT: oh, yes, and "clear", "sky" and "UV" filters. I don't spend more than a few dollars on these either. First all, UV filters are not necessary for digital SLRs. All of their lenses and/or sensors are already protected against UV. But, otherwise, you can still use UV, skylight or clear filters purely as physical protection. Replacing a filter is cheaper than replacing a lens in the event of a drop or scratch.
 

Redliner

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Thanks, I was thinking of buying filters and that was very helpful.
 

ALXBWSCREW

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A very, very nice tutorial. But how does turning the CPL filter affect the image?
 

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As you rotate the CPL in front of the lens (or even just your eye), you'll see blue sky darkening. This really makes clouds pop (the blue darkens, but the clouds don't). Note that this only occurs at 45 degree angles from the sun in any direction for a spread of 30 degrees or so. At very wide angles, you'll see dark and light areas of the sky separated from each other in the form of a sine wave.

CPLs also reduce surface reflections. You'll see reflections fade in and out as you rotate the CPL.
 
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BlaRo

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Fortunately, Lightroom 2 already has all of these filters supplied in the system. :D
 

Ramseus

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not really... you can fake a grad ND if you haven't completely blown the sky, but you can't fake a ND (just making the picture darker doesn't count :p) and you certainly can't fake a polariser - you can make sky blue darker, but you can't make reflections disappear and stuff.
 

AarheadC

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Can you explain the difference between a filter that is multi-coated and one that has none? I've heard that If I'm to buy a CPL filter, that I should get one that is multi-coated, but what is all that extra money improving?
 

Ladamaha

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Can you explain the difference between a filter that is multi-coated and one that has none? I've heard that If I'm to buy a CPL filter, that I should get one that is multi-coated, but what is all that extra money improving?
Multi coating should help with lens flair you get for adding more glass front of the lens.
 

ALXBWSCREW

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Ok, as good as epp_b's tutorial might have been, my knowledge on filters is still relatively low. Can anyone here point me to an advanced and in-depth tutorial on filters?
 

Dr_Q

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You're a lot better off getting a book on something like this, it's a pretty broad subject. The Photographer's Guide to Filters by Lee Frost is a really good start which covers filters for just about anything, if you're lucky you may be able to find it on Google Books. If you wanted a reason to use them I'd suggest you look no further than John Parminter, he uses them for pretty much everything he does and unlike some others in a subtle way too.
 

ALXBWSCREW

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You're a lot better off getting a book on something like this, it's a pretty broad subject. The Photographer's Guide to Filters by Lee Frost is a really good start which covers filters for just about anything, if you're lucky you may be able to find it on Google Books. If you wanted a reason to use them I'd suggest you look no further than John Parminter, he uses them for pretty much everything he does and unlike some others in a subtle way too.
Just took a short look at it. Thanks for the advice.
 

Ramseus

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Beyond the three filter types that Epp outlined there aren't many other filters (ignoring retarded effects filters) that are relevant to digital photography. Clear filters, which aren't really filters and are just for protection. Closeup filters for if you don't want to buy a macro lens and don't want extension tubes. Infrared filters if you like carrying a tripod and don't care enough to get an IR converted body. Colour filters for serious black and white. Other than that filters are pretty much for colour correction, which is pointless in digital.
 
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