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I have a fair idea of what a few filters do, but now I'm just after a clearer explanation of exactly what they do, and when they'd come in handy. Would help myself, and anyone else interested.

Namely thes types:
Polarizers,
Neutral Density,
Star,
UV,
Infrared,
Graduated,
Spot,
Close up.

I'll pick a couple off your list for you.

Polarisers remove some of the scattered light that exists in the normal visible light that we see, helping to give us a clearer image. You can remove reflections (from glass or water surfaces), deepen the color of the sky ....

Neutral Density filters are used to reduce the effective EV you may need to take a photo. In bright sunlight there might be too much light, preventing you from using, say, a slow shutter speed when the image that you're trying to make dictates your use of a slow shutter speed. Using a ND filter immediately cuts down the amoiunt of available light, thus oermitting the use of a slower shutter speed.

Next ?

i'll try to do justive to a couple of others from the list and add some

UV, (skylight)

Absorb UV rays and can help to reduce the "hazy" effect of outdoor color shots. In reality there main use is that of protection as they are suppose to have no negative effects on the image, and are alot cheaper than the front ellement of say a 70-200 vr.

Graduated,

Are filters who's effect reduces or increases along the surface of the filter eg a graduated ND filter can be used in a landscape where the sky is significantly brighter than the land forms. normally this would create an underexposed landform, an overexposed sky or even both. By using a graduated ND filter you can filter light coming from the top of the frame, while leaving the bottom giving you a correctly exposed landscape.

Close up, a filter that allows either a lense without macro ability to perform a macro funtion. Or a lense with macro ability to increase it's magnification depending on the ration of the close up filter. these are a good solution for people who do not take enough macro shots to warrant a specific lense, but that want the flexability to be able to dabble.

a couple of filters you havn't mentioned are:

Warming filters (81 series),

An amber coloured filter that can reduced a blue cast that comes from situations such as under shadows on a clear day(blue sky). gives the picture a "warmer cast"

Cooling filters (82 series),

A blue colored filter that reduces warm tones in an image used to take out the other redening (yay i invented a word:) ) that occures at certain times during the day. early and late being the main culprits.

dug up a pic to illustrate so i'll do star filter too

Star,

Causes a pronouced star effect around lsouces of light more than would normally be produced by long shutter speeds and small apetures.

eg,



*note this wasn't taken using a star filter but stopped down with a 20 sec exposure but it illustrates the effect.

This is a question that often confronts photographers, especially those new to (D)SLR cameras. Most camera shops will try to sell you one when you buy a new lens, but one suspects that is more about their profit margins than anything else.

There are, in fact, two schools of thought on this question; not surprisingly i) always have UV filter on lens and ii) it is not necessary to have a filter on permanently.

Those who recommend it say that it protects the lens against scratches, finger marks etc, and that it is easier/cheaper to replace a filter than a lens.

Those against it say that any extra lens, regardless of quality of the glass, adds to distortion and flaring. They also say that it is rare for lenses to be damaged if the photographer is careful.

Thom Hogan, who writes about general photography as well as about Nikon equipment, is one who does not support the universal application of filters to lenses. See his writing on this topic at:
http://www.bythom.com/filters.htm

What do I do? The lenses I use/carry frequently have UV filters on them; those that stay at home a bit more do not.

I also have been known to take the filter off the front of my lens in difficult shooting situations (eg into the sun, extreme close-up; unusual light conditions like sunsets etc), so I am sitting firmly on the fence.

cricketfan
You are not a fence sitter. You are a person who knows when to use a filter...and when not to. The distinction is important because too many photographers leave the filters on all the time and this costs them some image quality.

alot of people think that it doesn't reduce image quality at all obviously this depends on the quality of the filter. for some people they may never consider it i mean a landscape photographer is probably never going to encounter a situation in which there lense is in real danger but a sports photog will regularly other people feel that for the minimal if any loss of qaulity it is worth it to protect there investment. it really is each to their own

nodabs
Every extra glass/air layer costs quality. There is no escaping the fact. But there may be other reasons for not using a filter...for instance a UV filter cuts the effects of haze...but there may be times when the haze will actually enhance the image. So UV filter off to emphasize aerial, (Or atmospheric) perspective. I agree with the sports photography though...but I think if I was shooting a match for a prestigious publication I might even consider taking the filter off for that too. Bottom line is that it's a factor that every photographer should consider before blindly shooting away.

obviously it all has an effect but the question is could you take a photo of what you shoot with and without and then tell the difference between the two i would say that 99% of people in 90% of situations could not. if your answer is yes because you shoot landscape etc then take it off. I actually don't use UV filters because i feel my lenses lack the quality that i really want as it is (kit and 70-300 G) so i scrape everything i can out of them. i think what it comes down to is knobody should blindly follow advice and use/not use UV each person should consider there application and make a decision which i believe is what you origionally said lol anyway there is one situation where you definatly should if you ever shoot around a pool or fountain put a UV filter on just one spec of chlorinated water can totally kill a coated lense seen it happen and it's not pretty

Interesting posts on this. I have always had a UV filter on, as I am so protective of my 24-120VR and wouldn't want anything to scratch the lens - this could happen despite being very careful...things just happen. But now having read this thread, I might have to rethink this. I might try same shots with and without filter and see if I can tell difference. If I come up with anything, then I'll post here.

Sometime I would love for someone who claims that filters degrade quality (I'm not denying this fact) to post a picture that was taken with a filter on it and show where the quality degradation is.

I have filters on sometimes and off others, but when I do find the need for a filter, I just don't see where the image suffers as a result of the filter (now the result of the user on the other hand...). NOt to say it doesn't suffer, but I'm not astute enough to really see it. Also keeping in mind that most people here shoot with Nikkor glass, which is legendary in the world of lenses so any degrading of image would still rank quite highly among typical other glass IMHO.

dooda, your wish is my command:

http://www.cs.mtu.edu/~shene/DigiCam/Us ... er-UV.html

I suppose in one way I am lucky with the Sigma 12-24mm it will not accept a front lens filter

Chris

Onyx,

I went through the sight, and I don't see an explanation or illustration of image degradation. The biggest thing illustrated here was slight color casts from the original. Though a slight color cast may be seen as a degradation, the page that you linked to seemed to imply that the reason for this was to counter the blue that Haze and Skylight filters are meant to take care of.
It did make mention of UV contraction, but I don't know what that is and couldn't see it in the picture for the life of me.

Again, many people don't use filters (UV) because they may degrade or cheapen the lens. I'm not arguing with that point, but can anyone show me a clear illustration? Perhaps it was on the site that Onyx linked to and I just couldn't see it. I guess I can understand a pro justifying not using UV's or whatever, but they don't seem to baby their lenses either. That being said, I'm always taking my UV's off when I don't think that my lens is in danger because of everything I hear about degrading the lens quality etc. But I've only heard of it. I want to see it.

Vicareyus wrote:Interesting posts on this. I have always had a UV filter on, as I am so protective of my 24-120VR and wouldn't want anything to scratch the lens - this could happen despite being very careful...things just happen. But now having read this thread, I might have to rethink this. I might try same shots with and without filter and see if I can tell difference. If I come up with anything, then I'll post here.

Ive read that the problems occur when there are multiple filters on a lens .
Individually, the uv filter probably doesnt harm your image quality. But put a polariser(etc) over it and there is a additive effect that probably could, in certain lighting angles, cause refractions...
If you have filter (other)on, it will protect the lens just as well as the UV/skylight from scratches etc.

Two very important places where a ND filter is handy:

1) Waterfalls: slows shutter down to get that silk water effect
2)Lightning: Allows longer shutter time so yoiu can keep the CCD exposed to capture a lightning stroke without overexposing the background