I hаνе a Canon xti wіth thе standard 18-55mm lens thаt came іn thе kit. Thе guy аt thе camera store tried tο sell mе a polarized Tiffen filter, whісh I didn't bυу. Now I'm considering іt. Iѕ іt necessary, аnԁ іf ѕο, whаt аrе thе benefits? Whаt аrе negative things thаt саn come frοm using іt? Cаn іt bе left οn аt аƖƖ times fοr аƖƖ shooting conditions? Rіɡht now I јυѕt hаνе a hood, bυt аm considering returning іt fοr thе filter. Anу advice οn whаt tο ԁο аnԁ whаt positive аnԁ negative effects thе filter сουƖԁ hаνе wουƖԁ bе ɡrеаt.
axe_mupp said,
Short answer: You don’t need it.
A CPL (Circular Polariser) allows you to filter out polarised light. Effectively this lets you do several useful things:
It can make a sky turn a darker blue.
It can take the reflections off water, glass and reflective surfaces.
It also limits your light gathering ability so it can be used as a makeshift ND filter if you need one in a pinch.
It can also sometimes slightly alter the colour of other things such as foliage.
When using a CPL to darken skies, the effect is greatest when shooting at 90degrees from the sun. A word of warning: do not use a CPL to darken skies when using a lens any wider than your kit lens. This rarely gives anything other than a very uneven effect as the angle of view is too wide.
In some cases a CPL is a MUST, like when you need to reduce reflections but it’s not an essential piece of kit unless you have the specific needs mentioned above.
I definitely wouldn’t recommend leaving it on the lens all the time. All filters cause glare and ghosting, which can degrade your images and even show up as bright lights in your shot, especially when you have a strong light source in the shot.
If you want something to leave on your lens as protection, buy a good quality multicoated UV filter. Hoya are good. However, even very expensive filters can cause some glare, etc.
One thing you should know if you decide to get a CPL is that it won’t totally remove strong reflections from flash. Flash is pure non-polarised light and isn’t affected until it’s been polarised. If you do ever need to do such things then a second polariser can be fitted over your flash at 90 degrees to the one on your lens to give a flash lit picture with very little reflections, even when photographing things such as water.
Out of all these uses for a CPL, reducing reflections is the only one that can’t be done in post processing. For this reason, the CPL (along with ND filters) are amongst the few filters that are still useful in the digital age.
Goodluck!
EDIT: Holly9’s answer is partly incorrect. All filters, especially cheap filters and especially in bright sunlight can and will harm image quality. So even if you keep a UV protection filter on your lens, it is wise to remove it for important shots where there are bright light sources.
Also, Holly9s comment about UV filters filtering out UV light is also incorrect. Unlike in the film days, modern digital sensors are built with filters which block out almost all UV light. So a UV filter does nothing, at least not to UV light.
Proto said,
The previous posters have pretty much summed it up- a polarizing filter is an essential tool in your kit, but it’s not something to keep attached at all times.
When it comes to keeping filters on your lens, that’s basically a religious argument among photographers, much like Nikon vs Canon. All you need know is that Holly9 speaks the enlightened truth, while Axe_muppet flounders in darkness with the other bare-lens shooting heathen 
For me, the value of having a protective filter easily outweighs the potential side-effects upon image quality (especially when shooting outdoors or around physically active subjects), unless you’re using a really cheap filter. You do want a good filter that doesn’t generate tons of flare, but most filters such as Tiffen, Hoya, Nikon etc fall into this category.
Remember, even the most expensive filter will cause problems if it’s dirty and needs cleaning. If you’re shooting straight into strong light sources or other highly flare-vulnerable conditions, then sure- remove the filter for those unusual shots. And go to confession afterwards, LOL.
While UV filters don’t usually provide the same image enhancement that holds true for film cameras, you can always use a Skylight 1A filter. I’d rather have the dirt and gravel kicked up nearby skateboarders or kids playing strike an easily replaced filter, than my much-more-expensive front lens element.
Here are some links for more info:
Tanner M said,
In simple. Yes. This filter is almost a standard in landscape photography. That is, if you want to avoid bracketing exposures due to a high contrast scene. It really will make that sky pop out blue or if you want to take a photo of someone standing behind a window it will help to limit the reflections bouncing off the glass.
Of course, since you are shooting digital you can adjust the intensity of the blue in RAW. But in my humble opinion, I think it is better to start off with a good file that needs minimal adjustment. Keep in mind that the more adjusting of curves, high pass filters, etc. you do too a digital file, the more noise it will add to the final print. While it may be subtle if not even noticeable on smaller prints. On much larger prints, it will be noticeable.
Two things, in my opinion that no photographer should be without. A Polarizer, and a good Neutral Density filter.
The ND filter will allow less light to hit the film/censor allowing you to achieve longer exposures during daylight without affecting color balance.
I keep a Polarizer on my lens at all times simply because it allows you to keep your lens glass from getting scraped/scuffed.
CurtisNe said,
1. Yes.
2. It is necessary to filter out polarized light.
3. Polarized light is often in reflections like on water and off water in the otherwise blue sky.
4. It will act as a ND filter{neutral density} and reduce the transmitted light regardless of reflection.
5. It can, but so can the lens cap. Often the results will be similar.
5 questions?
Short answer is
yes.http://www.CurtisNeeley.com
arock75 said,
Get the CPL Circular Polarizing Filter so that you can use the polarizing effect as you see fit and simply turn the filter to see the effect it is having on the image.
midnight said,
I do tend to use one a lot for the mentioned reasons above and I also tend to leave a uv on for protection. But the other points some were made are correct as well. There are some cases where you just dont want either one.
Edwin said,
My “short answer” is “YES!” I cannot imagine shooting scenics/landscapes without a polarizer. It not only darkens a blue sky but it removes glare/reflections from water, snow, glass, sand and painted metal – but not polished metal. It also enhances colors and removes glare from waxy leaves.
In 37 years of using a Skylight or UV/Haze filter on 15 of the 16 lenses in my arsenal I have never noticed any image degradation. Lens flare usually happens when you have the sun high and off-center in your picture or when its coming through trees.
I would much rather replace a $20 filter than a $400 lens so I keep the Skylight or UV/Haze filter on all my lenses except the 16mm 180 degree full-frame fisheye. I never have to clean the front elements and they are protected from air pollution, diesel fumes, dust, etc. by the filter.
Although digital cameras may be protected from UV, they are not immune to the bluish cast seen in pictures taken in open shade or in distant snow or mountains. That is why I use the Skylight filter for those conditions.
Just be sure to buy quality filters – Tiffen, Hoya, B+W are all brands I use. I have a Tiffen polarizer that is almost 37 yrs. old and still working great.
Keep the lens hood and add the circular polarizer.
The Will 2 Defy said,
I would say buy it. Its useful for landscape photography. You can use it to darken overexposed skies and reduce reflective glare from water. It also saturates the colors slightly which is often desirable. However, I wouldnt leave it on all the time as in low light conditions you have to use an even slower shutter or higher iso setting than usual reducing the quality. This is not usually a problem when using a tripod though. Also it is a handy protector of the lens instead of a uv filter.
Holly9 said,
You should keep a filter on your lens of some sort, because it’s cheaper to accidentally scratch your filter and have to replace it than to accidentally scratch your lens!!!
I would get a U.V. filter, however. They are very neutral but because they filter out U.V. light your pictures will be sharper. Have you ever noticed the difference between U.V. sunglasses and cheap sunglasses? Same thing. I can’t think of a photo i’d want to take where a U.V. filter would harm it, and i’d always want it for outdoor photographs.
A polarizing filter allows light to enter your camera from certain angles only… and you can “dial” it so that it works at filtering from the direction you wish. It is often used to prevent glare or unwanted reflected light. You can, for example, take a photo through a shop window and eliminate the interference of the window.
