# Are UV and polarized lens filter a necessity?



## DScience (Apr 17, 2009)

The title says it all...When I purchased my DSLR last week, the sales guy tried to convince me that a UV lens filter is something that all photographers use to protect their lenses, and he said the polarized ones are great for almost all occasions? 

So I'm wondering if most people here have either filters, and if you do when do you use them?

Also, are they important and are they something you keep on ALL the time??

Thanks everyone!


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## bhop (Apr 17, 2009)

I have UV filters on my lenses with larger front glass (67mm 77mm threads) to protect it from stuff flying at it.  I shoot car events and sometimes there's bits of rubber and dirt flying around.  I'd rather it hit a filter than the actual lens glass.  I don't use uv filters on my smaller lenses (52mm filter size).  I leave the UV filters on all the time, unless i'm putting my polarizers on, which are used to reduce reflections on shiny things (cars usually for me), or to add more contrast in the sky, in which case I take the UV filter off so i'll be shooting through less glass.


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## DScience (Apr 17, 2009)

Thanks for the reply!

So if I understand correctly, having the UV filter on will never have a negative effect on the picture quality? it's simply for lens protection?


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## kundalini (Apr 17, 2009)

UV and Polarizers serve different functions.  *If* you want a front filter for protection, I would suggest looking at a clear *glass* filter.  I don't use them usually, but have a couple if in situations as bhop mentioned or at the beach on a windy day.... or similar where dust, debris, moisture, etc causes you to have to wipe the lens often.

There have been several threads on this discussion.  Try using the Search tool.


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## kundalini (Apr 17, 2009)

DScience said:


> So if I understand correctly, having the UV filter on will never have a negative effect on the picture quality? it's simply for lens protection?


Depends on the quality of the filter. Look at it this way. You are placing another item in front of your lens. Make sure it is a quality filter. I have spent close to $200 on a filter, but it is riding on a $1700 lens. The cost/benefit is up to you.

A poor quality filter will have a direct impact on your image quality.


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## dcclark (Apr 17, 2009)

For the record, in your original post, it sounded like you were calling a Polarizer a type of UV filter. It is not -- a polarizer has a specific function, which is to admit light which is polarized in only one direction. This has the effect of darkening skies and removing reflections from glass and water. It also absorbs around 1-2 stops of light (depending on quality), so it is not a good idea to have one in low light situations. But, polarizers are awesome when you need them -- it's one of my absolutely standard filters which I carry almost everywhere.


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## DScience (Apr 17, 2009)

kundalini said:


> UV and Polarizers serve different functions.  *If* you want a front filter for protection, I would suggest looking at a clear *glass* filter.  I don't use them usually, but have a couple if in situations as bhop mentioned or at the beach on a windy day.... or similar where dust, debris, moisture, etc causes you to have to wipe the lens often.
> 
> There have been several threads on this discussion.  Try using the Search tool.



Yea I have no worries about foreign objects hitting the front...i'm more worried about the UV rays. But, I don't see the point in getting them if they will make the quality of picks worse, with the added piece of glass.


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## kundalini (Apr 17, 2009)

Fogot to mention....... I always use a lens hood as the first line of defense for protection.  The second line is common sense along with just being careful.


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## dcclark (Apr 17, 2009)

DScience said:


> Yea I have no worries about foreign objects hitting the front...i'm more worried about the UV rays. But, I don't see the point in getting them if they will make the quality of picks worse, with the added piece of glass.



UV protection really isn't necessary nowadays. At one point, UV light could cause trouble on film -- but it's not an issue on digital sensors, nor even most modern films. UV filters really are just protection from foreign objects nowadays.


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## FrankLamont (Apr 17, 2009)

Basically, a UV filter can do both things; protect your lens and reduce UV. Really useful when you're hiking up high, with more UV radiation... still, the problem is *ghosting* and *flaring* - two common issues that come up with _cheap _and basic UV filters. I suggest that you get yourself a _multi-coated_ UV filter, with at least 95% transmission... Hoya series is good, but make sure it's the multi-coated version. The pro multi-coated version is only around $60, and hey, don't put a bad glass in front of an awesome lens. 

Polarising filters are different. Yes, they can protect your lens as such, but note that it really hightens the saturation of skies and such... here's a full run down, with sample pictures:
Polarisers - a guide to using polarizing filters


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## Joves (Apr 17, 2009)

DScience said:


> Thanks for the reply!
> 
> So if I understand correctly, having the UV filter on will never have a negative effect on the picture quality? it's simply for lens protection?


 Actually it will have a negitive effect. Your sensors filter already has UV or, AA filtration. Clears will not degrade the image if you get the Multi-Coated filters to kill glass reflection. Circular Polarizers are great for killing haze at the edge of the sky and, reflection on shiny objects.


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## Garbz (Apr 18, 2009)

Can only repeat whatever has already been said. I use GOOD UV filters on all my lenses for protection. Why UV than clear glass? Cost-benefit. UV are optically clear, but produced in greater numbers and thus cheaper. You gain no optical benefit. You only get optical degradation if you use a cheap filter (no anti-glare coating). 

Polarisers are different beasts entirely. They are used for artistic effect, and should be part of every landscape photographer's arsenal, although they could be used for a myriad of other things as well.



Joves said:


> Actually it will have a negitive effect. Your sensors filter already has UV or, AA filtration. Clears will not degrade the image if you get the Multi-Coated filters to kill glass reflection. Circular Polarizers are great for killing haze at the edge of the sky and, reflection on shiny objects.



Wrong. Digital sensors both CMOS and CCD are not natively UV reactive. You are right that there is an Anti-Aliasing filter on the sensor already, but this is to stop Aliasing effects of the Infrared range not the UV range. The only filtering on CCDs are optical Low-Pass Filters which filter out around ~780nm (well into the deep red) to the mid-InfraRed region. This varies with the sensor, but when this filter is removed all images come out reddish.

Long story short no performance is lost at all as a result of blocking UV unless it gets too close to the purple end of the spectrum. But since the original UV filter was only blocking extreme instances of UV in cases of snow or beach photography, they are all well out of the visible range anyway, and thus appear perfectly clear.


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## DScience (Apr 18, 2009)

Thank you everyone for your reply's. I think i'll pick up a nice quality UV filter, and just use it on special occasions.


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## flea77 (Apr 18, 2009)

I leave a UV on most of my lenses all the time, multi-coated Hoyas, not only do they protect against flying debris, fingerprints, dust, rain, etc, but the thing I like the best is when the filter gets dirty and I have to clean it (which will happen to everyone unless you shoot in a clean room) I am cleaning off a filter and not the actual lens. This means there will never, ever, ever, be cleaning marks on my lenses. If a scratch happens because I didnt get all the sand off before I wiped it with my cloth, bummer, $30 filter down the drain, $1000 lens just like new!

Allan


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## Garbz (Apr 18, 2009)

DScience said:


> Thank you everyone for your reply's. I think i'll pick up a nice quality UV filter, and just use it on special occasions.



Isn't this a strange way of thinking? Giving that some people insist that they cause a loss in quality wouldn't it make more sense to have it on for protection all the time, and take it off for special occasions?


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