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Polarizer Filter on top of UV filter
Hi folks,.

I use a UV filter to protect my lense. I have just gotten myself a Circular Polarizer (C-PL) filter..

I would like to know, do I have to unscrew my UV filter in order to get the desired effect with the CPL filter?.

Or can I just leave on the UV filter and screw the CPL filter on top of it..

Any difference between both methods? Appreciate all your comments...

Comments (16)

Every filter you add degrades the quality of your photos..

Jerryhttp://jchoate.zenfolio.com/..

Comment #1

Harisd40 wrote:.

Hi folks,.

I use a UV filter to protect my lense. I have just gotten myself aCircular Polarizer (C-PL) filter..

I would like to know, do I have to unscrew my UV filter in order toget the desired effect with the CPL filter?.

Or can I just leave on the UV filter and screw the CPL filter on topof it..

Any difference between both methods? Appreciate all your comments..

Always use as few filters as you can - using only what you need, when you need it. Many of us even forgo the 'protective' filter as a proper lens hood offers better protection and will never have a negative effect on IQ...

Comment #2

Harisd40 wrote:.

Hi folks,.

I would like to know, do I have to unscrew my UV filter in order toget the desired effect with the CPL filter?.

You don't have to... the polariser will still work.... but it is still wise to take off the UV..

The general rule is this....

The fewer pieces of glass interposed between subject and lens, the less chance of image degradation ...... because all filters degrade the image to 'some' extent..

For this reason most people don't bother with a UV filter at all..... especially as digital sensors are not sensitive to Ultra Violet light, and do not generate the horrid blue cast that used to happen with excesses of UV on film..

There is the additional problem with polas in that they are often used for landscapes with wide angle lenses, and a wide lens very often needs the polariser to have a specially "thin" mount, to avoid shading [vignetting] of the image corners. Naturally, stacking filters cancels that thinness and increases the chance of vignetting..

My advice? Don't use any filters at all unless you absolutely have to, and then limit yourself to one only.Regards,Baz..

Comment #3

If you shot mostly outdoors you can keep Circular Polarizing Filter on the glass insted of UV (sky will be blue, reduced glare from leaves, more sharp results with macro)..

Just don't forget to take it of indoors while making pics of kids. CPL filter eats lot of light..

Http://www.stan-pustylnik.smugmug.com..

Comment #4

Stacking filters is possible but inadvisable. Aside from the basic issue of adding extra glass surfaces (flat ones, at that), there is the distinct possibility of vignetting where the added filter blocks the lens's view "out of the corners"..

From a practical standpoint, when you stack two filters they love to stick together. Trying to remove one filter from another filter can be infuriating, especially in the case of a polarizer where part of the filter spins...

Comment #5

I think that the real impact on the image quality is pretty negligeable when leaving the UV filter. However, taking off the UV filter each time you mount the polizer increases the chances for dust on the lense or worse ... of scratches if you are unlucky..

I invite you to make your own opinion and to make a series of tests shots with both situation. Keep us informed of your results!.

_______________________________Have a look at http://photo4u.awardspace.com..

Comment #6

Harisd40 wrote:.

....

I use a UV filter to protect my lense. I have just gotten myself aCircular Polarizer (C-PL) filter.....

Out of curiosity, what are you trying to protect your lens from?.

The filter is at the very end of the barrel and is more likely to get fingerprints, than the recessed front element? Wouldn't a lens hood provide more protection (and increase image quality)?.

If the filter does get fingerprints, dust, smudges, etc, do you replace the filter, or clean it?.

If you clean the filter, why not just clean the lens?.

If you bought a cheap filter, are you worried about image degradation?.

If you bought expensive filters, for all your lenses, would it have been cheaper to just fix a lens if it breaks?.

Canon makes a very sharp 50mm f1.8 lens ($70 on the web)..

A good multicoated B+W UV-415 filter is $83. I'm not so sure I would want to use the $83 filter to protect the $70 lens..

I can get a cheap, non-multicoated UV filter for $11, but I'm not so sure it would help my images...

Comment #7

I see this is going the filter/no filter route quickly .

To answer your question. Yes, you can use the CPL over the UV filter, and the CPL will still do it's job..

However, if you use the CPL, I would remove the UV filter first. Two pieces of glass over your lens is probably not the best idea in terms if image quality..

UV filter quality DOES vary, and some do cause color and sharpness degradation - sometimes by a very large degree!.

So, if you use UV filters, you should get the highest quality you can find. Take different shots on a tripod shooting the same exact object (like a book, or something that has fine detail in it) and outside pics with the filter off, and then with the filter on. Compare the two sets of pictures. With a good filter, you will see absolutely no difference in color or sharpness or any other factor. And don't compare them on your camera's LCD, download them to your computer and inspect them there to make the evaluation..

You don't have to spend a ton of money, but know that you will have to spend some for good quality..

Good luck!.

Albert-OColoradoPlease visit me athttp://www.berto.zenfolio.com.

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Comment #8

Jchoate wrote:.

Every filter you add degrades the quality of your photos..

Jerryhttp://jchoate.zenfolio.com/.

So a lense with 11 elements isn't as sharp as a lense with 6 elements?.

Tim'Be the change you wish to see in the world.' -Mahatma Gandhihttp://www.flickr.com/photos/timskis6/..

Comment #9

Folks,.

Thanks for all the comments. Actually all I wanted to know is whether there will IQ degradation with the two filters on, because i'm just too lazy to take out the UV protector..

Interesting comments on the lense hood. The reason I got myself the UV protector is to protect it from dust/scratch. I have tested taking photos with/out the UV filter, and from my untrained eye I could not see any difference...

Comment #10

Timskis6 wrote:.

Jchoate wrote:.

Every filter you add degrades the quality of your photos..

So a lense with 11 elements isn't as sharp as a lense with 6 elements?.

Potentially, yes. But not all elements are created equal, so a really top class lens with a dozen elements could be sharper than a less-good lens with half as many. So perhaps the answer ought to have been:.

All other things being equal, yes..

Another issue, probably more important in the real world, is that extra surfaces, especially flat surfaces, can increase flare. Flare is sometimes very obvious - you've no doubt seen examples - but sometimes it is so diffuse that it is difficult to recognise and manifests itself as a loss of contrast...

Comment #11

Harisd40 wrote:.

I have testedtaking photos with/out the UV filter, and from my untrained eye Icould not see any difference..

Sometimes you won't see any difference. Then another day, in different lighting conditions, you will...

Comment #12

Timskis6 wrote:.

Jchoate wrote:.

Every filter you add degrades the quality of your photos..

So a lense with 11 elements isn't as sharp as a lense with 6 elements?.

Yeah, it might not be. Lens design is a trade off. Certainly, adding elements to a lens doesn't necessarily improve it... and adding flat sheets of glass in the form of filters definitely does not! The best you can hope for is a quality loss that's too small to be seen..

For your information......

In lens design a good deal of trouble is taken to simplify construction as much as possible and NOT just to keep it cheap..

Indeed, every element added to a lens has the potential to degrade the image by more than it is improved by that addition, so designers try hard to get the element count down, if they can. For one thing, it helps to get light transmission UP!.

Here is a quote from Wikipedia about aspheric lenses.....

(start quote).

An aspheric lens or asphere is a lens whose surfaces have a profile that is neither a portion of a sphere nor of a circular cylinder. In photography, a lens assembly that includes an aspheric element is often called an aspherical lens..

The asphere's more complex surface profile can eliminate spherical aberration and reduce other optical aberrations compared to a simple lens. A single aspheric lens can often replace a much more complex multi-lens system. The resulting device is smaller and lighter, and possibly cheaper than the multi-lens design.(end quote).

Because of modern high grade optical moulding, these sorts of lenses are now appearing in little point and shoots playing their part in making them compact!! .

So, if you think a lens is naturally better because it has more elements, think again. It ain't necessarily so.... and it never was, even before modern developments.Regards,Baz..

Comment #13

Harisd40 wrote:.

Folks,.

Thanks for all the comments. Actually all I wanted to know is whetherthere will IQ degradation with the two filters on, because i'm justtoo lazy to take out the UV protector..

Yes. You will get Image Quality degradation when you stack filters..

Depending on what you are shooting, and how critical you are, the amount of degradation may be small enough that you find it acceptable..

Interesting comments on the lense hood. The reason I got myself theUV protector is to protect it from dust/scratch. I have testedtaking photos with/out the UV filter, and from my untrained eye Icould not see any difference..

How do you protect the UV filter? As long as that UV filter is on your lens, dust/scratches on the filter are as bad as dust/scratches on the lens...

Comment #14

Yoel D wrote:.

I think that the real impact on the image quality is prettynegligeable when leaving the UV filter. However, taking off the UVfilter each time you mount the polizer increases the chances for duston the lense or worse ... of scratches if you are unlucky..

Dust? In what way does dust damage a lens?.

A few days ago I was looking at prices for a lens I'm hoping to buy. The lens is just over 800. The dealer was (unsurprisingly) recommending the purchase of a top quality multicoated filter to protect the lens, for almost 50. In effect a 1 in 16 insurance premium, to cover an eventuality which is actually very rare. How many people do you know who have taken reasonable care of their lenses (not obsessive, just reasonable is all I'm asking) and sustained any sort of damage that would have been avoided by the use of a filter? Also, if the worst should happen and a front element was scratched in a freak accident, it will usually be possible to replace the front element for very much less than the cost of the lens. And as a temporary measure - say if you are stuck in the middle of a wildlife safari with a stone-chipped mission-critical long lens - simply painting in the scratch/chip with black felt pen will completely cure any impact on image quality..

If you're simply not willing to take the risk, however small, then why not spend the money on an insurance premium instead? You can cover all your equipment for a year for the price of a couple of filters - you may even already have some sort of cover included in your house insurance, for no extra cost at all..

And if you don't own and use a lens hood, which offers very useful protection and actually enhances image quality instead of degrading it, you really ought to ask yourself why. Yes, the Canon ones are overpriced, but so too are filters..

Having said all that, it does make good sense to use a filter for protection if you are working in a difficult, dirty environment. If you know you are going to have to clean the front of your lens several times a day, a sacrificial filter can be cleaned much more roughly than the lens itself. I know of someone whose filters are subject to so much wear and tear that he routinely replaces them every few months. But that is not the average photographer, obviously..

I invite you to make your own opinion.

I couldn't agree more, but let's base it on reality, and not on the F.U.D. propagated by sales people who can easily double their profit on a camera by selling an overpriced memory card and an unnecessary UV filter...

Comment #15

I did a cp or not cp forum in the Nikon d80 forum last week, and put up some samples, and yes I found that the uv filter and cpl filter effects the focus slightly, so I will only use one filter from now on.

Here are my samples, first one with the CPL filter, and second without, heck of a difference.

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No CP.

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Http://s185.photobucket.com/.../albums/x223/eirianfa2002/?mediafilter=imagesMike Rudge..

Comment #16

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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