[luma]

I have been using SLR cameras with various lenses for at least past 35 years and in the “good old times” there was a rule that you should keep a “protective” UV or skylight filter on every lens, which I did religiously to this day.
I just bought a 52mm CPL filter for my Pentax kit lenses and started thinking if it is a good idea to have the two filters, UV and CPL on top of each other. So, I did some reading on the web, and it looks like few people do not recommend the use of “protective” filters at all, apparently they can have a deteriorating effect on the lens performance.
Is there any consensus on this forum regarding a general use of the protective (UV, skylight and similar) filters? Would you combine the polarizer and UV filters together? Thanks.

[MrApollinax]

I think in these parts the consensus is that if you put another lesser piece of glass in front of calibrated optics you are going to cause some deterioration in the image quality. I had a filter on my Sigma 105 that caused bad flaring. Once I took the filter off the issue went away.

[wallyb]

You won't degrade the actual image quality, such as properties like sharpness, coma, chromatic aberration, color representation, etc.

You might, in some rare cases, introduce more flare.

That's it. Period.

[kenyee]

yep, if you have to put one on (protection from waterfalls, salt spray, sand, etc.), put on a good one. It's better to clean a filter than the front element is how I look at it...

[Wheatfield]

You won't degrade the actual image quality, such as properties like sharpness, coma, chromatic aberration, color representation, etc.

You might, in some rare cases, introduce more flare.

That's it. Period.

I'm pretty sure that this has been proven wrong on many occasions.
A very high quality filter may have a negligible effect on image quality, but a mediocre filter can have a fairly serious effect on IQ, especially sharpness and contrast, and can also affect colour accuracy and can introduce flare.

[CWyatt]

There's a lot of opinions on this, either way.

There's certainly no need for a UV filter is terms of blocking UV rays like there was with film, it seems the sensors in DSLR's today do that anyway.

There's also the general consensus that a lens hood is better defence against damage from dropping a lens than any glass filter.

If you're taking your camera out once in a blue moon for the odd shot I'd say there's no need. I do use protectors/UV filters myself, as I have my cameras out lots, including in the rain, and prefer being able to wipe a filter quickly without worrying too much, e.g. if it was the lens front I'd be wanting to check I was rubbing anything into it first. I also use them heaps around town where there can be random things like sprays or paint on the odd occasion flying about. There are a few stories about what things like hair sprays have done to lens' front elements too.

I think the possibility of having a lens' front element scratched is pretty small, they're already quite resistant, but a filter provides some piece of mind, and I know my front element will be kept like new. It does seem like older lenses can get a lot of tiny scratches, which don't affect image quality.

As previous poster said, there's a BIG difference between good and bad filters. I would not use a cheap low-grade filter. No point in paying good money for good lenses to make the last element rubbish. I'd really only use a high-end, multi-coated filter like the Hoya Pro1 range, or it's asking for problems.

There's a test of UV filters on the net somewhere, and from what they tested the Hoya Pro1 and top B+W filters were the best.

[Al_in_the_Shire]

I have to agree that they can and will affect IQ. With film cameras, they were useful to cut down haze, but with digital, you dont need them and instead of buying two mediocre filters, buy one great CPL.

Now if you shoot where you have blowing sand or salt spray, yeah, I would use one, but under other conditions, no.

[tibbitts]

I have been using SLR cameras with various lenses for at least past 35 years and in the “good old times” there was a rule that you should keep a “protective” UV or skylight filter on every lens, which I did religiously to this day.
I just bought a 52mm CPL filter for my Pentax kit lenses and started thinking if it is a good idea to have the two filters, UV and CPL on top of each other. So, I did some reading on the web, and it looks like few people do not recommend the use of “protective” filters at all, apparently they can have a deteriorating effect on the lens performance.
Is there any consensus on this forum regarding a general use of the protective (UV, skylight and similar) filters? Would you combine the polarizer and UV filters together? Thanks.

I believe that you are mistaken that there is any more or less debate today than thirty or more years ago. It was same then as it is now.

However, I don't think that anyone had ever suggested stacking filters, unless a combined effect was required. Today, it would be hard to make the case that the combination would accomplish anything the polarizer alone wouldn't. So, combining those filters would be universally regarded as a bad idea. In many cases, stacking more than one filter would infringe on the corners of the image.

There is no consensus regarding filters for protection, except probably that uncoated or single-coated filters are undesirable when sources of light/reflections are involved. And it would probably be safe to say that if front lens elements were the same price as filters, and as easy to replace, there would be no use for protection filters.

Personally I have not been able to see a difference in my own tests with normal frontal lighting between my window-glass-quality filters and no filter at all. But you should test for yourself with your equipment, and come to your own conclusions. That's a great feature of digital: testing costs only your time; no materials are involved.

The problem I have with buying expensive filters is that a set for my lenses would cost about as much as a new lens, or even pay for a good part of an upgraded camera body. So if you have finite funds, the question becomes, what will give you the most image quality for the money.

Paul

[jjdgti]

Igree with Paul. Staking two filter or more in some of the new wide lenses is a no-no. It will infringe on the corners of the lens in the wide end.
As far as UV protecting the lens, it is always a good idea. Get the best filter you can afford. If you need the ultimate best IQ in a certain situation simply remove the filter, shoot the image and then put the filter back. I found out that medium grade lens is good enought for 99% of my shots. For the 1% I simply remove the filter.

[Ben_Edict]

I have been using SLR cameras with various lenses for at least past 35 years and in the “good old times” there was a rule that you should keep a “protective” UV or skylight filter on every lens, which I did religiously to this day.
I just bought a 52mm CPL filter for my Pentax kit lenses and started thinking if it is a good idea to have the two filters, UV and CPL on top of each other. So, I did some reading on the web, and it looks like few people do not recommend the use of “protective” filters at all, apparently they can have a deteriorating effect on the lens performance.
Is there any consensus on this forum regarding a general use of the protective (UV, skylight and similar) filters? Would you combine the polarizer and UV filters together? Thanks.

There is no consencus.

It is clear, that any additional glass in front of the lens will degrade image quality. The question is, whether this degradation is visible in the final image. And in my experience it is not, if you use high quality filters.

Nevertheless, there are some shooting conditions under which I always remove filters. Especially when shooting into lights (may it be natural sun light or artificial light sources), all filters I have used so far (B+W, Hoya Pro 1 mainly) lead to a visible increase in flareing and ghosting and decrease contrast and saturation.

In any case, a skylight filter is obsolete, as its slight reddish tint was used in film days, to give a more pleasing, warmer colour. That isn't needed with digital and would be countered by White Balance anyway.

Then there is your question about stacking a UV and a CPL. That is wholly detrimental. Filters should only be stacked as a last ressort, as you will add even more reflections between the different filter glasses. The CPL alone already consists of two glass plates!

I recommend protective filters mainly if you shoot under severe environmental conditions (salt water spray at the beach, windy and sandy conditions, mainly) or when there is a real mechanical hazard for the lens (rock climbing for instance). In almost all circumstances a good lens hood (aka one, that is not too short), will afford at least as much protection for the front element of the lens.

Ben

[Ratmagiclady]

Another exception, too, is that a UV might be good to put on a lens you expect to want to *sell* soon, (like, if it's a stopgap until you upgrade) ...People like to see that glass up front nice and pristine, even if the risk is small.

They aren't a bad thing for doing very informal things around toddlers' greasy little paws and dog noses, either. Which, really, people do a lot of, casually. I've got this old lens with a big front element, that I like to use for this: often one of the first things the little ones will do is run *right up to it and have to touch it.* I guess it is kinda neat-looking, after all. Dognoses are more random, but at least lenses don't *taste* very interesting, after all.

But, it kind of helps to not have to stop the fun to clean or anything, just remove.

[Ben_Edict]

Another exception, too, is that a UV might be good to put on a lens you expect to want to *sell* soon, (like, if it's a stopgap until you upgrade) ...People like to see that glass up front nice and pristine, even if the risk is small.

They aren't a bad thing for doing very informal things around toddlers' greasy little paws and dog noses, either. Which, really, people do a lot of, casually. I've got this old lens with a big front element, that I like to use for this: often one of the first things the little ones will do is run *right up to it and have to touch it.* I guess it is kinda neat-looking, after all. Dognoses are more random, but at least lenses don't *taste* very interesting, after all.

But, it kind of helps to not have to stop the fun to clean or anything, just remove.

These exampley are also too true… I think, they fit nicely into my "severe environmental conditions" category.

Ben

[reeftool]

When I bought my first DSLR, I also bought UV filters for the 2 lenses I also got at the time. I used them always with my film cameras. After reading through a few threads on the forum discussing this issue a couple of years ago, I removed the UV filters and did my own testing. Nothing scientific but just my own old eyes looking at full screen pics. The difference was remarkable, especially on my Sigma 70-300. It was almost a completely different lens. I no longer use them except when the conditions call for it, ie: wind/dust, salt spray, etc.

[Oldphoto678]

I use filters on all of mine, But only because I don't use lens caps until the lens goes back in the bag. I seldom see a lens cap on a pros lens while it's on the camera.

Rodney...

[Ratmagiclady]

I use filters on all of mine, But only because I don't use lens caps until the lens goes back in the bag. I seldom see a lens cap on a pros lens while it's on the camera.

Rodney...

That's probably cause the caps come off and stay in your pocket till you do laundry.