Why "protective" filters are a bad idea:

[chuxter]

I wanna chime in on this neverending debate. I dunno but the "goat" samples made me laugh a little bit. To me, those are unbelievable shots. Was it an L glass?

Anyway, I am not a filter believer but I have used them on my more expensive glasses, the EF 24-70 and EFS 15-85. For the kit lenses I don't really need them.

I did some test indoors a few minutes ago and these are what I came up with. Just normal incandescent house lights. Test is not scientific and maybe flawed but take it with a grain of salt. Guess which are with or without a UV filter:

















No flaming, please

OK. Those were interesting, but we were not discussing WB issues. ;-)

NOW...go point your camera at a bright light in a dark setting (streetlight/headlights in an otherwise dark scene...it should be dark in Portland)...take two pix w/ and w/o the UV filter...make sure the bright lights are not in the center of the frame...show us the results. I'd do it but I don't have a UV filter.

Also tell us what UV filter you use...

--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"Quantum Mechanics: The dreams that stuff is made of..."

 

[Steve H]

I wanna chime in on this neverending debate. I dunno but the "goat" samples made me laugh a little bit. To me, those are unbelievable shots. Was it an L glass?

The original thread is here:

http://forums.dpreview.com/forums/read.asp?forum=1029&message=33481535

Anyway, I am not a filter believer but I have used them on my more expensive glasses, the EF 24-70 and EFS 15-85. For the kit lenses I don't really need them.

I did some test indoors a few minutes ago and these are what I came up with. Just normal incandescent house lights. Test is not scientific and maybe flawed but take it with a grain of salt. Guess which are with or without a UV filter:

No-one is arguing that all shots taken with a filter will be discernibly different from those taken without. But some will, ranging from compromised AF, flare, reflections, poorer contrast. If you want to take the risk, that's fine.

That (compromised IQ) is just one of the downsides of fitting a "protective" filter. You haven't suggested any benefits to offset that. What are they?

--
Steve H



Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too? - Douglas Adams

 

[acsmith]

I saw a lenstip test of a dozen or so UV filters/skylight filters and the better ones didn't affect the images one bit in any way. Didn't add flare, change the color, etc.

And they actually improve IQ. UV filters cut down chromatic aberrations .

--
http://www.flickr.com/photos/techoutsider

I often refer folks to the Lenstip article so I was somewhat surprised to see your apparent or implied claim that the article says UV filters cut down chromatic aberrations. I brought up the article and did a word search within the article and the term chromatic aberrations was used nowhere in the article.

They did speculate on a condition that one might improve IQ but provided no evidence to support that claim. The best that can be said for the best of the filters is that they did not visibly degrade the image. For that you've paid good money. Buy the proper lens hood if the lens doesn't have one.

A. C.

--
I've taken a vow of poverty. To annoy me send money.

 

[cheezit]

I dunno if I'm proving anything here. But to my eyes (or maybe just in my head) images shot with the filter on seems to have a little more contrast. They were all shot on a tripod.

No flash:
img_3608 with filter
img_3609 without filter

With flash:
img_3612 with filter
img_3613 without filter

"NOW...go point your camera at a bright light in a dark setting (streetlight/headlights in an otherwise dark scene...it should be dark in Portland)...take two pix w/ and w/o the UV filter...make sure the bright lights are not in the center of the frame...show us the results. I'd do it but I don't have a UV filter. emoticon - smile

Also tell us what UV filter you use... "

chuxter: too much rain here to do some testing that you suggested. Will do the first chance I get tho. Thanx for the suggestion.

Filter is a ProMaster Digital HGX UV
Lens EFS 15-85mm

"That (compromised IQ) is just one of the downsides of fitting a "protective" filter. You haven't suggested any benefits to offset that. What are they?"

SteveH: I don't really see a compromise in IQ here. In fact like I said, it seems to have a little more contrast. About flare, etc, I agree with the consequences.

Anyway, I managed to scratch the front element on my 15-85. Had a hood on and was trying put the lens cap (pinch type) and it kinda slipped from my fingertips. The edge of the cap grazed the lens causing a small but very visible scratch. Clumsy me!

Cheers everybody and happy shooting.

 

[TechOutsider]

I think this would be much more helpful than scrolling through the numerous pages of arguments and rebuttals about the general usefulness of UV filters:

Pros:

1) Physical protection
2) Reduces CA
3) Improves color warmth slightly (esp. greens)

Cons

1) Flare
2) Vignetting
3) More CA

--
http://www.flickr.com/photos/techoutsider

 

[Steve H]

I think this would be much more helpful than scrolling through the numerous pages of arguments and rebuttals about the general usefulness of UV filters:

Pros:

1) Physical protection
2) Reduces CA
3) Improves color warmth slightly (esp. greens)

Cons

1) Flare
2) Vignetting
3) More CA

Well, it might have been a useful summary except that five out of the six points are nonsense. Where did you get this stuff about CA - I notice you still haven't responded to an earlier question about your source? As for vignetting, unless you stack filters or use the wrong type on a WA lens it's not actually a problem - most lenses are designed to accommodate one filter without vignetting. As for "improving color warmth", a clear protector or UV is designed specifically not to alter color balance in the visible spectrum but even if it does, AWB will tend to compensate.

Honestly, I don't know how beginners manage to navigate their way through all the profit driven and specious rubbish paraded as fact on this topic.

--
Steve H



Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too? - Douglas Adams

 

[Guidenet]

Anyway, I managed to scratch the front element on my 15-85. Had a hood on and was trying put the lens cap (pinch type) and it kinda slipped from my fingertips. The edge of the cap grazed the lens causing a small but very visible scratch. Clumsy me!

Ding ding ding! I knew it. If we waited long enough we'd get our obligatory story of damage to a lens or where a lens was protected by a filter. Here we go. Someone who supposedly used a filter just happened not to have one on, and a plastic cap caused a scratch. Amazingly hard plastic on amazingly soft glass. Maybe a superhuman amount of pressure applied or Canon makes super crappy coatings. A slip of the fingers and wham!

If this really did happen, try some tissue and wipe out that mar. If there is truly a scratch, it's less image intrusive than a filter. Try it with and without a scratch. Just kidding.
--
Cheers, Craig

Equipment in Plan via Profile

 

[cheezit]

Anyway, I managed to scratch the front element on my 15-85. Had a hood on and was trying put the lens cap (pinch type) and it kinda slipped from my fingertips. The edge of the cap grazed the lens causing a small but very visible scratch. Clumsy me!

Ding ding ding! I knew it. If we waited long enough we'd get our obligatory story of damage to a lens or where a lens was protected by a filter. Here we go. Someone who supposedly used a filter just happened not to have one on, and a plastic cap caused a scratch. Amazingly hard plastic on amazingly soft glass. Maybe a superhuman amount of pressure applied or Canon makes super crappy coatings. A slip of the fingers and wham!

If this really did happen, try some tissue and wipe out that mar. If there is truly a scratch, it's less image intrusive than a filter. Try it with and without a scratch. Just kidding.
--
Cheers, Craig

Equipment in Plan via Profile

Twas really a small scratch. Tried the wipes, no joy. Anyway, I guess I have to live with it. Damn lens cap...hehehe

 

[antoineb]

Mostly agree with you.

Though of course ND might be useful. Or polarizing.

AF can be thrown off - but only on old-world focusing systems ie phase-detect. Contrast-detect can use much more useful non-rotating polarizing filters.

 

[Guidenet]

I'd also really hate a scratch, though you'll see zero issues I'm sure. Try a little liquid lens cleaner, not glass cleaner.

Other's have told me that glass cleaner ought not to affect coatings, but my coating on my glasses have a warning not to use it. The coatings came off a pair and the Optomitrist told me it was Windex. For that reason, I'm afraid to use it on lenses. I don't know? I would assume that if Windex (or equivalent) can affect glasses coatings, it also might affect lens coatings. I wonder if it's amonia? I do know that my current pair of glasses which are the exact replacements have no coating issues since I quit using glass cleaner.

The also have zero scratches or mars and I don't have protective barriers in front of them. LOL They must have better glass than that Canon lens.

--
Cheers, Craig

Equipment in Plan via Profile

 

[JulesJ]

We have uses a Skylight filter on our D2x in the studio since day one of the camera when we bought it years ago. Every picture has been perfect and the value of work done by that one camera with filter runs into six figures (£). The camera has probably been used on 75% of days in the last five years. The original lens is and will be pristine to this day. Had we shot without a filter I guess the front would now look like a skating rink. What's the problem? What you might think right, others might not.
jules

--
Julesarnia on twitter

 

[Steve H]

We have uses a Skylight filter on our D2x in the studio since day one of the camera when we bought it years ago. Every picture has been perfect and the value of work done by that one camera with filter runs into six figures (£). The camera has probably been used on 75% of days in the last five years. The original lens is and will be pristine to this day. Had we shot without a filter I guess the front would now look like a skating rink. What's the problem? What you might think right, others might not.

I don't follow the logic, even if with controlled lighting in a controlled environment like this there isn't any visible image degradation. Why fit the filter in the first place? What are you protecting against?
--
Steve H



Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too? - Douglas Adams

 

[Steve H]

Mostly agree with you.

Though of course ND might be useful. Or polarizing.

No argument from me - have both and use them regularly. The thread was specifically about using a so-called protective filter 24/7

--
Steve H



Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too? - Douglas Adams

 

[MusicDoctorDJ]

And they actually improve IQ. UV filters cut down chromatic aberrations .

If guys like you would not make outlandish claims, like the above, these threads would be quite short! :-(

Perhaps you should listen your own words . . .

--
J. D.
Colorado

 

[MusicDoctorDJ]

Besides the "degrading" issue I asked a related question of how much a filter can physically "protect" the lens in an accident and how often lenses are really damaged. The response in the thread below seems to say damaged lenses from not having a lens filter on are uncommon.

http://forums.dpreview.com/forums/readflat.asp?forum=1002&message=36914534

It is not that it is uncommon for filters to protect lenses, but whenever someone here shows evidence that this is in fact true, the local chest pounders around here pounce for the kill!

Which is why you'll find that nobody cares to prove to you that they can, in fact, protect a lens from damage.

Unfortunately, most of us can't afford to have a news crew follow us around 24/7 to film an event where a filter can save a lens from damage just to prove a point to the chest pounders.

--
J. D.
Colorado

 

[TechOutsider]

A good $70 dollar UV filter has almost 0 effect on IQ.

Granted, there is a little of green flare at the extreme edge of sample 4 w/ the filter, and one extra polygon on the last picture.

But if I didn't see samples with and without the UV filter, I would have attributed the issue to the lens . The lens used in this test

Now whether or not that $70 is worth it to you or not is completely debatable.













--
http://www.flickr.com/photos/techoutsider

 

[chuxter]

I dunno if I'm proving anything here. But to my eyes (or maybe just in my head) images shot with the filter on seems to have a little more contrast. They were all shot on a tripod.

Nobody else sees a difference (because that type of photo will not show flare).

No flash:
img_3608 with filter
img_3609 without filter

With flash:
img_3612 with filter
img_3613 without filter

"NOW...go point your camera at a bright light in a dark setting (streetlight/headlights in an otherwise dark scene...it should be dark in Portland)...take two pix w/ and w/o the UV filter...make sure the bright lights are not in the center of the frame...show us the results. I'd do it but I don't have a UV filter. emoticon - smile

Also tell us what UV filter you use... "

chuxter: too much rain here to do some testing that you suggested. Will do the first chance I get tho. Thanx for the suggestion.

Filter is a ProMaster Digital HGX UV
Lens EFS 15-85mm

"That (compromised IQ) is just one of the downsides of fitting a "protective" filter. You haven't suggested any benefits to offset that. What are they?"

SteveH: I don't really see a compromise in IQ here. In fact like I said, it seems to have a little more contrast. About flare, etc, I agree with the consequences.

Anyway, I managed to scratch the front element on my 15-85. Had a hood on and was trying put the lens cap (pinch type) and it kinda slipped from my fingertips. The edge of the cap grazed the lens causing a small but very visible scratch. Clumsy me!

There is a lesson there...you missed it. I don't put my front lens caps on when I have the lens hood mounted (pointing out)...it's hard to do and as you discovered, it's possible to accidently flip the cap into the lens! It's also faster to not have the caps on and you don't have to find a place to put the cap when it's off the lens. I always suggest that beginners start out with a better paradigm:

• Don't use "protective" UV filters
• Do use protective lens hoods
• Don't use protective front lens caps

I leave the front caps at home in my photo plectra drawer... ;-)

--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"Quantum Mechanics: The dreams that stuff is made of..."

 

[JulesJ]

Uhm, using the camera so often do you vagely consider that one might not touch the lens with a greasy finger, something during those millions of shots might not hit the lens. fall onto it or into it, that you might not push the camera into something by mistake? Your so called 'controlled environment can get rough when we photograph a family of kids or dribbling youngsters. We are protecting against everyday life. If you don't need a filter fine, it doesn't mean others don't either. The filter we use has absolutely no visible negative effect at all on our final result. It's more a worry of idle forum posters than jobbing photographers.
jules

We have uses a Skylight filter on our D2x in the studio since day one of the camera when we bought it years ago. Every picture has been perfect and the value of work done by that one camera with filter runs into six figures (£). The camera has probably been used on 75% of days in the last five years. The original lens is and will be pristine to this day. Had we shot without a filter I guess the front would now look like a skating rink. What's the problem? What you might think right, others might not.

I don't follow the logic, even if with controlled lighting in a controlled environment like this there isn't any visible image degradation. Why fit the filter in the first place? What are you protecting against?
--
Steve H



Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too? - Douglas Adams

--
Julesarnia on twitter

 

[chuxter]

Uhm, using the camera so often do you vagely consider that one might not touch the lens with a greasy finger, something during those millions of shots might not hit the lens. fall onto it or into it, that you might not push the camera into something by mistake? Your so called 'controlled environment can get rough when we photograph a family of kids or dribbling youngsters. We are protecting against everyday life. If you don't need a filter fine, it doesn't mean others don't either. The filter we use has absolutely no visible negative effect at all on our final result. It's more a worry of idle forum posters than jobbing photographers.

Jules, in your studio environment, I'm sure you control where the lights are, thus you don't have many bright light sources in the frame to cause flare. I believe you...a good UV filter in that environment will not visibly affect IQ.

However, most beginners here don't work in a studio with controlled lighting. And may are sold really cheap UV filters by predatory stores, which DO visibly affect IQ...there are many posts here by beginners who have terrible IQ issues. We tell them to take the UV filter off and trash it.

--
Charlie Davis
Nikon 5700, Sony R1, Nikon D50, Nikon D300
HomePage: http://www.1derful.info
"Quantum Mechanics: The dreams that stuff is made of..."

 

[Steve H]

Uhm, using the camera so often do you vagely consider that one might not touch the lens with a greasy finger, something during those millions of shots might not hit the lens. fall onto it or into it, that you might not push the camera into something by mistake?

I guess it's possible but I didn't think a greasy finger could damage a front element. I guess the next most likely scenario is that the whole camera/lens/tripod assembly goes over, probably lens first, in which case the smashed filter really will make a mess of the front element. I assume that with all the poking and flying hazards capable of damaging a front element you wear eye protection on the job?

But to each his own....
--
Steve H



Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too? - Douglas Adams