# UV or clear protection filter?



## Marsu42 (Feb 16, 2013)

In my recent unintentional trivia series "I'm clueless, please help me out" I've stumbled across another question: I thought using uv filters were just a rip-off for old school amateurs who didn't know that a digital sensor isn't sensitive to uv - or for people who find a uv filter that is cheaper than a comparable clear filter.

My web research supports this, but I was told that just because it's in the Internet it isn't necessarily correct... and I've recently come across one application that might still prove a need for an uv filter except for protection or lens sealing:

* Vari-nd filters or two stacked polarizers - in contrast to "real" dark glass nd filters, they let uv pass and though the sensor is not very sensitive to uv, it still might make a difference with long exposures.

Is this correct? Are there any other reasons to get an uv filter over clear glass?


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## TexPhoto (Feb 16, 2013)

I am one of those live free and don't use any filter when you don't need one people. (I protect my lens with a lens cap) But i think even the UV filter or death people will tell you not to stack 2 filters if you can avoid it. Light bounces around between the 2 parallel filters and other problems.


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## Zv (Feb 16, 2013)

The best quality filter available was a kenko zeta UV filter so I bought that. The glass is decent and I can't tell the difference with it on or off. I use it to weather seal my L glass. If the situation doesn't require it I'll shoot without it. A b+w clear filter would have been more expensive and is harder to find here in Japan. It's all Kenko filters here. I believe they are the same as Hoya. But yeah, no real reason for UV filters. 

I also heard that using a UV filter for night landscapes is a bad idea. Forgot how and why. I guess you need as much light rays as possible in the dark and UV provides some form of illumination? Is that what gives the deep blue hue at blue hour?


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## neuroanatomist (Feb 16, 2013)

No difference between clear and UV for a dSLR. Well...I can't speak for all of them, but I can speak for the 7D and 5DII that I empirically tested with both short- and long-wave UV light sources - both were insensitive to UV.


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## TrumpetPower! (Feb 16, 2013)

neuroanatomist said:


> No difference between clear and UV for a dSLR. Well...I can't speak for all of them, but I can speak for the 7D and 5DII that I empirically tested with both short- and long-wave UV light sources - both were insensitive to UV.



Out of curiosity, how did you perform your test?

...and...again, out of curiosity, are there any dSLRs that _are_ sensitive to UV? I'm thinking that, if so, there might be interesting applications for, for example, getting a filter that blocks all but UV. I understand that there are flowers that are much more interesting in the UV spectrum than the visible spectrum....

In a similar vein, I'm also somewhat surprised that IR-blocking filters haven't become popular for DSLRs. Blown red channels when shooting certain subjects at least used to be a common problem, and that was because the cameras had some sensitivity to IR. Modern cameras have better IR-blocking filters built into the sensor, but for a time there, IR contamination was at least as big a problem for digital shooters as UV contamination ever was for film.

Cheers,

b&


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## neuroanatomist (Feb 16, 2013)

TrumpetPower! said:


> Out of curiosity, how did you perform your test?



My first test was just a 'quick and dirty' one - laying a B+W UV filter on a UV transilluminator (the kind used to visualize ethiduim bromide-stained DNA gels in the lab) and taking a picture (with no filter on the lens), to see if the UV filter blocked any of the light. It didn't appear to, but the light tubes in a typical transilluminator emit a lot of visible blue light, too. 

My second test was more specific. I used a mercury arc lamp (a bright 'white' light source for fluorescence microscopy) which has emission peaks at 254nm, 365nm, 405nm, and 436nm (and other peaks, too), and a set of 20nm bandpass filters centered on 250nm, 360nm, 405nm, and 435nm. The 250nm and 360nm filter images were black even with long exposures, the 405nm filter was very dim, and the 435nm filter was reasonably bright.


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## jrda2 (Feb 16, 2013)

yes, that is exactly how I would have set up the test too.....with only one minor change - in place of the mercury arc lamp, I would have used the much more precise settings of high, medium, and low emission peaks from my night stand light


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## bornshooter (Feb 16, 2013)

Just use a hood if something is going to break your filter then your lens will be scratched anyway,i use a filter though when raining near a beach etc i paid a lot of money for that glass no way i am sticking a filter in front of it no matter how good any one says they are.


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## TrumpetPower! (Feb 16, 2013)

neuroanatomist said:


> TrumpetPower! said:
> 
> 
> > Out of curiosity, how did you perform your test?
> ...



Ah -- you have (access to) actual equipment designed for that sort of thing.

I don't, so I was instead trying to think of kludges involving cheap fluorescent UV tubes, possibly with the assistance of papers with OBAs....

b&


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## LostArk (Feb 16, 2013)

Lots of messed up reasoning surrounding the UV filter "debate."

Here are some incontrovertible facts to help you decide if UV filters are right for you:

In favor of UV filters:

- Even with a lens hood, the front element is susceptible to damage from projectiles 
- Even with a hood, dust and gunk (fingerprints etc) WILL accumulate on the front element
- Cleaning the front element improperly may result in micro-abrasions
- It is inconvenient or impossible to properly clean the front element in the field
- _Quality_ UV filters do not degrade image quality or cause flare, they DO however exacerbate existing flare. 
- While micro-abrasions won't affect image quality, ask yourself if you'd rather risk your front element or a UV filter
- Using UV filters means you don't have to worry about fiddling with lens caps if you don't want to. I never use lens caps.

Against UV filters:

- It's true UV filters don't protect from impact, and may actually exacerbate damage from impact
- Inconvenient having to switch UV filter for ND or CP (stacking filters is inadvisable)
- Exacerbates flare in certain situations
- Low quality filters may affect sharpness and contrast
- Cost

I use UV filters but I'm not averse to removing them if they're exacerbating flare. I never attached a filter to my 50 1.8 and after two years it still looks brand new. I know as soon as I take a filter off one of my L lenses, a projectile will chip the front element. YMMV


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## brad goda (Feb 16, 2013)

I never thought the need for UV filters on great glass... but I was having some issues shooting with 90TSE outside... wedding... the lens seemed way to susceptible to flair and made images washed and soft... so I discussed with neighborhood Canon dealer and recommended UV filter... a Heliopan UV -0 SH-PMC was purchased and seems to help... 
I am so darn happy when I heard the news they MIGHT be redoing the 90TSE... I can only hope for larger image circle better coatings, UD elements...and of course the new rotator TS like the 17 and 24II TSEs
holy cow near and far IR... filters... will this allow my camera to see cloaked UFOs? lol


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## sandymandy (Feb 16, 2013)

Isnt a lenshood used to reduce/remove flare? I think you guys are just too sensitive with your gear often. Its made to be used professionally and not let it sit secured in a shelf. Lenses are just a tool its not something holy  To get lenses damaged u really need some hard work actually. With normal usage they will last a long, long time...


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## crasher8 (Feb 16, 2013)

I shoot in dusty, dirty, windy locales. I use clear B+W MRC XS Pro filters. I also do Macro in close quarters with dirt, branches and other mucky much. A hood is sometimes in the way and I need protection for the front element. Seems like a no brainer.


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## wayno (Feb 16, 2013)

For me, the only truly compelling reason is to weather seal the lens ( in most instances).


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## TrumpetPower! (Feb 16, 2013)

Since this has inevitably moved on to the merits of filters as protection...

...the simple rule of thumb is that lens hoods improve image quality, protect against all the common types of damage lenses suffer, and under no circumstances will cause damage to a lens; and protection filters degrade image quality (even if imperceptibly with the best of filters), protect against only those situations where you as a human should also be wearing safety goggles; sometimes are necessary to complete environmental sealing; typically cost almost as much as replacing the front element; and will likely further damage the lens in common damage situations (especially by jamming the filter threads).

So, if you yourself should be wearing eye protection (such as if you're getting gravel kicked in your face at the rodeo, or if you're ringside and are getting splashed by bodily fluids); or if you're using one of a small number of L lenses in inclement conditions (including seaside); or if you're handing your camera to people (especially children) who can't keep their grubby fingers off the lens; then a protection filter is called for _in addition to the lens hood._

The lens hood is always called for, except for situations where it's causing a physical obstruction.

Cheers,

b&


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