Does a UV filter make sense for digital sensors?

[colinsouthern]

As a matter of fact I do Larry ...

 

The aperture doesn't appear to make any difference, although I do believe that vignetting & CA have been totally eliminated<div></div>

[andrew robertson]

Leave it off!

[markonestudios]

:) Good one, Colin ;-) back to the OP, I can (almost) swear by lens filters. During one of the first weddings I shot a couple of years back, I had my 2 SLRs, one on my neck, the other on my shoulder. I was tying my shoelace when my Canon (with lens hood on), slipped off my shoulder strap and landed, lens-first, on hard gravel. Guess what broke... yup. The filter. Shattered into little pieces but with the retaining ring intact. I carefully unscrewed it, cleaned off the fragments and to this day that lens is still optically sound. For those advocating for lens sans filter, you're asking for trouble IMHO... If you really think it'll degrade IQ, unscrew it while shooting, then screw it back on when you're done. You never know what might happen in between shots! As for quality, try and get the best filter you can afford. Cheap is often expensive ;-)

<p>That's my 2 cents...

[robin_sibson1]

There are two different questions here.

 

Is it a good idea to use a filter to protect the front element of a lens? Answer YES, provided it is a filter of sufficiently high quality to have negligible impact on image quality. I'm 100% with Colin on this issue.

 

Does the UV-cut behaviour of a conventional UV filter provide any benefit? Answer probably a little on film, probably none at all on a digital sensor. These days you can buy PROTECT filters to do the job their name suggests, and those are what I use.

[darren_sandford]

@Colin:

 

The EXIF appears to be stripped out of that image. Did you perform any retouching?

[lester_wareham]

I have a balanced FAQ prepared for protective filter questions as there are such polarised views about it, there are lots of informative links, it should help you come to a sensible view.

 

http://www.zen20934.zen.co.uk/photography/LensTests/Flare/Protective_Filter_FAQ.htm

[gdanmitchell]

Colin probably had fun misconstruing the point of my post. To make it clear - and repeat what I wrote:

 

"Use your lens hood and a lens cap..."

 

The hood provides _some_ protection for the front element, in a case where it rather than the front element of the

lens bumps into an object that might cause a scratch or other damage. Also, to state the obvious, the deeper hoods

used in telephotos will provide greater protection than the shallow hoods used on wide angle lenses. Also, the rigid

hoods (like those supplied by Canon) will provide more protection than collapsible rubber hoods. (These do have their

place though.)

 

Again to restate the obvious, a lens hood provide little protection from dust. But...

 

First of all, the effect of a bit of dust on the front element is far less than you might imagine. Test this yourself and

you'll see what I mean. (Dust or other stuff on the rear element, on the other hand, can be a big issue. I use a rear

cap on my lenses when they are not on the camera, and I check the rear element frequently.)

 

Second, I did include the words "and a lens cap" in my post. The lens cap (which I do typically remove before

shooting... ;-) does provide excellent protection for the front element - both from dust and from objects that might

damage it. The _combination_ of lens cap and hood offers a great deal of protection - more, I would say, then a front

filter alone.

 

All of that said, YMMV.

 

You might find that the potential for slight image deterioration and/or the cost of expensive high quality UV filters

for each of your lenses insignificant compared to the convenience of not using a hood and lens cap. So be it. I will

say that the use of both of these is now so automatic for me that I really barely think about it at all.

 

Do investigate some of the online tests of how image quality can be affected by these types of filters (sorry I don't

have any links handy) and then decide whether you think that this is significant or not.

 

Take care,

 

Dan

[colinsouthern]

"The EXIF appears to be stripped out of that image. Did you perform any retouching?"

 

I had to remove the exif data for that lens to protect the guilty :)

[colinsouthern]

Dan Mitchell wrote:

 

"Colin probably had fun misconstruing the point of my post. To make it clear - and repeat what I wrote:"

 

Dan, in all seriousness, I'm not trying to misconstrue anything. The beleagured point that I'm trying to make is that it's rather silly to suggest that using a lens cap contributes ANYTHING towards front-element protection when it has to be removed prior to use. Admittedly, using one when the lens ISN'T in use is a no-brainer, but unfortunately that's not when the majority of the damage is likely to occur. As a protection strategy it's about as effective as using a condom all the time then removing it before you "do the deed".

 

In terms of hoods providing protection - I think you'd be surprised at how little they do actually provide. If you take something like an EF16-35mm F2.8L USM, the hood is so short & wide that it's not that far from being on the same plane as the front element, and in reality doesn't protect it in any way, shape or form against fingers, wet noses, beer glasses, salt air, tree branches etc. If you take something like an EF70-200 F2.8L IS USM (with a deep hood) then you face another problem - although the hood is nice and deep, this depth generates a large mechanical moment against the weak mount - combine this with the large mass of the lens and you find that with any "more than trival" knock, the hood pops off.

 

In contract, we've had example after example after example of people who have had lenses saved by using some form of sacrificial protection - it's even recommended by the lens manufacturer - which is why I feel like it's time for the old wives tales of "hoods & caps providing protection" and "filters causing everything from a theoretical degradation to massive loss of IQ" to be laid to rest.

 

Cheers,

 

Colin

[andrew robertson]

Even the best, most expensive filters can hurt image quality, especially in difficult lighting.

[colinsouthern]

"Even the best, most expensive filters can hurt image quality, especially in difficult lighting."

 

Which would be a perfectly valid reason to temporarily remove it. Having said that, many of those "difficult lighting" situations bring out issues with flare and ghosting even without a filter.

[roger_smith4]

"Even the best, most expensive filters can hurt image quality, especially in difficult lighting."

 

Well, then test for it. As I mentioned above I shoot scenes with point light sources at night, and couldn't tell the filter shots from ones without a filter. That's not true of previous MC filters I had used where there was some pretty incredible ghosting going on. Test your filters to figure out if there are times when they must be removed.

[lester_wareham]

"Even the best, most expensive filters can hurt image quality, especially in difficult lighting."

 

But in most cases not to see tests for the effect of filters on flare and lens resolution (basically not a lot) please check the link in my earlier post.