Download Filter Video Camera
Kenya Nguyn
This question is highly controversial amongst photographers and the forums of DPREVIEW have seen many long discussions/arguments on the subject. The only thing we can say for sure is that there is no definitive right answer. In this article, I will attempt to explain my own point of view and discuss the main arguments for and against using UV filters. Most of these arguments apply equally to clear protective filters.
I assume that the UV filter being used is of similar optical quality to the lens elements themselves. This is generally true for the best multi-coated filters from good manufacturers, but may not be true for the cheaper filters.
This argument is almost completely spurious for modern digital cameras. With old film cameras it was often necessary to use a UV filter because film is extremely sensitive to UV light. However, digital sensors are generally rather insensitive to UV, so the problem doesn't arise to anything like the same extent.
Having said that, I have seen some evidence that for certain lenses a UV filter can reduce the purple fringing caused by longitudinal chromatic aberration. The purple fringing of longitudinal chromatic aberration only occurs in particular circumstances and is not to be confused with the much more common coloured fringing caused by lateral chromatic aberration (most noticeable in the corners of the frame).
Firstly, protection against damage caused by rough handling or dropping the lens/camera -
I doubt if anyone has done a proper scientific study of this, but personal experience suggests that a mishap that damages the filter will probably also damage the lens. I have seen no good evidence that the presence of a filter significantly reduces the chances of seriously damaging the lens.
Secondly, protection against dust, dirt, smears and scratches on the front element of the lens - The presence of a filter on the lens certainly protects the front element, as the dust, dirt, smears and scratches get on the filter instead. Which is preferable?
The filter is flat and easily removed, which makes it much easier to clean. Also, if it does get scratched, or gets so dirty that it is too difficult to clean thoroughly, then it typically costs much less to replace than the lens.
On the other hand, many photographers argue that lenses do not need cleaning very often and the chances of scratching the lens are very low, so it is better to save your money and go without the filter.
This is true in theory (except possibly in those rare cases of lenses that have been specially designed for use with a filter). However, the loss of image quality is likely to be very small in practice and so the real question becomes: Is the loss of image quality significant to me?
Both flare and ghost images are caused by unwanted reflections or scattering from the various exposed surfaces within the lens and camera body. The glass surfaces of all the lens elements will contribute, as will the glass surfaces of the filter. Typical modern lenses contain up to 15 or more elements, and the addition of one more element (the filter) is not likely to make much difference in most practical circumstances.
However, there is a particular circumstance in which the presence of a filter may cause noticeable ghost images. With some lenses, when used at full aperture (or nearly so), light reflected from the sensor back through the lens may be reflected from the rear surface of the filter back into the camera producing a ghost image on the opposite side of the optical axis. Ghost images of very bright lights are often visible in night shots taken with a very fast lens at full aperture if a filter (any filter, the type is irrelevant) is being used.
Although much fainter than the primary images, they can be very noticeable as they will be in focus if the lens is focussed at infinity and the lights causing them are in focus. These ghost images will disappear if the filter is removed, or if the aperture is reduced sufficiently (i.e. the F-number is increased).
With a UV filter on the lens. The greenish spots of light in the central portion of the frame are ghost images of some of the very bright floodlights. It is only a circular area around the centre of the image that is subject to these ghost images. The diameter of this area reduces as the F-number is increased.
I have never seen any convincing evidence that a good quality UV filter causes noticeable loss of light through the lens. Indeed, that would not be expected as the filter is just one additional glass element and most modern lenses already have at least 7 elements and often twice that number or even more.
Again, I have never seen any evidence that this is significant for a good quality filter on normal camera lenses. Good quality filters should have optically flat surfaces that do not disturb the direction of the light rays passing through the filter. If there is any slight variation from optical flatness (as may occur with a very cheap filter), the effect will be most noticeable with extreme telephoto lenses because of their magnifying effect.
My evaluation of the evidence is that there is no really compelling evidence either to use a filter or not, except in a very few situations when it is better not to use a filter to avoid in-focus ghost images.
Personally, I do have UV filters on all my lenses and only remove them in those very rare situations for which I know they may cause ghost images. My main reason for using filters is that I like to keep my lenses very clean and I feel more confident in cleaning the filter than in cleaning the surface of the lens.
In comparing images taken with and without a filter, one thing I have noticed in doing the tests is that even a slightly dusty lens occasionally has a noticeably deleterious effect on the image. This only occurs in extreme lighting conditions such as when the sun is shining brightly and is within the image frame, or very close to it. Under such circumstances, light scattered by dust particles on the front element of the lens or on the filter can significantly increase the stray light falling on the image.
It's generally not worth worrying about a little dust on the lens (or filter). In normal circumstances dust on the front element has no visible effect at all. But, if you are shooting into a bright sun or other very bright lights, then it is a good idea to clean your lens (and filter) first.
11 Years ago I bought my first DSLR, and a cheap superzoomlens to go with it. The shop sold me a UV filter, one for each lens (kit-lens and the superzoom).
I put them on my lenses and never gave it another thought.
Until a week ago after looking over another batch of pictures I started to think, what about that UV filter...
So last weekend I took some photos under more-or-less controlled circumstances, outdoors with good sunlight, with and without UV filter.
I just sold a vintage Leica lens. It was in otherwise nearly mint condition except some well meaning previous owner seriously damaged the front element by cleaning it, greatly reducing its value. Without doubt, today's coatings are much more durable than the ones used in those old lenses, but they can still be easily damaged. I agree with the author, leave the filter in place unless there is a reason to remove it.
I'm in the camp of better safe than sorry. I mainly work photographing children in schools and at events and anything can happen around children. I've definitely had a couple instances where an accidental drop or hit with an errant ball thrown by a 10-year-old has broken the filter and not damaged the lens at all.
FWIW, I somehow got a drop of coffee on a lens several years ago. I noticed it in the field and did not have decent cleaning cloths with me and it did not seem to affect the image so I left for later cleaning. I cleaned it that night and the coffee eroded a surface coating and the erosion was plainly visible by the human eye, but did not seem to affect image quality. It did, however, affect re-sale value.
From that day on, I put protective filters on my camera on the day I receive them.
I don't use any UV filter on any of my lenses, I just keep the lens hood on, and when the lens hood is not used I make sure not to drop the camera or bang the lens against anything. I have NEVER dropped my gear or banged the lens against anything.
On two occasions I found my filters badly cracked or shattered but the lenses they protected remained undamaged and allowed me to continue with my photographic assignments. We forget to include in our calculations the time and the loss of heart when you've lost the use of a lens you were counting on. As the commercial says, don't leave home without it.
How can you assume the lens would have been broken if it weren't for the UV filter? Two things: the UV filter sits much further forward of the front element so is significantly more exposed and at risk. Secondly, the front element if a lens is significantly tougher and more scratch resistant than any filter. UV filters are fragile; it's hardly any surprise they break so often.
ok i am very new to all this and looking for some help. not sure where to look on this group yet.
i am trying to use an action camera through a 10x25 monocular. since action cams dont have zoom. it is doing well indoors but once i go outside during the day all i get is white. any info and help would be great .
thank you so much
The degradation due to the UV filter only occurs under very rare conditions. NOT using it causes instead serious issues! Except for the small pocket-camera lenses, the lenses of any camera (even when getting continuously covered-uncovered) get exposed to dirt, fingerprints and other types of smears: they even get scratches! To avoid degradation of pictures and long-term degradation of the lens, they require frequent and difficult cleaning, and there is no remedy when there is a scratch! It is much better to keep the lens at factory quality by having a permanent UV filter which can be easily cleaned and also inexpensively replaced if it gets scratched.
df19127ead