Many photographers go out UV filters on their lenses more-or-less permanently. Many others do not. Who is right? Should you bargain UV filters (or clear protective filters) for all your lenses?

This oppugn is highly disputable 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 more definitive right answer. In this article, I will seek 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 same optical quality to the lens elements themselves. This is loosely actual for the best multi-coated filters from good manufacturers, just may not be true for the cheaper filters.

The filter blocks UV luminance and removes the blue vagabond from images taken in very bright sunny conditions

This debate is almost completely spurious for nonclassical digital cameras. With old film cameras it was a great deal necessary to use a UV filter because pic is exceedingly sensitive to UV light. Still, digital sensors are loosely rather insensitive to UV, so the problem doesn't arise to anything ilk the cookie-cutter extent.

Having said that, I have seen some evidence that surely lenses a Ultraviolet filter out put up reduce the purple fringing caused by longitudinal chromatic aberrancy. The royal fringing of longitudinal brownish-orange aberration only occurs in particular circumstances and is non to cost dazzled with the much more than common coloured fringing caused by lateral chromatic distortion (most noticeable in the corners of the frame).

My personal view is that these effects are most always unmeaning and do not provide a good reason for using UV filters on a regular basis with digital cameras.

The filter provides shelter for the lens

There are two types of protection to consider.

Firstly, protection against wrong caused by rough handling or dropping the lens/camera -
 I doubt if anyone has done a proper scientific study of this, but ad hominem undergo suggests that a mishap that indemnity the filter will believably 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 presence element of the lens -  The comportment of a filter on the crystalline lens certainly protects the front constituent, as the dust, dirt, smears and scratches get on the filter instead. Which is preferable?

The sink in is flat and easily removed, which makes information technology much easier to clean. Too, if it does convey scratched, or gets soh dirty that it is also delicate to clean thoroughly, then IT typically costs much less to replace than the Lens.

On the other deal, many photographers argue that lenses do non need cleanup precise often and the chances of scratching the lens are precise low, sol it is punter to hold open your money and go without the filter.

The filter causes a exit of image quality

This is true in theory (except possibly in those rare cases of lenses that induce been specially designed for use with a separate out). Nonetheless, the loss of image quality is likely to be very small in practice session and and then the really question becomes: Is the loss of image quality significant to me?

In trying to respond this, there are several different aspects of image quality that need to be thoughtful:

Flare and specter images

I wont the term blaze up to mean an overall veiling of the image (operating theater parts of the image) due to divagate light, while ghost images are secondary images of very bright luminousnes sources, usually badly proscribed of focus and sometimes showing extreme comatoseness, astigmatism and chromatic aberration as well.

Both flare and ghost images are caused by unwanted reflections or scattering from the various exposed surfaces within the lens and television camera dead body. The glass surfaces of all the lens elements will contribute, arsenic will the glass surfaces of the dribble. Typical nonclassical lenses contain adequate to 15 or more elements, and the addition of one more element (the filter) is non likely to make much difference in most practical circumstances.

I have never seen any persuasive grounds that the presence of a good quality filter increases flare to any broad extent with ordinary camera lenses.

Nevertheless, on that point is a particular circumstance in which the presence of a trickle may cause noticeable specter images. With some lenses, when misused at full aperture (or nearly so), light reflected from the sensor back through the lens may be mirrored from the rear surface of the filter back into the camera producing a wraith image on the opposite side of the optical axis.  Ghost images of very colorful lights are oftentimes visible in night shots taken with a very fast lens at brimming aperture if a filter (any percolate, the type is irrelevant) is being used.

Although much fainter than the primary images, they can be same noticeable as they will be in centerin if the lens is focussed at infinity and the lights causing them are in focus. These haunt images will disappear if the filter is removed, or if the aperture is attenuated sufficiently (i.e. the F-number is increased).

Without a separate out along the lens. Both this and the image below were taken at filled aperture (f/1.7 for these images) with a standard lens.

With a UV filter on the lens. The greenish spots of light in the central component 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 diam of this region reduces as the F-number is hyperbolic.

Both the above images are overexposed and this makes the ghost images more noticeable. Even and then, it is only the brightest lights that produce ghostwriter images that are bright enough to be seen (and then only when they occur against a comparatively tenebrous background). In daytime images, it is super rare for ghost images to be discernible unless the sun is panoptic in the human body (and the air is clear thusly the insolate shines brilliantly).

Notice that there is considerable burst out near the floodlights and this is the similar in the two images. The leftmost flood lamp produces in particular strong flare which can be seen both as a fuzziness and airing of the floodlight itself and also as a violet haze which seems to environment the stretch out on the extreme left.

Loss of light

I take over never seen any convincing evidence that a good quality UV filtrate causes noticeable loss of light through the lens. So, that would not be foretold American Samoa the filter is merely uncomparable extra glaze over element and most modern lenses already have at least 7 elements and often twice that total or even more.

Loss of resolution

Once again, I have never seen any evidence that this is significant for a upstanding quality filter along normal television camera lenses. Good quality filters should have optically flat surfaces that do not upset the direction of the light rays passing through with the filter. If there is whatsoever slight fluctuation from optical flatness (as Crataegus oxycantha go on with a precise cheap filter), the effect will equal about noticeable with extreme telephoto lenses because of their magnifying core.

Conclusions

My evaluation of the demonstrate is that there is no really compelling evidence either to consumption a separate out or not, except in a very few situations when information technology is better non to use up a filter to invalidate in-focus ghost images.

Personally, I do have UV filters along wholly my lenses and entirely slay them in those very rare situations for which I roll in the hay they may cause ghost images. My main reason for victimisation filters is that I like to keep my lenses rattling clean and I tone more confident in cleaning the filter than in cleaning the surface of the lens.

However, I think those photographers who choose not to use filters have a sound case besides!

The force of a dirty lens (or filtrate)

In comparing images taken with and without a filter, one thing I have detected in doing the tests is that straight-grained a slightly dusty lens at times has a noticeably deleterious upshot on the image. This only occurs in extreme lighting conditions such as when the sun is shining brightly and is inside the image frame, or selfsame some it. Subordinate such circumstances, light scattered by dust particles happening the front element of the lens or happening the filter can significantly increase the stray light falling on the image.

It's generally non worth worrying about a trifle dust on the lens system (or filter). In normal circumstances dust on the advanced element has no visible effect the least bit. Simply, if you are shooting into a bright solarise or other very bright lights, then IT is a good musical theme to fresh your crystalline lens (and filter) first off.