There are good filters, and there are not good filters. Good filters cause minimal effect of flare, passing 99.7% of the light, whereas not good filters cause very visible evidence of flare by passing only 93% of the light. Here is a test series which gives you an idea of the difference of 'no filter' vs. 'good filter' vs 'not good filter'...http://www.kenandchristine.com …ter-Tests/1054387_ucZqa/2
Don't be tempted to cheap out of filter purchase, for your pictures will definitely suffer. Buy good ones, or none.
Because digital SLRs have UV filters immediately in front of the sensor, they are superfluous on the lens except for protection from blowing sand or salt spray or gooey toodlers' fingers during closeups. UV filtration and 'haze' are two different things with the same root cause, UV light. Film used to be sensitive to invisble UV light (whereas dSLRs filter that out), so that was the reason in the past for UV filters. But additionally, UV light can cause visible atmospheric haze, so these filters tried to balance out some of the visible effect via a yellow filter to filter out blue light rays. That was use primarily for B&W film shooting; a Skylight filter did the same thing for color film.