This is the most common question I get?
Which Filter should I get? My answer it makes no real difference.
The filter as far as I am concerned is there to protect the lens glass from scratches, that’s it full stop. Especially, if you are using digital camera because you can change the colour cast in your software.
The UV, Skylight and UV Haze Debate has gone on for years, they are differences - a UV should cause no colour shift, just reduce blue distance haze, a Skylight adds a VERY slight warming effect.
If I showed you a photo taken at the same time same camera on a tripod side by side with Skylight on one, UV and UV Haze on the other respective cameras. It is unlikely you could tell the difference.
In terms of image modification, these will make no practical difference to negative film or digital, the variations in image processing will swamp the very subtle effect of these filters. Critical slide shooters may find some benefit in certain conditions.
Most people including me use these filters for lens protection ... and ever since I've been into photography there have been articles and debates about the pros and cons. It also seems to be rather cyclical - at one time they're out of favour, at other times in favour.
In theory, another piece of glass is a potential source of problems -
1 - Some form of distortion. If it’s a very poor filter! I do not have any of these.
2 – Flare, the top lens makers spend a lot of money developing lens coatings to minimise the potential for flare. Flare can be either an obvious shape or blur in the image, or less obviously a slight reduction in overall contrast which you would only notice by comparing images.
3 Vignetting - as a filter adds a small ring to the end of the lens, there is a danger of vignetting. If your lens already suffers in this respect, any screw on filter will make it worse.
Seriously though, as long as the maker used the bottom of Coke bottle it will make no difference.
Against this, there is the benefit of protecting the lens glass.
Since for any digital, scanned or camera image, there are no visual benefits to be gained from using a filter, it comes down to whether you think the added protection is worth a possible loss of quality.
But remember, you might only see this loss in very specific conditions eg. shooting into the sun, so if you want to test, test in a wide range of circumstances.
My recommendation if you get into photography and decide to sell your lens on ebay one day to upgrade to a better lens, it always help that your lens does not have a scratch or marks on it.
I have traded my lenses and I can tell you that a scratched lens might sell for 40 percent less then a lens described as MINT with Perfect Glass.