UV or not UV

Good morning,
I joined the forum last December as I know nothing about photography. I have started evening classes and hopefully something will stick. However last night the instructor was telling the class about filters and their uses. From what I can gather there is little UV light at sea level and unless you go into the mountains UV is unlikely to be a problem. The question was raised,if UV light was not a problem why use a UV filter?. The answer we were given was that the filter protected the valuable camera lens.
I can accept that but a member of the class who seems to know a fair bit about photography said that modern lenses do not need protection as the glass used in the manufacture was very hard and sticking an unneccessary filter in front of the camera effected the light entering the camera and was a needless expense.
Can someone advise me on this as I am confused.
Glenafton

There is quite a bit of debate about UV filters on lenses.
Some people would rather have a UV filter on their lens to protect it from getting scratched.
I personally don't use a UV filter because I don't want to put a piece of cheap glass in front of an expensive piece of glass.

I used to always have a uv filter on but after reading several logical arguments against it, I no longer use them. I would if I was in very dusty, sandy areas I guess.
Does your lens have a hood?; 99% of the time it is probably protection enough unless someone is throwing rocks at you.
Also, a uv filter is not necessary for uv or haze or anything else on a digital camera.
A polarizer or neutral density may be useful at times, but not a uv.

I have a lens that got scratched because the cap came off as a result of grab and go (don't always pack the camera like fine china)

Use a UV filter now, and trying to get used to using the hood more ;)

A good UV filter is now days coated just like the lens and has little or no affect on the image quality. But like any thing there are exceptions and it can cease flare if you don't have a lens hood on the lens and even with a lens hood on do to the sun.

Personally it a personal choice but I rather clean the gunk of the UV filter than the lens any day of the week.

My thanks to all for sharing your knowledge with me. I get the impression that the using or not using a UV filter as a lens protector is all a matter of personal choice. I think that for the interim I will continue to use the filter, a Hoya UV [O] along with my hood until I have sufficient understand of the camera.
Once again my thanks to all.
Glenafton

In some cases, a UV filter can cause problems - such as with a light source in the frame, you might see ghosting where you wouldn't without the filter. A lens hood with no filter would be the best in a situation like this. But in some cases the filter is good to have. It's really a personal choice, and like a lot of things in photography it's a compromise.