Do you use filter to protect your lens?

[JIMBO]

Yes except when I am shhoting a low light shot [landscape] late in the day. I will then take the filter off and then put it back on after the shot. JIM

[Prieni]

I use them too although a few pro photo sites recommend against them because of flare. As far as degradation of IQ the newer filters are made of the same glass as the lenses and are coated the same as well. So I'll keep using them.

So how often do you have to buy new ones?

[jazz28]

All being well, never, but the day you turn round quickly and hit a branch, you'll be glad it was in place

[Prieni]

I wear glasses for more than 10 years. My last pair lasted perhaps seven years or so. Daily use, no stain, no scratch, cleaning with cloth, with soap water etc., no wear. Oh, and I did make contact with the odd branch when walking off the path in the woods.
I think it's pretty safe without filter.

On the other hand, I don't think that a filter will degrade image quality noticeably in general. There might be some odd situations where they do and then you always can take them off.

All in all I think it's a bit of a red herring...

Prieni

[Ferry_Cung]

yes i do