Very interesting ladies! I thought a $20 filter was a no-brainer if it protected my lens but it also seemed hard to believe it wouldn't impact image quality. I guess it does. Well, the one I bought doesn't fit so it will be returned. The question is whether to invest in the more expensive filter or just take my chances? Hmmm.
I bought a filter (I think) that screws onto my DSLR lens. I went back and forth, but the lady who was selling it said that she recommended it because I could always remove it if it didn't work with my shot, it didn't mess with the image too much, and it provided affordable scratch-proofing for the lens. In her words "Would you rather place a $15 filter, or an entire lens?" For me, it made more sense to buy the filter and remove it when needed.