Wondering what I should do about this crack in my Nikon 70-300mm lens. It seems to work the same and has no negative impact on photos but I’d still like it fixed or at the least suggestion to help prevent it from getting worse.
It's probably a filter. If there is printing or embossed lettering around the outside of the rim near the front, that would indicate a filter is screwed on.
Remove the filter by unscrewing it. If it doesn't seem to want to come off, see: How do I get a stuck screw filter off of my lens?
After comments, the filter is a Rocketfish RF-CP67 Circular-Polarising 67mm diameter filter which unscrews using the knurled section highlighted. The section forward of that with the RocketFish logo will turn infinitely - which is how it varies the polarising layer.
As previously stated, it looks like the filter is damaged, not the lense. But, of course, take the filter off and inspect the lens for damage too. That being said, I was a professional photographer for years and initially, as a budding amateur, I always had a Sky or UV filter on all my lenses to protect that precious glass from damage. Certainly a Sky or UV filter has some benefit in filtering out certain wavelengths of light that you may find unattractive in your photographs. But, unless you keep them sparkling clean, they will impart some issues in your shots. So, I took any filters off my lenses unless I had a photographic reason to add them, was extra careful in protecting my lenses and used metal sunshades when possible to minimize stray light and put something in front of my glass that would help protect, yet not interfere with the quality of my photos.
After working in a camera store I learned that the sales people always recommended a protective filter on any lense they sold. Why? So they could make additional money on the sale, back then (80’s) a Sky A1 filter cost you about $20, cost to the camera store was $2 or 3, nice profit margin. I won’t tell you what they made on batteries. 😳 Keep your lens clean and use a good shade to help keep it out of harms way.