Nikon 77mm NC Neutral Colour Filter

'NC' stands for Neutral Color, indicating that the filter is designed not to alter the color balance of your images.

Yes, you can stack filters. However, stacking filters can increase the risk of vignetting (darkening at the corners) and flare, especially with wide-angle lenses. It's generally recommended to use only the filters you need.

Check the lens barrel; the filter size is usually printed near the front. It will typically look like a circle with a line through it, followed by a number (e.g., ø77mm).

No, a neutral color filter like this does not typically interfere with autofocus systems as it does not significantly alter light transmission or polarization.

While it protects the lens and offers neutral color, it does not have special coatings for light pollution reduction or enhanced light transmission for astrophotography. It is primarily for general use and protection.

It acts as a physical barrier on the front element of your lens, protecting it from scratches, dust, moisture, and minor impacts.

Ensure you are screwing it onto the correct lens thread and that the lens thread itself is clean and undamaged. Screw on firmly but without excessive force.

While the multi-coating reduces glare, extreme light sources can still cause some. Ensure the filter surface is clean. If the issue persists, it may be inherent to the shooting conditions.

Check for cross-threading or debris in the lens threads or filter threads. If the filter is stuck, gently try to unscrew it with a rubber grip or by using a filter wrench (use with extreme caution to avoid damaging the lens or filter).