.6 and f/8.

Do filters cause vignetting?

most of the time, Mechanical/accessory vignetting is caused by filters, filter holders and other 3rd party tools. Most manufacturers design their lenses to accommodate a single filter, whether for protection or other purposes.

What is a focus ring?

focus ring

This is part of the lens that rotates to allow the photographer to focus the image. . . For manual focus, you will turn the ring until the image is in focus. The focus ring is usually marked with a guide number that shows how far the subject is in focus.

What is filter thread?

Glossary.Filter threads or filter rings are Threaded section on the front of the lens for attaching accessories such as filters and lens hoods.