When I was new to photography, I remember being overwhelmed with the number of different lens choices and max apertures for each lens. I was clueless to how this would change my photos. These days there are so many lens options out there that I wanted to give a few examples to help anyone that may be in that same boat when considering buying lenses like the Canon 200800mm, Sony 200600mm, Nikon 180600mm, Canon 100500mm, Sigma, Tamron etc.... hopefully this will help you understand what you are buying and manage expectations.