From internet: A long focal length is the biggest benefit to the 500mm f/4L. Super image quality and sharpness are notable features.
Utilizing a ring USM (Ultrasonic Motor), the Canon EF 500mm f/4L IS USM lens focuses fast, accurately - and quietly.
Autofocus Stop buttons (near the objective lens) allow autofocus to be temporarily stopped. This feature is handy when tracking action in AI Servo mode and one-shot-style focus is needed for a specific situation - perhaps a focus-and-recompose portrait of a motionless person, bird, landscape or other subject. The 500 f/4L IS is equipped with a Focus Preset feature. Set the Focus Preset to a specific distance - when your shooting needs require that specific distance, simply turn the white knurled playback ring on the end of the lens. Autofocus Stop buttons near the objective lens allow autofocus to be temporarily stopped.
The lens can be used with or without the detachable lens shade (thus reducing its overall size). Weight is 8.5 #.
The lens condition is very good to excellent. There is some residue from camo tape that shows on the exterior … I need to clean it off. I did not notice it prior to ad photos. There is dust on the lens that is easily blown off … again not noticed prior to ad photos.