By definition a fusion means two parts are held together permanently. There's no movement between the two parts. In the case of a spinal fusion, there's motion at the segment above and below, but not at the level fused. The idea is to hold the section steady or stable. You'll lose motion but you should also stop having the difficult symptoms.
Usually a fusion at only one level will not prevent you from doing what you need to do. You may have to be a little creative for those shots that require just the right twist and bend of the neck. You can carry small pillows and props to help for still photography or viewing wildlife for long periods of time.
One other option may be available soon. That's an artificial disc replacement for the neck. Surgeons at several centers around the United States are already using these implants in the low back (lumbar spine). It's only a matter of time before they will be ready for the neck (cervical spine). Ask your doctor about this option for you.