The top photograph No.1was taken without the fieldscope attached to the camera and zoomed in to a focal length of 27.6mm.
No.2 focal length = 7.31mm
No.3 focal length = 7.93mm
No.4 focal length = 7.9.0mm
No.5 focal length = 11.25mm
You will see if you compare them with the Test Photographs taken with the Nikon 4500 that the vignetting gets progrsively worse as the camera zooms in on the subject, showing that the zoom mechanism on cameras behave differently depending on the camera.

If you are curious about the rig on display above it is called Thialf one of the largest Deepwater Construction Vessels in the world operated by Heerema Marine Contractors. It is capable of a tandem lift of 14,200 metric tons
Length overall = 201.6 meters
Length of Vessel = 165.3 meters
Breadth = 88.4 meters
Depth to workdeck = 49.5 meters
Draught = 11.8 to 31.6 meters
The living quarters are equipped to accomodate 736 men
The helicopter deck is suitable for a Boeing Chinook 234
Have a look here at enlarged photograph (Large File)