Swan neck camera
February 28, 2008 § Leave a comment
When I first started filming surgery I was presented with a camera I’d never seen before. They called it a “swan neck camera” and the department that used it thought it was the greatest invention in video ever.
Two swan neck cameras had been custom built by an audiovisual company for this hospital department. It was supposed to solve the problem of access to the surgical field.
A pen-sized camera is placed on the end of a flexible metal arm (hence the name “swan neck”). At the other end of the arm a metal tube is fitted. This tube can be fixed to the operation table and the camera bent in position over or close to the wound. The camera is placed in the sterile zone, so it also has to be sterile. This is accomplished by putting a laparoscope camera cover over the flexible arm and a sterilizable metal cover over the camera.
Being sterile, the videographer will have to put on sterile gloves and gown to handle it. This task can also be handed over to the surgeons or sterile nurse, but in my opinion this is seldom a good idea. The surgical team is in the OR to operate, not to think about video. In many cases they’ll be so focused on the surgery that they will forget a camera is even present. This may not be a problem for some purposes, but if you want consistent quality video, a videographer should be present.
During the operation the surgeon’s gloves will be covered in some blood. If she’s also handling the camera, the glass covering the lens can easily become dirty.
A great advantage with the swan neck camera is that it is placed below the surgeon’s head, thus avoiding the age-old problem of heads getting in the picture. But the low placement is also the biggest problem with this camera. To get good pictures it has to be placed very close or over the wound, where it inevitably gets in the way of the surgery. A focused surgeon can easily bump into the camera, altering the framing.
The camera arm picks up vibrations from bumping or movements of the operating table very easily. The flexibility results in these vibrations lasting for several seconds, possibly ruining important footage.
As I said, a pen-sized camera was used in this construction. A larger camera would have weighted the flexible arm down. Small cameras are getting better all the time, but size still matters. Small cameras still have inferior optics and controls compared to larger ones.
The camera used in this particular system has fixed focal length. Focus can only be adjusted by turning a ring on the camera itself. Being covered with the sterile metal cover it can not be adjusted during the operation. This of course also limits the moving of the camera, as the picture will easily get out of focus. This problem can be limited by increasing the depth of field. This can be done by keeping the focal length short (wide angled). This, however, also results in perspective distortion, as you can see in the video still below. Another still can be seen here.
I’m not saying the swan neck camera is useless. The idea was good, but it is not the greatest invention in surgical video production. It simply does not get good enough footage to justify the placement in the sterile surgical field. Too much hassle for the surgeons. Good access – no excess of quality.
The enthusiastic users of the swan neck camera offered me the opportunity to borrow one of the cameras for my work. After a few tests I left it in the corner of my office. After three years they still haven’t asked to get it back.