Canon 5D MkII put to the clinical test
February 24, 2009 § 1 Comment
I was scheduled to film an Isolated Limb Perfusion (ILP) this week and decided it was a nice opportunity to test the Canon 5D MkII’s video abilities in a clinical setting. How would it handle the combination of high contrasts and shades of red of an operation?
As I’ve posted on before, the unique aspect of the 5D MkII DSLR is that it can shoot full HD (1920×1080) video, in addition to being a superb still camera. There are however, a few downsides to the video module, the most important being:
- Lack of manual controls when shooting video (aperture/shutter/ISO).
- The video is compressed using H.264, an end format, not very suited for editing.
The intervention I was filming is a procedure where the blood circulation of a limb is isolated using a tourniquet, and chemotherapy is then circulated in the limb, through catheters placed in an artery and a vein, without reaching the rest of the patient’s body. As the chemo don’t reach the heart and other vital organs, higher doses can be used than in normal chemo infusions. This particular procedure was done on a patient with a leiomyosarcoma in the right upper arm.
I mounted the MkII on a camera support I normally use for my Panasonic AG-HVX200, called DV Rig Pro (top picture). It has a counterweight hanging over your shoulder and the whole rig rests on a pod fixed to a support belt. It worked very well with the MkII.
The pictures above and below both show the armpit, where the axillary artery and vein have been dissected and identified with colored rubber bands. These are unadjusted stills from the video. Shooting video with the MkII you only have manual control of focus and exposure compensation. Shooting this scene with the bright surgical light pointed straight at the wound, the camera stopped down to f/16, chose a shutter of 125 and ISO 200. Stopping down resulted in a quite deep depth of field (DoF). Not a problem shooting a scene like this, but if I wanted a more shallow DoF, that would be hard to obtain.
If we take a look at the close-up of the wound and the scope analysis of it below, we see that no details are lost in the upper range (the little areas of 100 % is the reflections in the retractors). The waveform scope (bottom left) shows that there is a little detail lost in the lower end. It looks like the contrast range is comparable to medium sized HD video cameras like the AG-HVX200.
If you look at the area to the left of the wound, where the light level diminishes on the arm, there seems to be some banding. I have not seen this at any time with my AG-HVX200, and it may be caused by the H.264 compression.
The biggest problem here however seems to be the redness of the wound. Bring up the full size image to see this better. The wound is more or less a big, red blur. And as the scopes show, even though the image has little white clipping (bottom left), the red channel has severe clipping at the top (bottom right). I shot this video with automatic white balance, and only found out later you can actually set white balance when shooting video with the MkII. Setting this manually may have produced a better result.
Not a scientific test of course, but the surgical video from the MkII looks better than I expected. The two problems listed above will however keep me from replacing my trusted workhorse with the MkII. It simply doesn’t have all the functionality I demand from a professional video camera. But it has one major advantage. When editing videos I like to freeze the picture at important steps in the procedure and identify anatomical landmarks, blood vessels etc. With the MkII I could take still photos at this moments and use them instead of just freezing the video. full size still from the MkII is 5616×3744 pixels, which means I can zoom in on parts of it in my editing software. This is very handy and gives me more possibilities when editing.
I’ll probably keep testing the MkII’s video, but in my day to day work I’ll stick to my video camera and use the MkII for what it’s primarily made for – still photography.
Some facts and numbers:
- Camera: Canon 5D MkII
- Lens: Canon EF 24-105 mm 1:4 USM
- Card: SanDisk 16 GB 30 MB/s Compact Flash
- Camera support: DVTEC DV Rig Pro
- Video recorded: 29 min 55 sec
- Still photos: 74
- Battery charge pre/post: 100% / <10%