I don't know if the Kodak designers had the old iron-clad fighting ship in mind when they named their camera The Monitor.
There does seem to be something of a family resemblance in the boxy
lines and metal top deck. Still, it is a handsome camera and somewhat
better built than its predecessors. Like most of the other Kodak
mid-century cameras, my Monitor was made to take 620 film, and it yields
a 6cm by 9cm image.
The lens on my Monitor is the 101mm f/4.5 Anastigmat Special; it is
front-focusing, with four elements in three groups. The shutter is the
No. 1 Supermatic with speeds from 1 sec. to 1/400 sec. and B. I have
the same lens and shutter combination on my Vigilant, so much of these
notes also apply to that camera. The main difference from the Vigilant
is the metal top plate which houses a film advance and double-exposure
prevention mechanism. There is also a pretty little dial-type Depth of
Focus scale similar to those found on the Retina I. My Monitor arrived
with a new-looking and light-tight bellows, but I think that is rather
unusual.
Servicing the lens and shutter is relatively easy on the Monitor.
Removing the front lens requires that the little post that stops the
focus travel be screwed out. Then, you just unscrew the lens and focus
scale; be sure to note the point at which it comes loose so you can get
it started right when you go to put it back in.
The next step is a little trickier. The rim of the central lens
group projects only a small lip above the surface. This kind of
thin-walled brass housing is easily deformed, so it is important to keep
pliers and other dangerous tools well away from it. A good tool for
getting a grip on the rim of the center lens mount is one of the
Flexiclamp wrenches sold by Micro-Tools. I used a 1 3/16" size.
Before you start unscrewing the center group, it is a good idea to make a
mark crossing the rim to the body so that you can put it back without
over-tightening. Also, you will want to note that the group housing
comes loose in about one full turn. A friction tool made from a dowel
and a piece of rubber will also work.
Once the center lens is out, you can lift off the face of the
shutter and get easy access to the internal levers and gears for
cleaning with something like Ronsonol lighter fluid. I also removed the
back lens group with a lens spanner so as to not get debris on the
lens. The whole thing should go back together pretty easily.
With the lens and shutter clean and reassembled, you are
ready to shoot pictures, as long as you are comfortable with re-spooling
120 film onto a 620 metal reel. The Kodak engineers went to some
trouble to design a camera that will not permit the use of film on a
modern 120 spool. I experimented with using trimmed 120 reels in a film carrier from an old Agfa folder, but am happier just re-rolling 120 to 620. There is also a version of the camera which was built for 616 film.
The Monitor user manual advises that the film initially be advanced
until the number "1" is just visible in the red window. You are then
supposed to move the little lever from "wind" to "1-8" and slightly turn
the advance knob which activates the double exposure prevention and
moves the "1" into the center of the film frame window. From there you
can just crank the knob until it stops without opening the red window
for positioning each frame. I initially had some problems with frame
spacing but taking off the top, cleaning the mechanism and adding a
little lubricant got things straightened out.

The Monitor's sleekly modern design and the nice eye-level finder will
propel the user toward camera technique appropriate to a more compact
camera. However, that is probably a mistake as the long 101mm lens
really demands a thoughtful approach suitable for any of the older
medium-format folders. A tripod and a cable release will enhance the
chances of success with this camera. It is also important to ignore
that pretty depth-of-field dial on the top deck as it is completely
inaccurate; hard to imagine what Kodak's engineers were thinking with
that feature. Luckily, there are a number of good depth-of-field table
gnerators available on the web including a particularly nice one at
johnhendry.com.
Below are some images from the Monitor Six-20 shot at The National Museum of Nuclear Science and History in Albuquerque:
And one from the War Eagles Air Museum at Santa Teresa:
A manual for the Monitor Six-20 and Six-16 models is available on line at the Butkus site.