Watching underwater videos made with small, lightweight cams and video recorders, one can often notice that slight, jerky lateral swaying out of the horizontal plane.
It is caused by the movement of the cam operator's fins, as the body in swimming counteracts the forward push of the legs. This affects the camera stability, since the swimmer / diver does not have the benefits of solid ground under the feet. The effect can be likened to the one noticeable in records shot in walking; hard steps transmit through operator's body to the camera.
This camera instability is usually so small that the cam operator might not even notice, but when the video is replayed on the large screen, it becomes quite apparent. And then it's too late to do anything about it except apologizing...
So we might say that underwater cam operator is „mobilis in mobile“, or moving in the moving element. Add that to the fact that waters are not always calm and smooth. Nevertheless we'd wish for our videos to be smooth, and contain only the kind of movement that was intended.
For smooth movement of camera on land, the stabilizers with gimbals and/or counterweights have been devised. For the smooth camera travel through the water, consider another old and simple device.
In "olden days" we used a hydro-plane to stabilize the camera against that swimming movement. It is simply a wing fastened to the camera's tripod connecting point. It helped a lot, although the cameras were much more massive and had a lot of own inertia to keep them steady. Even then, the wing "leaned" solidly on the surrounding water (which is 900 times denser than air), and totally neutralized the fin effect.
New video recorders, and especially the minuscule action cams, are very small and of no mass to speak of. Every slightest hand or body tremor easily swerves them out of their intended direction. This makes the stabilization of cam travel even more important.
An example of lateral camera swaying out of horizontal plane caused by swimming.
I'd suggest to anyone interested in smoothing out their camera glide through the water to simply make themselves such a wing, since no manufacturer seems to be sufficiently aware of the problem to offer such a thing among all the optionalia usually available with their products. It will require just a little work and material, but will surely help a lot in creating better underwater videos.
For the size and mass of smallish action cams or photo cameras that record video, a rectangle of some acryllic transparent (Plexiglass-like) material measuring 40 x 15 centimeters in 6-8 milimeter thickness will be more than sufficient. Transparent material is best, since it does not hinder your view and control of the ambient.
Cut the wing carefully to size, and round the corners and edges nice and smooth.
- TIP: to cut an acryllic plate by jigsaw, cover the cutting line with Sellotape first. It will "lubricate" the sawteeth bite, making the cut clean, and also help against the saw getting stuck in the material by friction heat. You can also draw the cutting lines over the tape. But remember to remove the Sellotape before filing the edges of the cut; you don't want the sticky remnants all over your file!
Mount the cam along the middle line (i.e. place the camera center 20 centimeters from either side) and far enough forward so the camera can't "see" the leading edge from its mount. Follow the manufacturer's idea of cam mounting, of course, only take care to mount it as low above the wing surface as you can. See the vertical dot-dashed line in the sketch!
Fasten two handles to the left and right of the camera, at the symmetrically spaced points on the line going through the middle of the smaller sides of the rectangle (i.e., distanced 7.5 centimeters from the leading and the trailing edge of the wing). See the horizontal dot-dashed line in the sketch!
You can adapt any kind of material for the handles, even two short pieces of broomstick attached by (stainless !) screws through the Plexiglass. Main idea with the handles is that you can comfortably see the monitor between your hands, and also touch the command buttons. The most elegant version would be for the handles to be cut from the same acryllic material as the wing, but it requires a bit more work.
- TIP: you can seamlessly glue the handles cut out of the acryllic material right to the surface of the wing. Save the material filings from the cutting and melt those in a small bottle of Acetone or Chloroform. It will be the glue to attach the handles, utilising the same material as your wing components. Mark and roughen the wing surface carefully where the handles will be attached. Paint all connecting surfaces with glue, attach and press until the solvent evaporates. Be careful not to breathe in the solvent, and keep the whole process well away from sparks or fire!
Should you decide to add some lights (for use in darker ambient, like in greater depths, in caves, or in the night), now you also have one practical baseplate to mount those! Same goes for things like weights or floats, if you want to trim the cam for positive or negative buoyancy. Or you might decide to add something you'd like to maybe have in the cam's field of view - or just along: a compass, depth meter, thermometer, "frame", filters...
In water, just "fly" your camera as if it were a small airplane model! I'm sure you'll like the stabilizing effects gained with the wing, as well as its other practical applications.
Finally, one more TIP: if you use bigger underwater video camera and find out that you need even more stabilisation, simply add more surface - another wing attached to the handletops, and turn your hydro-plane into a bi-plane! It works like charm.
Anyway, although winter may not be very suitable for underwater videos, it certainly is just perfect for DIY action!
Simple sketch of the wing, seen from behind and from above.