capturing video underground
There has been a relative explosion in the number of videos of caves being published on platforms such as Facebook and YouTube. Much of this has been due to the availability of reasonably low-cost, small, light, rugged and waterproof action cameras such as the GoPro. It’s relatively easy to mount one of these to a caving helmet and capture some of the experience of exploring caves. There has also been a revolution in higher-end cameras such as interchangeable lens DSLRs and mirrorless cameras made by Canon, Sony, Nikon, Panasonic, and Fuji. These cameras have high resolution sensors that do extremely well in low-light conditions, and they are now being made smaller, lighter, and more weatherproof.
size and weight
Caves can be unforgiving environments and camera gear must be protected from impacts, dirt, mud and water. It also must be capable of being carried to remote areas through crawls and down pits. For these reasons action cameras such as the GoPro are very popular. Interchangeable lens cameras (ILCs) will typically be the largest, heaviest and most difficult to protect from water or impacts, but there are trade-offs in terms of image quality.
Video Frame-rate
The FPS (frames-per-second) can be adjusted on most cameras. The standard in North America for film is 24 fps (or more precisely 23.976). It is argued that this frame rate provides the best viewing experience, and will generate a video that is more “cinematic”.
Shutter Speed
Lenses
Camera lenses have a maximum aperture, generally characterized as a f-stop, which is a ratio of the maximum aperture to the focal length. The smaller the denominator, the larger the aperture, and the more light can pass through to the sensor. The other key characteristic affected by aperture is depth of field. The wider the aperture setting, the shallower the depth of field.
camera sensors
One of the most critical considerations for cave videography is sensor size. Caves are of course low-light environments and in videography there are limitations on shutter speed. Shutter speed can be no slower than the interval allowed by the frame rate, and for better image quality it is recommended that shutter speed be half the frame interval (e.g. a 30 frames-per-second video clip should ideally have a shutter speed of 1/60 sec).