Learning to shoot photos underwater can be overwhelming. There’s a lot of stuff to remember – f-stops, shutter speeds, ISO settings – and some of these things have different names, even though they refer to the same thing.
You just want to shoot some pictures, right?
Here's a quick primer on what all those terms are and mean, then I'll give you 3 quick tips to get started.
Disclaimer: these tips assume two things. One, that you have a digital camera. Two, that your digital camera will allow you to manually control the settings. If you're on a cheap-and-cheerful point-and-shoot, you're out of luck; you did choose to point and shoot, not point and adjust...
A Quick Primer
- this is the size of the hole for light to enter - the higher the number, the smaller the hole
- aka aperture setting
- for any given shutter speed, the smaller the hole (high F-number), the shaper the image and the greater the depth of field (more things in focus)
- tip: start with F8 and adjust shutter speed and ISO settings until you achieve the results you're happy with
- this refers to how long the shutter curtain is open
- numbers are in fractions of a second: 1/30, 1/60 etc of a second - one-thirtieth of a second, one-sixtieth of a second, etc.
- for any given f-stop, the faster the shutter speed, the less time the curtain is open to let light in, the sharper the image
- tip: if in well-lit water 60 feet or shallower, you should be able to shoot at 1/60 or 1/100 at f8 with strobes
- this is a legacy of print film and refers to the film speed or how photo-sensitive the film is
- the higher the ISO number, the more photo-sensitive it is; a high ISO allows you to capture more light at the same shutter speed (or the same length of time your film/sensor is exposed)
- the higher ISO number, the grainier the image will be; i.e. less sharp and crisp
- on land, ISO 100 is ideal for sunlit conditions outdoors; indoors, ISO 200 will typically be required unless you use flash to provide artificial lighting
- tip: underwater, treat the conditions as if you're indoors in a darkly lit room - water absorbs light, or as I like to think of it, sucks the light out of your photo
Now that the vocabulary lesson is out of the way, here are the 3 tips I promised.
- Aperture and shutter speed: shoot at F8 or higher if possible and as fast as possible (1/60 or faster)
- Review histogram for each shot to ensure you've captured as much of the light in the scene as possible (or as they say, "shoot to the right"; for tips on this, see http://www.luminous-landscape.com/tutorials/expose-right.shtml)
- Get close to your subject to minimize the distance that the light has to travel from the subject to your camera's sensors.
Obviously, there's so much more to underwater photography than the 3 tips cover; e.g. composition, the quality of your lenses, the availability of light (strobes or ambient - aka sunlight), etc. I'll cover those topics in other posts, but if you can manage to keep these 3 tips in mind, they will at least get you started.
There is science behind photography, but great images are the result of trial and error, based on some basic knowledge of the science. There is no magic bullet. To get images you're happy with, there is only one path: