The Light Enviroment Water strongly attenuates long wavelenghts of light & UV (see video below, Fig 1). Depending on the visibility and the type of disolved matter in the water, the ambient light quickly turns into a dim blue (clear
Essential Photo-Taking Checklist
Taking photographs for objective analysis requires careful consideration. Here are the important aspects: Spectral Range If you intend to model the vision of a particular animal, ensure the spectral range of your equipment is appropriate for its visual system (e.g.
Exposure
Correct exposure is important for objective imaging, but can be difficult to achieve. Over-exposure will result in the brightest pixels in the image being “clipped” or “saturated”. As pixels become brighter they reach this level and cannot go any higher,
ISO
ISO refers to the level of sensor gain, taking the name from “film speeds” back when we photographed on analogue film. Higher ISOs make the camera sensor more “sensitive”, allowing for photography in lower light levels. However, increasing the ISO
Focus and Aperture
A wider aperture lets more light onto the sensor, so is useful in lower light conditions, however wide apertures also reduce the depth-of-field (so out-of-focus parts of a scene are more blurred) and will tend to exacerbate lens design imperfections
Grey Standard
At least one grey standard of known reflectance is required in each photograph (or in a separate photograph taken under exactly the same conditions and with identical camera settings). Greyness and Diffuseness The standards used should ideally have equal levels
Direction & Diffuseness of Lighting
The direction and diffuseness of the light source can interact with the three-dimensional shape of the target, and with the “shinyness” or “glossiness” of its surfaces. A point-source of light (such as the sun, or a small light bulb) is
Ultraviolet Photography
Vision into the ultraviolet spectrum is thought to be the “norm” for tetrapods (e.g. amphibians, reptiles, birds), fish and insects. Even small mammals have shortwave sensitivities which stretch far deeper into the UV than human vision. Photography in the UV
Light Source
Photography is entirely dependant on light and the way it bounces off or through objects, so is an important consideration before starting data collection. In an ideal world, all photographs that you want to compare should be taken under uniform