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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. is a UV system required?) Photograph a colour chart with known reflectance values under the same lighting as your typical subject if you wish to convert to animal vision cone-catch images (this only needs to be done once for a given illuminant/camera/visual system combination). |
| Format | Photograph in RAW format if possible. The camera white-balance is not important (this is ignored during RAW import). If using non-raw images (e.g. JPGs or video frames), ensure the highest possible quality image is used and be aware that you will need to create a linearisation model for your camera. If your non-raw images are not in sRGB space (e.g. the newer DCI-P3 colour space) you will probably also need to convert to cone-catch before the image colours are objective. |
| Aperture | Use a fixed aperture between all photos in the study if possible to have a uniform depth of field – use changes in shutter speed to control the exposure. |
| Zoom | When using a zoom lens only use the maximum or minimum focal length, not an intermediate. |
| Lighting | Ensure the lighting is suitable and the angle of the grey standard(s) relative to the light source follows a clear, justifiable rule, and that the colour and brightness of the light falling on the standard is as close as possible to that of the sample. |
| Scale bar | For pattern analysis or scale measurements place a scale bar level with the sample and photograph from a consistent angle (e.g. overhead). |
| Label | Place a label in each photograph if practical and make a note of the photo number linked to each sample. |
| Background | If you are placing samples against an artificial backgrounduse a spectrally flat colour (e.g. black, grey or white). When photographing samples in-situ in the field their natural background is normally most suitable unless you are comparing the sample directly to its surroundings, in which case it may be desirable to photograph the sample separately against a dark background so that it is measured independently of its surrounds (obviously only if it can be moved without risk of harm to yourself or the sample). |
| Tripod | Use a stable tripod & remote shutter release if possible (tripods are essential for UV photography). |
| Exposure | Consider using exposure bracketing to get the best exposure and regularly check photo histograms on the camera to make sure they are well exposed. The bars of the histogram should be as evenly spread from left to right as possible without quite touching the right-hand side. |
| “Looks good” | Always check the photos “look good”, that everything important is in focus, and fills the frame as much as possible |
Essential Photo-Taking Checklist