Full-Spectrum Cameras — PRN Equipment Guide

## What full-spectrum means A standard consumer camera has a hot-mirror (infrared-cut) filter in front of its sensor. This filter blocks near-infrared (NIR) and ultraviolet (UV) wavelengths, restricting the camera to roughly 400–700 nm — the human visible range. A full-spectrum camera has had this filter removed, allowing the sensor to respond to a wider range: roughly 350–1100 nm depending on the sensor, which includes UV, visible, and near-infrared light simultaneously. **Note:** a full-spectrum camera is not a night-vision device. Without an appropriate external light source providing NIR illumination, it will simply be dark in a dark room. Many investigation setups use separate IR illuminators, which the modified sensor can then detect. ## Why investigators use them The working hypothesis is that certain visual phenomena may manifest outside the human visible range — in NIR or UV wavelengths. Whether or not this holds, full-spectrum cameras do provide a richer photographic record of the environment and allow you to use IR illumination for low-light documentation without visible light disturbing the scene or participants. ## Things to understand before purchase **Colour response is different.** With no IR-cut filter, foliage appears white or pink in daylight and colour balance is non-standard. If true-colour documentation of a scene matters (e.g., photographing environmental conditions accurately), you will need to apply a custom white balance or colour correction profile. Raw capture is strongly recommended over JPEG. **Lens choice matters.** Not all lenses transmit UV equally — some glass types absorb it significantly. Purpose-built UV lenses exist but are expensive. For NIR-only work, most standard glass is fine. **IR-pass and UV-pass filters** can be placed in front of the lens to isolate one spectral band at a time, which is more methodologically useful than recording all three bands simultaneously. **Sensor noise increases at longer exposures**, especially in NIR. Long-exposure artefacts (hot pixels, banding) can look dramatic in processed images and must be distinguished from scene content. ## Practical considerations - Use a tripod: long exposures and low-light conditions require it. - Log every illumination source active during capture (IR illuminators, visible torch, torch bleed from adjacent rooms). - For video, use a camera with an appropriate frame rate and shutter speed for your investigation conditions — ensure rolling shutter artefacts are understood. - Document lens and filter choices per session. ## False-positive risks Dust particles illuminated by near-IR (or visible) light close to the lens produce bright circular bokeh artefacts — so-called "orbs." These are a well-understood optical phenomenon and not evidence of anything anomalous. Sensor hot pixels in long exposures, lens flare from IR illuminators, and reflections from glass or polished surfaces are all common sources of "unexplained" imagery. Maintain a clean lens and controlled illumination.