CPI Full-Spectrum Photography 2 — Questions and Answers
Question 1: Which wavelength range does a full-spectrum camera capture that a standard camera cannot?
- 400–700 nm visible only
- UV below 400 nm and IR above 700 nm (Correct answer)
- Only infrared above 900 nm
- Microwave radiation above 1000 nm
Correct answer: UV below 400 nm and IR above 700 nm
Full-spectrum cameras capture ultraviolet (below ~400 nm) and near-infrared (above ~700 nm) in addition to the visible spectrum.
Question 2: What modification is required to convert a standard DSLR into a full-spectrum camera?
- Replace the shutter curtain
- Remove or replace the hot mirror (IR-cut) filter over the sensor (Correct answer)
- Swap the lens mount to a wider bayonet
- Install a UV-coated lens cap
Correct answer: Remove or replace the hot mirror (IR-cut) filter over the sensor
The hot mirror (IR-cut) filter placed in front of the sensor must be removed or replaced with a clear glass to allow UV and IR light to reach the sensor.
Question 3: During a paranormal investigation, a full-spectrum photograph shows a bright orb absent in the simultaneous visible-light image. What is the MOST likely mundane explanation?
- A spirit manifestation detectable only in IR
- Dust or moisture particle reflecting IR or UV light near the lens (Correct answer)
- The sensor overheated and created a hot pixel cluster
- The shutter speed was too slow for the available light
Correct answer: Dust or moisture particle reflecting IR or UV light near the lens
Dust and moisture particles close to the lens reflect IR and UV light strongly, producing orb artifacts that do not appear in visible-light images.
Question 4: Which filter, when attached to a full-spectrum camera, produces a pure infrared image by blocking visible and UV light?
- UV-pass filter (Hoya U-340)
- Polarizing filter (CPL)
- IR-pass filter (e.g., 665 nm or 720 nm cut-on) (Correct answer)
- Neutral density filter (ND400)
Correct answer: IR-pass filter (e.g., 665 nm or 720 nm cut-on)
An IR-pass filter (such as a 665 nm or 720 nm cut-on filter) blocks visible and UV wavelengths while transmitting only infrared light to the sensor.
Question 5: In full-spectrum investigation photography, what purpose does using a UV-pass filter (e.g., Hoya U-340) serve?
- Isolates only ultraviolet reflectance by blocking visible and IR light (Correct answer)
- Extends exposure time by reducing overall brightness
- Converts the image to monochrome automatically
- Reduces chromatic aberration in wide-angle lenses
Correct answer: Isolates only ultraviolet reflectance by blocking visible and IR light
A UV-pass filter transmits only ultraviolet wavelengths (~300–400 nm), allowing investigators to photograph UV-reflective phenomena invisible to the naked eye.
Question 6: Why is a tripod considered essential equipment when using a full-spectrum camera in paranormal investigation?
- Tripods prevent the sensor from overheating during long sessions
- Long exposures in low-light environments require camera stability to avoid motion blur (Correct answer)
- Tripods block stray IR radiation from contaminating the scene
- Camera manufacturers void warranties without tripod use in IR mode
Correct answer: Long exposures in low-light environments require camera stability to avoid motion blur
Full-spectrum investigation photography often requires longer exposures in dim environments, and a tripod prevents camera shake that would blur the image.
Question 7: A paranormal investigator photographs a location with a full-spectrum camera and notices foliage appears white rather than green. What best explains this?
- The camera white balance is set incorrectly to tungsten
- Healthy foliage strongly reflects near-infrared light, appearing bright or white in IR-sensitive images (Correct answer)
- The UV filter is blocking all wavelengths above 500 nm
- The location has unusually high electromagnetic interference
Correct answer: Healthy foliage strongly reflects near-infrared light, appearing bright or white in IR-sensitive images
Chlorophyll in living plants strongly reflects near-infrared radiation (the 'Wood Effect'), causing foliage to appear bright white or silvery in IR photography.
CPI Full-Spectrum Photography 2
Which wavelength range does a full-spectrum camera capture that a standard camera cannot?