Camera types, lenses and pixels on target
Choosing the camera and lens for a written purpose: what each camera type is good and bad at, how focal length and sensor size set the field of view, what the f-number and iris do, and how the IEC 62676-4 operational levels (detect to identify in the 2014 edition, overview to scrutinize in 2025) turn a purpose into pixels per metre at the target.
- Level
- Intermediate
- Length
- About 60 minutes
- Contents
- 3 lessons · 1 video · final exam
- Status
- Published · updated 3 Oct 2026
Skills you'll practise
- Match camera types (fixed, box with interchangeable lens, PTZ, panoramic, thermal) to purposes they suit and explain their limits
- Calculate the scene width at a distance from focal length and sensor width, and the focal length needed for a required scene width
- Convert a purpose into a pixel density using the IEC 62676-4 levels and check a camera schedule against it
- Explain how f-number, iris type and depth of field affect low-light and long-range images
- Verify a camera's purpose in recorded footage with a walk test rather than the live view
Course outline
- 1.Camera types, lenses and pixels on targetVideo · 2 min
- 2.Camera types and what each is forLesson · 18 min
- 3.Lenses, field of view and focusLesson · 20 min
- 4.Pixels on target: from purpose to pixels per metreLesson · 22 min
- 5.Camera types, lenses and pixels on target: knowledge checkKnowledge check · 21 questions
- 6.Final exam10 questions · passing it completes the course, so people who already know the material can test out
Sources it draws on
The lessons and questions are written from these references, so learners can go back to the original.
- Axis Communications white paper: Pixel density based on IEC 62676-4:2014 (DORI: detect 25, observe 63, recognize 125, identify 250 px/m; 16 cm face width)
- Axis Communications white paper: Pixel density based on IEC 62676-4:2025 (overview to scrutinize, 20 to 1500 px/m; LPDO and HPDO)
- IEC 62676-4: Video surveillance systems for use in security applications, Part 4: Application guidelines
- Axis Communications white paper: Lenses in surveillance (focal length, field of view, f-number, iris, depth of field, lens and sensor match)
- Angle of view (photography): α = 2 arctan(d / 2f) for rectilinear lenses
- Axis Communications white paper: IR in surveillance (day-and-night cameras, IR-cut filter, 850 nm and 940 nm, thermal versus IR, IR-corrected lenses)
- UK Home Office / Dstl: UK Police Requirements for CCTV Systems (quality, storage, export, playback) (UK example)
See it with your own jobs and topics
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