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Guide

How to Choose a Borescope for Inspection Work

A borescope is only as useful as its ability to reach the place and show a clear picture there. Diameter sets what it fits through, probe type sets how it steers, focal distance sets what is sharp, and lighting sets whether you see anything at all.

By the Akermin Editorial Team · 3 min read

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Choose a borescope by starting from the smallest opening you need to pass: 8 mm probes give the best image and suit drilled wall holes, drains and engine bays; 5.5 mm fits spark plug holes and most tight spots; 3.9 mm and below for the tightest work at a cost in image quality. Then pick the probe type (semi-rigid for pushing into cavities, articulating for looking around once inside, flexible for long runs), a camera with at least 720p and a focal range that covers 20 to 100 mm, adjustable LED brightness, and a built-in screen for professional use. Add length, waterproofing and a side-view or dual lens for pipes and cylinders.

Step 1: Diameter

Probe diameter Fits Image quality
8 mm Drilled inspection holes, ducts, drains, engine bays, behind appliances Best; larger sensor and more LEDs
5.5 mm Spark plug holes, small conduits, tight cavities Good
3.9 mm Very tight gaps, small ports Fair; fewer LEDs
Under 3 mm Specialist industrial use Limited; expensive

Step 2: Probe type

  • Semi-rigid: holds a bend you set; pushes into wall cavities and along ducts; the most useful general type.
  • Articulating: tip steers 180° or more from a wheel or lever on the handle; lets you scan a cavity or look back at a joint. Teslong and similar models make it affordable.
  • Flexible: soft cable that follows the path; for long drain and duct runs where stiffness would jam.
  • Rigid: straight tubes for machinery and bore inspection; precise but inflexible.

Step 3: Camera and focus

  • Resolution: 720p adequate; 1080p better for reading labels and seeing hairline cracks.
  • Focal distance: most fixed-focus probes are sharp from about 20 to 100 mm. Check the stated range against how close you will be; some models offer adjustable focus.
  • Dual lens or side view: a second camera looking sideways for pipe walls, cylinders and cavity sides; saves fitting a mirror.
  • Lighting: 6 or more LEDs with adjustable brightness; too much light washes out close subjects.

Step 4: Display and recording

  • Built-in screen (4 to 5 inch): works with gloves, no pairing; records to a card.
  • Phone or tablet via Wi-Fi or USB-C: larger display; easy sharing; occupies the phone.
  • Stills and video capture for reports, with a card slot or app storage.

Step 5: Length, stiffness and waterproofing

1 to 2 m suits walls, engines and appliances; 5 to 15 m suits drains, ducts and chimneys, and needs a stiffer cable so it can be pushed. IP67 at the probe for drains, tanks and wet cavities; check whether the handle or screen is also rated.

Step 6: Accessories

Hook, magnet and mirror tips; a protective cap; a carry case; a drill bit sized to the probe; plugs or caps for the holes you make. See what a borescope is for uses.

Picks by use

Use Choose
Building inspection (walls, ceilings, under floors) 8 mm semi-rigid or articulating, 1 to 2 m, built-in screen, adjustable LEDs
Automotive (cylinders, intake, behind engine) 5.5 mm articulating, dual lens, 1 m
Plumbing and drains 8 mm flexible, 5 to 15 m, IP67, stiff cable
HVAC ducts and flues 8 mm semi-rigid, 3 to 5 m, wide angle
Occasional household use 5.5 or 8 mm phone-connected semi-rigid

Where a borescope fits alongside thermal cameras and moisture meters is covered in thermal camera vs borescope and how to choose a measurement tool for home inspection.

Teslong Articulating Borescope for Mechanic Automotive HVAC Wall Inspection

Teslong Articulating Borescope for Mechanic Automotive HVAC Wall Inspection

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Endoscope Camera with Light, 1920P HD Borescope Tools(16.5FT)

Endoscope Camera with Light, 1920P HD Borescope Tools(16.5FT)

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Endoscope Camera with Light: 5" 1080P HD Dual-Lens Inspection Borescope Camera for Sewer - 16.4ft Waterproof Industrial Endoscope - Flexible Snake BoreScope for Plumbing Automotive - Gift Tool for Men

Endoscope Camera with Light: 5" 1080P HD Dual-Lens Inspection Borescope

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Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.

Frequently Asked Questions

What borescope diameter fits a spark plug hole?

Spark plug holes are typically 10 to 14 mm, so a 5.5 mm probe fits easily and a 3.9 mm probe allows angling. Wall inspections through a drilled hole suit 8 mm probes.

Are articulating borescopes worth the extra cost?

For regular inspection work, yes. Steering the tip from the handle lets you look around inside a cavity instead of only where the probe happens to point.

Built-in screen or phone app?

A built-in screen works with gloves, has no pairing issues and keeps the phone free. Phone models give a bigger screen and easy sharing. Professionals usually prefer the screen.

Affiliate disclosure: Akermin earns a commission from qualifying Amazon purchases made through links on this page. Our editorial picks are based on documented specifications and owner feedback, not commissions.