Things like megapixels (MP), high definition (HD), and whatever ingress protection (IP) rating devices have can all get a bit confusing. We’ll start by clarifying how these things apply to inspection cameras.

Some inspection cameras have switchable resolution. Lower resolution means smaller file sizes, so you can store more images, and many people don’t need a highly detailed image. However, the maximum resolution is usually what we look for.

Inspection cameras start at 720 pixels (p), which represents the number of pixels on the shortest side of the image. The resolution is actually 1280 x 720p, which is a total of 921,600 pixels, just shy of 1 megapixel (MP).

The majority of inspection cameras use 1080p resolution, also known as 2 MP (though to be picky, it’s actually 2.1 MP). A few use 2560p (5 MP). They can all be called high definition. None are ultra-high definition (UHD), which requires 8 MP.

Inspection cameras can be separated into three main categories: USB, WiFi, and self-contained.

USB: These models are frequently the cheapest. They plug directly into a laptop, but even the smallest are comparatively bulky. It might not always be convenient to take your computer into a particular environment.

WiFi: These models are designed so you can use your smartphone or tablet as the monitor  and have no physical connection, so you can keep your device at a safe distance. Some also work with laptops, so it’s important to check compatibility. Not all inspection cameras support iOS.

Self-contained: These models include their own monitor, typically 4.3 inches or 5 inches, though larger ones can be fitted to industrial cameras. These may also offer on-screen controls.

The inspection camera and cable are invariably dustproof and waterproof to various degrees, depending on their intended use.

Diameter: The cable diameter varies from a minimum of about 5.5 millimeters (0.2 in.), up to 40 mm (1.5 in.) for commercial drain cameras, but 8.5 mm (0.33 in.) is the most common size.

Length: Cable length is anywhere from 54 inches on gun bore cameras to several hundred yards (on commercial drain models). Most range from 15 to 50 feet.

Flexibility: For most people, it’s important that the cable is what’s called semirigid: the fiber optics are protected by a fine, woven steel sheath and then coated with rubber. The cable has a degree of stiffness so it can be used vertically (inspecting wall-mounted air conditioning units, for example) or pushed along pipes and tubes. As the cable gets longer, it’s more likely to flex and be difficult to control, so it’s sensible to buy the minimum length you need.

The camera head usually has between four and six LEDs around it to provide illumination. In almost all cases, there is a brightness control, either in several stages or fully variable.

An optimum focal length is usually given, though some have variable focus, which can be a major advantage for users who need high levels of detail.

All the inspection cameras we looked at use rechargeable lithium-ion batteries, often charged by USB (though, oddly, the charging cable is not included with some). Run time of the inspection camera depends on the size of these batteries: 2600 milliampere hours (mAh) models generally run for three to four hours, while 4500 mAh models run for up to nine.

You can usually expand the memory of self-contained inspection cameras by using a TransFlash (TS) or microSD card. These range from 8 GB to 64 GB. Depending on the resolution, an 8 GB version can record for about 40 minutes and a 64 GB version for several hours. Sometimes a card is included in the price, but often it is not.

A set of accessories is frequently included as part of the kit, usually an angled mirror and a hook and magnet for picking things up. The mirror is useful for seeing areas outside the viewing angle of the camera, for example, the sidewalls of pipes or tricky corners inside engines.

The warranty is usually a minimum of 12 months, but some are several years. Manufacturers usually quote a “limited” warranty, so it’s worth checking what those limits are. Inspection cameras get pushed into some dangerous areas, and it’s unlikely that mechanical damage to the cable or camera will be covered.

Inexpensive: The cheapest inspection cameras are in the $20 to $25 range, which is excellent value if they work, but reports of faults (particularly an inability to connect to phones and tablets) are higher than we like to see.

Mid-range: Reliable, good-quality inspection cameras paired with wireless devices cost between $35 and $65. Those that include their own screen cost $70 and up.

Expensive: Industrial cameras with handheld monitors can cost anywhere from $90 to $250, and commercial long-range sewer/drain cameras can top $500.

If you don’t see what you need in our matrix, we found a few more options. The IWOBAC USB Inspection Camera is a budget model that connects directly to your Windows or Mac laptop. Resolution is selectable up to 1600 x 1200p, the camera is rated IP67, and the 8.5 mm cable is 16 feet long. If you don’t mind using your laptop, it’s a great value.

The 5.5 mm Depstech Ultra-Thin WiFi Snake Camera is among the smallest-diameter models on the market. Despite the tiny size, the camera offers a useful digital zoom. Resolution is 720p, the cable is 16.5 feet long, and it’s Android and iOS compatible.

Avid shooters and gunsmiths will be interested in the Teslong Rifle Bore Scope which fits .20-caliber firearms and up. It’s specifically designed with a short focal length and side-view mirror for close-up barrel inspection. The cable is just 40 inches, so it’s fine for rifles but not much else. It can be used with Android, Windows, and Mac, but not iOS.

Q. How can I be sure my inspection camera is waterproof?
A. Look for an ingress protection (IP) or IPX rating. This tells you it has been independently inspected. Actual ratings can be found online, but IP67, for example, means the camera is completely dustproof and can be immersed in up to 39 inches of water (though the manufacturer may recommend a maximum duration for submersion).
 

Q. What’s the difference between a borescope and an endoscope?
A. Both are inspection cameras. Strictly speaking, an endoscope is a medical device. Endoscopy is the introduction of a device into the body for the study of internal organs or cavities. A borescope is not for use on people! However, the technology is basically identical, and the two terms have become interchangeable in general use. An otoscope, by the way, is specifically for ears!

Q. Are TF and SD cards the same?
A. No. Although they both do the same job of adding storage for video or stills, a TransFlash (TF) card, also called a microSD card, is physically different than an SD card. The two are not interchangeable, so be careful when ordering.