IR Resolution: What You Actually Need

IR resolution is the most commonly cited specification, but it is also the most misunderstood. Higher resolution allows you to detect smaller temperature differences on larger targets, or to inspect from greater distances. However, for most electrical inspection applications, the resolution requirements depend on your inspection distance and the size of the components you are inspecting.

A useful rule of thumb is the 2-pixel rule: to accurately measure the temperature of a target, it must occupy at least 2×2 pixels on the detector. This means that with a 320×240 camera and a 25° lens, you can accurately measure a target as small as 2.5cm at 5 meters distance.

IR Resolution	Typical Application	Minimum Target Size @ 5m (25° lens)
120×90	Basic electrical checks, entry-level	~10cm
256×192	General electrical maintenance	~5cm
384×288	Professional electrical inspection	~3.5cm
640×512	High-precision substation inspection	~2cm
1280×1024	Long-distance, high-precision thermography	~1cm

Recommendation: For most electrical inspection applications (switchgear, transformers, cable terminations), a 384×288 camera provides an excellent balance of resolution, cost, and portability. For substation inspection at distances over 10m, consider 640×512 or higher.

NETD: The Most Overlooked Specification

NETD (Noise Equivalent Temperature Difference) measures the smallest temperature difference the camera can detect. A lower NETD means the camera can detect subtler temperature anomalies — critical for identifying early-stage faults before they become serious.

Most industrial thermal cameras have NETD values between 15mK and 100mK. For electrical inspection, we recommend:

• ≤40mK for general electrical maintenance (switchgear, panels)
• ≤25mK for professional electrical inspection (transformers, substations)
• ≤20mK for precision thermography and research applications

The EasIR S-series achieves 15mK NETD with a 12μm pixel pitch detector — performance that was previously only available in cameras costing 3–5x more.

Temperature Range

For electrical inspection, the standard temperature range of −20°C to +550°C covers virtually all applications. However, some specialized applications require extended ranges:

• Furnace and kiln monitoring: Up to +2000°C or +2500°C (PT II Series)
• Cryogenic applications: Down to −40°C (Hammer II Series)
• Firefighting: Auto-switching ranges up to +2000°C (XF300-C)

Lens Selection and Field of View

The lens determines how much of the scene is captured (field of view) and the minimum focus distance. For electrical inspection, you typically need:

• Wide lens (45°–48°): For inspecting large panels or equipment at close range
• Standard lens (24°–25°): The most versatile choice for general inspection
• Telephoto lens (12°–6°): For inspecting equipment at distances over 10m

The PT II Series TwinView DFOV technology is particularly innovative: it captures both wide and telephoto images simultaneously with a single lens, eliminating the need to carry and swap multiple lenses during inspection.

Form Factor: Tool-like vs. Traditional

Thermal cameras come in two main form factors for field use:

Tool-like (pistol-grip): Compact, lightweight cameras designed for one-handed operation. The EasIR Series weighs only ~0.4kg and fits in a tool bag alongside other instruments. Ideal for technicians who need to carry the camera all day.

Traditional (binocular-style): Larger cameras with bigger displays and more advanced features. The PT II and Hammer II Series fall into this category. Better for detailed analysis and long inspection sessions.

Connectivity and Software

Modern thermal cameras should include WiFi for wireless image transfer to smartphones and tablets, and PC software for detailed analysis and report generation. Key software features to look for:

• Isotherm and alarm highlighting
• Multiple spot, line, and area measurement tools
• PDF report generation
• Trend analysis and historical comparison
• GPS tagging for asset management

Product Comparison Table

Model	IR Resolution	NETD	Temp Range	Form Factor	Best For
EasIR Series	Up to 384×288	15mK	−20°C to +650°C	Tool-like	Daily electrical maintenance
Hammer II Series	Up to 640×480	<20mK	−40°C to +2000°C	Traditional	Professional electrical inspection
PT II Series	Up to 1280×1024	<20mK	−20°C to +2500°C	Traditional	Substation & precision thermography

Our Recommendations by Application

Application	Recommended Camera	Reason
Electrical contractor (daily use)	EasIR E3S or E4S	Lightweight, affordable, 384×288@12μm, 15mK NETD
Facility maintenance engineer	Hammer II H4S or H6S	Dual FOV, wide temperature range, professional features
Utility substation inspector	PT II PT650S or PT870S	High resolution, TwinView DFOV, long-distance capability
Thermography consultant	PT II PT870S	1280×1024 resolution, highest accuracy, comprehensive software