What IR Resolution Actually Means

IR resolution is the number of temperature pixels in the detector array. A 256×192 detector contains 49,152 individual temperature points; a 384×288 detector contains 110,592; a 640×512 detector contains 327,680.

More pixels mean two things for an inspector:

• Finer detail at the same distance — small components such as a fuse link or a cable lug occupy more pixels, so their temperature is measured more reliably.
• Longer usable distance — a target that fills only a few pixels on a low-resolution detector will fill many more on a higher-resolution detector at the same distance.

Resolution does not replace NETD (thermal sensitivity) or accuracy. A 640×512 camera with a poor NETD still misses fine temperature differences. For electrical work, resolution and sensitivity are complementary specifications.

256×192 vs 384×288 vs 640×512: Side by Side

Specification	256×192 Class	384×288 Class	640×512 Class
Total temperature pixels	49,152	110,592	327,680
Typical pixel pitch	12 µm	17 µm / 12 µm	12 µm / 17 µm
Typical role	Entry tool / screening	Standard electrical inspection	Substation, small-target, reporting-grade
Relative cost	$	$$	$$$
Suited working distances	Short (under ~3 m for small lugs)	Medium (up to ~5-8 m)	Long (10 m+) and small targets

Rule of thumb: if you inspect panels and switchgear from arm's length, 256×192 or 384×288 is enough. If you inspect substations, busbars or overhead terminations from several metres away, choose 640×512.

Resolution and Measurement Accuracy

Every thermal camera reports one average temperature per pixel. If a hot spot is smaller than one pixel, its temperature is mixed with the cooler background and reads low. This is called the spot measurement error.

For a reliable temperature reading, the target should fill at least 3×3 pixels. With a 25° field of view, at 10 metres a 640×512 detector gives roughly 2-3× better linear detail than a 256×192 detector, which is the difference between seeing a loose busbar joint clearly and seeing only a diffuse warm area.

If your inspection report must document a specific temperature value for a small connector, higher resolution directly improves the defensibility of that number.

How Working Distance Decides the Detector You Need

Use this simple planning sequence:

1. Estimate the smallest target you must measure (for example a 30 mm cable lug).
2. Estimate the typical distance from which you can safely inspect (2 m in a panel room, 8-12 m for substation busbars).
3. Select the detector that keeps that target above roughly 3×3 pixels at that distance.

For most indoor panel and switchgear work at 1-3 metres, a 384×288 detector is a balanced choice. For outdoor substation work, live-line scans and pole-top terminations, the extra pixels of 640×512 are worth the price.

Cost and Budget Trade-Offs

The price difference between resolution classes is significant. A 256×192 tool typically costs a fraction of a 640×512 unit, which makes it attractive for crews that need many units for routine screening. The higher-resolution unit earns its cost where one bad reading can justify a shutdown or a full report.

For a one-person electrical contractor doing panel inspections, a 384×288 camera often delivers the best balance of cost and capability. For a utility with substation and transmission responsibilities, 640×512 should be the baseline.

Unitech Tools Model Recommendations by Task

Unitech Tools supplies thermal cameras across all three resolution classes, so the recommendation can follow the task rather than the available stock.

Task	Suggested detector	Unitech Tools models
Routine panel / breaker screening, close range	256×192 or 320×240	EasIR Series, H3 Series
General electrical inspection, 1-5 m	384×288	E4S, SC-A Series
Substation, busbar, small-target, reporting	640×512	E600, SC-B Series
High-end / HD thermography	1024×768 / 1280×1024	PT II Series, G Series

Tell your distributor the smallest target, the working distance and whether you need autofocus or interchangeable lenses. The same resolution class is available in different body styles, from tool-style units to full radiometric platforms with interchangeable optics.

Before You Buy: 5-Point Checklist

1. Smallest target you must measure, and the distance you can inspect from.
2. Whether readings must be documented in a report (higher resolution helps).
3. Thermal sensitivity (NETD): prefer ≤40 mK for electrical work.
4. Temperature range coverage for your environment (switchgear rarely exceeds 150 °C; process may need 650 °C or more).
5. Software, report format and calibration certificate availability by model.