testo 883

Focus Is a Measurement Feature, Not Just an Image One

This is one of the most misunderstood things about thermal imaging, and it’s the reason this camera exists.

An out of focus photograph looks soft. An out of focus thermal image is worse than soft, because the energy from the target is spread across more pixels than it should be. Each of those pixels sees part of the target mixed with part of its cooler surroundings, so the peak temperature reads lower than it really is.

A fixed focus camera is sharp within a range, and less accurate outside it. That’s acceptable for spot checks. It isn’t acceptable when the output is a survey report with temperatures a client will act on.

The testo 883 has manual focus, with sharp images from under 10 centimetres using the standard lens. That puts the operator in control of the accuracy of the reading, rather than hoping the target falls in the sharp zone.

The Lens Decides How Far You Can Stand

The other cameras in the range have one fixed lens. The testo 883 takes two, and the difference at a distance is substantial.

Why this matters comes back to spot size. A narrower field of view spreads the same 320 x 240 pixels across less of the scene, so each pixel covers a smaller area of the target.

On the standard lens, one pixel covers about 17 millimetres at ten metres. On the telephoto, it’s about 7 millimetres, less than half. A target that needs you within three metres on the testo 860i can be measured from more than ten metres with the telephoto lens fitted. For solar arrays, high level electrical work, elevated pipework and anything behind a barrier, that’s the difference between measuring it and estimating it.

Lenses can be changed while the camera is running, and it detects which lens is fitted. Each lens is adjusted to its own camera, and the serial number on the lens must match the camera, so a telephoto lens bought later needs to be ordered for your specific unit.

SiteRecognition Changes the Job, Not Just the Camera

This is the feature most likely to justify the price.

On a survey with two hundred measurement points, taking the images isn’t the hard part. Filing them is. Matching hundreds of thermal and visual images to the right switchboard, panel and asset is hours of desk work afterwards, and it’s where mistakes happen.

testo SiteRecognition removes that. QR code markers are created in testo IRSoft and placed at each measuring location. The camera reads the marker with its built in digital camera, and the images are automatically assigned to that measurement location.

That turns thermography from a one off task into a programme that can be run annually, compared year on year, and handed between technicians without the record falling apart. It pays off most when you take a lot of images of similar measurement objects, such as switchboards.

Building Work

testo ScaleAssist automatically sets the optimum thermal image scale, which makes construction defects and thermal bridges easier to assess, and keeps images comparable even when ambient conditions change.

For mould and condensation risk, humidity mode uses surface temperature from the camera, with ambient temperature and humidity from a testo 605i thermohygrometer sent over Bluetooth, or entered by hand. A dedicated humidity palette shows the results.

testo ε-Assist automatically recognises emissivity and determines the reflected temperature, using Testo’s ε-markers, so readings on different surfaces are corrected properly.

Load Current in the Image

The same Bluetooth link carries testo 770-3 clamp meter readings into the thermal image, or current, voltage and power can be entered by hand.

On a switchboard survey, that closes the gap between an observation and an assessment. A connection at 60°C drawing 20 amps and the same connection at 60°C drawing 200 amps are entirely different findings, and the thermal image alone can’t tell them apart. Recording the load alongside the temperature is what makes the conclusion defensible.

For solar PV inspection, solar mode lets you enter the solar radiation value with each image.

Analysis and Reporting

On the camera, up to five individual measuring points can be placed in an image, alongside hot and cold spot detection, delta T, area measurement (min and max), alarms and isotherms. Voice notes can be recorded with each image through a Bluetooth headset. A laser marker helps identify the target.

testo IRSoft, a free download, handles in depth analysis on a PC and produces professional reports. The testo Thermography App turns a phone or tablet into a second display and remote control, and creates and sends compact reports on site.

Two Versions

The testo 883 comes with the 30° x 23° standard lens. The testo 883 kit adds the 12° x 9° telephoto lens, a spare battery and a battery charging station.

If distance work is part of the job at all, the kit is the better buy, because the telephoto lens is the capability that sets this camera apart from the rest of the range.

Where It’s Used

Contract thermography services. Annual electrical survey programmes. Solar PV array inspection. Building energy consultancy and thermal performance assessment. Mould and condensation risk investigation. Facility and asset management programmes. Industrial and mechanical maintenance. Elevated and hard to reach plant. Quality assurance and production monitoring. Insurance and dispute investigation, where the report has to hold up.