FLIR A35 vs. FLIR One Gen 3: What I Recommend When an Inspection Can’t Wait

When a plant engineer calls with a true emergency, the first question isn't which brand should we buy. It's how many hours do we have. In my role coordinating emergency equipment deliveries for industrial and electrical testing clients, I've arranged more than 200 same-week requests over the past seven years. A call in March 2024 still stands out.

A food processing plant had a refrigeration compressor running hot and a six-hour overnight window before restart. The engineer asked for a FLIR A35 thermal camera by name. Normal lead time for a mounted industrial camera project is not overnight. After a handful of questions, we sent a FLIR One Gen 3 smartphone thermal camera, a spare charging cable, and an inspection plan for comparing the hot compressor with the one running next to it.

The camera brand wasn't wrong. The model was wrong for the deadline.

FLIR A35 Thermal Camera vs. FLIR One Gen 3 Smartphone Thermal Camera

The FLIR A35 is a fixed-mount thermal sensor, not a handheld camera. It has a GigE Vision interface and hardware designed for machine vision or OEM integration. The FLIR One Gen 3 is a mobile thermal imager that connects to a smartphone and uses the phone's display. One is built to be installed. The other is built to be carried.

They are not competitors in the normal sense. Yet they end up on the same urgent order when a customer searches for flir a35 thermal camera or flir one gen 3 smartphone thermal camera and needs a fast thermal answer. I compare them by the questions a cranky maintenance planner would ask: How fast can I see an image? Can I actually see the problem? Can I defend the result later?

1. Setup Speed: Minutes vs. Installation Project

The FLIR One Gen 3 wins on first image almost every time. You connect it to a compatible phone, open the app, aim, and get a thermal image in minutes. In an emergency, that speed matters more than any spec sheet number.

The A35 needs a mount, a lens decision, power, network access, and software configuration before it becomes useful. If the A35 is already installed on the equipment, it is the fastest option in the world. If it is still in a box, it is not a camera; it is a project.

I still kick myself for not asking about network access on an A35 rush order in 2023. The site had no available switch port and no IT approval. The camera sat in receiving while an engineer used an infrared thermometer. If we had sent a phone camera, the after-hours inspection would have been done that same night.

2. Useful Detail: Pixels on Target, Not Megapixels

Thermal camera specs can confuse more than help. What matters is how many thermal pixels cover the object you need to inspect. Yes, the A35 has a more capable sensor than the FLIR One Gen 3. But in a cramped electrical room, you can often get a smartphone camera closer to the suspect breaker, coupling, or pipe.

The surprise for me was how often a less expensive camera produces a more useful field diagnosis. More pixels don't fix a shaky tripod or a bad angle. A FLIR One Gen 3 in the right operator's hand can flag a failing component much faster than a fixed A35 with the wrong lens and no network connection.

The A35 earns its place when consistency is the job. If the same conveyor, motor, or process has to be inspected from the same distance and angle every day, the installed camera wins because the geometry repeats.

3. Data Integrity: An Image Is Not a Measurement

When you use a thermal camera for predictive maintenance, the image is a measurement. The A35 is designed for radiometric process control and machine vision, which makes it a strong building block for permanent monitoring. The FLIR One Gen 3 can capture and export thermal images, but I wouldn't rely on a smartphone attachment alone for a safety-critical temperature conclusion without comparing it to a known reference and recording emissivity, distance, and reflected temperature.

That caution is not unique to FLIR. The same logic applies to any instrument. I have seen rush orders caused by a failed inspection where the camera had a calibration sticker but no real calibration history. A sticker is not proof. A traceable certificate is proof.

How to Read a Rice Lake Weighing Systems Calibration Sheet

Load cells, pressure transducers, and thermal cameras share the same problem: the pass/fail line on a certificate is less useful than the story behind it. If a customer sends a Rice Lake weighing systems calibration sheet during an urgent call, here is what I look for before recommending anything.

1. Device ID and capacity. Confirm the sheet is for the exact scale, load cell, or indicator in question. A certificate from a different unit is not a certificate.
2. Calibration standards. Look for unique identifiers for the weights or electrical standards used. Without traceability, the calibration means little.
3. Test points across the range. A good sheet should show data at zero, mid-range, and near capacity. A single test point can hide nonlinearity.
4. As-found and as-left results. As-found shows how the instrument performed before adjustment. As-left shows the final condition. If as-found failed and as-left passed, find out what was changed.
5. Tolerance and uncertainty. A borderline result within tolerance but with large uncertainty should not be treated the same as a clean pass with wide margin.

Why does this matter for a thermal camera buyer? Because a temperature reading needs the same discipline. Before any urgent scan, note the camera serial number, emissivity setting, target distance, and reference temperature. Without those details, a hot spot is just a picture.

Thermal Camera News: Why I Watch the PMD 3D Sensor Space

Most thermal camera news focuses on detector resolution or price drops. The trend I follow is sensor fusion. Some new industrial vision systems combine a thermal imager with a depth sensor such as the PMD 3D sensor from pmdtechnologies, now an Infineon company.

To be clear, a PMD 3D sensor is not a thermal camera. It is a time-of-flight depth sensor that measures distance to many points in a scene. When depth data is added to thermal data, a system can tell which physical component is hot, even when the component is hidden in a cluttered control cabinet or moving on a production line.

Does the FLIR A35 include a PMD 3D sensor? No. Does the FLIR One Gen 3 include one? Not as far as I know. But if you are building a permanent monitoring station where equipment geometry changes, depth information can make a thermal camera far more useful than another few pixels.

For a one-time emergency inspection, I wouldn't choose a camera because it has 3D depth integration. The calibration history and lens choice matter more. But the next generation of automated thermal inspection tools will likely combine visible light, thermal, and depth data into one decision.

Which One Should You Order For an Urgent Job?

If the job is tonight and you need a quick portable answer, choose the FLIR One Gen 3 smartphone thermal camera. It helps you get close, share images quickly, and narrow a fault without installing network infrastructure. Carry a spare phone cable and verify phone compatibility before the call.

Choose the FLIR A35 thermal camera when the job is about repeatability and integration. If the same machine needs to be monitored continuously or compared at the same angle every hour, a mounted A35 provides a stable long-term answer. But don't expect a shipping department to solve an IT project overnight.

Before ordering, ask the same question a calibration tech would ask: What is the reference, what is the measurement range, and will I be able to defend this later? For the A35, that may mean verifying the lens configuration and calibration certificate. For the FLIR One Gen 3, it may mean testing emissivity and distance on a known hot surface. The thing that protects you isn't the brand. It's the method.