Ecology applications vary widely depending on the job, so there isn’t really a one size fits all device (unless your budget can cover the top end! Read on..) so you really need to see what would fit both your budget and needs, and choose accordingly.
Pulsar is a popular scope choice amongst ecologists and Guide is a relative newcomer to the scope market. I am a FLIR user and have used FLIR cameras for over 5 years now – the investment in TI technology was a big one for my small company back when only a handful of ecologists were pioneering its use within the professional sector. As a bat specialist approximately 95% of my professional work related to bats and so for me the investment was a no brainer. I am also a trained veterinary thermographer and so could apply the technology for my other business.
What To Look For In A Thermal Imaging Device
From the most common application of bats surveys to nesting birds surveys, especially cryptic ground nesting species, there are a few things to consider when it comes to specifications:
- Detector IR Resolution – this is how many pixels the camera can render the scene, the higher the resolution means more information in each image, more pixels =more detail. Measuring small targets, such as bats, from further away will require a higher resolution. This is therefore related to detection distance, the higher the resolution of the detector the greater the detection distance for a small target.
- Field of View – this is determined by the camera lens. It is the extent of a scene that the camera will see. A fixed lens camera will only give you one FOV so you need to choose wisely! Cameras with interchangeable lenses are available to suit a range of applications.
- Refresh Rate/ Frame rate – 30 Hz and above is recommended as anything below will mean image blur especially on fast moving animals.
- Thermal sensitivity – (Noise Equivalent Temperature Difference) is a measure for how well a thermal imaging detector is able to distinguish between very small differences in thermal radiation in the image. Measured in milli-Kelvin, the lower the number the better the thermal sensitivity. In general, any value under 50 mK will produce noise-free images under normal conditions. It should be noted that the standard for determining NETD is measured at 30 degrees C, if this is not stated in the specifications, then the value might look great, but it may have been determined under non-standard conditions.
- Type of data collected – what format is the data recorded in? Un-Editable jpeg or editable radiometric jpegs? Does it matter?
- Available accessories – spare batteries, lenses, external monitors, smart phone apps – these can all make your life as an ecologist easier in the field.
- Data management – thermal images and video are memory intensive so having backup drives and portable hard drives in the field is important.
The thermal imaging guidelines (KWF 2020) sets out the minimum specifications required for bat surveys and is a great document to get started when choosing a device and is available for download here.