There is much to be understood when it comes to comparing two thermal cameras. There are cameras costing a few hundred Dollars and others that cost tens of thousands of Dollars. They are equal only in that they can detect heat and display it to the human user.
In simple terms, the E6 is part of the Ex series of cameras that were developed as an entry level thermal imaging camera that meets the needs of less demanding users of the technology. The series uses a cost reduced microbolometer sensor that was developed for use in automotive night vision Thermal cameras and the lens is quite basic. The camera is fixed focus but achieves decent performance. The physical resolution of the cameras microbolometer sensor is 320 x 240 and this is what was released in the E4 upgrade
The Ex series is a decent product thanks to the quality of the microbolometer, lens and firmware that processes the thermal scene coming from the sensor array. In terms of value for money, the Ex series WERE reasonable but since its release, other, more affordable cameras have been produced by other competing companies. BUT, and it is a big BUT, the E4 camera remains the darling of the series thanks to the E4 upgrade that has been created on this forum. The upgrade means a user can buy a bottom of the range E4 and upgrade its resolution to the full 320 x 240, switch off the artificial noise generator and add functionality that goes beyond that offered by even the top of the series E8
An upgraded E4 is a thing of beauty that costs less than $1000? In terms of value for money and the image that it can produce, there is not much to touch it, if anything. Dongle based thermal cameras are cheaper but you need a phone and some people want the all-in-one solution rather than using a phone with something hanging off of it.
The TG series are bottom end thermal imaging intended for users who are very limited in their needs. They are “budget budget” thermal cameras. What is amazing about these TG series cameras is that they are relatively inexpensive. This is all thanks to FLIR developing the Lepton Core. This is a thermal imaging sensor array with 80 x 60 or 160 x 120 pixels that integrates significant image processing within its diminutive physical dimensions. The whole core is smaller than a sugar cube ! Sadly to create such a marvel of engineering, FLIR had to accept some compromises in terms of the cores performance. The sensor array uses the 12 micrometer size pixels that are still relatively insensitive and so the noise content of the produced images is relatively high. They used a silicon ‘printed’ diffractive lens structure that further reduces sensitivity and imaging performance. The result is an amazingly compact thermal imaging core that produces OK images, but not great images. FLIR use a lot of image processing to improve the images that come from the Lepton core, but there is only so much that can be done with sub optimal data as the source.
Basically the FLIR Lepton is intended to be a very affordable thermal imaging core that may be easily integrated into products that do not need to provide impressive thermal imaging output. The scene just needs to be ‘adequate’ for the expected users needs. The FLIR One series is an example, as is the Thermal dampness meter and the TG series thermal imagers..... they produce an adequate, if a little disappointing thermal image. To improve that image would require the Lepton core to be completely redesigned from the ground up as the current design has reached its limits. That is exactly what FLIR did when they embarked on the FLIR BOSON core Project. That Core has proved to be disappointing however !
With thermal imaging, you often get what you pay for and if you need high quality imagining with accurate temperature measurement that can be trusted, it does not come cheap. There are some nice affordable options available though that would easily out perform any Lepton based camera.
If you need to know exactly what makes one thermal camera ‘OK’ and another ‘Amazing’ in terms of the images it produces, you will need to study IR lens design, microbolometers, NeTD and image processing algorithms. These dictate the quality of the image, measurement accuracy and the cost of the product to manufacture.
It is not just about the pixel count.
Fraser