Best thermal camera for $300

[Fraser]

Irisys IRI 4035 pictures - no post processing and in the RAW.

Fraser

[jean-paul]

Thanks for these image Fraser! I thought the Lepton3 would have been better

The Irisys IRI 403 outputs better images! For it's a different price.

I think I need to save money and spend at least 500€ to have something decent. I'll look on eBay if I can get a core or a Flir E4 for this price tag.

So to sum up this thread:
- $300 is not enough for building thermography, a budget of at least $600 is needed
- $800-$1000: we can get a Thermal Expert or a Therm-App or a decent used FLIR
- For $300 what would the best? A used LWIR core? or a Lepton3 + PureThermal2?

Thank you

[mahony]

Just to bring another option on the table, that might be quite close to your budget is the Seek Compact Pro currently on eBay for ~500€:
https://www.ebay.de/itm/Thermal-Imager-Seek-Compact-Pro-FF-Android-320x240p-Wärmebildkamera-Compactpro/282203560246?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

I would actually like to try one of those but maybe someone from the forum can help you with actual building images for this dongle. 320x240 with 32° FOV should be quite o.k. for the task.

[Spirit532]

For $300 and building inspection I recommend buying a used core. There are a few options on eBay just a hair over $300 for a 320x240 core with composite output.
A budget of ~$600-750 expands your options vastly.

I would actually like to try one of those but maybe someone from the forum can help you with actual building images for this dongle. 320x240 with 32° FOV should be quite o.k. for the task.

I have a Compact Pro - it works, definitely. The standard apps are quite meh, but JoeC's software allows you to push it quite far.

[jean-paul]

The Compact Pro is much better than the non-Pro? I haven't read good review on the non-Pro.

Do you have a link of a used core around 300€ please? I don't find one on ebay.

Thank you

[Spirit532]

The Pro is 320x240 and has a much better sensitivity and noise characteristic than the non-Pro.
As for links - just keep searching, they pop up once in a while. You may have to negotiate shipping with the US sellers and confirm with them that you're in an STA-exempt country(and therefore do not require export licensing).

[Bill W]

Good to see some examples of a FLIR with a decent lens. 
This is my thoughts too, the Flir-One modules are simply not even focused.
Experiments ongoing (slowly) putting a Flir-One behind decent germanium.

As for second hand cores, there's the GBP150 Raytheon 2000AS's from the thread
https://www.eevblog.com/forum/thermal-imaging/raytheon-2000as-core-teardown-and-back-up-again/
http://www.fire-tics.co.uk/project1/index.htm

regards
Bill
(fire-tics is my site and goods, but better someone here than eBay or even the wider forum !)

[Revan]

I have some questions about the Flir Lepton 3.

1. Is it possible to see smoke leaving from normal house chimneys or charcoal grills at a distance of 40-60 m and < 80 m?
Especially smoke that is only visible in IR?

2. The PureThermal 2 has an onboard STM32F412 ARM microprocessor running at approximately 100 MHz. Isn't a breakout board for the Lepton 3 and a Raspberry Pi 3 a much better choice? The Raspberry Pi 3 has a much faster processor.

3. If 1. requires some sort of lens optics what kind of low price optics would work and were can they be bought at low prices.

[Spirit532]

1. Is it possible to see smoke leaving from normal house chimneys or charcoal grills at a distance of 40-60 m and < 80 m?
Especially smoke that is only visible in IR?

No. This is exactly why LWIR cameras are used by firefighters - to see through smoke. At 60-80m you'll be lucky if the Lepton can differentiate between a working grill and a burning car.

2. The PureThermal 2 has an onboard STM32F412 ARM microprocessor running at approximately 100 MHz. Isn't a breakout board for the Lepton 3 and a Raspberry Pi 3 a much better choice? The Raspberry Pi 3 has a much faster processor.

It's only for reading the sensor out and serving a UVC device to a host computer. Not much processing required. It's barely enough to attach a display to it(and with the new firmware features, I doubt even that is possible).

3. If 1. requires some sort of lens optics what kind of low price optics would work and were can they be bought at low prices.

LWIR optics are just expensive, period. You're never going to find anything new for a low price.

Best you can do is probably hacking together your own lens using CVD ZnSe or GaAs elements for CO2 lasers, but that's on the fringe of what's possible, and still in the hundreds of dollars range.

[Revan]

Thanks a lot for your answers.

1. Why is it possible to see the heat emission on these pictures with an IR camera?
http://www.flir.eu/fire/blog/details/?ID=73308
http://www.alamy.com/stock-photo-infrared-thermography-image-showing-the-heat-emission-at-the-chimney-78791517.html


Something like this is all i want to be able to see with such an IR camera, a difference between the cold sky and the heat emission of the none visible smoke.

EDIT:
Here are two more pictures:
http://baltimorefishbowl.com/stories/greenlaurel-surprisingly-senate-blocks-trumps-attempt-to-cancel-methane-rules/
https://www.alternet.org/environment/hold-your-breath-nearly-200-infrared-videos-expose-methane-pollution-all-across-united

[Fraser]

Revan,

I think this is a terminology issue. You stated you wanted to see "smoke" leaving a chimney. As has been stated, Longwave thermal cameras are useful for seeing through "smoke". What you are actually wanting to image is the thermal energy leaving a chimney and this can be imaged with a thermal camera. It could be argued that there is always heat accompanying smoke coming out of a chimney but I think your specific request to see "smoke" caused some confusion.

Whether a Lepton core can image such thermal energy is actually a little hard to answer. The Lepton3 cores come with a wide angle lens so the minimum resolvable target at a stated distance applies. Heat emissions out of a chimney should be DETECTABLE at around 50m but I would not want to say they would be seen at 100m. I have no suitable chimneys around me to check.

One thing to be aware of, the sky is very cold to a thermal imaging camera. This can force quite wide thermal imaging spans in a fully automatic camera. Such wide spans can be detrimental to imaging some temperature differentials. It is better to manually select the temperature span of, for example, 10C and then set the centre temperature to that of the emission coming out of the chimney. You may need to set a wider span in order to gain the best image of the emissions.

This sort of imaging is normally the realm of industrial thermal cameras and a resolution of 320 x 240 pixels with 24 Degree, or less, FOV lens is preferred. The Lepton series of cores are at the bargain basement end of the market. You will not achieve impressive imaging with such a core, but if "detection" is your intention, it may work well enough for you if a Lepton3 is used.

You have not detailed why you wish to image the thermal emissions out of chimneys etc. Is it a project to study the thermal air behaviour, vorticies etc ? If so, that is beyond the capabilities of the Lepton3 and its wide angle lens. To study heated air interaction with the surrounding atmosphere and vorticies etc, I would use a high performance 320 x 240 pixel thermal camera fitted with a telephoto lens. The telephoto lens would provide the confinement of view needed to extract decent thermal scene detail with only 320 x 240 pixels. The telephoto lens FOV would be chosen to suit the distance from the target and required detail in the image. I would expect to use a 7 Degree FOV lens to look at a chimney on a house. That is a sixth of the FOV provided by the Lepton3.

On the 'cheap' telephoto lens front, there are none    Thermal camera lenses are made from materials that are inherently expensive. Germanium, IR Chalcogenide Glass and ZnS being commonly used. Telephoto supplimentary afocal lenses do come up for sale on eBay occasionally but they are by no means "cheap". New supplimentary lenses from FLIR and FLUKE cost thousands of US Dollars.

If you have a project that needs to image the thermal emissions from chimneys etc, it might be better to hire a suitable professional thermal camera and telephoto lens. It will be cheaper than buying equal performance, even used.

Fraser

[Fraser]

Further to my last, I see you have included references to imaging Methane gas emissions using thermal imaging techniques. These emissions are not "smoke" But some are IR reactive and can emit thermal energy.  You would need to study gas imaging with thermal cameras to determine what wavelengths are involved and whether one of the specialist gas imaging thermal cameras is required.

Fraser

[Spirit532]

I'd also like to add that some of the linked pictures are either fake(like the alamy one), or use midwave infrared(MWIR) cameras with specific filters for OGI(optical gas imaging), in the 3.5-6um range, with a few notches for absorption lines of various carbobyhdrates like methane.
The only exception is the first FLIR one, which is seeing a huge fire and only a few wisps of extremely thick smoke.

[Revan]

Fraser & Spirit532,

thanks a lot for your answer this will help me a lot.

You will not achieve impressive imaging with such a core, but if "detection" is your intention, it may work well enough for you if a Lepton3 is used.

Yes, detection is all i need.

You have not detailed why you wish to image the thermal emissions out of chimneys etc. Is it a project to study the thermal air behaviour, vorticies etc ?

No, all i want to do is just detect if and which chimney is active and in summertime which neighbor has an active charcoal grill running.

Some might ask, why not just use your eyes?
Well, this isn't as simple as it sounds. The main problem is the smoke is not always visible in the visible electromagnetic spectrum.
It depends on light conditions, the burning material and its humidity and for charcoal grills vegetation is often obstructing direct visual contact.

That's why i was thinking about detecting these things by the thermal energy of the smoke or the surrounding of the fireplace.
All i need to detect is if there is something active and in which direction/location.

I would expect to use a 7 Degree FOV lens to look at a chimney on a house. That is a sixth of the FOV provided by the Lepton3.

On the 'cheap' telephoto lens front, there are none    Thermal camera lenses are made from materials that are inherently expensive. Germanium, IR Chalcogenide Glass and ZnS being commonly used. Telephoto supplimentary afocal lenses do come up for sale on eBay occasionally but they are by no means "cheap". New supplimentary lenses from FLIR and FLUKE cost thousands of US Dollars.

Could i also use a Newtonian telescope with a mirror made of blank metal instead of a lens and attach the Lepton 3 to it?
As far as i know blank metal can reflect IR radiation quite good and the shaped metal mirror might magnify the image too.
Such a metal mirror would be also much cheaper.

This principle work's at least in the visible light with normal Newtonian telescopes and mirrors.

[Vipitis]

So, I looked around my neighborhood. I saw a few chimneys steaming. It's visible and also visible in the shadow. I pulled my phone phone, which features a 80x60 Lepton2.

I took images of steaming chimneys about 30meters away. And then our own chimney, from just 2.5m away. I believe all Houses in this neighborhood use gas based heating.

I attach some images, taking in FLIRs MSX Mode and in the Thermal Camera + superresolution mode, with limited minium temperature to reduce the dynamic range of the cold sky.


I think it's save to say that you can see nothing.  Might be the emissions that get burned here, but you get the wide angle idea. The Lepton3 has higher resolution, but that won't make a huge difference.

Newtonian telescope with mirrors should in theory work. I think Ultrapurple has pulled off some moon shots with a ThermApp and a newt; most telescope mirrors have glass with a coating that reflects quite okay in the LWIR spectrum. I don't have the scope to try it. But you could theoretically make a mylar based mirror with good reflection.

[mahony]

As long as the gas or particles or whatever exits the chimney of interest is warm enough your will be able to see it on a thermal camera.
I don't see why the alamy picture should be fake. Especially warm/hot water vapor will be happily recognized by a LWIR camera. Clouds are nothing more than water vapor at roughly ambient air temperature and will give you significant thermal contrast with respect to surrounding blue sky.

Attached is a picture of Christmas decoration with some candles, you can actually see the hot/warm gas quite far up. Note, that the color scale is logarithmic, otherwise to  only visible parts would be the very center of the flames.

With the TE-Q1 I saw smoke/hot air off chimneys quite often, but have no image at hand...
If interested in I can try to take some with me 13mm Lepton setup as over the next couple days.

[mahony]

I couldn't resist and pulled out the Lepton3 with the 13mm TE-lens and looked around a bit. The 'smoking' chimney is on the next house, according to google ~60m away.
On the other 2 images you can see nothing but the 'hot' stove pipes + I guess the gas is so cold that there is simply not enough  contrast to the surrounding roof tops...

All images are from raw digital values with linear scale from min to max pixel value.

[Revan]

These are great pictures. Thank you very much to both of you for sharing.

@mahony
If i get this right, you put the lense of the TE–Q1 on top of the  Lepton 3, is this correct?

[Bill W]

3. If 1. requires some sort of lens optics what kind of low price optics would work and were can they be bought at low prices.

From the teardowns on here you can see the lens is removable.  We also know the sensor is small and also small pitch.
This means tow things, one good and one bad.
On the good side you will not need a 200mm lens - 'not too long' focal length will still be a fairly narrow field of view and likely narrow enough for handheld use.
On the bad side many older lenses will not be resolving well at 12µm pixel pitch, a lot were designed around 50µm pixels.

That said I have this as an experiment in the 'to do' pile, putting a open F1 body behind all the lenses I have.  If any work Ok then I will say so.

What would you think is low cost ?
GBP/EUR 1 is not happening
GBP / EUR 50-100 opens up the kind second hand / recovered lenses from equipment mentioned above.

There used to be a rule of thumb that once the lens cost more than the camera, you had the wrong camera.....

regards
Bill

regards
Bill

[mahony]

Yes, I took the lens from the TE-Q1+ (the 13mm version) as I am mostly using the TE with a 36mm FLIR lens (from a FLIR A20 I think).
I just removed the lens a described  on one of the tear down videos. You can also put it back on later - the big benefit is you can then fine adjust the focus. Both Leptons I pulled from F1G2s where a bit too close focused / not at infinity - probably for indoor use.

On the Lepton you get a FOV of ~8.5°x6.4° (12µm/13mm -> 0.93mrad iFOV @160x120px results in ~148x110mrad). The 36mm on the TE-Q1 result in 0.47mrad iFOV and 10.4°x7.8° full FOV which is quite nice for longer range playing. Detection of people/animal is possible up to ~800m, probably even more. I was not sure about the sharpness of this 'old' lens on a 17µm Imager but turns out it has totally sufficient sharpness. At some point I am going to test is on the Lepton too because I want to see if it might be an option for a Boson core at some point in the future :-D

I have attached some images of both conversions. The Lepton setup is still very 'experimental' whereas the TE-FLIR combo is finalized after 2 iterations of prototypes.

[Vipitis]

You should take a panorama tripod head and stich multiple images of the Lepton with the lens to see if you can get good results for a high resolution stiched image. You will need to lock palette, gain and stretching to get consistent results. Also consider the FCC shutter cooldown.

[mahony]

Yes, I am planning on something like this. I already have a self-made Pan-Tilt head that would need some software mods to do an automated pattern for panorama stitching. BUT if I do this I probably just use the TE-Q1 ;-) and before I have to check-out Photoshops capabilities in stitching 16bit monochrom .tif files.
It might be interesting to see the differences on a final high-res image between the Lepton and the TE.

[jean-paul]

Hello,

To conclude this thread, the best it an used camera!

Here is an example of a panorama with 7 images 160x120

[Fraser]

Jean-Paul,

Nice Panorama 

I am so pleased that the camera went to a good home where it will get plenty of use.

Warning - You could catch the 'thermal bug' and start your own collection of cameras 

Fraser

[jean-paul]

Hi Fraser,

Yes I need to be careful! If I win at the lottery I'll know what to buy!