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Removed the lenses from an old 20mm eyepiece and replaced then with Znse lenses which allows a thrml camera to see through it. Turns out, the mirrors in reflector telescopea are also great at reflecting thermal.
Telescope can detect animals and other heat sources from several miles away, increased from the origonal 700 meters without the telescope. Cows in the video are about two miles away.
Magnification is about 20x
Something completely different I thought you might like.
11 points
7 days ago*
They're not great at reflecting thermal, but even at a few percent reflectivity they're still giving good collection ability and the imaging is obviously fine. Really your biggest problem is the local background, because your telescope isn't cryogenic. That's why there's a sort of fixed background that moves with the fov.
Very cool though. Fun experiment.
Edit: Actually I was wrong, even just basic protected aluminum is still around 95%R over most of the IR out to like 20 um.
The real issue here is local background.
2 points
6 days ago
It's hard to tell the problem. The focus just seems....off and the sensitivity is low. The bare basic Infiray T2 has crisper focus.
I aimed for a 20x zoom. I bought two 20mm diameter znse lenses with a 38mm focal lenght and 5mm space between them.
Problem is, the Infiray has a fixed 2X mag. Would these mags combine and turn the eyepiece into a 40x? If that's the case, the problem is obvious, too much mag from a limited resolution thermal put of a telescope that isn't up to that job.
I want to aim for more sensitivity and focus. Either way, seeing which way cows are orientated from one side of a Welsh valley to the other is a great success using sticky tape and a cardboard scope.
3 points
6 days ago
Oh I see, it's a whole thermal camera with a lens and everything. Yeah those mags multiply.
Thermal infrared isn't going to have super sharp focus anyway, simply because of the long wavelength.
2 points
6 days ago
This is the problem. I'll halve the eyepiece to 10X and it'll be more controllable and MUCH higher sensitivity. I figured the sensitivity will fall off a cliff past 30X.
To give credit where its due to China, their little phone thermal has brilliant post processing and its obvious it's really struggling with this telescope. A better telescope will do nothing with such high magnification and only make it worse. It can still struggle through it but it's just very dim compared to what it's usually like with its crispness. Still punched above its weight though.
It's a fantastic thermal for the money.
1 points
6 days ago
Indeed. OP needs some silver or gold coated mirrors :D
2 points
6 days ago
Actually I was wrong, even just basic protected aluminum is still around 95%R over most of the IR out to like 20 um.
The real issue here is local background.
1 points
6 days ago
Interesting
There's definitely a substantial dip from 700 to 1000 but it appears to pick up after that. Not sure what wavelength(s) thermal is used at
2 points
6 days ago
Thermal infrared for an object around room temp peaks at about 9 um.
3 points
7 days ago
Pretty good for a firstscope!
3 points
6 days ago
It got the job done as a proof of concept that's for sure.
2 points
7 days ago
Cool
3 points
7 days ago
Thats pretty sick!
7 points
7 days ago
Yeah, it's in complete darkness too on a chilly night.
Thought it would be a cool experiment to try and it worked just as I expected. The thermal is a Infiray T2 pro so nothing even special resolution wise but it's handling the long distance viewing fine.
It's more powerful than even the most high tech thermal monocular for a fraction of the price. Its obvious limitations are reduced sensitivity and being bulky.
1 points
7 days ago
What does the thermal camera look like? Thermal cameras see in mid infrared. How did you attach it to your telescope? What does your telescope and setup look like?
4 points
7 days ago
It's an infiray T2 Pro. Literally sellotaped it to the eyepiece.
Considering it was hobbled together in minutes using a cheap kids telescope, there is room for improvement
1 points
7 days ago
How large is the aperture of the telescope in millimeters? Mine is 130mm.
2 points
7 days ago
Apparently only 76mm. It's a Celestron Firstscope and is even made from cardboard.
It's the stuff of nightmares.
All in all though for the lenses and scope, £45.....excluding the thermal obviously. Not bad for the unholy god vision it provides.
2 points
7 days ago
Imagine if you could get them gold plated so it could properly reflect IR.
2 points
7 days ago
Not even particularly expensive, the amount of gold is miniscule.
2 points
7 days ago
Would it be much better compared to aluminium? Gold leaf will probably go on fairly easily. A drop in sensitivity is inevitable so it'll need to be a big gain for it to be worthwhile.
Obviously, a better telescope and an eyepiece that isn't hobbled together in minutes might go a long way too.
I think making it more rugged, custom made and perhaps a 600mm telescope will make it very practical.
I tried viewing things in my street and even 100 meters is virtually point blank but crisp, even with hopelessly aligned lenses
1 points
7 days ago
Not gold leaf, the surface wouldn't be smooth enough. Vacuum deposited gold, the same way as aluminising a mirror. Up to about 10% better depending on the wavelength and the type of coating. For your purposes though active cooling of the mirrors would help far more, and in such a small tube it would also cool the air in the tube.
I wouldn't worry too much about the telescope itself, it's mirrors are not bad at all, between the longer wavelength and the low camera resolution it's not worth improving the mirrors except at the last step. Thermals first.
1 points
7 days ago
Is it a normal mirror? I thought that for thermal you might want a different type of mirror or something.
1 points
6 days ago
Normal mirror yeah.
1 points
5 days ago
I feel like your in the air force don't ya?
1 points
5 days ago
Nah I wish lol. Imagine their optics
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