> I see in the local glossy a firm offering to take "thermographic" > (infra red) pics. of houses etc. The intention is to spot local > hotspots (ie because of missing insulation), and damp areas. Seems > like a good idea - I have no idea how expensive it is. Just wondering > though if anyone knows if/where these cameras can be hired from. Seems > like a good diy task.
> > I see in the local glossy a firm offering to take "thermographic" > > (infra red) pics. of houses etc. The intention is to spot local > > hotspots (ie because of missing insulation), and damp areas. Seems > > like a good idea - I have no idea how expensive it is. Just wondering > > though if anyone knows if/where these cameras can be hired from. Seems > > like a good diy task.
NT wrote: > On Nov 9, 1:26 pm, Owain <spuorgelg...@gowanhill.com> wrote: >> On 9 Nov, 12:12, dave <d...@127.0.0.1> wrote:
>>> I see in the local glossy a firm offering to take "thermographic" >>> (infra red) pics. of houses etc. The intention is to spot local >>> hotspots (ie because of missing insulation), and damp areas. Seems >>> like a good idea - I have no idea how expensive it is. Just wondering >>> though if anyone knows if/where these cameras can be hired from. Seems >>> like a good diy task. >> "thermal imaging camera hire" produces several results - most of >> which are rather reluctant to measure pricing, eghttp://www.thermascan.co..uk/assets/ir-camera-hire.php
Owain wrote: > On 9 Nov, 12:12, dave <d...@127.0.0.1> wrote: >> I see in the local glossy a firm offering to take "thermographic" >> (infra red) pics. of houses etc. The intention is to spot local >> hotspots (ie because of missing insulation), and damp areas. Seems >> like a good idea - I have no idea how expensive it is. Just wondering >> though if anyone knows if/where these cameras can be hired from. >> Seems like a good diy task.
Easier & cheaper. Get a local scroat to steal a car, joyride until the Police bring out the helicopter, then abandon the car & run into your garden to hide.
Then wait until its shown on Police Camera Action or Sky Cops.
> We were somewhere around Barstow, on the edge of the desert, when the > drugs began to take hold. I remember dave <d...@127.0.0.1> saying > something like:
>>I see in the local glossy a firm offering to take "thermographic" >>(infra red) pics. of houses etc. The intention is to spot local >>hotspots (ie because of missing insulation), and damp areas. Seems >>like a good idea - I have no idea how expensive it is. Just wondering >>though if anyone knows if/where these cameras can be hired from. Seems >>like a good diy task.
> Afaik (I haven't tried it), many older webcams and small point and shoot > digicams can be easily converted to being IR sensitive by removing an > IR-blocking filter on the sensor - then you use an IR-transmissive > filter on the lens. I suggest a google on the matter.
That'll be near Infrared, and not the right spectrum for thermal vision.
> I see in the local glossy a firm offering to take "thermographic" > (infra red) pics. of houses etc.
It's now easy to buy these, and relatively cheap. Two grand gets you a handheld with a (rather small) colour LCD screen that only weighs a pound or so and doesn't require any cooling. Try the FLIR systems i5 and similar. Hire on these is a couple of hundred / day (but varies a lot).
The thing is remember is what "IR" and "hot" mean, for your application. Read up on "Planck distribution" for why: the hotter things are, the shorter the wavelength you need to look at and the easier this is. For things as hot as lighbulbs (or reflected light from them), or even "red hot" ironwork, a standard issue Mk1 eyeball can see the glow. For "heating systems" then it's no so hard either, for "spotting people" it's moderately difficult and for spotting through military camouflage it gets awkward. In particular, the sensor needs to be cooled down, so doing this handheld becomes very tricky.
So if you do hire, make sure you hire something that's capable of seeing what you need, but not over-capable or you'll be paying for it. File export capability probably matters too and although that's trivial to build in these days of digital cameras, it carries a price premium.
An "IR camera" isn't the same thing, nor is a "night vision" rig. IR cameras work in the very near infra red, with LED illuminators, and won't see anything glowing from its own heat alone unless it was too hot to tough. They'll see chimneys, but not heating radiators.
A night vision camera works at similar wavelengths to eyeballs, hardly even IR, but is hugely sensitive as they have an "image intensifier", an internal amplifier.
Military-grade (and fire-brigade / rescue) kit has to work at really long wavelengths to see things that are merely cool rather than cold. They still can't (AFAIK) use a "camera" sensor for this, but suitable single spot detectors have been known for 100 years or so. Their complexity is in mechanically scanning mirrors, so as to image the whole scene with a raster scan using this single point detector. They're thus heavy and complicated. Although they're not actually too hard to find on the surplus circuit, they're a bit of a swine to get working again.
> They still can't (AFAIK) use a "camera" sensor for this, but suitable > single spot detectors have been known for 100 years or so. Their > complexity is in mechanically scanning mirrors, so as to image the > whole scene with a raster scan using this single point detector.
I was wondering about a cheap IR thermometer (Maplin etc) combined with some sort of DIY scanning arrangement.
> On 9 Nov, 14:27, Andy Dingley wrote: >> They still can't (AFAIK) use a "camera" sensor for this, but suitable >> single spot detectors have been known for 100 years or so. Their >> complexity is in mechanically scanning mirrors, so as to image the >> whole scene with a raster scan using this single point detector.
> I was wondering about a cheap IR thermometer (Maplin etc) combined > with some sort of DIY scanning arrangement.
> Owain
Two main problems with that:-
1) The type of sensor you are talking about will have an very long response time - probably 0.5s or more which means to generate a raster scan of any significant resolution will take bloody ages!
2) You also need to focus the object imaging spot onto the sensor - glass lenses are no good at far IR - they appear black!. So you will need a ££££Germanium lens.
>"Owain" <spuorgelg...@gowanhill.com> wrote in message >news:78990b20-f5ed-42a9-b90c-ebfe044bd2d9@a21g2000yqc.googlegroups.com... >> On 9 Nov, 14:27, Andy Dingley wrote: >>> They still can't (AFAIK) use a "camera" sensor for this, but suitable >>> single spot detectors have been known for 100 years or so. Their >>> complexity is in mechanically scanning mirrors, so as to image the >>> whole scene with a raster scan using this single point detector.
>> I was wondering about a cheap IR thermometer (Maplin etc) combined >> with some sort of DIY scanning arrangement.
>> Owain
>Two main problems with that:-
>1) The type of sensor you are talking about will have an very long response >time - probably 0.5s or more which means to generate a raster scan of any >significant resolution will take bloody ages!
>2) You also need to focus the object imaging spot onto the sensor - glass >lenses are no good at far IR - they appear black!. So you will need a >££££Germanium lens.
On 9 Nov, 17:22, "Phil Jessop" <p...@noname.org> wrote:
> 2) You also need to focus the object imaging spot onto the sensor - glass > lenses are no good at far IR - they appear black!. So you will need a > ££££Germanium lens.
Usually they go to mirrors instead, for much that reason.
> > I was wondering about a cheap IR thermometer (Maplin etc) combined > > with some sort of DIY scanning arrangement. > 1) The type of sensor you are talking about will have an very long response > time - probably 0.5s or more which means to generate a raster scan of any > significant resolution will take bloody ages!
If you do 10 "pixels" per metre (every 100mm) for a 8m wide x 6m high frontage and it takes 30s to take a reading, it would take 4h.
> 2) You also need to focus the object imaging spot onto the sensor - glass > lenses are no good at far IR - they appear black!. So you will need a > ££££Germanium lens.
I didn't think any lenses would be required, I was thinking of mounting the thermometer on something like a uniselector to rotate it round about a 90deg arc and then return it to start and increase the inclination. With a timer circuit to pulse the uniselector and press the 'read' button the thermometer could either store a sequence of readings, which could be correlated to position afterwards. If the thermometer doesn't store a sequence of readings then a cheap digital camera mounted over the display and connected by a delay timer to the 'read' impulser would handle the logging. The thing could then run unattended assuming it didn't get nicked.
This supposes the thermometer works when pointing at an angle to the target surface.
> I didn't think any lenses would be required, I was thinking of > mounting the thermometer on something like a uniselector to rotate it
A stepper motor?
> round about a 90deg arc and then return it to start and increase the > inclination. With a timer circuit to pulse the uniselector and press > the 'read' button the thermometer could either store a sequence of > readings, which could be correlated to position afterwards. If the > thermometer doesn't store a sequence of readings then a cheap digital > camera mounted over the display and connected by a delay timer to the > 'read' impulser would handle the logging.
Interface the display driver output directly to a PC and you can then log it on the PC.
> The thing could then run > unattended assuming it didn't get nicked.
The problem is the aspect ratio of the IR thermometers - nine foot back from a wall they are looking at a one foot square area, so not really useful.
On Mon, 09 Nov 2009 18:30:24 +0000, dave wrote: > On Mon, 9 Nov 2009 06:27:51 -0800 (PST), Andy Dingley > <ding...@codesmiths.com> wrote:
>>On 9 Nov, 12:12, dave <d...@127.0.0.1> wrote: >>> I see in the local glossy a firm offering to take "thermographic" >>> (infra red) pics. of houses etc.
>>It's now easy to buy these, and relatively cheap. Two grand gets you a
> Ah - hang on just there. I think you can see the snag.
I don't know if it covers the right wavelengths, but you can certainly buy 35mm infra-red film for a good old fashioned SLR.
Andy Dingley wrote: > On 9 Nov, 17:22, "Phil Jessop" <p...@noname.org> wrote:
>> 2) You also need to focus the object imaging spot onto the sensor - glass >> lenses are no good at far IR - they appear black!. So you will need a >> ££££Germanium lens.
> Usually they go to mirrors instead, for much that reason.
The systems I have worked on used a polished tilting rotating polygon to scan the image over the detector (the rotation and angle synced to TV line and field rates). The detector being a cryo cooled linear strip detector. However for most applications there would be and additional "lens" (typically made from germanium) of some description on the front end of it. The most elaborate airborne systems have a thermal telescope (again all germanium). These beasties typically cost in excess of £100K just for the telescope.
> > I didn't think any lenses would be required, I was thinking of > > mounting the thermometer on something like a uniselector to rotate it > A stepper motor?
I suppose a couple of them would do if you don't have any spare uniselectors :-)
> Interface the display driver output directly to a PC and you can then > log it on the PC.
Need a heck of a lot of uniselectors though :-)
> The problem is the aspect ratio of the IR thermometers - nine foot back > from a wall they are looking at a one foot square area, so not really > useful.
On 9 Nov, 19:40, Harry Bloomfield <harry.m1...@NOSPAM.tiscali.co.uk> wrote:
> Owain submitted this idea :
> > I didn't think any lenses would be required, I was thinking of > > mounting the thermometer on something like a uniselector to rotate it
> A stepper motor?
Easiest would be a polygonal mirror (laser printer or barcode scanner) that rotates continuously and generates a sync pulse. Especially so if you want to scan quickly.
> Easiest would be a polygonal mirror (laser printer or barcode scanner) > that rotates continuously and generates a sync pulse. Especially so if > you want to scan quickly.
>> The problem is the aspect ratio of the IR thermometers - nine foot back >> from a wall they are looking at a one foot square area, so not really >> useful.
> How high-res does would it really need to be?
One foot square would be enough, but if it is only nine feet from the surface and looking at a house the angles would be acute to cover the entire house width and height. Moved parallel and by hand, with aiming points marked in chalk on the wall, it might produce some interesting data.
On 9 Nov, 20:11, Steve Walker <st...@theend.demon.co.uk> wrote:
> I don't know if it covers the right wavelengths, but you can certainly buy > 35mm infra-red film for a good old fashioned SLR.
No, it doesn't. The first rule of IR film is that if you can store it at all conveniently, you can't do much useful with it! Also to focus it you needed to use an old plate camera with a single lens mounted far from the film plane (modern 35mm lenses performed wonderfully well in the visible, but not so well at IR) and also a glass plate back helps a lot (and an IR converter tube to watch it!). For years the best lenses available were WW2 German kit, developed for aerial recon in the IR. Germany led the way in near-IR imaging. These cameras, heavily adapted over the years, were fairly common in university labs into the '80s.
"IR thermographs" of vegetation (back in the film days) weren't usually anything of the sort, they were false-colour images of the state of leaf senescence (chlorophyll being present or absent changes their brightness considerably).
> "IR thermographs" of vegetation (back in the film days) weren't > usually anything of the sort, they were false-colour images of the > state of leaf senescence (chlorophyll being present or absent changes > their brightness considerably).
On Mon, 9 Nov 2009 12:19:08 -0800 (PST), Owain <spuorgelg...@gowanhill.com> had this to say:
>On 9 Nov, 19:40, Harry Bloomfield wrote: >> > I didn't think any lenses would be required, I was thinking of >> > mounting the thermometer on something like a uniselector to rotate it >> A stepper motor?
>I suppose a couple of them would do if you don't have any spare >uniselectors :-)
>> Interface the display driver output directly to a PC and you can then >> log it on the PC.
>Need a heck of a lot of uniselectors though :-)
I have loads of uniselectors, and a few Ledex switches, which are very similar in principle.
In fact I have a few 2-motion selectors, which could replace several uniselectors, if one really could be arsed. :-)
Just do it analoguely - take a photo or two of the house with infra-red film or filters and look for the 'hot spots'.
In the winter and there's snow about, it's pretty obvious who has reasonable loft insulation (or has little heating!) by looking at roofs... Although most of you 'dahn sarf' don't know about this 'snow' thing :-)
On Nov 10, 3:08 am, Grimly Curmudgeon <grimly4REM...@REMOVEgmail.com> wrote:
> We were somewhere around Barstow, on the edge of the desert, when the > drugs began to take hold. I remember dave <d...@127.0.0.1> saying > something like:
> >I see in the local glossy a firm offering to take "thermographic" > >(infra red) pics. of houses etc. The intention is to spot local > >hotspots (ie because of missing insulation), and damp areas. Seems > >like a good idea - I have no idea how expensive it is. Just wondering > >though if anyone knows if/where these cameras can be hired from. Seems > >like a good diy task.
> Afaik (I haven't tried it), many older webcams and small point and shoot > digicams can be easily converted to being IR sensitive by removing an > IR-blocking filter on the sensor - then you use an IR-transmissive > filter on the lens. I suggest a google on the matter.
You really need to put a piece of plain glass in its place or it doesn't focus properly. The cameras are quite complicated inside. I'd say that it would never work again if you take it apart.
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