Thermal Imaging Camera?

[The Natural Philosopher]

Foucussing probably. You need a fairly 'manual' camera.

[The Natural Philosopher]

It does. You tend to keep it in a fridge.

[Velvet]

They do indeed. Some of the higher range ones use other methods, but certainly mine uses IR internally for film speed detection, I believe.

Velvet

[Grunff]

Are you saying there's IR film sensitive at 3um+ ?

[Grunff]

Ok, here's my thought. I have an IR thermometer which I got from Maplin for ~£30. This does what a thermal imager does, but only over a single pixle. Very useful it is too.

[James Hart]

A lot of Sony camcorders have a nightshot button that moves into IR, I wonder if they'd do the job.

[James Hart]

If you don't want to wait til it snows, you can get it delivered if you want.

[all mail refused]

Oh right - you mean he can destroy the house in order to save the house ?

[all mail refused]

You can do heat transfer calcs using a code such as FLHE and large tables of conductivity, heat-capacity-at-constant-pressure and density, together with heat transfer coefficients calculated using Stanton numbers.

It's not as much fun as it sounds.

[Dave Liquorice]

Another wuss... B-)

Whats wrong with a basin/sink/bowl of water, bar of soap and, if you must, a flannel? If you want to be really posh you can heat the water first.

[The Natural Philosopher]

No, but I seriously doubt you have to go to that lengh to get a meaningful image.

>

[Grunff]

You gone and done it now - you made me think about it.

Gut feeling says you'll get next to nothing under a micron at 300K.

This is backed up by this graph:

I dusted off the old calculator, and calculated the emitted power per square metre (black body) using the Planck energy distribution formula.

For 300k and 1um, and it came to ~6x10-7 W/m^2. I don't reckon any film has the sensitivity to pick that up out of the overall background. I may be wrong, but I remain to be convinced.

[Mary Pegg]

Was *down* as far as possible. Was *up* as far as possible. Then you wash "possible".

[Mary Pegg]

Do you mean one of them fancy thermometers that has a laser spot aiming doo-dad in it? They are *really* fun. And you can acksherly measure the difference in temperature between floor and ceiling. And the angular resolution is good enough to compare the radiator with the bit of wall two inches to the side.

Anyway, that'd be my thought too.

[Dave Gibson]

Even if it was, it wouldn't be very useful in a camera, the glass in the lens would block the IR .... I believe that's how windows work.

Special gallium something or other lenses are required which are mega expensive - one of the main costs of a thermal imager.

IR film *mainly* detects the shorter (near visible) wavelength radiation that is mainly reflected - not emitted - from objects (unless they are very hot).

Dave

[Grunff]

That's the ones.

Yes, the first week after I bought it I measure the temperature of just about everything around me :-)

Indeed. Also really handy for car work. And for finding out how warm your dog actually is under thei fur.

[The Natural Philosopher]

Well, I have seen a few IR photos, and they definitely seem to show people and faces as rather bright.

Probably the only thing to do is to try it.

Film can pick up just one photon you know. It is sensitive...the point being does the near infra red actually give any meaningful correlation with heat? I also vaguely remember flash guns usd in dark places coverd with IR filters.

[The Q]

Not sure of it's range but our dear Friends "Screwfix" do a lazer spot temperature meter I've used one at work and certainly over the couple of metres I was using it, it successfully read the temperature of the outside piping. If the range is enough this would do for you.

The Q

[Andy Wade]

This makes me wonder whether you watched /Mind Games/ on BBC4 on Monday, which included a demonstration of how to measure the speed of light using a plate of grated cheese, a rule and a common item of kitchen equipment.

[James Hart]

Come on then, don't keep us guessing. How warm is the dog?