Dark Water 1000nm with converted Sigma fp.

Started 2 months ago | Discussions thread
xpatUSA
xpatUSA Forum Pro • Posts: 19,488
Re: Dark Water 1000nm with converted Sigma fp.

Scottelly wrote:

xpatUSA wrote:

D Cox wrote:

SigmaTog wrote:

D Cox wrote:

Maybe you could photograph CO2.

A container full of dry air, and the same after you drop a lighted match or a small candle in before closing the lid.

Don Cox

I tried this out Don, but I didn't get anything exciting.
Perhaps it is a very narrow band, or I need some more details ?

Col

"Carbon dioxide and water vapor are responsible for energy absorption in the troposphere in this model. Absorption bands of carbon dioxide are centered at 15, 4.3, 2.7, and 2 μm (see Fig. 1).

Ergo, there would be no absorption by CO2 below 2um - thereby making the CO2 transparent in the wavelengths captured by Colin's camera.

I don't understand. Are you saying Colin's camera can only see light with wavelengths shorter than 2 um? (That's μm, right?)

I am saying that Colin's camera can see from about 0.2 to about 1.15 um and that would be with no filter on the lens.

Yes, Scott, by um I mean micrometers.

I thought it could see the beginnings of infrared light, which is around 700 nanometers, or .7 μm.

Again, Colin's camera can see from about 0.2 to about 1.15 um.

I know thermographic cameras can see light with much longer wavelengths, like 10,000 nanometers, or 10 μm.

So do I.

Are you suggesting that the sensor in the fp can not see light that is 2 μm wavelengths,

Yes ...

because he did not "get anything exciting" in his experiment?

... but not for that reason.

I wonder if releasing CO2 from a CO2 canister into a large, transparent plastic bag might give different results.

Straw Man. CO2 is transparent below 2um, ergo, Colin's camera can see through it.

Maybe since the CO2 gas is not as dense as a liquid, the experiment requires a much larger "chamber" to absorb a significant amount of light.

How much larger?

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Pedantry is hard work, but someone's gotta do it ...

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