Is the human eye capable of seing infrared?

I did a little test today and I was surprised of the result. I took my Hoya R72 filter and put it in front of my eye, covered the visible light as much as possible so no light will go to my eye from the ambiant light and I was surprised to see that the foliage looked white!

Now can the human see IR light? Am I the only one seing infrared light with my own eyes?

I know I am not allucinating or imagining things because I can see the wall is light and the vegetation is dark green without the filter and if I put the filter in front of my eye, I can see the vegetation sudendly is lighter than the wall and if I stare a bit, I can really see that the vegetation is white with a red tint. I can see the dark grass patches become very light when I look at them through the IR filter.

Of course it is not as well defined as when I capture the actual image with my camera CCD, but I still can see that the ratio light/dark for the vegetation changes.

Is the human eye capable of seing IR light but we don't realize it because it is hiden by the stronger visible light?

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com

c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND, Hoya-red-Intensifier, Hoya R72.

Hi, Daniella,

We can only see into the red up to about 700nm but IR goes on past that up to 900ish. Some people will be able to see a little into the extended red area like cats. Cats, we believe from vet studies, can see quite a lot of the IR spectrum.
This link explains the colour spectum visibility quite nicely:
http://www.coolmint.co.uk/infrared/guide/
John.

======

Daniella said:

I did a little test today and I was surprised of the result. I took
my Hoya R72 filter and put it in front of my eye, covered the
visible light as much as possible so no light will go to my eye
from the ambiant light and I was surprised to see that the foliage
looked white!

Now can the human see IR light? Am I the only one seing infrared
light with my own eyes?

I know I am not allucinating or imagining things because I can see
the wall is light and the vegetation is dark green without the
filter and if I put the filter in front of my eye, I can see the
vegetation sudendly is lighter than the wall and if I stare a bit,
I can really see that the vegetation is white with a red tint. I
can see the dark grass patches become very light when I look at
them through the IR filter.

Of course it is not as well defined as when I capture the actual
image with my camera CCD, but I still can see that the ratio
light/dark for the vegetation changes.

Is the human eye capable of seing IR light but we don't realize it
because it is hiden by the stronger visible light?

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com
c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND,
Hoya-red-Intensifier, Hoya R72.

Click to expand...

Supposedly, not really. Your skin does though I am not sure what is happening when you put the filter to you eye, someone will be able to explain it better than me, I'm sure. Your eye can't really see the frequency range that ir is.(without help) Here is a link, don't know if it applies correctly for you. It has been a while on this stuff for me.
If you don't like the link just kick me.

Parker

I can see it well enough to have a good idea of what the scene will look like once taken by the camera. I took a photo with it just to compare and the longer I leave the filter in front of my eye and let it adjust to the dark light, the better I see it. Kind of neat to evaluate how a scene would look in IR if one cannot see it through the LCD because of bright sunlight.

john farrar said:

======

Daniella said:

I did a little test today and I was surprised of the result. I took
my Hoya R72 filter and put it in front of my eye, covered the
visible light as much as possible so no light will go to my eye
from the ambiant light and I was surprised to see that the foliage
looked white!

Now can the human see IR light? Am I the only one seing infrared
light with my own eyes?

I know I am not allucinating or imagining things because I can see
the wall is light and the vegetation is dark green without the
filter and if I put the filter in front of my eye, I can see the
vegetation sudendly is lighter than the wall and if I stare a bit,
I can really see that the vegetation is white with a red tint. I
can see the dark grass patches become very light when I look at
them through the IR filter.

Of course it is not as well defined as when I capture the actual
image with my camera CCD, but I still can see that the ratio
light/dark for the vegetation changes.

Is the human eye capable of seing IR light but we don't realize it
because it is hiden by the stronger visible light?

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com
c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND,
Hoya-red-Intensifier, Hoya R72.

Click to expand...

--

Click to expand...

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com

c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND, Hoya-red-Intensifier, Hoya R72.

how can this be true?

"Our eyes only see the tiny fraction of energy emitted by the sun in the form of visible light. However, if we could see the infrared rays emitted by all bodies--organic and inorganic--we could effectively see in the dark."

we cannot see infrared light unless there is some source of IR light first...in the dark, there is no source of IR so how can this statement be true?

Parker North said:

http://www.omega.com/literature/transactions/volume1/historical1.html

Click to expand...

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com

c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND, Hoya-red-Intensifier, Hoya R72.

Daniella said:

how can this be true?

"Our eyes only see the tiny fraction of energy emitted by the sun
in the form of visible light. However, if we could see the infrared
rays emitted by all bodies--organic and inorganic--we could
effectively see in the dark."

Click to expand...

Daniella68313 said:

we cannot see infrared light unless there is some source of IR
light first...in the dark, there is no source of IR so how can this
statement be true?

Click to expand...

Yes, there is a source of light in the dark, you just are not seeing beacuse the human eye is not developed to do so. Other creatures have eye aparatus, that can see in the dark.

If you think of ir goglles the soldier uses, just pretend your eyes had that extended frequency range, then you ARE seeing in the dark. Our eyes just are not sensitive enough, and we have no other additional equipmet package on the human body that allows us to do this.

Does that help a little bit.

Daniella68313 said:

Parker North said:

http://www.omega.com/literature/transactions/volume1/historical1.html

Click to expand...

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com
c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND,
Hoya-red-Intensifier, Hoya R72.

Click to expand...

In earth darkness terms, now in a complete vacume, with complete abscence of an light of any freq. Totall darkness, like beyond deepspace black. Then I am not sure, but for regular darkness that is the facts.

Maybe that helped a bit more??

Hi, Daniella,

There are two kinds of IR light sources. Those that reflect and those which emit from residual heat. So the police helicopter tracking a fugitive at night will be able to pick up the heat signal emitted from his body.

In daytime this emission component is overpowered out by reflected sunlight. That, at least is how I think it works.
John

.

john farrar said:

In daytime this emission component is overpowered out by reflected
sunlight. That, at least is how I think it works.

Click to expand...

Hi John, I am not sure that last statement is totally correct, seems if that were the complete case, we would not need ir goggles to see heat at night. You see what I mean?? Or did you mean something else??

Parker

Well, infrared light is almost essentially equivalent to heat (I think that specifically, it's a certain range of infrared wavelengths). One reason plants are brighter than the sky in an infrared photo is that their metabolism produces heat (also, they reflect more infrared, of course). So energy emitted as heat even when it's pitch black can be "seen" as infrared radiation by the right sensors.

Depending on the sensitivity range of the red pixels on a CCD, you could probably take an infrared photo in pitch darkness, although it might be a very long exposure - maybe you could run that experiment and let us know?

I'm also guessing that that is one reason why there is more noise on a CCD when it is hot....

Daniella said:

"Our eyes only see the tiny fraction of energy emitted by the sun
in the form of visible light. However, if we could see the infrared
rays emitted by all bodies--organic and inorganic--we could
effectively see in the dark."

we cannot see infrared light unless there is some source of IR
light first...in the dark, there is no source of IR so how can this
statement be true?

Parker North said:

http://www.omega.com/literature/transactions/volume1/historical1.html

Click to expand...

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com
c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND,
Hoya-red-Intensifier, Hoya R72.

Click to expand...

Passive IR cameras pick up the infrared heat signal emitted by hot objects.

Active IR cameras pick up the infrared signal reflected and so they could have large IR lamps used to illuminate the scene.

We must ask our cats what it is really like to bear witness to the infrared world. The parrot on the other hand can see into the UV if I recall rightly.

John.

Parker North said:

Daniella wrote:
Yes, there is a source of light in the dark, you just are not
seeing beacuse the human eye is not developed to do so. Other
creatures have eye aparatus, that can see in the dark.

If you think of ir goglles the soldier uses, just pretend your eyes
had that extended frequency range, then you ARE seeing in the dark.

Click to expand...

Army IR google are used in combinaison with an ir illuminator if I understood correctly. In order to see IR you definily need a source or emitter.. If there is no moon, or other sources of light, as I understand it, there is no night vision.

I tried my camcorder with the night vision and I could see in total darkness...pretty cool but it also emit IR light.

Parker North said:

Our eyes just are not sensitive enough, and we have no other
additional equipmet package on the human body that allows us to do
this.

Does that help a little bit.

Parker North said:

Parker North said:

http://www.omega.com/literature/transactions/volume1/historical1.html

Click to expand...

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com
c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND,
Hoya-red-Intensifier, Hoya R72.

Click to expand...

Click to expand...

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com

c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND, Hoya-red-Intensifier, Hoya R72.

I was curious to know if anyone else can see this?

the sun came out and now it's bright light outside and I tried it again...I can definitly see it with my own eye, about the same as the camera CCD see it but a bit underexposed if you would call it like that.

Parker North said:

Parker North said:

In daytime this emission component is overpowered out by reflected
sunlight. That, at least is how I think it works.

Click to expand...

Hi John, I am not sure that last statement is totally correct,
seems if that were the complete case, we would not need ir goggles
to see heat at night. You see what I mean?? Or did you mean
something else??

Click to expand...

Parker,

All warm bodies emit infrared light. Try taking a photo of your clothes iron in the dark with an ifrared sensitive film or digital image sensor. It should come out white. As someone said, that's how the cops track fugitives at night from the helicopter. The infrared emitted by their bodies is sensed by highly sensitive cameras. If the fugitive wore enough insulation (winter parkers), they would be much harder to dedect.

What surprised me about Daniella's original post is that she claimed to see infrared emitters as white. The reason film and digi-cams see it as white is that the exposure is such that the infrared light saturates the film or image sensor and it appears white. I would expect the human eye to adjust and see the infrared as a deep red color. In my iron example, if you ran the iron very hot and turned out the lights, you might see the higher end of it's spectrum as a dull red glow. With an electic stove, you can keep cranking up the power and eventually the stove coils will appear orange. If you could go further, they would eventually emit white light. However, they'd probably burn out or melt before that point. There are lots of such examples, but these illustrate where I'm coming from

Dewdrop

john farrar said:

Passive IR cameras pick up the infrared heat signal emitted by hot
objects.
Active IR cameras pick up the infrared signal reflected and so they
could have large IR lamps used to illuminate the scene.

We must ask our cats what it is really like to bear witness to the
infrared world. The parrot on the other hand can see into the UV if
I recall rightly.

Click to expand...

How about birds, bugs, bats, and other weird undersea creatures. If we only had all of those effects, with controls, on the side of our head or cameras.

How much does a intro level, commercial grade active ir camera run anyway.
New or used?

Parker

You can find an Olympus c2020 or c2000 for about 250$. it's 2mp but it's very sensitive to IR light and not too expensive. Nikon 800 or a used coolpix 950 will work also very well.

The filter cost around 30$ for the Hoya R72.

Not all cameras are good for IR and not all are sensitive as you probably already know. The bests are the olympus 2mp camera (3mp are not). Nikon 2mp cam, Canon 2mp cameras and G1.

Exception, my olympus c700 2mp is NO good for ir, that is the reason why i bought the Dimage7

Parker North said:

john farrar said:

Passive IR cameras pick up the infrared heat signal emitted by hot
objects.
Active IR cameras pick up the infrared signal reflected and so they
could have large IR lamps used to illuminate the scene.

We must ask our cats what it is really like to bear witness to the
infrared world. The parrot on the other hand can see into the UV if
I recall rightly.

Click to expand...

How about birds, bugs, bats, and other weird undersea creatures. If
we only had all of those effects, with controls, on the side of our
head or cameras.

How much does a intro level, commercial grade active ir camera run
anyway.
New or used?

Parker

Click to expand...

Dewdrop1 said:

Parker North said:

Dewdrop1 said:

In daytime this emission component is overpowered out by reflected
sunlight. That, at least is how I think it works.

Click to expand...

Hi John, I am not sure that last statement is totally correct,
seems if that were the complete case, we would not need ir goggles
to see heat at night. You see what I mean?? Or did you mean
something else??

Click to expand...

Parker,

All warm bodies emit infrared light. Try taking a photo of your
clothes iron in the dark with an ifrared sensitive film or digital
image sensor. It should come out white. As someone said, that's
how the cops track fugitives at night from the helicopter. The
infrared emitted by their bodies is sensed by highly sensitive
cameras. If the fugitive wore enough insulation (winter parkers),
they would be much harder to dedect.

Click to expand...

Actually, we are just talking wavelengths, I studied them a lot when I was an radio frequency tech, and then in nuclear power school, you may have missed my later posts referring to the heat, anyway, it is just all relative to sensitivity of the sensor, freq range of the sensors systems, and how small amount of heat (thermal radiation I believe?).

The thing that freaks me out is in the radar range, where you need a square hollow pipe and bends at half and quarter wavelengths to make the electrons keep flowing. And then you have to track the hole flow backwards, which is actually forwards.

Dewdrop1 said:

What surprised me about Daniella's original post is that she
claimed to see infrared emitters as white. The reason film and
digi-cams see it as white is that the exposure is such that the
infrared light saturates the film or image sensor and it appears
white. I would expect the human eye to adjust and see the infrared
as a deep red color. In my iron example, if you ran the iron very
hot and turned out the lights, you might see the higher end of it's
spectrum as a dull red glow. With an electic stove, you can keep
cranking up the power and eventually the stove coils will appear
orange. If you could go further, they would eventually emit white
light. However, they'd probably burn out or melt before that
point. There are lots of such examples, but these illustrate where
I'm coming from

Click to expand...

I am not sure on the exact frequencies and colors and rendering oddities the eye performs. I do know, when camcorders first came out and were 2500 bucks, I used to test suspect remotes by beaming them into the lens,

worked great, cant rember if it was red or white because the viewfinders were b/w and I can't remember what shades the dots were. I never did record the beams to find out.

Oh yeah, the primary colors combined make white, correct??

Parker

Dewdrop1 said:

What surprised me about Daniella's original post is that she
claimed to see infrared emitters as white. The reason film and
digi-cams see it as white is that the exposure is such that the
infrared light saturates the film or image sensor and it appears
white. I would expect the human eye to adjust and see the infrared
as a deep red color.

Click to expand...

I see it with a red tint of course...but it is lighter. For exemple, If I look at the little tree near by with my eye alone, it is a dark green color over a light ciment wall in the background.

Now If I look through the R72 filter...I can see that now the tree is lighter than the wall..sort of light red color. Everythign is tinted with red, but it is easy to see what is lighter and what is darker before and after the filter.

The more you let your eye adjust to the dark environment, the better you can have the idea of what vegetation reflect well or not IR light.

I can see for exemple that the fur tree stay dark..whereas the foliage of the tree is really light, withe with a red tint.

In my iron example, if you ran the iron very

Dewdrop1 said:

hot and turned out the lights, you might see the higher end of it's
spectrum as a dull red glow. With an electic stove, you can keep
cranking up the power and eventually the stove coils will appear
orange. If you could go further, they would eventually emit white
light. However, they'd probably burn out or melt before that
point. There are lots of such examples, but these illustrate where
I'm coming from

Dewdrop

Click to expand...

--
Daniella
http://www.photosig.com/viewuser.php?id=26918
http://www.pbase.com/zylen
C7OO FORUM: http://www.c700uz.com

c7OOuz, Dimage-7, Tcon14tele, C210tele, Cokin-173, Grad-ND, Hoya-red-Intensifier, Hoya R72.

Parker,

I think the goggles bend the IR wavelength into the visible range.
Bry

Parker North said:

Parker North said:

In daytime this emission component is overpowered out by reflected
sunlight. That, at least is how I think it works.

Click to expand...

Hi John, I am not sure that last statement is totally correct,
seems if that were the complete case, we would not need ir goggles
to see heat at night. You see what I mean?? Or did you mean
something else??

Parker

Click to expand...