What is IR?

[Weaving Wax]

I've heard the term used here before and I'm not sure what it is..

I've looked in the search, but to no avail...

 

[Icon72]

IR stands for infrared.

Here's a wiki link that explains more: http://en.wikipedia.org/wiki/Infrared_photography

 

[Groupcaptainbonzo]

Light ranges from Far Infra red to X-Ray . and in the middle of all this somewhere is what we call Visable light. The eyes only detect a very narrow band of frequences. Some sensors / films are responsive to wavelengths which lie out side of the Visable. at the short end is IR. (about 700-800 nano meters).

http://i142.photobucket.com/albums/r87/groupcaptainbonzo/TheFootpath.jpg

http://i142.photobucket.com/albums/r87/groupcaptainbonzo/Footpath.jpg

 

[Hertz van Rental]

Light ranges from Far Infra red to X-Ray . and in the middle of all this somewhere is what we call Visable light. The eyes only detect a very narrow band of frequences. Some sensors / films are responsive to wavelengths which lie out side of the Visable. at the short end is IR. (about 700-800 nano meters).

To be accurate, they are all electromagnetic radiation ranging from Gamma rays, through X-rays, ultra-violet (UV), visible light, Infra-red (IR), microwaves, short radio waves and down to the long radio waves.
Infra-red is beyond the red wavelengths and so is down at the long end

 

[Weaving Wax]

Thanks!

 

[Majik Imaje]

well I SEE SOME, have given their answers, and links

I want to explain HOW to use it. it is on your camera LENS, I think if you have a 35 mm camera & lens.. it is a little l mark near the f-sTop ring. this is how it works..

When your taking photos USING Infra-red color or black and white. the wave length is a different spectrum. who cares about all the technical data here.

Lets make this simple.. you have infraRed film in your camera. good.. now focus. ready / you cant take that picture yet. look at the focus ring.. see that small mark, that is usualy a different color? now move your focus point to that mark. now. your all set. that is how it is used.. that simple and that is the only time it is ever used.!

Infra-red film is mainly used for Scientific purposes and for agricultural purposes by farmers! Yes ! they can have a plane fly over their crops and with just one click. .they have all that data! IF they do the right thing.

using the CORRECT FILTER. they can now SEE. where the dry spots of the land are.. ! they can pinpoint diseases etc..

JUST BECAUSE YOU READ SOMETHING ON THE NET.. OR IN WIKI that does not necessarly mean that it is TRUE.

I have proven Kodak WRONG on so many things. DON'T BE AFRAID TO THINK.. outside THEIR box!

Get a yellow filter and go shoot a roll of infra red FILM color wise.. anything green will come out magenta.. whoa.. wild colors.. veins in people come out much different. Time/Life series has some great photos!

 

[Weaving Wax]

Hmm. Thanks..but...

Call me blind, but I don't see the little mark. I have a Canon EF 50mm f/1.8 Lens. Is this only for zoom lens' or am I missing something?

 

[fightheheathens]

Infra red color film does not need to have the focus adjustment done, only Black and White.

As far as the mark on your lens goes, I believe it would only be on Manual focus only lenses and most likely not on any Canon EOS lenses. (I believe the EOS series had a date time stamp thing that fogged infra red film so you cant use it with the EOS series and thus pointless to put the focus mark on any EOS lens.) IF you have a PreEOS lens, it should have the focus mark.

 

[Weaving Wax]

So, can I use Infra B&W film with my camera?

 

[Majik Imaje]

i DON'T have a lens here .. but I do know how and where it is located.. IF it is on your lens. LOOK" .. see the numbers for how far way..

10 feet on one end and infinity at the other end.. THAT IS NOT where it is.


now on the F-stop ring.. NO! it is not there either. i gotta find a picture.

this mark.. is on the depth of field numbers look closely...see the white line middle of lens. this is lined up with the distance. now that white mark either side of it.. (right side) should be a smaller red / orange mark

that is your IR focus point, for color or b&w INFRARED FILM

Not every lens has these.. but 90% of lenses have this tiny mark I believe it is located slightlly to the right of that middle white line?
I will try and find another image

 

[Hertz van Rental]

that is your IR focus point, for color or b&w INFRARED FILM

As has already been stated, the second mark on a lens is just the focus adjustment point for use with B&W IR film only. It is not for use with 'colour' IR films.
Colour infra-red film is not, strictly speaking, true infra-red film.
The three emulsion layers are sensitised to green, red and infra-red - that is, it is colour film with extended infra-red sensitivity. Which is not the same as being true infra-red.
Exposure is made through a yellow filter to completely remove blue light, but as you are still focussing with visible light you do not need to make any adjustment to the focus at all.
The green, red and infra-red sensitive layers produce yellow, magenta and cyan dyes as normal but produce a false colour record. Objects which reflect IR record as red, non IR reflecting green pigment records as purple and objects reflecting IR and red record as yellow.
The film was originally developed during WWII for aerial reconnaissance for camouflage detection.

 

[Majik Imaje]

HERTZ VAN RENTAL:

thanks for letting me know about Color Infra-red. I never ever knew that,

and I have never found anything that said that before.(I BELIEVE YOU)

BUT .. when I used to shoot color infra-red.. stupid me always, changed the focus point to that mark.

I guess it didn't affect my focus because I always try to shoot for maximum depth of field.


HERE ARE SOME LINKS.(for the other people)


http://www.google.com/search?source=ig&hl=en&q=focus+mark+infra+red+film&btnG=Google+Search

 

[Weaving Wax]

i DON'T have a lens here .. but I do know how and where it is located.. IF it is on your lens. LOOK" .. see the numbers for how far way..

10 feet on one end and infinity at the other end.. THAT IS NOT where it is.


now on the F-stop ring.. NO! it is not there either. i gotta find a picture.

this mark.. is on the depth of field numbers look closely...see the white line middle of lens. this is lined up with the distance. now that white mark either side of it.. (right side) should be a smaller red / orange mark

that is your IR focus point, for color or b&w INFRARED FILM

Not every lens has these.. but 90% of lenses have this tiny mark I believe it is located slightlly to the right of that middle white line?
I will try and find another image

But I have this lens;

 

[neea]

holy man is this thread ever confusing.
i may have just decided to never buy IR film.

 

[Majik Imaje]

Some lenses have this mark and some newer lenses don't have this mark

and the mystery mark is just about 1/8" to the left of your actual focus mark

so if you have depth of field you shouldn't even have to worry about it that much

i thought it was the right side of center but after reading today .

I read those words! so take it for what it is worth.. and in all actuality and aside from vibrant false color

and false tones in B&W I don't think you will go too far with it.! Practice!