In General

Well, a few words about Infrared.
I will not get too technical cause it’s not my strong side, just a few words about it. Infrared photographs show a kind of thermo effect. Trees with white leaves and luminous white clouds against colored skies are the most common use for it. Many photographers on DA have tried it in the last few years and it seems to be more and more popular.
The Infrared opens a window on a parallel world intriguingly different to the one we usually see. The effect is surreal ans it shows a different kind of "documenting reality".

Here you can see the scene in normal view


And here is when using the IR filter -


We can't see Infrared light without the filter, we can only see it when It's isolated. Infrared photography is often confused with thermal imaging. It's not, It's just shows an effect similar to that. The difference is basically one of wavelength of electromagnetic radiation.
The filter shows the object because the sun (or some other light source) shines infrared light on it and it is reflected or absorbed by the object. You could say that this reflecting or absorbing of infrared helps to determine the object's color in a four-dimensional color space made up of blue, green, red and infrared.



Camera and filter

If you are using film camera, I won't get into this.
Important you know! Digital cameras don’t work evenly with IR filter.
Digital sensors have a special infrared-blocking filter in front of the light-sensitive CCD array, as the IR light degrades the visible-light image quality. The question is how much of infrared will the filter let through.
There are a few great compact digital models like the Sony 717, The Olympus C-2020z, Minolta Dimage 7, and the canon G1 (the G2 is great too). Among the DSLR the Nikon D70 and D50 are the best option right now. Canon popular models don't support high quality IR (and most other models and brands). That means that it can shoot IR but in lower quality (clarity, sharpness, colors) then the Nikon D70 (D70s) and D50.
Check out more about the Infrared sensitivity here [link]

Of course it’s much harder working IR with DSLR, since you have no preview of the result, and it’s impossible to see anything through the viewfinder, with the filter attached. I’ll get to this later (In technique).
The filter I use and recommend is Hoya R72.
There are several others that get good results, but this one gets the classic color effect in the best way possible.



You can test your non DSLR camera for IR photography
Use the “TV remote test” to determine if your digital camera is sensitive to infrared light. Television remote controls use infrared light to turn the TV on and off and to change channels. Aim your TV remote control at the lens of your digital camera from a few inches away, push a button on your remote, and view the image on the LCD panel (not the optical viewfinder) of the camera. If you see a white flash of light coming from the TV remote on your camera’s LCD screen, you’ve just determined that your camera is infrared-sensitive. That only means that the camera is capable of shooting IR, but not the quality of the results.



What if my camera is not IR sensitive?
Well, there are options to shoot IR with models that don't support it. However, they mean you damage the ability of the camera to capture 'normal' photography. Basically you remover the glass that protects the CCD in the camera.
You can remove it and replace it with a built in IR filter (convert the camera completely for shooting IR), or simply replace the glass for a regular glass and reducing the IR block of the camera (could damage you normal photography, and you still need to use a filter for IR).
If you really love IR it is recommended you convert your camera. Working with a converted camera is much easier. You can shoot short exposures and get better details. However, you need to do it on a spare camera since the camera is useless for regular photography.

For more on that - [link] and [link]



Technique

OK, so we are talking about shooting IR with a DSLR (a regular one)

Tripod -
Besides your digital camera and filter, a tripod is an absolute necessity since exposures through the infrared filter should be long. For long exposures, some cameras will automatically fire the flash to light the scene, because the camera’s “brain” thinks its dark. But you don’t want to use flash. Be sure to turn off the flash so the camera will make the exposure by infrared light.

Iso settings -
Work in low Iso (50-200) so you won’t pick up too much noise.

Camera function -
Work in fully Manual (if possible) to get a good light reading from the camera, so You’ll know if you are using a long enough exposure.

Set White Balance -
This is the part that most beginners go wrong...
You will have to measure the white balance yourself. That’s the secret of getting a good color balance in IR photography (with digital photography). Measure the WB in ‘RE’ condition with your filter ON from something green as green grass (not in the shade.. in a sunny area). That would get you the right balance. Test the result, and if needed, try measuring it again.
You should know: Nikon generates more colors in IR then Canon. The canon will get almost B&W when adjusting the WB. Nikon will get B&W and also brown.

Composition -
To begin, photograph a daylight scene in auto WB. Mount your camera on the tripod and compose the shot normally (Take the widest angle possible for a landscape shot) without the infrared filter over the lens, and make a normal, color picture. The color picture will be a “reference” picture. You might want to combine it with the infrared picture for creative effect later.

Final steps -
After you composed it, and focused it, in the color version, take it out of Auto focus. Mount the filter carefully, so you won’t destroy the camera position and composition. Switch your WB to the pre position (that you measured earlier). Now, shoot a second picture in exactly the same way except go through the infrared filter. With the infrared filter on the lens, you’ll see the infrared effect on the camera’s LCD viewing screen (or only in the result in DSLR cameras). The image will appear dark and a monochromatic red-pink in color. This is normal for an infrared picture. After you shoot the picture, you should review the image on the camera’s LCD screen and check for proper exposure. If the image is dark, you might want to switch the camera to manual and increase the exposure.





Post processing

Once you’ve captured your infrared images, you’ll want to do a little clean up in an image-processing program like Photoshop.



When you open the infrared image file, you’ll probably see a monochromatic red-pink image that might be a little bit dark. You may want to adjust the curves or levels to brighten the image.





Also, you may want to adjust the contrast to your liking. By Now you have an image very similar to one shot on infrared film, but without the hassles.



I usually love to change the channels, to replace the red with a blue.
In Photoshop go to Image>Adjustments>Channel mixer you will first see the setting to the red channel.



The red is on 100 and the green and blue are on 0. Turn the red to 0 and the blue to 100.



Now go to the blue channel (the top drop down menu in the message box). Turn the red to 100 and the blue to 0.

Now, look at the difference -

Before - After -

The channels have switched and if you want a better balance change the settings a bit.

If the ‘Whites’ are a bit ‘Reddish’, you can go to Image>adjustments>Hue/saturation and lower the saturation of the red (and yellow) channel.

That’s the IR story in short.
Photography by the “invisible” light of infrared can open a new world of artistic expression. I love it, and I hope you do too
Feel free to add from your own experience, add tips, and ask questions.
Again, I’m not sure I’ll be able to answer all, But I’ll try.



Good Links: [link] [link] And a wonderful galley to enjoy [link]

I submitted a tutorial on IR in my journal, and I got many questions regarding technique ans models fitting for IR photography. Please take a look to know more - [link]