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Infrared with color - a tutorial
Posted By: xs400, 05-05-2007, 12:01 PM

Several members have asked how I prepare some of my digital infrared pictures with a color cast. So I have written up a tutorial and posted it on my website. Below is one of my IR shots with a color cast. If you want to see how I did it, check out Frank's Digital Infrared Photography - Part 2 Let me know what you think.
Frank


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05-05-2007, 12:09 PM   #2
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Thanks for posting this.

Great simple tutorial to follow and I really missed the days of infra red films mainly produced by kodakchrome that already stopped film manufacture.

A quick question: Do you know how to creat the look of infra red colour effect?? Like green leaves turning out orange and blue becomes yellow etc

Cheers

James
05-05-2007, 12:14 PM   #3
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QuoteOriginally posted by roentarre Quote
Thanks for posting this.

Great simple tutorial to follow and I really missed the days of infra red films mainly produced by kodakchrome that already stopped film manufacture.

A quick question: Do you know how to creat the look of infra red colour effect?? Like green leaves turning out orange and blue becomes yellow etc

Cheers

James
Thanks for your comments. Sorry, but I don't how to create the infrared colour effect you describe. This is as far as I have gotten with IR.

Frank
05-05-2007, 02:23 PM   #4
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Very good tutorial, Frank. I'll have to play around with it later this weekend. There is one minor error in your text that you may want to change. You state,

But since infrared is in the red portion of the light spectrum, the original shot looks red.

This is incorrect. There are no exact limits on what wavelengths represent various named bands, but in general, it is widely accepted that electromagnetic energy at a wavelength that we humans perceive as red tops out at around 750 nanometers. Most people can only see visible light up to about 700nm, some rare individuals can sense up to about 780nm. The infrared wavelength is generally accepted to have its shortest wavelength at 750nm and extends up to about 1 millimeter. This range is named "NIR" or "near infrared".

The Hoya R72 filter blocks energy below 720nm, and even then, allows a slight bit below that wavelength. The transmittance spectrum of the Hoya R72 is buried pretty deep on their websites. Even at 750nm, the Hoya filter only passes about 40% of the energy it senses. The rest is blocked.

The Hoya RM90 filter is a much better filter for infrared work, but it is so expensive that none of use are going to get one.

So, your statement that infrared energy is in the red portion of the spectrum is incorrect. The best you can say is that they are adjacent bands and that the Hoya R72 filter passes a very minor amount of red visible light, and that is why the images appear dark reddish. All blue and green light is absolutely blocked by the filter.

Does this make sense?

05-05-2007, 03:41 PM   #5
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QuoteOriginally posted by volosong Quote
Very good tutorial, Frank. I'll have to play around with it later this weekend. There is one minor error in your text that you may want to change. You state,

But since infrared is in the red portion of the light spectrum, the original shot looks red.

This is incorrect. There are no exact limits on what wavelengths represent various named bands, but in general, it is widely accepted that electromagnetic energy at a wavelength that we humans perceive as red tops out at around 750 nanometers. Most people can only see visible light up to about 700nm, some rare individuals can sense up to about 780nm. The infrared wavelength is generally accepted to have its shortest wavelength at 750nm and extends up to about 1 millimeter. This range is named "NIR" or "near infrared".

The Hoya R72 filter blocks energy below 720nm, and even then, allows a slight bit below that wavelength. The transmittance spectrum of the Hoya R72 is buried pretty deep on their websites. Even at 750nm, the Hoya filter only passes about 40% of the energy it senses. The rest is blocked.

The Hoya RM90 filter is a much better filter for infrared work, but it is so expensive that none of use are going to get one.

So, your statement that infrared energy is in the red portion of the spectrum is incorrect. The best you can say is that they are adjacent bands and that the Hoya R72 filter passes a very minor amount of red visible light, and that is why the images appear dark reddish. All blue and green light is absolutely blocked by the filter.

Does this make sense?
You are correct. I should probably say that "since infrared is near the red portion of the visable light spectrum, the CCD sensor records the shot so it appears red when we view it after processing by the camera." Is that better?
05-05-2007, 05:55 PM   #6
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QuoteOriginally posted by xs400 Quote
You are correct. I should probably say that "since infrared is near the red portion of the visable light spectrum, the CCD sensor records the shot so it appears red when we view it after processing by the camera." Is that better?
If it were me, and it isn't, I would just add one word, as such:

since infrared wavelengths are near the red portion of the visible light spectrum, the CCD sensor records the shot so it appears red when we view it after processing by the camera.

or

since infrared band is near the red portion of the visible light spectrum, the CCD sensor records the shot so it appears red when we view it after processing by the camera.

(note: it is "visible", not "visable")
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