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I'm new to IR photography. I'm trying to get the white colour out of green plants (leafs, grass etc.).

Here is my setup:

  • Canon EOS 100D full spectrum - IR filter in front of sensor removed
  • Samyang 24mm f/1.4
  • Zomei 680 nm IR filter

I'm using Digital Photo Professional 4 to set the white balance.

Below a photo where white balance is set on the green colour of plants.

White balance set on green colour of plants

The second photo white balance is set on a white sheet of paper.

White balance set on a white sheet of paper

Am I missing something? Why I'm not getting the white colour like on all of the photos on the internet?

I don't have any experience in post-processing and I do not own Photoshop or Lightroom so if there is something else I should edit in the RAW files please suggest what software I should use.

Is there something else in the camera or lens that might be blocking the IR light?

Here is a link to RAW file of the above photos: RAW photo

EDIT: I did a small experiment. I used a filter that was removed from my camera which should block all IR light. I did two photos: with and without the 680 nm filter. So in theory the camera filter should be completely black when taking a photo with 680 nm filter which blocks all visible light. Here is the result:

visible infrared

As you can see the camera filter is not completely dark so either the 680 nm filter is passing some visible light or the camera filter is passing the infrared light (or a mix of theese two?).

Can that cause the plants being not white in the IR photos? Maybe I should try a deeper infrared filter like 850 nm or 950 nm?

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Ok guys, here is an answer. It turns out that the weak point of my IR photography setup is... Zomei IR filter. I bought a high quality Hoya R72 (720 nm) infrared filter. I was shocked by the result.

  • The first photo is made using the Hoya filter. White balance set on green leaves.
  • The second photo is made using Zomei filter with exactly the same
    settings (exposure, ISO, aperture, white balance) as the first photo.
  • The third photo is made using Zomei filter, changed exposure time and adjusted focus slightly, rest of the parameters unchanged.
  • The fourth photo is made using Zomei filter, exposure slightly
    changed, white balance set on a green colour.

There was no post processing of any kind made to these photos except setting the white balance.

I do not know where all of these good reviews about Zomei filters come from. For me the filter I received from Zomei is totally useless in terms of infrared photography.

I hope my investigation will help others.

Hoya Zomei same Zomei Zomei WB

  • Isn't your original filter 680 nm? This one is 720 nm. I don't really have experience with IR, but maybe it's not that the Zoya filter is bad, it's just that it's a different filter? – relatively_random Sep 21 '18 at 8:47
  • The most characteristic thing in IR photography is that green plants reflect large amounts of infrared light which is visible on photos as white, snow-like colour. Here with the 680 nm filter there is no sign of white colour, only dark grey or even black - see the last photo where white balance is correctly set. The 680 nm filter, as oppose to 720 nm, should only add some more colours in the background (sky, buildings etc.) but trees, grass and other plants should always be very bright. – Luke Sep 21 '18 at 9:12
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You're not missing anything - some epic post production is pretty much always used to create digital IR images.

Life Pixel is a company that does conversions, but they've also put together an extensive list of video How-To's for post.

To boil it down, you need to use a program like Photoshop or Gimp and get familiar with the channel mixer. When converting to black and white using this tool, you get to select which color channels map to the brightness of the black and white. This allows you to select which colors become white and which colors become black, and every shade in between.

There are other ways, of course, as there always are with post. But, this should get you started.

  • Thanks for an answer, have a look at my edit above. I know post processing can make a huge difference but even without it the plants that reflect a lot of IR light should be brighter with 680 nm filter on, here I cannot see any increase in brightnes of leafs on the trees (grass on my photo seems a bit brighter but it is due to fact that it's dry and in visible light it has light brown colour). – Luke Sep 15 '18 at 22:18
  • @Luke sorry i didn't catch the filter before. Visible light goes up to 700nm. So, yes, you need a new IR filter that blocks at least up to 700nm. – Hueco Sep 15 '18 at 23:11
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I've used a few cameras with the hot filter removed, including a Canon DSLR. In your case, the problem is twofold:

  • On Canon DSLRs, the sensor stack seems to be somewhat insensitive to IR. There is likely an element on the sensor stack (other than the hot mirror) that blocks a significant amount of IR. I suspect the Bayer filter.

  • You are using a 680nm filter which lets red and orange light through. You will need to use a high-quality 720nm filter that does not let visible light through, so that the IR-insensitive sensor is not distracted by it. The less visible light, the more monochromatic the image will be. If too much visible light is allowed through, the filter will behave like a deep-red filter and foliage will not be bright.

    good filter

You'll get best results by using in-camera white balance.

  • For IR, use something that reflects pretty much everything, like concrete pavement. Then swap the red and blue channels in post for faux-color IR with golden-colored leaves.

    pavement WB RB channel swap

  • You can get a different look by setting white balance on grass or other foliage.

    foliage WB

  • For visible light, any white surface should work fine. No need to use a hot filter because the filter stack is already so insensitive to IR.

Other suggestions:

  • Use Live-View mode for both focus and exposure when capturing IR images.

  • Use manual focus and focus bracketing because autofocus doesn't have enough light to work with through near-IR filters.

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