This is a description of how I capture and adjust infrared images using a digital camera. I know there are other ways to accomplish this, and I know many people adjust images differently to suit their taste. I am providing this as a simple tutorial on the basics of how to get a better color than the red image that will come from your camera, or without having to save as a black & white image.
Note: you can easily take infrared images hand held with a camera that has been converted to only take infrared photographs. If you decide to spend a lot of time shooting infrared, you can purchase a camera that has had the conversion (removal of the infrared blocking filter in front of the sensor), or you can send a camera in to have the conversion done. Many places will do the conversion for less than $300.
The following information will help you do it for much less. An infrared filter can be purchased for less than $40 and used with your existing equipment.
What is infrared?
Infrared is a light that is beyond the normal light range that we can see with our eyes. The wavelength is longer than visible light, and as such we will need a filter to block the visible light and allow the infrared light to reach the camera sensor. Sometimes it may be called “near infrared” to differentiate from the “far infrared” spectrum that is used for thermal imaging.
What you will need to take a digital infrared image…
A Digital Camera that allows a strong infrared signal to reach the sensor – For my infrared shots I use an older model Pentax K100d.
An Infrared filter (attaches to any lens) – For my infrared shots I am using a Hoya R72 screw on filter.
A lens that will work for infrared (some lenses will have a hot spot, or an area that will just show up as a bright spot instead of the image you are trying to capture. This happens because of the coating on the lens that was designed for visible light. You may have to search the internet to find a lens that will work with your particular camera) – For my infrared shots, I use the standard kit lens (Pentax 18-55mmm)
Software to convert your image – I am using Photoshop CS5 in this tutorial. You may use any software that will allow you to swap the red & green channel.
A sturdy place to set your camera or a tripod – Using a filter to block the visible light will require longer exposure times to capture an image. A tripod or a sturdy base to hold your camera will be necessary for almost any infrared image taken this way.
Choosing a camera:
All digital cameras are sensitive to infrared light. Because the infrared light can be a problem for image quality on normal, visible light photos, camera manufacturers place a filter in front of the sensor to block infrared light. Some cameras have weaker filters than others, and the weaker the built in infrared filter, the easier it is to get a good infrared image. Newer cameras have much stronger filters built in than older cameras. The stronger the filter is, the longer the exposure necessary for good results.
I use an older Pentax K100d to take infrared images. My newer Pentax K-r has a much stronger filter in place, and I have not been able to
get a satisfactory infrared image even after exposing for several minutes.
You can test your current camera to see if it will work for infrared images by taking a picture of a television remote. Simply take an image of the remote as you are pressing a button (Point the remote at the camera and press on a button). If you can see light was emitted from the remote (a bright spot), then you know infrared will pass through the built in filter on your camera. This doesn’t guarantee a great image, but it does mean you have a camera that will work with this tutorial.
Choosing a filter for your camera
A filter to block the visible light (or most of it), and allow infrared to pass to the camera is the key to taking infrared shots. I am using a filter from Hoya (R72).You can get different filters to allow more or less visible light to pass through, and the number of the filter is an indication of where the cutoff will be in the light spectrum.Wavelengths for photography will basically be between 700 and 900 nm. The Hoya filter I am using has a cutoff at 720 nm.
(Note: the Hoya R72 has been replaced by the RM-72 filter. The RM-72 will work the same for this tutorial, but the older R72 filters can still be found. I picked mine up on ebay for much less than most stores sell the RM-72 for, and other brands will work. I chose the Hoya filter based on so many good reviews, and it is built well enough to last a lifetime.)
The filter will come with threads to attach to your lens, so you will need to know the largest size lens you will be using to pick the correct size.
You may want to purchase a larger ring size, and use step rings to fit smaller lens sizes so you can use it on multiple lenses. The only problem
with buying a larger filter is the price will be much higher for larger glass.
Filters for infrared photography are very dark, as they are designed to block visible light. You will not be able to see through the filter.It will appear black, or possibly very dark red if held up to a light source. Because of this, you will need to compose your shot and then add the filter
when you are ready to take a photo.
Tip: If you have a lens hood, use it. Adding a filter to the front of any lens adds a possibility of flare, ghosting, and reduced contrast.
Setting up to take an infrared photograph
The first step in taking an infrared photograph is choosing a subject that will work in a different light.Bright and direct sun will help to amplify infrared on your subject, and because of this, shots taken in the middle of the day will yield incredible results. Most photographers prefer to capture visible light images during early morning or late evening times to optimize light, color, and shadows. Infrared can be a way to break free from the normal shooting times, and take advantage of light that would seem overly harsh for a normal photograph.
Tip: Contrast between living plants, animals, and hard surfaces or water will add to an infrared image, because of the way the longer wavelength light is absorbed.
After you decide what to take a picture of, you will need to setup your tripod, and camera.A tripod will be needed because a very slow shutter speed is needed to capture enough light as it passes through the filters. Even in the middle of a sunny day, we will need exposures that may be 2 seconds or longer.A hand held image at those speeds will surely be a blurry mess. You do not need to purchase a tripod if you have a good surface to set your camera where it will not move. Placing your camera on a large rock, bench, or ledge will work in many situations as a makeshift tripod. I have even braced against a car for some of my shots. As long as you can keep the camera from moving for a few seconds to take the photograph, you should be fine.
Because you will not be able to see through the filter, you need to compose your shot without the filter installed on your camera. After you have your shot lined up, you can thread the filter onto your lens and take the shot.
Camera Mode
I set the camera to manual mode to take infrared images. In order to adjust the time required for the light to pass through the filters, manual changes need to be easily adjusted. Manual mode allows the aperture, and the shutter speed to be changed quickly.
If your camera allows a choice of RAW images instead of JPG, do it!
RAW will allow you to make far more adjustments to your images, and it will make setting the white balance easier if you don’t get it correct in camera.Trying to adjust a JPG to get the right colors will be much more difficult.
White Balance in Camera
I will start by taking a shot to set the white balance. If your camera allows adjustments for a custom white balance, I recommend you do it. There should be instructions on how to set the white balance in your manual. A custom white balance will make it much easier to adjust you images later. To setup a custom white balance I find it is best to aim the camera at something that will expose brightly, such as grass or trees. After the white balance is adjusted your images will have much less red cast, and will start to look closer to normal – please note they will never be completely normal color with just a white balance adjustment so don’t panic if they are not what you expect.
Time to shoot
I set the aperture to f/8 – f/11 for most landscape shots. This will allow everything in the image to be in focus, and if my focus is slightly off because of the filter I will still have a useable image. You can try to use a larger aperture, but with infrared it becomes very difficult to focus correctly as the aperture increases.
Note: your camera may be able to focus automatically with the filter installed, but for most landscape shots I recommend focusing manually.
Simply turn off the auto focus on your camera, and focus on or near infinity. Every lens is different for infrared, and older lenses have a red
mark on the focus scale to show where it will focus for infrared. You may find that you will need to adjust your focus point a small amount when shooting in infrared. You can either remember how much adjustment you will have to make, or mark your lens after you have found the sweet spot for infrared.
For most mid day shots I will start with a 2 second exposure test shot. This has been a good exposure for my camera in many attempts, but your camera may need much more or much less time to get a good image. After I take a shot I will view the image on the camera to see if the exposure was correct. A histogram is a very easy way to tell if you have exposed correctly. If your camera has a built in histogram, I highly recommend
using it to make adjustments. I will then change the shutter speed if needed to allow a longer or shorter exposure for my next shot.I continue to check each image until I am sure I have a good shot with correct exposure and focus… then I shoot one more just to be safe.
Tip: Because we are dealing with a very dark filter that is blocking visible light, there is a chance for stray light to enter the camera through the
view finder. Covering the view finder during shooting will help prevent some problems such as flare, ghosting, bright spots, overexposure, and lack of contrast in your images.
Adjusting the Image
To adjust the colors so we can have blue skies instead of orange or red, we will need to swap the red and blue colors. This can be done very easily in Photoshop. If you do not have Photoshop, try using the software that came with your camera. Many photo editing programs have the ability to adjust the color channels. Please note, Photoshop Elements is missing the ability to swap color channels in most versions. Newer versions may include this ability; however I have not used any version newer than Elements 8.
Open your image in Photoshop.
Below is an image directly from my camera:
Click on Image > Adjustments > Channel Mixer
With the Red Channel Mixer open,Change the value for Red (from 100 to 0), and the value for Blue (from 0 to 100).
Next – Change the Output Channel from Red to Blue
With the Blue Channel Mixer open,Change the value for Red (from 0 to 100), and the value for Blue (from 100 to 0).
Then click on OK.
This should change your image from a red/orange color to a blue shade.
Below is my image after swapping the red and blue channels:
Normally I then use:
Image > Auto Tone
Image > Auto Contrast
Image > Auto Color
After these auto corrections are done, I will make final adjustments using curves, adjust contrast, and sharpen my image. If the image is adjusted the way you want, save it as a JPG to share or print and you are done.
Compare the Infrared image above to an image of the same scene taken normally as shown below:
Here is a different scene taken with a normal camera:
And here is an infrared version of the same place:
And here are some more examples of infrared photos that I have taken using this method:
I hope by sharing this, I am able to help you take your own infrared images.
FEB