Many years ago Kodak made colour infrared (CIR) film called Aerochrome III that was sensitive to the colour spectrum and infrared light. It was originally designed for aerial surveillance to filter people who were trying to camouflage themselves in the woods. With the right filter colour, you can filter out a spectrum of colour which yields these red/magenta colours; the healthier the vegetation, the more vibrant the colours.
Due to how it rendered the world differently with grass and other vegetation taking on pink or red hues creative photographers found a love for its unique rendering but the film has been discontinued from production for many years. Any stock of the film is expired and depending how it was stored may produce some undesirable colour shifts. However there are alternative solutions to achieving the desired Aerochrome affect without sourcing & processing the film and of course the best advice from me, the Foveon wizard, would be to use a SIGMA camera! Let me explain why:
One of the things that make SIGMA’s interchangeable lens cameras so unique is the ability by the user to remove the Infrared (hot mirror) filter in the camera.
This allows the ability to capture the full spectrum of light or with the use of additional filters, Infrared only. Kolari Vision, a company who specializes in Infrared or full spectrum conversions for digital cameras now offer an IR chrome lens filter which is designed to emulate Kodak Aerochrome III when used with a full spectrum Bayer sensor. So I wondered how well this new filter would work on a SIGMA Foveon sensor camera, if it would emulate the look of the old Aerochrome III film and decided to test it for myself.
The first step in my test was to find a reference scene to capture my comparison images of normal, full spectrum, IR only and finally IR Chrome. These images would be used to compare the differences and get a better understanding of how the filter worked so I decided to use the Luggie River as my reference image and captured these frames.
There is a noticeable difference between each frame with increased brightness of the dark green vegetation that occurs after the IR filter is removed. The chlorophyll in plants reflects infrared light and makes the colours more vibrant. You get some interesting black and whites images without the normal infrared filter in place which are either too red or pink. The Kolari Vision filter tends to keep the brightness of the infrared light while also allowing blue into the water and sky almost giving an alien world feeling to the image. I then tweaked the image in Sigma Photo Pro and the removed the power line in Photoshop to achieve the below image.
It’s an unusual look to a landscape image; the dark healthy foliage is now a vibrant red, there’s a distinct visible difference of the trees that have moss growing on them compared to those that don’t, plus the deep blue water really helps to make it stand out.
Next up on my list was to take some close up images of vegetation to see how they rendered as not all parts of the plant will turn pink or red. This image of the flower below shows the petals are white and remained somewhat normal with the filter but notice the orange hues going into the flower stem and the pink leaves looking almost transparent in places.
It produces a very creative, artist image of the flower so I decided to try the filter on my African grey parrot which is mostly monochrome herself. She looks almost normal with the white, blue, black and grey in all the right places but with a little more red in the eye area. However the bright red part that appears under her in the image and reflects some red is actually the arm of my sofa which is black. It obviously reflects a lot of infrared light making it appear such a vibrant red which is intriguing. It seems most grey and black fabrics respond the same way yet black paint or plastics stay black.
I noticed also with the SIGMA Foveon sensor that the pink/red hues are very strong leading me to believe that this sensor is more sensitive to infrared than what the Kolari Vision filter is designed for. It is after all tuned for Bayer sensors but playing around with some of the settings in Sigma Photo Pro I’ve found that the Cinema colour mode (also available on the camera) helps to bring everything down a notch and I can get results like this;
The ball is still yellow/green and the houses in the background are almost normal in colour. The grass is now a muted pink hue instead of bright red which I feel suits this image better. From what I have seen when searching the web for Kodak Aerochrome III images, the look can depend on how it was processed but the results I received with this setting seems to be similar.
Next I decided to experiment with the filter and camera combination on a scene where almost everything is man-made. My first stop was just outside of Glasgow Central Station and it was interesting to see the mix of colours from the infrared light and the interactions with the different materials of each structure.
Fabrics tend to take on a red or pink hue while rubber, plastics and paint still seem to be black. While none of the colours here are going to be true to their original, the taxi was pretty close to this shade of green.
It is strange to see how some parts of a scene render normal, such as the street or building, while trees and clothing always take on the red hue. Skin tones look normal so I decided to do some portraits of my son who has ginger hair and pale skin to see what results would occur.
James’ black coat is now red and much brighter than it would be otherwise which a consistent rendering of fabric material. While his hair appears more pink and brighter in the image than would be in a normal image.
Overall I really enjoyed using my SIGMA sd Quattro H camera in a new creative way by combining it with a Kolari Vision filter. It let me see the world in a new way with surreal colour differences and I love the versatility of the camera to allow me to try a new creative approach. Of course the Kolari Vision filter is designed for use with a typical full spectrum Bayer camera but I feel it worked really well with the Foveon sensor of the SIGMA sd Quattro H camera. Plus utilizing the options that are available in Sigma Photo Pro or the in-Camera settings really allow you to create really vibrant images that show stark differences between the red and blues such as this image of Saint Mary’s Parish Church.
Or create a much muted tone image that allows the normal and infrared colours to mix well such as this image of the Glasgow Cathedral
The SIGMA Foveon system offers a wide variety of creative opportunities to those who are willing to explore its many possibilities. Pairing it with creative accessories such as the Kolari Vision filter shows how easy it is to replicate the look of Kodak Aerochrome III without the stress of sourcing outdated film and worrying about the proper exposure or processing. A few simple adjustments are all that is needed achieve this desired effect. No wizardry skills required!
All images in this article shot with a combination of the SIGMA sd Quattro H with the SIGMA 18-35mm F1.8 DC HSM | Art or the SIGMA 50-100mm F1.8 DC HSM | Art lens.
You can see more images created by SCA Paul Monaghan on one of the following links: