If you've just received your first full spectrum camera and taken it outside for a test shot, there's a good chance you were greeted with an image that looks nothing like what you expected — a strong red, magenta, or orange cast over everything, with colours that look completely wrong. Don't panic. This is entirely normal, and it's actually a sign that your conversion has worked perfectly. Here's why it happens and what to do about it.
Why the Colour Cast Happens
A standard camera has an infrared cut filter (hot mirror) placed in front of the sensor. This filter blocks near-infrared light, which the sensor would otherwise detect. Without it, images look normal to our eyes because the sensor is only receiving the same visible light wavelengths that we see.
When that filter is removed during a full spectrum conversion, the sensor is suddenly receiving a much broader range of light — including near-infrared wavelengths that were previously blocked. In daylight, there is a significant amount of near-infrared light present (sunlight contains a great deal of it), and the sensor picks all of it up.
The problem is that the camera's colour channels — red, green, and blue — respond differently to infrared light. The red channel in particular is highly sensitive to near-infrared wavelengths, which causes it to become overloaded relative to the green and blue channels. The result is a strong red or magenta cast across the entire image.
In short: the colour cast is caused by infrared light contaminating your image, and it's a direct consequence of the conversion working exactly as intended.
The Solution: Use the Right Filter
The colour cast is not a problem with your camera — it's a reminder that a full spectrum camera is a tool that requires the right filter for the right job. For a complete guide to which filters you need and what each one does, read: Essential Filters for a Full Spectrum Camera.
For Standard Colour Photography
Attach an IR cut filter (also called a hot mirror filter) to your lens. This filter blocks infrared light, restoring the camera to standard behaviour. With an IR cut filter in place, your full spectrum camera will produce normal-looking colour images, just like any standard camera. Not all IR cut filters are equal — read our guide on choosing the right IR cut filter to make sure you get the best results.
For Infrared Photography
The colour cast you're seeing is actually the raw material for infrared photography. Attach an infrared filter — such as a 590nm, 680nm, 720nm, or 850nm filter — and the camera will produce infrared images with the characteristic glowing foliage and dark skies that make IR photography so distinctive. The stronger the filter (higher nm value), the more infrared-dominant the image will be.
With a 590nm or 680nm filter, you'll still have some colour information to work with, which can be manipulated in post-processing to create false-colour effects. With a 720nm or 850nm filter, the image will be predominantly monochromatic and ideal for black and white infrared conversion.
For UV Photography
Attach a UV pass filter, which blocks visible and infrared light and allows only ultraviolet wavelengths through. UV images have their own distinctive look and require a UV light source, but the colour cast from unfiltered shooting is not relevant here — the UV filter takes care of it.
Can You Fix the Colour Cast in Post-Processing?
To some extent, yes — but it's not ideal. You can use the white balance tool in Lightroom, Capture One, or any other raw processing software to shift the colour balance and reduce the cast. However, because the infrared contamination affects the colour channels unevenly, a simple white balance adjustment rarely produces a fully natural-looking result. For consistent, high-quality results, using the correct filter is always the better approach.
Setting a Custom White Balance
If you're shooting infrared and want to reduce the colour cast in-camera for a more workable starting point, you can set a custom white balance by pointing the camera at a patch of green grass or foliage in bright sunlight and using that as your white balance reference. For a detailed guide to this process, read: White Balance and Exposure Settings for Infrared Photography.
Summary
A colour cast on a full spectrum camera is completely normal and expected. It's caused by near-infrared light reaching the sensor without the original IR cut filter to block it. The solution is straightforward: use an IR cut filter for standard colour photography, or use an appropriate infrared or UV filter for specialist imaging. A full spectrum camera without a filter is like a paintbrush without paint — the tool is ready, but it needs the right medium to produce the result you're after.
If you're unsure which filters to start with, take a look at our guide to essential filters for full spectrum cameras, or get in touch and we'll help you put together the right kit for your needs.