How to Focus Infrared Photography
Making infrared photography, especially for beginners, can be quite a difficult task, that’s why we are here today to explain how to focus infrared photography. This article will help you get the most out of your camera and get the best possible infrared photo.
To learn more and educate yourself about infrared photography, we would recommend our articles Complete Guide to Digital Infrared Photography, Camera Settings for Infrared Photography or where this method of photography is described in detail. So now, let’s find out how to focus infrared photography without further ado.
- Focusing Infrared Photography
- „R“ – Red Dot Mark for Infrared Photography
- How to Focus Infrared Photography – Problems
- Why is focusing important in infrared photography?
- How does infrared light affect focusing?
- Can I use autofocus for infrared photography?
- How can I achieve manual focus in infrared photography?
- Are there any specific focusing techniques for infrared photography?
- Are there any recommended lenses for infrared photography?
- Can I use autofocus lenses with infrared filters for infrared photography?
- Are there any infrared-specific focusing aids available?
- How can post-processing software help with focus in infrared photography?
Focusing Infrared Photography
DSLR stands for “Digital Single Lens Reflex”. This phrase would mean that it is a digital camera that uses a mirror system to reflect light from the lens to the optical device, that is, by moving the mirror during the exposure, it allows light to pass directly to the sensor. This “single l
If in infrared photography the lens is pointed at infinity in visible light, then in the infrared range it will be pointed a little closer, and front focus will appear. This can be considered a certain type of error, but there is also a good side to this error – the lens is stable and it is enough to turn the focus ring at a certain angle. This is exactly why many lenses have an additional red R mark. To focus correctly in infrared, you must first focus on visible light and then turn the focus ring to the R mark. With modern lenses, this mark is quite rare, and for zoom lenses, its position depends on the focal length.
Therefore, you should not particularly trust the usual phase autofocus of SLR cameras. You can work around the problem by using Live View and hovering over the contrast or manually focusing by controlling the sharpness of the screen. If the camera does not have Live View, then you can simply open the lens wider and thus hide the focus error in the depth of field.
On lenses with a fixed focal length, you can set this mark yourself by taking a few shots and choosing the position with maximum sharpness. The position of this mark does not depend on the focus distance and aperture, so it is enough to draw it once and use this correction in the future.
„R“ – Red Dot Mark for Infrared Photography
Most camera lenses have an “R” word or Red Dot, which represents the focus mark for infrared light. Infrared light of a wavelength, through a camera lens, has a refractive index smaller than visible light, so that it forms a central point behind the normal point of the field of view. In normal mode, the focus is first adjusted and then rotated slightly forward to match the “R” point, and if the object is far away you can freely ignore that point and just focusing to get an infrared photo is much more convenient.
How to Focus Infrared Photography – Problems
As lenses and cameras are primarily intended for photographing the visible part of the spectrum, IR light is refracted somewhat differently in the lens, which leads to photos being slightly out of focus. Older lenses solved this by having a special red dot to focus on for IR photography.
Of course, not all new lenses have this, but if you primarily focus on landscape photography with ultra-wide lenses where the depth of field is huge anyway, it probably never bothered you too much.
However, if you want to use lenses with longer focal lengths and larger apertures, you will have to adjust the distance between the lens and the sensor. Fortunately, new generations of digital cameras have brought the possibility to adjust the lens ourselves and have our photos properly focused. Note that this is a distance change of about 0.15mm for 50mm lenses.
Today we talked about How to Focus Infrared Photography, where we highlighted the most important focusing factors that affect the quality of your infrared photography, but we also mentioned some of the problems when focusing on infrared photography.
Although invisible to our eyes, infrared light has some similar characteristics to visible light: it can be focused and reflected and, like visible light, it can be polarized. As far as focusing is concerned, it should be noted that most lenses cannot focus on infrared radiation like visible radiation.
That is why it is necessary to shift the focus. The smaller the lens opening and the larger the focal length, the greater the focus shift. Some manufacturers mark the infrared range on the lenses for easier navigation and shooting. Sharpening (focusing) is best done in the following way, mainly for the reason that practically nothing can be seen through the infrared filter: determine the composition of the image without a filter, then apply the filter, and finally perform manual focusing.
Why is focusing important in infrared photography?
Knowing how to focus infrared photography is crucial knowing that infrared light behaves differently from visible light. Since infrared light has a longer wavelength, it does not align perfectly with the camera’s autofocus system designed for visible light. Achieving accurate focus ensures that your subject appears sharp and detailed in the final image.
How does infrared light affect focusing?
Infrared light has a longer wavelength than visible light, which means that it focuses at a different distance. This can cause a discrepancy between the focus position for infrared light and visible light. Consequently, when shooting infrared, you may need to adjust the focus manually to compensate for this difference.
Can I use autofocus for infrared photography?
Autofocus systems in most cameras are primarily designed for visible light photography and may not work accurately for infrared. The camera’s autofocus sensor relies on visible light to determine focus, so it might struggle or produce inconsistent results when focusing in infrared. Manual focus is generally recommended for achieving precise focus in infrared photography.
How can I achieve manual focus in infrared photography?
To achieve manual focus in infrared photography, follow these steps:
- Set your camera to manual focus mode.
- Use Live View mode if available, as it provides a real-time preview of the scene.
- Look for high-contrast areas in the scene, such as edges or textures.
- Gradually adjust the focus ring on your lens while observing the changes on the LCD or electronic viewfinder.
- Fine-tune the focus until the desired area appears sharp.
Are there any specific focusing techniques for infrared photography?
Yes, there are a few techniques that can help improve focus accuracy in infrared photography:
Focus Bracketing: Take multiple shots with slight focus adjustments to ensure at least one image is perfectly focused.
Hyperfocal Distance: Calculate the hyperfocal distance for your lens and aperture settings to maximize depth of field and keep most of the scene in focus.
Trial and Error: Experiment with different focus positions and review the results on a larger screen to determine the optimal focus for your specific camera and lens combination.
Are there any recommended lenses for infrared photography?
Infrared photography does not require specific lenses, but some lenses may perform better than others due to their coatings and construction. Generally, prime lenses (fixed focal length) tend to produce sharper infrared images compared to zoom lenses. It’s advisable to test your existing lenses to see how they perform in infrared, as results can vary.
Can I use autofocus lenses with infrared filters for infrared photography?
Yes, you can use autofocus lenses with infrared filters. However, keep in mind that autofocus may not work accurately in infrared, as mentioned earlier. It’s best to switch to manual focus mode and follow the steps outlined earlier to achieve precise focus in infrared photography.
Are there any infrared-specific focusing aids available?
While there are no infrared-specific focusing aids, you can use some general techniques to assist with focusing. For example, using a magnifying viewfinder or focus peaking (if available on your camera) can help identify areas of sharp focus. Additionally, some photographers find it useful to use an infrared conversion service to modify their camera specifically for infrared photography, which may improve focusing accuracy.
How can post-processing software help with focus in infrared photography?
Post-processing software can be useful for refining focus in infrared photography. If you notice minor focus issues in your images, you can utilize software tools such as Adobe Photoshop or Lightroom to apply selective sharpening or increase clarity to enhance the apparent sharpness of your subject. These tools allow you to make precise adjustments to specific areas of the image, helping to bring out the details and improve overall focus.
Additionally, post-processing software offers the ability to crop and reframe your image, which can be particularly useful if the initial focus was slightly off. By cropping strategically, you can eliminate any out-of-focus elements and emphasize the properly focused areas, giving the impression of a sharper image.