Why IRND filters are so important
For natural and smooth looking motion
In video shooting, it is fundamental to keep the shutter speed fitting the frame rate setting, that is, to keep it equal to double the frame rate for optimal results. This is because, unlike still photography, an excessively fast shutter speed may create a jarring effect and produce afterimages that will not look good at all in the final video.
As you can see from the image below, unlike still image, video clip is made of a sequence of still images. With low shutter speed, each still image will blur but will look smooth in the video sequence. On the contrary, a higher shutter speed will capture the object solid and sharp, but once in a video sequence all objects will appear separated, creating jarring and unnatural looking motion.
By using IRND filters, the shutter speed can be adjusted to the proper value to get that natural and smooth looking motion requested in video footages, as shown in the image below.
For optimal exposure and resolution
Drones are mostly used outdoors in daytime, high-lit environments. In these light conditions, as ISO setting should be fixed at the minimum level of ISO100, setting the aperture remains the only way to adjust exposure and thus avoid overexposed images.
When shooting videos in high-lit environments high above the ground and with related to frame rate shutter speed, you will need IRND filters to obtain the optimal aperture.
The image below shows the difference between an overexposed video footage and a video shot with appropriate aperture setting during a sunny day in a snowy mountain area.
Also, without IRND filters, any f/11 and upward aperture value will cause diffraction effects that will generally reduce the overall resolution of the image. It can be particularly experienced when shooting in 4K mode. Extremely close aperture may also create unwanted flares and ghosts on the image, as shown below.
High-quality IRND filters are required to be extremely and accurately neutral to prevent color shift or IR pollution from affecting the final image.
Accurate neutrality of Kenko IRND filters is achieved by adopting Accu-ND Technology that is exclusively developed for DSLR camera filters. Accu-ND Technology provides constant and fine-adjusted light density within a wide spectrum range, including the infrared area (400nm-1000nm)