The wing beat of honey bees is approximately 230 beats per second. In order to study the wing beat pattern, angle of wings, or even how the bees approach the hive, and interactions between individuals, it is necessary to film at much higher speeds than normal filming (25 pictures or frames per second (fps)), and then play back the footage at 5 or 10 fps in order to study the movements in detail.
Below are two video examples of high-speed footage of bees approaching a hive, which was inside a building wall. These videos were taken by Mad Hornet Entomological Supplies and all copyright and ownership resides with the owner.
As everyone knows, who has watched a beehive, the flight and movement of the bees is so fast that one cannot plan filming, so the camera was simply triggered when it looked busy, and the below footage resulted. The grainy appearance of some of the video is a result of compressing the files to save space (800x600 pixels = ±0.5MB per frame x 1200fps = 600MB/second.
Video taken at 1000fps, resolution 800x600 pixels. Note the video size is 2.5MB. As can be seen in the video, even filming at 1000fps the wingbeat is too fast to be able to gain good and effective footage of it. Here, likely double that speed is needed. Also, light levels were quite low, which means that the exposure was too low, allowing motion blur.
Video taken at 1000fps, resolution 800x600 pixels. Note the video size is 17MB. As can be seen in the video, even filming at 1200fps the wingbeat, although better than the first video is still too fast. Here, likely double that speed is needed. In this video, a lot of supplmentary light was added (2.5kW) which allowed a much lower exposure time (shutter speed). However, improvements could still be done in this footage.
It is however, very clear and visible footage, which allows a very good appraisal of bee actions and interactions as they approach the vertical entrance to the hive.
As can be seen in the interactions, it appears like most bees wanted to have some sort of better surface to land on, rather than having to flare and try and catch hold of the wall. However the bees already on the wall clearly objected to this, and actively defended themselves.
Thermal High-Speed & Resolution
Thermal high-speed and high-resolution filming is a lot less common that visual filming. The main reason being that the IR sensors used are further behind in technology, however the field is advancing quickly. Speeds of up to 3000fps at 320x256 pixels, and even 100 000fps at 64x4 pixels are now possible. Furthermore, resolutions of 2048x2048 are possible, allowing incredible detail. It may be questioned why thermal imaging would be needed in entomology, watching the video below will give some insight into that.
This video, taken at 1280x1024 pixels shows the great detail that can be seen from a high-resolution thermal image. The contrast in temperature between the snake nose area and tongue and the rest of the body is clearly visible there. Even the scale pattern in the body is nicely visible. The appearance of the ant on the right side of the clip shows up incredibly clearly. Despite the tiny size of the ant, in comparison to the snake, good detail can be seen. The ant also highlights why thermal imagers can give good footage and data - the thermal difference between the organism and the background allows fine detail to stand out.
Depending on what, as well as where, one is filming, different accessories may be required. Typical for high-speed filming additional light is required. As such high frame rates are used, the shutter speed (exposure time) ends up being very quick, due to the physics of high-speed filming (1000 fps, means there is an absolute maximum possible of 1000 milliseconds per frame), as well as wanting VERY short exposure times to reduce motion blur in fast moving subjects.
Incandescent lighting is the easiest to obtain, for very bright lights, but the heat generated tends to be detrimental to both subjects as well as camera people. Therefore LED lighting is becoming more popular. As a rule of thumb in high-speed filming - you can NEVER have too much light. Any experimental filming set up therefore needs to consider lighting even if outdoors, but most certainly if in the laboratory. The stands and clamps required for lighting can take up space, so this should be considered when setting up an experimental scene.
Most times it is desirable to have the insect subject able to act at least semi-naturally - i.e. if filming walking, it needs to have space to walk around. So an arena or stage needs to be prepared, which not only allows it to move about, but also prevents it escaping, but also does not create too many reflections, hot spots, shadows and obstructions for the camera. Insect flight can be easier, using a tether. However the very shallow depth of field when filming can tend to create issues if the insect can fly towards or away from the lens, starting from a central point.