Subject:
A Clear Cleaner Shrimp (Urocaridella antonbruunii) is swimming from one client Moray Eel to another. These little shrimps belong to the Palaemonidae family and are known to act as cleaners, feeding on external parasites, copepods, and mucus from client fish, mainly moray eels. Sometimes they also feed on microorganisms and debris that they collect on the seafloor.
The swimming legs (pleopods) situated under the abdomen move rapidly to propel the shrimp towards the client fish, while the walking legs (pereiopods) loosely hang under the carapace, giving the shrimp the appearance of levitating in the water column.
The pleopods are also used to keep the shrimp's eggs in place under the abdomen. These little shrimps (approximately 3cm/1.2 inches) use their tail fan just like the rudder and elevators on an airplane's tail to steer.
Unlike most species of cleaning shrimp that have white antennae, Clear Cleaner Shrimp have long and transparent antennae, and they are characterised by red and white banded walking legs (pereiopods).
These little translucent shrimps inhabit overhangs, nooks, and crevices. They often aggregate in large numbers, hovering like a bee swarm in front of cleaning stations and moray eel's hideouts.
Technique:
Filming small, frantic moving animals is quite difficult. The trick is not to film them from too close, allowing them the freedom to move around. In post-production, it is easy to zoom in on the subject and keep it centred as much as possible using keyframes. Unfortunately, this trick is only applicable if you film in a higher resolution (e.g., 4K or higher) than the one used for the finished product (e.g., 1080 HD).
Another challenge can be achieving focus on the little critter. These shrimp are small and quite transparent, making it difficult for the camera to detect a subject to focus on. You can counter this by combining the manual and automatic focus of your camera. First, set your camera to manual focus. Once the shrimp is in focus, you can switch to automatic focus, allowing the camera to track and adjust the focus as the shrimp moves within the water column.
However, there are a few factors to consider:
Depth of Field: When filming underwater, the depth of field tends to be shallower compared to shooting in air. This means that even with autofocus, the camera may struggle to maintain sharp focus on the shrimp if it moves too far forward or backward within the water column. However, you can counter this by adjusting the position of your underwater camera slightly forward or backward, attempting to keep the distance between your subject and camera constant.
Autofocus Speed: The speed and accuracy of autofocus systems can vary between camera models. Some cameras have advanced autofocus systems that can effectively track subjects, while others may struggle.
Environmental Factors: Underwater conditions can be complex, with varying water clarity, debris, and other factors that can affect autofocus performance. These factors may impact the camera's ability to accurately track the shrimp's movements.
Another great tool to determine if your subject is in focus underwater is the peaking tool. This built-in camera tool will overlay all parts of your image in your viewfinder or on your screen that are in focus, appearing red (in some cameras, the colour of the overlay can be chosen).
For another post about the Clear Cleaner Shrimp go to post 137 or click following link https://www.beyondscuba.com/post/a-few-too-many-clear-cleaner-shrimps-urocaridella-antonbruunii
and post 142 or click https://www.beyondscuba.com/post/sharing-a-toothbrush
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