Notes:
In general, the higher the spatial resolution and the lower the frame rate, the greater is the
maximum possible light sensitivity of the camera. This is because with higher resolution
comes more rows of pixels and it takes longer for the rolling shutter to read through all
those rows of pixels before getting back to the first row meaning exposure interval for all
rows is longer. Also, the lower the frame rate, the longer interval between frames which
allows each frame to expose for longer.
This has the consequence that for the best low light level imaging, the camera cannot
record fast moving objects clearly (they will appear as a streak across the field of view if
detected).
The ‘
Max. FPS
’ shown in table 3.3 are the maximum possible frame rates achievable
under ideal conditions of adequate illumination, fastest exposure settings and a good
clear USB 2.0 connection to a computer with sufficient processing speed, read-write
speed and memory capacity. The actually achieved frame rate may be slower due to
limitations in any of the above factors such as a shared or busy USB 2.0 hub, slow,
delayed or queued processing by the host computer, low light levels resulting in longer
frame exposure times, etc.
3D Printed housing
The sensor chip and interface board are set in a 3D printed enclosure made with PLA
filament and designed to enable adjustable mounting of the camera on a variety of
eyepieces or on a standard tripod and to provide heat sink passive cooling for the sensor
chip and interface board. The casing is made with an Ender 3 FDM 3D printer.
Heat sink enclosure
The camera chip can get very hot especially when streaming large format images. If this
heat is not effectively dissipated it can cause malfunction of the camera. Also, the hotter
the sensor chip, the more dark current noise is present in the image signal which
adversely affects the ability to capture high quality images at low light levels.
For all these reasons the camera housing is specially designed with carefully placed vent
holes as well as an internal aluminium and steel passive double heat sink system what is
directly applied to the back of the sensor chip module (see figure 3.8). Part of the heat
sink foil is directly applied to the back of the casing over some of the vent holes to radiate
heat directly up through these holes and be cooled by air currents entering from the other
holes. The free holes allow circulation of air within the housing to cool both the sensor chip
and the interface board components.
OptArc AF51 Camera Page 34 of 99 User Guide v1.02
