Photometrics Evolve 512, User Manual

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16 Evolve 512 Users Manual
Bulb Mode
In Bulb mode, exposure time for each frame is determined by the trigger pulse width.
Exposure time entered into the software is ignored in this mode (see Figure 14). If a trigger
arrives during the readout of the previous frame, it is ignored. The Trigger Ready signal
goes high when Read-out has been completed. It then goes low when the Trigger signal is
accepted and exposure is started. The shaded areas
denote the idle time between
exposures. Bulb mode only operates in Non-Overlap mode.
Figure 14. Bulb Mode Timing Diagram
Notes:
1. When the clocking mode is "Alternate Frame Transfer", the camera can be operated in "Overlap" or
"Non-Overlap" mode as explained previously.
2. Trigger-first mode allows overlap or non-overlap modes. In strobe and bulb triggering modes, the
camera can be operated in non-overlap mode only.
Conversion Gain
Apart from multiplication gain, which actually multiplies the number of electrons generated
in each pixel, the Evolve 512 also has three (3) conversion gains. Conversion gain simply
quantifies how the resulting electrons are converted into ADU (Analog-to-Digital units) and
displayed on the display screen.
Typical conversion gains for the readout port are listed later in this chapter. Your camera is
individually calibrated for these gains. So, please refer to the certificate of performance that
accompanied your camera.
Note: As the on-chip multiplication introduces additional noise, it is recommended that the
multiplication be used only as required. For more information, refer to the "On-Chip Multiplication
Gain" technical note. This technical note can be accessed by going to the Photometrics web site at
www.photomet.com, clicking on "Library", clicking on "Technical Notes", and selecting the title from
the list of notes.