Contents
- Index
Readout Modes
Some cameras support multiple readout modes. Maxim version 5 has been adding support for these multiple readout modes and CCDAutoPilot allows selecting appropriate readout modes for focusing, plate solving, light, dark and flat frames independently on the appropriate CCDAutoPilot pages. (This feature is not supported currently by CCDSoft.) Choosing the appropriate readout mode can be most helpful in optimizing session efficiency.
For example, some large format cameras suffer from residual bulk imaging, RBI, in which ghosts of previously exposed bright stars or objects appear in successive frames. Some manufacturers, notably Apogee and FLI, have developed techniques to reduce or eliminate RBI. However, these techniques can add significant time, 5 to 20 sec. or so, to the expose/download process and there are some cases where RBI elimination is not needed. For example, focusing consists of a number of generally short exposures. With a 5 - 20 sec. RBI elimination process, which is not necessary for focusing, focusing will be significantly longer. CCDAutoPilot gives you the capability to choose when to use such RBI elimination techniques and when not to.
For your light frames, where you want the highest quality, RBI elimination should be activated. For the corresponding dark frames, it should be activated as well. However, for focusing and plate solve exposures, you want things to move fast and RBI elimination can be deactivated. Similarly if you are taking sky flats, the twilight interval is relatively brief. Here RBI is much less of an issue and RBI elimination can be deactivated here to maximize the number of twilight exposures. Of course, when bias-subtracting your sky flats, you should use a master bias frame created from a number of bias frames with RBI elimination disabled.
If your camera supports it then, here are some recommendations:
Apogee cameras: Use Monochrome (Preflash) for best quality light and dark frames; use Monochrome for plate solving, focusing and sky flats.
FLI cameras: Use Normal for best quality light frames and dark frames. Use Fast for plate solving, focusing and sky flats.
Reminder: If you follow these recommendations, be sure to use a master bias for flat calibration using the same readout mode as the flat frames themselves.