More On Ccd Binning; Demo Images - Lacerta M-GEN User Manual

6 More on CCD binning

Hereby I try to describe the hardware binning operation modes of the Camera. The
following modes can be selected:
The default is 1×1, used in the older Firmwares.
Note that the guiding window is constant 48×48 pixels, for example at 6×6 binning mode
the guiding window covers half of the available vertical area (48 out of 97 pixels). You can
see the guiding window sizes on the LiveView screen when selecting the guiding window.
As the pixel size 'grows' (one binned pixel) so do the other parameters. The thermal dark
current is multiplied with the binning block size (N×N) but the total sensitivity of the binned
pixel changes the same way. There is some 'amp glow' (at left top) due to the CCD
construction, You could see this in LiveView with long exposure time. This also increases
with the binning as a part of the increased sensitivity. The left top area of the CCD may be not
used if the glow seems to be too hard. We are planning some software compensation to this
effect.
Due to the increased horizontal transfer time (binned pixel), the readout noise grows some
with the binning size. My measures showed less than +40% for the 6×6 mode so the read
noise is still below 10 electrons for most of the Camera instances in any modes.
Using binning modes is advised for extreme long (above ~1.5m) focal length guiding
scopes or optics. Use binning only if Your guiding star is way too fast moving and has a
'large spot'. Don't use it for short focal length guide scopes because it may only make the
guiding accuracy become worse!

6.1 Demo images

The common setup and settings:
 LMG Camera @ gain 5 (11 e
 Objective: Canon EFS 18-55 @ 22mm (f/4.2 approx.)
 Filters: Baader UV/IR block + 30% polarizer + 30% neutral
 Light condition: 40W bulb 2 metres to the objects
Binning
CCD area
mode
1 × 1 752 × 582
2 × 2 376 × 291
4 × 4 188 × 145
6 × 6 125 × 97
- /ADU)
Binned pixel size
(um)
4.85 × 4.65
9.7 × 9.3
19.4 × 18.6
29.1 × 27.9
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