• The ZWO ASI120MM Mini Monochrome Astronomy Camera is one of their most popular guiding and planetary cameras due to its reasonable price and advantages for guiding.
• Uses the AR013CS 1/3" CMOS sensor with a 1.2mp (1280x960) resolution and 3.75µm pixel size.
• Compatible with USB 2.0 interface.
• Quantum efficiency is almost 80% which is more than sufficient for most guiding purposes.
• Analog to Digital Conversion A/D is 12-bit, enough to accommodate and pinpoint different levels of brightness for each pixel without loss of data.
• Read noise of 4.0e, low enough to detect signal difference enough to guide properly.

Quantum efficiency is the blueprint of the effectiveness of any sensor and is one of the most important factors in determining its effectiveness for image capture. It reveals how much of the photons that hit the sensor are then converted into electrons. In the case of the ZWO ASI120MM Mini Monochrome Astronomy Camera, measurements have shown a near 80% QE peak which is remarkable for a guide camera.

While quantum efficiency measures how effective a sensor is at converting photons to electronics, that is only the first part of the equation. The full well capacity is what determines the amount of charge that can be accommodated within each pixel before any saturation may occur. Why is this important? If pixels cannot accommodate any more charge, the signal becomes degenerated, and the sensor cannot process accordingly. The ZWO ASI120 Mini Monochrome Astronomy Camera has a measured full well capacity of 13,000e which is perfectly in line with the amount of signal a guiding camera would need to pickup.