What's AZ Mode:
It can be roughly observed from the image that there are two rotatable axes: one oriented horizontally, known as the azimuth axis, and the other oriented vertically, referred to as the altitude axis.
The coordinate system defined by rotations along these two axes is the alt-azimuth coordinate system, and the mount constructed based on this principle is the Alt-Az Mount.
What's EQ Mode:
In astronomical observations, another coordinate system is commonly used: the celestial coordinate system.
It is formed by projecting the Earth-centered longitude and latitude coordinates onto the celestial sphere. The mount corresponding to this coordinate system is the Equatorial Mount.
AZ mode VS EQ mode
AZ mode:
Although an Alt-Az mount can track celestial objects by rotating its two axes, the objects themselves do not move along these directions. As a result, both axes must rotate simultaneously during tracking.
During long-exposure imaging, the field will rotate around the frame center, causing field rotation, which can lead to star trailing and other artifacts.
Why EQ mode?
In contrast, an Equatorial Mount mimics the actual motion of celestial objects. Its RA axis (Right Ascension axis) is parallel to the Earth's rotational axis. After aligning the DEC axis
(Declination axis) to the celestial object's declination on the celestial sphere, continuous tracking can be achieved through the single-axis rotation of the RA axis.
This design eliminates Field Rotation and enables longer exposure times. However, this functionality relies on a critical prerequisite: the RA axis must be precisely parallel to the Earth's rotational axis. This process is commonly referred to as polar alignment.
EQ Mode or AZ Mode: Which is better?
Alt-Az Mode: operates on a coordinate system that is easier to understand and use, requiring little to no manual calibration-making it highly accessible for beginners. However, it is less suitable for long-duration deep-sky photography.
EQ mode: requires prior polar alignment and involves more complex operation, but it supports extended deep-sky imaging sessions and delivers higher-quality images.
