Celestron EDGEHD - EdgeHD Optical Performance Comparison; Spot Diagram Analysis

The Celestron EdgeHD 5
On-Axis 5.00 mm 10.00 mm 15.00 mm 20.00 mm
100 μm
Off-axis distance (millimeters)
CLASSIC SCT
“COMA-FREE” SCT
EDGEHD
THE OPTICAL PERFORMANCE OF THE EDGEHD COMPARED TO OTHER SCTS
FIGURE 2. Matrix spot diagrams compare the center-to-edge optical performance of the classic SCT, “coma-free” SCT, and EdgeHD.
The EdgeHD clearly outperforms the other optical systems. The classic SCT shows prominent coma. The “coma-free” SCT is indeed
free of coma, but field curvature causes its off-axis images to become diffuse and out of focus. In comparison, the EdgeHD’s spot pattern
is tight, concentrated, and remains small from on-axis to the edge of the field.