Celestron CGX Equatorial 800 HD Telescopes Whitepaper EdgeHD Optics - Page 5

Classic Sct, Coma-free Sct, Edgehd

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THE OPTICAL PERFORMANCE OF THE EDGEHD COMPARED TO OTHER SCTS CLASSIC SCT "COMA-FREE" SCT EDGEHD 100 μm On-Axis 5.00 mm 10.00 mm 15.00 mm Off-axis distance (millimeters) 20.00 mm 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. The Celestron EdgeHD 5

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The Celestron EdgeHD
5
On-Axis
5.00 mm
10.00 mm
15.00 mm
20.00 mm
100
μ
m
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.