Resolution Limits Visualizer

Compare the achievable angular resolution of several imaging setups. The total resolution is the root-sum-square (RSS) of four blurring contributions — seeing, guiding, diffraction, and the sensor (pixel sampling) — combined in quadrature. Smaller is sharper. The equations are at the bottom of the page.

Pixel Scale Visual Guide

Over-sampledAcceptableOptimal (1.0–1.5″)Under-sampledYour setups

	80D ETX90	R6 ETX90	80D 400mm	R6 400mm
Seeing (″)	3.0	3.0	3.0	3.0
Guiding (″)	1.5	1.5	1.5	1.5
Diffraction (″)	1.7	1.7	2.1	2.1
RSS on sensor (″)	3.7	3.7	4.0	4.0
Image scale (″/px)	0.6	1.1	1.9	3.4
Sampling (px/FWHM)	6.1	3.5	2.1	1.2
k(s) (sensor coeff.)	0.7	0.7	2.8	3.0
Sensor (″)	0.4	0.7	5.5	10.1
Total RSS (″)	3.8	3.8	6.7	10.9

All values in arcseconds (") except image scale ("/px), sampling (px per FWHM), and k(s) (dimensionless).

Equations

Inputs: D = aperture (mm), f = focal length (mm), p = pixel size (µm); seeing & guiding in arcsec. All θ are in arcsec; image scale θ_px in ″/px; sampling N in px per FWHM.

Image scale (″/px)

θ_{px} = \frac{206.265 \cdot p}{f}

Diffraction limit

θ_{diff} = \frac{149}{D}

Optics blur (RSS)

θ_{optics} = \sqrt{θ_{see}^{2} + θ_{guide}^{2} + θ_{diff}^{2}}

Sampling (px/FWHM)

N = \frac{θ_{optics}}{θ_{px}}

Sensor coefficient (logistic blend)

k (N) = k_{o} + \frac{k_{u} - k_{o}}{1 + e^{α (N - N_{0})}}

k_u = 3.0, k_o = 0.68, α = 6, N₀ = 2.5

Sensor blur

θ_{sensor} = k (N) \cdot θ_{px}

Total resolution

θ_{total} = \sqrt{θ_{optics}^{2} + θ_{sensor}^{2}}

Bar segment (variance share)

h_{i} = \frac{θ_{i}^{2}}{\sum_{j} θ_{j}^{2}} \cdot θ_{total}

Resolution Limits Visualizer v20260612