Original Critical Focus Zone Calculation:
CFZ = 1.6 * λ * f^2
λ = 500 nm (green) f = 10 for Edge11
New Critical Focus Zone
CFZ = 4.88 * λ * f^2
NCFZ = .00225 * θ * sqrt(τ) A f^2
θ = seeing (3 arc seconds)
τ = focus tolerance 15% visual, 5% AP?
A = Aperture
Edge11
CFZ1 = 1.6 (500) (10)^2 = 80 micron
2 micron/step per spec
CFZ1 = 80 micron (1 step/2 micron) = 40 step
CFZ2 = 122 steps
NCFZ = .00225 (3) sqrt(5) (279.4 mm) (10)^2 = 420 micron (1 st/2 micron) = 210 steps
NCFZ is 5 times bigger than CFZ1, twice CFZ2
Tak
CFZ1 = 1.6 (500) (4.5)^2 = 16 micron
6000 steps / 2.1 cm * (100cm/m) * (1/10^-6) .28 step/micron or 3.5 microns per step
16 micron (.28 step/micron) = 4.57 step
CFZ2 = 13.9 step
NCFZ = .00225 (3) sqrt(5) (90 mm) (4.5)^2 = 27.4 micron
* (.28 step/1 micron) = 7.67 steps
NCFZ is 1.7 times CFZ; still very small