Telescope Thermal Calculator
How long until your
telescope is ready?
Thermal equilibrium is the #1 overlooked cause of blurry views. Enter your scope specs and temperature difference — get an exact cooldown timeline.
Telescope parameters
Design affects heat retention
Primary mirror / lens diameter
Where scope is stored
Current outside air temp
Cooling fan?
Estimated time to thermal equilibrium
—
minutes
—
Thermal performance during cooldown
Move outside
25%
50%
75%
Equilibrium
ΔT (delta)
—
°C temperature gap
Thermal mass
—
relative to 100mm
Fan speedup
—
vs passive cooling
Usable at
—
min — fair views start
Speed up cooldown — practical tips