focuser for a telescope.
In July 2017 I bought a
motor focuser from USB_focus.
to motorize your telescope focuser? A
telescope requires adjustment of focus after a temperature drop of a
few degrees Celsius only. The temperature influences the APO focus by
changing the refractive index of the lenses and less by
contraction of telescope tube. For me too many images did do not
To cope with this problem I ordered a focuser motor drive
with a step motor rather then DC motor and temperature sensor,
This will allow direct focus compensation for
any temperature change.
mount the motor and electronic box, I made home made adapter of
some 3mm thick aluminum strips. The motor is coupled using a toothed belt.
This makes it easier to remove the focuser and allows a very
compact design preventing the telescope assembly hitting the pier. It is also easier to
remove the focuser for storing the telescope in the storage
motor is coupled with a toothed belt to the fine knob 4 mm
shaft. This still allows for me about 40 mm adjustment in 65535 steps (6 mm/10000 steps) and less load on the
system. The toothed belt (209520) and toothed pulleys (209514, 209515)
ordered from Conrad. Due to the low load it allows running
focuser on USB 5 volt only without any external supply.
Here some pictures.
toothed belt and pulleys:
Adapter home made
Motorised focuser in service:
Last update July 2017