Application example: ESATTO with Schmidt-Cassegrain and EdgeHD tele-
scopes
Schmidt-Cassegrains and EdgeHD are great# instruments because they combine high performance with ease of
use (for example, they are simple to collimate) and portability (they are among the most compact optical tubes, al-
though the diameter can also be large). However, the internal focuser of these telescopes (which allows focusing
by moving the primary mirror) generates image shift and mirror flop problems that we can now avoid# thanks to
ESATTO.
Problems caused by internal focuser of!Schmidt-Cassegrain or EdgeHD telescopes
Image shift is generated when the focus with
the internal focuser generates a displacement
of the image: this problem is evident
during# high-magnification astrophotography# of
planets and the Moon# when recovered# object
can even be# moved out of the sensor field of
view. By using ESATTO# as focuser for Sch-
midt-Cassegrain or EdgeHD, we can avoid#the
image shift since# we focus with the external
focuser (and no longer using the internal
stock#focuser). Since ESATTO has a precision
micrometric control with a 0.04 micron resolu-
tion, we can also focus with much greater pre-
cision than you have with standard manual
focusing, without introducing vibrations during
focusing (since we don't touch the telescope to
focus but we control ESATTO#with a USB connection from EAGLE or an external Windows computer or through the
Virtual HandPad with WiFi connection from smartphone or tablet).
Mirror flop is the displacement of the primary mirror which tends to move due to its own weight and it's a problem
for long-exposure astrophotography of deep-sky objects. This problem was fixed#by Celestron EdgeHD telescopes
which introduced an integrated primary mirror locking system. Unfortunately this also# prevents focusing between
expositions# (that is commonly done when doing long-exposure astrophotography, for example when changing fil-
ters) and is therefore a problem also for the remote control of the telescope. Instead, by using ESATTO#as focuser
for Schmidt-Cassegrain or EdgeHD, we can use the primary mirror locking system (in telescopes equipped with
this system) and perform micrometric focusing using ESATTO. This way Schmidt-Cassegrain telescopes and,
especially, Celestron EdgeHD become ideal instruments also for remote control!
Connect ESATTO to!Schmidt-Cassegrain or EdgeHD telescopes
ESATTO#is available in different diameters but, if you want to use it as focuser for Schmidt-Cassegrain or EdgeHD,
we recommend the 2" model since#it has the lower thickness #(as we will see later it avoids back focus problems)
and it already has of a larger free aperture#(51mm) than the diameter of the#baffle tube#of these telescopes. As fo-
cuser for Schmidt-Cassegrain or EdgeHD, it is therefore not necessary to use ESATTO# 3". Removing the visual
back#of Schmidt-Cassegrain or EdgeHD telescopes, you will find a thread that can be:
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