Since ESATTO#2" is installed after the corrector or after the focal reducer, it can also be used to perfectly set#the
backfocus distance using the 15mm draw tube travel#(thus obtaining the best performance from the telescope). In
order to do this, just follow these#steps:
1) Adjust the backfocus distance from the corrector or reducer to the camera sensor: in the example of the Ed-
geHD 9.25" telescope with focal reducer in the photo above, since we still have 73mm of backfocus and since
the sensor of a DSLR#camera is#55mm away from the front T2 thread (by connecting a T2 ring to the camera
body), we will still have#18mm distance, so we used a 10mm T2 extension (screwed in front of the camera) and
we will use 8mm of focus travel to bring the camera sensor perfectly at 146mm distance from the reducer. Note:
using the saved positions of the Virtual HandPad you can also save the ESATTO#position that brings the sensor
to the perfect backfocus distance and recall it on the following nights!
2) Point the telescope to#the stars and focus with the internal focuser: this way we will find the#focus point without
changing the rear backfocus and therefore we will obtain the ideal optical configuration that allows the telesco-
pe to work with the best performance.
3) Close the locking knobs of the EdgeHD primary mirror: this#will avoid problems associated with mirror flop.
Celestron EdgeHD telescope is now ready to be used with the ESATTO#focuser that you will use to adjust the focus
varying the position of the camera only by fractions of a millimeter. These very small#movements in fact do not af-
fect the telescope's performance since#the EdgeHD optics (with or without reducer) are designed to allow a certain
tolerance (+ - 0.5mm) in the backfocus distance.!
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