ESATTO is the perfect focuser for Ritchey-Chretien telescopes, that are great instruments for deep-sky astrophotography at medium-long focal length. Ritchey-Chretien telescopes were, just a few years ago, very expensive but now, especially the models produced by GSO, are very affordable and allow any amateur astronomer to own and use a Ritchey-Chretien telescope. Unfortunately these telescopes comes standard with a focuser that has not the load capacity requested for the heavy cameras and accessories commonly used in deep-sky astrophotography: let's see how you can use ESATTO as a new and better focuser for Ritchey-Chretien.
The right adapter to use ESATTO as focuser for Ritchey-Chretien
Ritchey-Chretien telescopes produced by GSO have 2 different threads in the rear part of the telescope and that you can find by removing the original focuser. A 90mm male thread on 6" and 8" models or a 117mm thread on larger 10", 12", 14" and 16" models. In order to use ESATTO as focuser for Ritchey-Chretien, we designed 2 adapters: the PL3600235 adapter allows you to use the ESATTO 2" on GSO Ritchey-Chretiens 6" and 8". The PL3600236 adapter allows you to use the ESATTO 3" on GSO Ritchey-Chretiens 10", 12", 14" and 16".
ESATTO 2" on GSO Ritchey-Chretien 6" and 8"
Ritchey-Chretien telescopes usually have a long back focus and the GSO models make no exception allowing to attach camera also many astrophotography accessories like e.g. off-axis guiders, filter wheels etc. In order to easily reach the focus position, usually you will need to use one or more extensions (provided with the telescope). Then, in order to use ESATTO 2", you connect the PL3600235 adapter and finally the ESATTO 2".
ESATTO 3" on GSO Ritchey-Chretien 10", 12", 14" and 16" (also truss)
The larger diameter Ritchey-Chretien telescopes by GSO are available also with truss type tube and this guide is valid also for these configurations. In order to easily reach the focus position, usually you will need to use one or more extensions (provided with the telescope). Then, in order to use ESATTO 3" to the Ritchey-Chretien telescope, you connect the PL3600236 adapter and finally the ESATTO 3".
Using Ritchey-Chretien correctors or reducers with ESATTO
GSO Ritchey-Chretien telescopes offer also correctors and reducers in order to allow you to better adapt your telescope based on your imaging needs. Usually these correctors comes in a 2" diameter barrel that you can easily connect to the ESATTO by adding the 2" visual back: you need the PL8410001 visual back if you want to connect the corrector to the ESATTO 2" or the PL8410002 visual back if you want to connect the corrector to the ESATTO 3". Please note that every corrector is designed with a precise back focus distance (the distance from the corrector to the camera sensor) so, after the corrector, you will need the proper photo adapter based on your camera model and the accessories you may want to use.
GSO Ritchey-Chretien telescopes are now ready to be used with the ESATTO: this way you will have a better focuser with a very high load capacity (perfect also for heavy cameras and accessories for astrophotography), with a built in motor and electronics for remote control by connecting it to USB port of your EAGLE or external Windows computer of with WiFi by using the ESATTO Virtual HandPad.