What part of my telescope is the 'focuser'

[AlistairW]

Hello,

I was looking at the link below, but now I am confused as to what part of my scope is 'the focuser'. Looking at picture 1 below, I would have assumed it was the bit up to the main red ring section. But here it look that the focuser was unscrewed from the OTA body. So is this correct if I wanted to install a new focuser, or is this specific to what this chap was doing ?

http://www.spacerock.nl/2012/installing-a-feathertouch-focuser-on-the-gt81/

 

Thanks

Alistair

[Putaendo Patrick]

As I understand it, in this case the new focuser is significantly shorter so he's adding another component between the OTA and the focuser which is essentially a 3.75" extension tube. Technically I guess this is not part of the focuser, but at the same time it could be considered part and parcel of the overall focusing set-up. If you choose to upgrade, this may or may not be necessary depending on which replacement focuser you go for - I think .