Focuser is an additional one of benefit sc scope

[Ukastronomer (Jeremy)]

I have seen this on scopes, and wondered about my 8" Edge celestron

Is there any real benefit.

The problem is that i have a Baader click lock on my Sc and would not want to be without one

Many thanks

[bojan]

The benefit is because "mirror" flop is avoided with external focuser.
You fix the mirror and focus with external focuser (I don't use one on my C11, because I have to modify it first to be able to fix the mirror).

[morls (Stephen)]

Originally Posted by Ukastronomer

The problem is that i have a Baader click lock on my Sc and would not want to be without one

If it's the Baader Steeltrack focuser you're considering there is a clicklock that fits: https://www.firstlightoptics.com/ada...teeltrack.html

Originally Posted by bojan

You fix the mirror and focus with external focuser (I don't use one on my C11, because I have to modify it first to be able to fix the mirror).

Is it necessary to fix the mirror? I've recently added a steeltrack to my scope, and while I'm yet to test it (lack of mount issues ) I have assumed I would use the stock focuser to get close and then fine-focus with the Steeltrack...

[bojan]

Originally Posted by morls

.. Is it necessary to fix the mirror?...

That depends... my C11 mirror non-axial movement is very small, so I am not in a hurry to do it.

But there were cases out there it was really necessary because the whole thing went out of colimation after moving the SCT to another target.

[morls (Stephen)]

cheers

[The_bluester (Paul)]

If it was not for the curvature and off axis coma I would have seriously thought about locking my C925 mirror permanently in a suitable position and fitting an external focuser, even using SGP for automated focusing with the focus motor is is a bit of a challenge to get really consistent results. I am happy that at least the results are as good as I am likely to get doing manual focus and SGP can refocus as often as once per sub all night if I want it to.

Jeremy, it probably really coms down to how good the focuser on your particular scope is. Mine I would say is middle of the road, not great but not bad and I could really see the benefit of mirror locks and an external focuser (Not being an Edge I dont get mirror locks) but if yours is good in the focuser you might not be able to justify it.

The only disadvantage I can see to the mirror locks on the Edge would be that for unattended imaging you either need to have a focus motor fitted to the stock focuser (The Edge will shrink and expand with temperature just like anything else) so you can't use the locks, or you need to rough focus it, lock the mirror and use an external focuser to deal with the temperature changes.

[Ukastronomer (Jeremy)]

Thank you, you have saved me money, appreciated