Focusing issue

[AshleyCUK]

So I have just got a new an 8" stellalyra Newtonian and just got wondered about the focusing.  If I just drop an eyepiece into the focusser and tighten it up, the scope won't focus, I have the pull the eyepiece out 5 to 10mm in order to get focus on it. 

That doesn't seem normal to me. Is there a problem with the mirrors or focussed?  The image is pin sharp once focussed but that just doesn't seem right as the focusser will always be maxed out to get focus.

My eyepieces are svbony 23mm and 10mm with a celestron 2x Barlow. I'm trying to focus on something maybe 100m away as that's the only point of interest from my back garden!

 

Edited January 1 by AshleyCUK

[azrabella]

Ideally your scope is designed to operate at "infinity". The closer your subject the more back-focusing you will need. You should find that your 23mm eyepiece will require less back-focus than your 10mm eyepiece. Your target at 100 mtrs is too close. Probably nothing to worry about.

[Astronomist]

I would suggest attempting to focus on a star but alas most of the uk is covered in clouds...

[Naughty Neal]

The ep's require some back focus or an extension tube. For the EP's use a sleeve to fit over  the lower barrel that will set them at the correct height .