Trouble focussing my telescope. Is something missing?

[Mr Golding]

I know this an old topic but I am also a newbie and I am having the exact same problem. Everything was just a blur night and day. Collimating was fine. Eyepiece able to extend in and out. I thought it was light pollution but took it out to dark areas and still moon just a big blur with out focus. I was just about to give up when one day I manually removed the eyepiece out of the focuser manually and all of the sudden everything came into bright sharp focus. I thought it was strange as sometimes the eyepiece would get stuck to far down. Am I missing a piece that should hold the eyepiece further out of the focuser? At the moment I have to hold it manually to see anything. I have Orion starblast 4.5 EQ.

[RT65CB-SWL]

Hi 'Mr Golding' and welcome to SGL.

Did you buy the 'scope new or secondhand? - I am not au-fait  with your particular 'scope, but looking at you photos I would say "Yes!" because I can't see a 'locking screw'. I think there is supposed to be a collar with the 'locking screw' at the end of the drawtube.

Hopefully someone with more experience will be able to answer. Sorry I cannot offer more help. 

[brantuk]

Ideally a scope would come focus around half way along the focal plane in order to have a little throw both sides of the focal point. But sometimes it depends on how the scope has been set up and which type of eyepiece/scope you're using. I have over the years found that not all eyepieces are parfocal - sometimes even within the same manufacturer or range, and you usually have to tweak the focus each eyepiece change.

It can also depend on how long the focus tube is - occasionally the focal point is a little off at one end or the other of full throw (for a specific eyepiece) and you end up pulling the eyepiece out a little to "lock on" to sharp views.

The design of the scope is sometimes responsible for this - eg in the case of Bird-Jones style set ups where a small lens is used within the focus tube to achieve the focal length of the scope. In this case the distance between an eyepiece and this Bird-Jones lens can be critical. In your case you had to slide the eyepiece out of the tube a bit to achieve focus. Beware though it might not be necessary for all eyepieces - some will work ok straight away. Hth  

 

[Tony72]

1 hour ago, Philip R said:

Hi 'Mr Golding' and welcome to SGL.

Did you buy the 'scope new or secondhand? - I am not au-fait  with your particular 'scope, but looking at you photos I would say "Yes!" because I can't see a 'locking screw'. I think there is supposed to be a collar with the 'locking screw' at the end of the drawtube.

Hopefully someone with more experience will be able to answer. Sorry I cannot offer more help. 

Hi and welcome to the lounge.

As Philip R has stated you should have a collar that screws on top of the focuser draw tube with some locking screws to hold the eyepiece in place. 

Tony

[moriniboy]

Hope this helps, hopefully its in the box waiting to be discovered.

[knobby]

Yep, should be a collar / eyepeice holder that screws onto the chrome coloured focuser tube ... lets hope it's in the box somewhere.

If you cant find it, you could knock up a temp jobby by wrapping bubble wrap or masking tape around the eyepeice til it's a tightish fit, just be careful.

[laudropb]

Hello and a warm welcome to the SGL. As others have said you are missing a piece.

[brantuk]

Ahh yes - second look at the pictures and I see now you're missing the eyepiece holder. Looks like it's been taken off - probably to screw a camera adaptor on for imaging. Did you get the scope new or used? If you can't find the holder in the packing you will need to go back to the seller and ask him for it. Hth

[Charic]

.........I would suggest don't use the scope until the  eyepiece adapter is replaced. Should/if you release an eyepiece down the focuser and it strikes the secondary, the least damage could just be an alignment issue with the secondary mirror, the worst, marking the secondary mirror.

It would appear from your second image that the eyepiece rubber is going to stop the eyepiece from slipping right down, but without the adapter, the eyepiece is not in the correct position, hence the out of focus issue.

[ronl]

If the scope didn't come with the 2" to 1.25 adapter then you will want one that looks 

like this http://www.ebay.co.uk/itm/2-to1-25-eyepiece-adapter-/140759717722?hash=item20c5eed75a:m:ma_szvZWlsgDDZtcHQks7lA