Barlow lens doesn’t focus with eyepieces

[Hal-9000]

I have a 6.6 focal ratio telescope with 10mm and 20mm eyepieces, but when I put my 2x Barlow lens on the telescope I can’t seem to focus on any object. Does the Barlow Lens magnify too much for the scope or is there a way I can fix this?

[Mart29]

1 hour ago, Hal-9000 said:

I have a 6.6 focal ratio telescope with 10mm and 20mm eyepieces, but when I put my 2x Barlow lens on the telescope I can’t seem to focus on any object. Does the Barlow Lens magnify too much for the scope or is there a way I can fix this?

Sometimes you literally need tiny tiny movements on the focuser knobs . The difference for me being in focus and out is literally a couple of millimetres. 

Also , the barlow and eyepiece should be outside to cool for 30 mins plus or it looks misty / out of focus 

[PeterStudz]

@Hal-9000 A bit more about the telescope might help. Eg what is the make and model?  And welcome to the forum!

[Guest]

I have a 14mm that is very tricky to focus when in a 2x Barlow.  It is literally just a millimeter and it comes into focus.  Go 2mm....and you miss it 

[bosun21]

Need your telescope details before I can make any assumptions or advice.

[Louis D]

It could be you don't have enough in travel or out travel to reach focus with the fully inserted Barlow lens.  Try this first.  Bring an object to focus with the eyepiece alone and lock the focuser.  Next, put the eyepiece in the Barlow.  Now, slide the Barlow/eyepiece combination into the focuser slowly while observing the object through the eyepiece.  Does the object come to focus before the Barlow is fully inserted in the focuser?  If so, you may not have enough out travel to use the Barlow fully inserted.  If that is the case, simply partially insert the Barlow and tighten it down.  There's no harm in using it this way.  If on the other hand you inserted the Barlow all the way and the image never reached focus (got smaller and smaller and then you ran out of travel) even after loosening the focuser tube, then you don't have enough in travel to use the Barlow, period.  Try finding a longer Barlow since they tend to require out focus relative to the eyepiece alone focus position and sell the Barlow you already have.