Orion SPX 300 Focusing travel problems

[neil phillips]

As some might be aware I recently had Orion build me a custom SPX 300 F6 Newtonian. This telescope came with a 2" adapter (for 2" eyepieces) and also to allow focusing travel differences for visual or imaging applications. John fron Orion optics told me that I should remove the 2" adapter for imaging applications. However so far I have found this often is not the case.

On my old 10" Europa F6.3 without any adapter I used to be able to use a 5x Antares barlow, I used to have to pull the barlow out of it's housing about 5mm to get focus ( slightly short focusing travel ).

On the SPX 300 without adapter ( as John advised ) I could not reach focus at all by quite a large margin. So I then put the 2" adapter on and still found this barlow would not focus. But by pulling it out from it's housing about 1" focusing was achieved, the only problem is with the extension already mentioned I don't think I was at 5x anymore more like 6 or 7. What could this problem indicate ?

A televue 3x which has a long barrel I could reach focus with. But if I remember correctly I think the draw tube went inside the image, so I then used a small extension and the draw tube was just ouside of it's housing. ( I will need to write these things down as my memory might be wrong on this one ) but I'm sure there was some kind of focusing issue.

A Celestron 2x that I used to use with a 3" tube extender on my old Europa with no problem, also caused problems. Without the 2" adapter ( supplied by Orion ) to reach focus with the 3" tube extender ( for more power ) went right inside the focusing housing and hence the image causing a large bite out of the image. I had none of thse problems with my old Europa 10" F6.3 what could these problems be indcating, any help much appreciated.