moosestang

I may have found the problem. I discovered that the 6mm should have lenses in the chrome barrel at the bottom of the eyepiece. Mine doesn't. But the 15mm does. I suspect the previous owner swapped the chrome part of the lenses. Swapped them back, and now both focus at about the same spot.

I've also tried using the 15mm with a 2x barlow. This will focus ok, but almost all the way to the bottom of the focuser travel. So there is a trend: higher magnification requires the focuser to be lower. No adapter

I recently acquired an Orion StarBlast 4.5 EQ. I can focus on objects with the 15mm eyepiece with the focuser in about the middle of it's travel. But if I switch to the 6mm eyepiece, I have to move the focuser down to the bottom of it's travel where it is still not in good focus. I posed this question in another forum, and it was suggested that the primary mirror might be too far back. I did move it as far forward as I could using the adjustment screws, and it did help some. But the focuser still seems to want to be lower to achieve focus. I was also told by another user who has the same telescope that he can achieve focus with either eyepiece with only a slight adjustment of the focuser, not the extreme travel I seem to require. So it seems something is not right with my setup, but I don't know what. Collimation seems ok. Looking for suggestions on what to try next.