It must be something I did, since I used to be able to come to focus while using a barlow in my 10-inch dob. Now, however, there’s not enough in-focus travel.
I assumed that it must have resulted from my having drawn the primary mirror too far down in the tube (away from the secondary mirror) during collimation, so I tried to fix the problem by pushing it up (back toward the secondary) and recollimating. But that seems to have made it worse. I can come to focus on objects up to several hundred feet away, but not on anything significantly more distant. This applies to my eyepieces of all focal lengths.
I can’t believe the solution is to draw the primary back down in the tube, because there wasn’t much, if any, more room in that direction on the collimating bolts when I first tried to fix the problem.
Can anyone tell me what's going on?
I assumed that it must have resulted from my having drawn the primary mirror too far down in the tube (away from the secondary mirror) during collimation, so I tried to fix the problem by pushing it up (back toward the secondary) and recollimating. But that seems to have made it worse. I can come to focus on objects up to several hundred feet away, but not on anything significantly more distant. This applies to my eyepieces of all focal lengths.
I can’t believe the solution is to draw the primary back down in the tube, because there wasn’t much, if any, more room in that direction on the collimating bolts when I first tried to fix the problem.
Can anyone tell me what's going on?
