Once adjusted, the phase ring should be able to be rotated in the condenser and come back in alignment.
So there is slop somewhere in your system. Some possibilities:
- Your condenser isn't properly locked in place. I believe you'll have one locking screw, a spring loaded locator, and two adjusting screws. All of 'em need to be present and accounted for.
- The phase ring is loose in the condenser turret. Ought to have a spring and two adjusting screws holding it in place.
- Your condenser turret has a loose indent.
- Your nosepiece has a loose indent.
- You're adjusting the condenser vertically and not returning it to the same place
Do you have a phase telescope? If not, this will make it easier to figure things out and make future adjustments.
If things are a bit worn, you might also try always approaching the phase ring from the same clock direction. Could be the indents will have a bit of backlash that's not symmetrical.
Worst case it takes you under 60 seconds to get the annuli aligned once you have a bit of practice and a phase scope.
Thanks so much Pete-- Very comprehensive list and as soon as I read it, I knew it was probably e a loose phase ring. Sure enough one was loose. I tightened the adjusting screws and its all good now.
I do have a phase telescope and not sure how I would do the phase alignment without it. I do need to get an eyepiece adapter so I don't have to take my camera off and use it in the photo tube.