Cheshire/Sight tube to loose!

[RonVen]

I have a Astromaster 114EQ and purchased the Cheshire/sight tube combination. Unfortunately, the Cheshire/sight tube is loose in my focuser. Apparently the eyepiece part of the focuser is a separate piece (the piece with the screws that tighten the eyepiece). That does measure 1.25" but the rest of the focuser tube is 1.5". The Cheshire/sight tube goes down to the corrector lens (bird/Jones) and stops. No matter how I tighten the Cheshire/sight tube, it flops in the focuser. I'm assuming that the ring holding the corrector lens is 1.25", but am unsure of this. Does anyone have a similar experience and a way around it? Thanks - Ron

[umadog]

Umm... I'm confused. Why can't you hold the combo tool in the 1.25" adaptor that your eyepieces go into?

[RonVen]

Umm... I'm confused. Why can't you hold the combo tool in the 1.25" adaptor that your eyepieces go into?

When I put the tool in the eyepiece/focuser it flops off center. I tighten the screws and the Cheshire/sight tube leans away from the center of the eyepiece. The eyepiece screw down ring is about 1/2" wide and the Cheshire/Sight tube is about 4" long. When I tighten the 2 screws the Cheshire goes off center. I was wondering if my scope requires you to take the bird/jones out, so that the Cheshire/tube rests in 2 spots: on a 1.25" ring (one at the eyepiece & one holding the corrector lens)? I've read some posts where people say that they didn't take out the bird/jones, but I am baffled how they get the Cheshire/sight tube centered. Perhaps a shim, but even so, this would mean that I would be determining the center point of the cheshire/tube. So I'm perplexed. Thanks for your help. Ron

[steppenwolf]

As the Bird Jones lens assembly forms part of the light path, I would think it unwise to remove it to collimate the instrument. I think that making up a shim - perhaps wrapping electrician's insulating tape around the nose of the Cheshire - to ensure it remains central would be the best option.

[umadog]

If it helps, the most important thing is that the collimator is not tilted. Being a little off-centre is not a big deal.

[RonVen]

As the Bird Jones lens assembly forms part of the light path, I would think it unwise to remove it to collimate the instrument. I think that making up a shim - perhaps wrapping electrician's insulating tape around the nose of the Cheshire - to ensure it remains central would be the best option.

I tried that, but the Cheshire/sight tube wouldn't fit. The eyepiece assembly is a true 1.25", so the Cheshire/tube doesn't get past the eyepiece screw assembly. It's the inside focuser tube (just past the eyepiece assembly) that is 1 1/2" wide. So the dilemma remains, that the cheshire/sight tube is tight at the very top, but once it is in the focuser it leans to one side (no matter how I tighten it down). Thanks for your suggestion though. I think the Astromaster 114EQ is unique and this wasn't thought out in the manufacturing process. When I call Celestron, they recommmend using only a collimator cap and then a star test.

[RonVen]

As the Bird Jones lens assembly forms part of the light path, I would think it unwise to remove it to collimate the instrument. I think that making up a shim - perhaps wrapping electrician's insulating tape around the nose of the Cheshire - to ensure it remains central would be the best option.

I tried that, but the Cheshire/sight tube wouldn't fit. The eyepiece assembly is a true 1.25", so the Cheshire/tube doesn't get past the eyepiece screw assembly. It's the inside focuser tube (just past the eyepiece assembly) that is 1 1/2" wide. So the dilemma remains, that the cheshire/sight tube is tight at the very top, but once it is in the focuser it leans to one side (no matter how I tighten it down). Thanks for your suggestion though. I think the Astromaster 114EQ is unique and this wasn't thought out in the manufacturing process. When I call Celestron, they recommmend using only a collimator cap and then a star test.

[kirkster501]

As the Bird Jones lens assembly forms part of the light path, I would think it unwise to remove it to collimate the instrument. I think that making up a shim - perhaps wrapping electrician's insulating tape around the nose of the Cheshire - to ensure it remains central would be the best option.

That, or plumbers PTFE tape - the white, not the yellow.

Electrical Insulation tape can be a bit thick. PTFE is just the job.