Meade AR6 Length

[haitch]

Just got my hands on one of the above and am really pleased with the views I've had with it so far.

The one I've got has been shortened by a previous owner to enable it to come to focus for imaging. I'm currently using it with a Revelation 80mm extension and a vixen flip mirror and it comes to focus without problem.

The one thing that I'm wondering about is whether, with a shortened tube, the focuser housing interferes with the light cone effectively reducing aperture and increasing f ratio (when I look down the focuser, placing my eye centrally at the point I believe it comes to focus, I can't see the edges of the objective).

So 2 things...

1. Am I worrying about nothing?

2. Could someone tell me how far it is from the focuser housing to the objective cell casting? (I.e. the white tube part) so I can figure out exactly how much has been removed.

Ok, a 3rd thing...Anyone any idea where I might get hold of replacement tubing to put it back to its original dimensions?

Cheers

[GazOC]

Not being able to see the edges of the objective isn't a good sign. You could also try measuring the exit pupil that a eyepiece gives.

aperture (in mm) = Mag * exit pupil (in mm).

[haitch]

So...

152 = (1200/say 10mm EP = 120) x exit Pupil mm

1.266667=Exit Pupil mm for a 10mm EP in this scope

I take it them I need to measure actual exit pupil and see what I should be getting? Never done that so will need to figure it out.

[GazOC]

Yep.

[haitch]

Cheers Gaz - I'll have a play when I've got chance (this purchase is still hiding from the missus and as my 1st refractor it can't pose as another scope).

Would still love to find someone with one of these and a tape measure so I can find out exactly what has been done to it.

[JohnC]

Will measure my AR6 this afternoon and let you know.

[JohnC]

From the rear face of the lens cell the tube length is 835mm.

[haitch]

Thanks for that John. Looks like I've lost around 15cm then. Hmmm might be looking to source some new tubing or find a way to re-extend the old one back out.

[haitch]

From the rear face of the lens cell the tube length is 835mm.

John,

Can you just confirm that the length you gave me is for the visible white bit? (I.e only to where the focuser flange begins)

Thanks

Paul

[JohnC]

Hi

The length is from the rear of the lens cell to the fube end without the focuser fitted.

[haitch]

Cheers John.

Right that's more like 11ish cm I've lost.

Save me taking my focuser off to determine tube diameter and thickness does anyone (John maybe ) know the tube OD & wall thickness.

I don't mind taking it off but I'm not sure about getting it back on (in case it has nuts on the inside of the tube like I can see the screws holding the lens cell in do).

Thanks

Paul

[JohnC]

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