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michaelmorris

Diagonal Slippage

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I've currently got a stock Meade 1.25" diagonal in the rear cell of my 8" LX200 Classic. Unless I put my binoviewers in with the diagonal pointing pretty much straight up, the diagonal rotates downwards under the weight. This is both alarming and a major pain in the neck.

Ideas please.

I would consider changing the diagonal and SCT adaptor as solutions, but only if strictly necessary and not too expensive.

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Maybe try a fitting with a compression ring rather than the screw in pin.

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I would consider changing the diagonal and SCT adaptor as solutions, but only if strictly necessary and not too expensive.

I suggest you change the diagonal for a 2" model.

Sometime ago, when I worked as a salesman for another dealer, someone arrived to collect an LX200. We opened the box to check the contents; when he saw the 1.25" diagonal, he asked me where the bin was then tossed it into the bin without batting an eyelid :shock:

I have since learnt that the difference, mechanically and optically, between Meade's 1.25" diagonal and their 2" version is huge!

Most 1.25" diagonals, because of the small mirror size and the way imperfections occur mostly along the edges, achieve 1/4 wave accuracy. A 2" diagonal will typically deliver 1/10th.

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I would consider changing the diagonal and SCT adaptor as solutions, but only if strictly necessary and not too expensive.

I suggest you change the diagonal for a 2" model.

Won't a 2" diagonal add even more weight and hence make rotation even more of a problem?

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I would consider changing the diagonal and SCT adaptor as solutions, but only if strictly necessary and not too expensive.

I suggest you change the diagonal for a 2" model.

Won't a 2" diagonal add even more weight and hence make rotation even more of a problem?

Nobody has reported a problem.

Haven't tried it myself though...

I mention changing the diagonal not so much as a fix for your binoviewer problem as for its ability to deliver better views.

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Lo Michael

If You change to a 2" SCT diagonal the screw fitting onto the rear cell will hold it in place. I made the change on my LX90 and what a difference it makes. :)

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Won't a 2" diagonal add even more weight and hence make rotation even more of a problem?

No. There is more weight but there is also a much larger surface area to give more friction.

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My 2" diagonal is attached to the focusser on my Skywatcher 100ED by two set screws but I've still had a couple of scares with my diagonal moving unintentionally :shock:. It might be because I'm being too gentle and not wanting to mark my lovely new diagonal with the set screws :lol: However, I believe you can buy a compression ring type attachment for the scope that the diagonal slips in to. Anyone know what this part is called and where I can purchase one from? It would certainly hug my diagonal better than set screws AND keep it looking loooooovly! :)

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Lo Michael

If You change to a 2" SCT diagonal the screw fitting onto the rear cell will hold it in place. I made the change on my LX90 and what a difference it makes. :)

Hi MP, I wondered about a 2" diagonal on the back of my LX90, but the optical path through the rear mirror is only about 1 & 5/8 inch. So wont part of the light be path be obstructed if I move to a 22 optical back + diagonal?????? Would this not negate many of the advantages in having a 2" back on this 'scope? I realise that I could then fit a 2" Crayford style focusser on and say "Goodbye" to image shift - which would be good.

How does your set up work? Is it all okay?

Tom

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Lo Michael

If You change to a 2" SCT diagonal the screw fitting onto the rear cell will hold it in place. I made the change on my LX90 and what a difference it makes. :)

Hi MP, I wondered about a 2" diagonal on the back of my LX90, but the optical path through the rear mirror is only about 1 & 5/8 inch. So wont part of the light be path be obstructed if I move to a 22 optical back + diagonal?????? Would this not negate many of the advantages in having a 2" back on this 'scope? I realise that I could then fit a 2" Crayford style focusser on and say "Goodbye" to image shift - which would be good.

How does your set up work? Is it all okay?

Tom

Lo Tom

It is well documented on the Yahoo LX90 and LX200 site that the 8" LX tubes have this restriction but the stock 1 1/4" diagonal is sooooo bad it is worth getting the 2" just so You can try 2" eyepieces then try Your 1 1/4" EP's in this diagonal and realise justhow bad it is. I use the Meade SCT diagonal and it is good but the WO SCT one is much better made and in My opinion :lol: a better buy :)

The Crayford is a great idea but :) imaging or just eyeballing near the zenith is a no-no, though You could set limits so the scope wouldn't crash into the base but I wouldn't trust those limits myself :D All the people I observe with who own 8" LX's have all changed to 2" diagonals of various types and don't regret their purchases.

HTH

Kev

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Thanks Kev,

I think I will have to invest in the 2" WO SCT diagonal :shock: Another cost - but hopefully a positive one.

Cheers

Tom

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