Fitting a Moonlite crayford focusser to 250 flextube dob

[DaveGibbons]

I received my single speed moonlite focusser today for fitting to my 10" skywatcher flextube dob. I thought I would post a few pictures for anyone thinking of doing this for the first time as it is relatively simple to do , although care must be taken with loose screws and mirrors.

It's an upgrade (albeit expensive) that will enhance both the mechanical performance and ability to achieve perfect optical alignment with zero image shift and of course they are just so beautiful to look at.

Heres what we start with the not bad original crayford

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Original focusser from inside tube, note I had flocked the draw tube to eliminate unwanted reflections.

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Ensure you protect your main mirror by keeping your tube horizontal before removing the 4

screws ands nuts holding original in place. The flextube has the advantage of fitting the dust cap over the lower tube assembly meaning this scope can be done upright.

Heres the hole were your focusser sat.

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Here's the Moonlite unit with curved adapter for 10" tube' spacer for focusser height and main crayford body

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The universal adapter plate is multi threaded on the underside to allow it to fit many different hole patters found with the various scope manufacturers. You need to offer up the adapter plate to your tube and whilst maintaining the adapter visually central find the threaded holes that fit your scope. Use the provided allen screws and fix to your tube. Note you do have a very small amount of flexibility with positioning , I just ensured the adapter edge is perfectly parallel with upper telescope tube edge with a steel rule.

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That really was the hardest part! The main body can now be placed on top of the spacer (or spacers depending on how high you need or want the focusser to sit) Long allen screws fit through both body and spacer and can be bolted up ensuring all straight edges are flush with each other. And here she is-

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If your collimation was good before you fitted the moonlite only minor adjustment should be necessarry to keep it that way. I had to adjust mine the main reason being you will find the usually loose fit of laser /cheshire in the standard crayford is a nice tight fit as the compression ring fitting along with tighter tolerence makes a real snug fit.

Collimation is a topic I don't wish to go into in detail, as like most of us my way of doing it may differ from you, I only use a laser to adjust secondary to hit the centre spot on primary I then use a collimation cap for main mirror adjustment

The scope looks great now, I just need to finish my light shroud for truss section and that's about it for the Skywatcher.

cheers

Dave

[philsail1]

Looks very nice Dave. Gives your Dobsonian an even more professional look!

A good looking set up.

Now all you need is (dare I say it) a clear night!

REgards,

philsail1

[zhgutas]

Maaaan that looks good! 8) a very nice looking detail, not even talking about it's quality

Marius

[A McEwan]

I wish I'd never seen this post. I wish Skywatcher had never made these things. I can see I'm going to have to buy one sometime....

And I was enjoying my 8" f6 so much too.....