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Extending eyepiece for QHY5 camera?


PTone

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I have a Skywatcher ST80 and QHY5 camera.

Looking at the forums i need to extend the scope before attaching the camera in order to get a good focus.

To do this I bought a 65mm extender which fits perfectly but, here's the problem, the extender is a wider diameter than the camera (or an eyepiece for that matter).  

Looking at the focus tube on the ST80, the back of the original tube reduces so that a 1.25" eyepiece/QHY5 can fit.

So I  need to attach some kind of reducer to the end of the extender down to 1.25"so that I can attach the camera, but  have no idea what I am looking for or what its called.

If someone could help me out and let me know what I need to look for and buy , I'd appreciate it

Thanks

Paul

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I think i've found the problem - the eyepiece end of the ST80 has an ID of 1.25" so the QHY5 will fit in ok (with the nose piece on), the OD of the eyepiece end is 1.75" The extender will screw onto the end of the eyepiece end of the ST80 but at the eyepiece end of the extension tube both the OD and ID is 1.75".  So the extender tube is literally that - a straight tube of 1.75", with an internal thread at one end an an external thread at the other

Looks like i need a 1.75" to 1.25" reducing piece.  this will then fit on the end of the extender and then i can put the QHY into that

No idea what this is called though

Or perhaps i need to get a different extender??

BTW i cantt just take the eyepiece end off the scope as the extender will not fit into the resutling aperture

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on the st 80, take off the diagonal and the end of the focuser should have a black threaded T2 fitting, then you need a 63mm T2 extension, £5 from astro boot, then the qhy 5 needs to un screw the 1.25" nosepiece and it should have a female T2 fitting which then allows the camera to screw onto the T2 extension tube.

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Thanks again red Dwarf

Is this the one you mean? 

http://www.astroboot.co.uk/AstroBoot/telescope-and-astronomy-stuff.html?highlight=AB7020#AB7020

62mm T ext tube
New item. T thread extension tube (male T thread at one end and female T thread at the other). The tube provides an extension of 62mm.
£4.50 IN STOCK

The reason I ask is because that is the one I already bought and which does not fit and hence the reason why I am somewhat confused

There are  couple of other extenders though including:

http://www.astroboot.co.uk/AstroBoot/telescope-and-astronomy-stuff.html?highlight=AB3198#AB3198

It states the same info as the same info as other extender:

62mm T thread ext tube
New item. Extension tube 62mm long with male T thread at one end and female the other.
£5.00 IN STOCK
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I've just taken the focuser off the tube again.  the external thread of the focuser looks like a different thread (larger) to the internal thread at the other end where the eyepiece fits.  So its no wonder that the extender i bought doesn't fit into the tube.

The female thread of the extender does, however, fit the male thread of the focuser.

So its just the tube end that is a problem

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I had exactly the same problem and it drove me nuts !! The thread on the end of the drawtube is NOT 42mm (T2) !!!

The only solution I have come up with is as shown in the second photo - take the nosepiece off the camera - screw the extension tube into the camera - put the nosepiece onto the scope end of the extension tube and pop it into the eyepiece adapter.

I wish I could find a solution that screws together rather than using the sloppy eyepiece holder but I haven't found anything that screws onto the drawtube except the adapter that came with the scope. 

If anyone has cracked this issue please post the answer!!  :grin:  :grin:

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post-33941-0-60106400-1416421259_thumb.j

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The alternative is to leave the nosepiece off the extension and screw it straight onto the scope adapter - that does away with the floppiness of the eyepiece adapter but leaves you with two thumbscrews with nothing to screw into - I suppose you could remove them and tape over the holes but its not a very elegant solution. 

The best solution would be an extension tube of about 70 - 75 mm long that screws straight onto the drawtube and has 42mm (T2) male thead at the other end to screw straight into the camera - but I have never found anything that will screw straight onto the drawtube !! (I have a sneaky suspicion its 44mm)

Good luck !!

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My st 80 was an older blue version and it screwed to the back of the black bit of the focused, so no need to unscrew and take off the black bit, I sold the st 80 a while ago but I still have the extension tube and it certainly had T2 male end as that went into my asi 120 camera, I'll double check the other end tomorrow for you.

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