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My new focuser will not focus!!!

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I need some help here folks...I've said it before and I'll say it again, I am not at all a mechanically minded guy so quite often I can't see a logical solution to mechanical problems...Anyway, I just replaced my standard R&P focuser on my SW 250 PX Dob with a Revelation Crayford two speed focuser and after hearing a lot of good things about them, could hardly wait to get out tonight on the first clear night for months and get wowed by the heavens and the new focuser.....Disappointment or what !!!!....I zeroed in on the Orion Nebular and couldn't get the thing in focus. The Revelation wouldn't wind out enough to bring anything in focus !!! After I had calmed down a bit, and the dogs stopped barking and all the neighbours closed their curtains again, I came inside and scanned this forum and I understand maybe an 'Extension Tube' is in order.....If this is right, where can I get one...what size...and most importantly, can I fit it myself...I honestly have not got a clue :rolleyes: ....I await any reply with anticipation.:eek:

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Just had a look at a picture of the revelation crayford and it appears to be lower profile that the standard skywatcher R&P focuser which will result in not reaching focus. If you measure the difference in height between the two focusers with the drawtube racked in, that should give you and idea how long an extension tube needs to be. The modified barlow idea will work enough to achieve focus but a 2" diameter extension tube will enable you to use a 2" eyepiece.

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While you need an extension tube you don't want one that's to long. When I had a 250PX fitted with a Revelation crayford I found the Moonlite one was the best as it's only 1.5" high so all my eyepieces would focus.,even those that needed a lot of in-focus.

FLO does a few different ones.

Moonlite 1.5" high extension


William Optics 2" focus extender tube


Two-inch Focus Extension tubes



Edited by johninderby
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