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Dyptorden

Problems attaching 2" accessories

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Hi,

My first two 2" accessories arrived, just to take me from smile to anger in a second.

I just bought a 2" Powermate and a 2" T-Adapter but they won't fit my focuser ring.

I took some measures, and they both are 50.8mm but the ring has the inner diameter of exact 50mm.

Is there any alternative to grinding the ring's interior diameter for 0.8mm? Or are there on the market similar but better constructed rings? (I didn't find rings only, and I can't afford at the moment buying another and maybe better focuser)

I attach some photos,

Thank you for your time,

post-40094-0-26439400-1421508428_thumb.j

post-40094-0-41522100-1421508433_thumb.j

post-40094-0-55922300-1421508436_thumb.j

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You need to unscrew the eyepiece holder from the Powermate and fit the T Ring in it's place.

Dave

post-21198-0-36505400-1421510051_thumb.j

Edited by Davey-T

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It has nothing to do with no T-Ring :)

I have two 2" accessories, and none of them can be inserted into the focuser's ring, since the focuser's ring is 0.8mm narrower in diameter (it only has 50mm and the 2" accessories are 50.8mm).

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What make is the scope / focuser ?

I that the focuser ring with two thumb screws in it ?

Dave

Edited by Davey-T

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What I just tryed was obtaining focus while holding the powermate in my hand, and I have observed that i must scroll the focus out at maximum and still hold the Powermate almost 1cm at distance to the focuser.I guess I need some kind of extender... but if I buy it... will it fit if no other 2" accessory fits the focusers ring?

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May need a 2" extension to reach focus (more money) can you post a pic of the focuser on the scope ?

Everything should be a standard size, has that "focus ring" got a thread in it ?

Dave

Is it one of these, why are you using it?

http://www.teleskop-express.de/shop/product_info.php/info/p4147_Skywatcher-short-design-2--adapter-for-Crayford-focusers.html

Edited by Davey-T

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It has no threads and looks similar to the one you've shown me.

(sorry... but I can't edit my posts, don't know why I don't have the Edit button)

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2" accessories should fit straight into the focuser, did the "ring" come with it ?

Dave

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The ring came with the telescope.

If I take the ring away, I remain with the focuser's tube only which is larger than the barrels... I can't fit the 2" accessories directly in the focuser's tube without the ring.

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I think you've got a bit missing, the focuser should be much deeper.

Try reposting with Skywatcher Dob in the title, should get the attention of somebody who has one, lot's on this forum.

Dave

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What do you mean by "the focuser should be much deeper" ?

I just pulled the tube out so that you can see it in the picture... i can roll it inside until there's nothing out.

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You need a 2" eyepiece adapter which is missing from your setup.

See photo below. It fits into the ring you were trying to fit the Powermate barrel into. This arrangement is unique to Skywatcher:

post-118-0-34571400-1421513482.jpg

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#1 shows the two new accessories. T-Ring left, EP Right.

#8 Why unscrew the fitting? The right image is correct but where is the standard skywatcher 2" adaptor. Fit that and the Powermate fits inside, then put your EP in the powermate.

You don't need that T-ring (yet)


Thats how it looks to me.  


And boy, don't folk type quicker than me? but I did have to pull my scope apart!

Edited by Charic

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Guys, no offence ... but I write again... there is NO T-Ring picture in this whole topic.

Thank you for the pictures John and houston, it's clear now.... since I never used 2" accesories until now, I forgot about that accessory.... Everything is fine now !!!

Thank you very much !

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I'm glad it's sorted. The Skywatcher arrangement is unique to their scopes and can be confusing. Another common mistake is to leave the 2" adapter in place and fit the 1.25" eyepiece adapter into the top of it. The result ? - 1.25" eyepieces won't come to focus anymore !

That internal rim in the ring that threads onto the drawtube will stop accessories with long 2" barrels from being fully inserted. This does not apply to the Powermate but there is a popular 2" ED barlow lens that won't fit all the way in !

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Hi,

My first two 2" accessories arrived, just to take me from smile to anger in a second.

I just bought a 2" Powermate and a 2" T-Adapter but they won't fit my focuser ring.

I took some measures, and they both are 50.8mm but the ring has the inner diameter of exact 50mm.

Is there any alternative to grinding the ring's interior diameter for 0.8mm? Or are there on the market similar but better constructed rings? (I didn't find rings only, and I can't afford at the moment buying another and maybe better focuser)

I attach some photos,

Thank you for your time,

Your right.......apologies. 

Some folk come across this accessory in the first place, and fit both the 2" and the 2" -1.25"  adaptors, unable to achieve focus. Only one adaptor at a time is required.

Glad you got it fixed.

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Guys, no offence ... but I write again... there is NO T-Ring picture in this whole topic.

Thank you for the pictures John and houston, it's clear now.... since I never used 2" accesories until now, I forgot about that accessory.... Everything is fine now !!!

Thank you very much !

It's your fault you said "T" adapter and confused me  :grin:

Dave

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However, long 2" accessories like barlows and coma correctors will bottom out on the focuser ring before they rest on the shoulder of the 2" adapter.

And, because they are pulled so far back, they won't come to focus.

That ring is about 1-15/16" I.D. below where the 2" adapter rests.

You will need to machine out the inside of the ring to 2" I.D. so the long 2" accessories will rest on the 2" adapter.

You could add a 2" I.D. focuser ring (available from some retailers), but then everything would move in too far and still wouldn't come to focus.

So your best bet is to sand out or have machined the I.D. of the focuser ring to 2".  Then, your 2" adapter would work great with 2" eyepieces

and all long 2" accessories would slide past the ring and rest on the shoulder of the adapter.

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