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2" thread/M48 thread

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gabrieli
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2" thread/M48 thread

Post by gabrieli » Sun Aug 04, 2019 11:23 am

In some current work, I'm attaching a 2 inch focal reducer to a 2 inch extension tube with a good fit. Then I attach the 2 inch extension tube to an M48(2") to T2 adapter. Finally, I attach a T2 to 1.25 inch eyepiece holder (see image). Although the M48 thread is described as being 2", the fit is not perfect and the threads seem to cross after about 1.5 turns. The attachment is secure since it's not carrying significant weight but I find the same situation trying to connect other M48(2") devices to "true" 2 inch threads. I've had some difficulty finding a "true" 2" to T2 adapter.

Does anyone have any source for a "true" 2" to T2 adapter without the "M48" in its name?

Lou
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christian viladrich
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Re: 2" thread/M48 thread

Post by christian viladrich » Sun Aug 04, 2019 8:35 pm

Maybe, have a look at Telescope Service, they have a lot of adapters. I have not checked whether they have that one.
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Re: 2" thread/M48 thread

Post by marktownley » Mon Aug 05, 2019 6:01 am

I've found this sort of thing before too. Telescope service is excellent for things. Does the reducer thread onto the m48/t2 adaptor properly?
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Re: 2" thread/M48 thread

Post by AndiesHandyHandies » Mon Aug 05, 2019 9:42 am

Hi

Baader use a different thread on their 2" extension tubes to Revelation ones.

Revelation M48 to T2 seem OK to me.

I am thinking of using T2 instead for a DS as it seems to be more 'standard'.

Andrew.

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Re: 2" thread/M48 thread

Post by gabrieli » Mon Aug 05, 2019 10:41 am

Hi, Mark

The 2" reducer fits the 2" extension tube perfectly but doesn't fit the M48/T2 adapter. That tells me that the 2" extension tube threads and the reducer threads are a perfect match. However, when I try to attach the reducer to the M48 threads on the m48/T2 adapter, the threads will seize after 1.5 turns. There is an obvious difference in M48 threads and what I call a "true" 2" thread.

In the post above, Andrew mentions Revelation extension tubes. Although extension tube threads are not an issue. Its the M48 threads that cause the problem. I'll look into that and see if there is a Revelation adapter that fixes the issue.

Lou

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Re: 2" thread/M48 thread

Post by marktownley » Mon Aug 05, 2019 6:07 pm

Your other way then Lou would be to ditch the 2" extension tube and get a 2" T2 extension, put it between the ep holder and the m48/T2 adaptor.
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Re: 2" thread/M48 thread

Post by AndiesHandyHandies » Tue Aug 06, 2019 9:37 pm

Hi

I have been trying to mount the PST Etalon in a 2" focusser, with the Collimator lens in a 1.25" barlow nosepiece suspended inside and a 2" extension on the front for a possible 2" ERF or just an extra baffle for the Sun cone. Photos to come.

The Revelation 2" extension threads onto a Guan Sheng ED Barlow nosepiece and Kood 48mm to 43mm step down ring threads.
And their M48 to 42T2 threads into their extension ring properly.

They are a different thread to the Baader extension rings and filters.

The Kood 48mm to 43mm step down adapter threads onto the Revelation and Baader extension rings so tolerance designed in?

The front PST to 48mm adapter I bought does not match the Revelation extension tubes or Baader threads on their extension tubes or filters. A bit annoying.

Andrew.

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Re: 2" thread/M48 thread

Post by AndiesHandyHandies » Tue Aug 13, 2019 6:48 pm

Hi

More playing about the Revelation extension tube does screw into the AOK Swiss PST front adapter, the Black2 paint making it tight.

Andrew.

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