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2" T-adapter, do I need any special equipment?

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#1 SpaceFreak131

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Posted 15 January 2013 - 08:36 PM

Hey guys,

I have the standard T-adapter for Canon cameras from Orion (http://www.telescope.../sc/62/e/44.uts)

Right now I'm using a 1.25" adapter. I want to move up to 2", do I need a new T-adapter?

#2 Phil Sherman

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Posted 15 January 2013 - 10:18 PM

As long as the 1.25" nosepiece unscrews from the T adapter, no. You'll only need a T to 2" adapter. When I needed one, I purchased a 2" to 1.25" compression adapter. When I remove the compression ring, the remaining part is a 2" to T adapter. This was less expensive than a T to 2" adapter and serves as a dual use piece of gear.

Phil

#3 SpaceFreak131

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Posted 16 January 2013 - 12:21 PM

Thank you Phil, however I need a little more clarification. You have the T-ring attached to the camera, and the 1.25" T-adapter on the camera, and then you bought a 2" to 1.25" compression adapter. I can picture that in my head, but I don't understand how when you remove the compression ring, you have a 2" to T adapter. Maybe if you linked me to a part that youre referring to, I'll know better what you mean.

#4 cavefrog

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Posted 17 January 2013 - 10:28 AM

If you look at this picture, you see there is actually 2 rings. one inside the other. this combo is your t adapter for a 1.25". when you remove the inner ring, it becomes a 2" adapter.

the chain goes as such...
camera...2" T-adapter...2" camera adapter...2" focuser. or
camera...1.25" T-adapter...1.25" camera adapter...1.25" focuser.

There are quite a few variations of these camera to telescope setups, and these are the simplest.

it's ok, this confused me at first also.

If at first you don't understand.... GOOGLE!

Theo

#5 cavefrog

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Posted 17 January 2013 - 10:58 AM

I just reread the op. the answer is if your T-ring is a 2 piece ring , then no you do not need another one, but you will need a new 2" camera adapter.
If your T-adapter is a 1 piece, then yes, you will need both a new 2" T-ring and a 2" camera adapter.

What Phil was talking about was a using a common 2" to 1.25"
adapter with a compression ring in it, that is used for many different applications, but most commonly for using 1.25" EP's in a 2" focuser.

hope this helps.

Theo

#6 cavefrog

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Posted 17 January 2013 - 11:08 AM

I looked at your T-ring, and it looks like it is a 2 piece. tiny holes in the edge have jeweler size screws that lock the 2 rings together. loosen these (3 I think) and the 1.25 will unscrew from the 2".

probably! there might be other circumstances of which I do not know, like they might be glued! be careful! you will be working with very tiny setscrews and very fine threads that can crossthread easily.

Theo

#7 SpaceFreak131

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Posted 18 January 2013 - 07:18 AM

You know, I was looking at it before I ever posted this thread, and I was like, why is there a semi-loose inner ring and does it come out..?

But I guess I know why now! Thank you

#8 Geo.

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Posted 20 January 2013 - 05:05 PM

The reason is that the standard T adapter front flange is 55mm from the film plane of your SLR, that is the back space is 55mm. The T thread is a standard too: 42 by .75mm. Every brand SLR may have had a different back space. To get the T lens to focus properly in all these cameras require the body of the adapter be machined in a specific thickness for each manufacture's camera. Camera back space + adapter thickness = 55mm. However, the T thread insert can be made in volume and fit to the different adapters. Also allowing the insert to rotate in the adapter lets you loosen it and rotate the camera body to the orientation you need. some adapters will have a thumb screw in the place of one set screw to facilite loosening and resetting the T ring's position.

To avoid vigetting the image you should get a T male to 2" insertion barrel adapter. See image below of the APS-C imager and the T ring opening. Telescope Warehouse, scophed1, on eBay sells one for about $20, he may be a vendor here, too. Best price I've seen.

Attached Files



#9 SpaceFreak131

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Posted 21 January 2013 - 08:26 AM

That's definitely an attractive price, the only caveat though is that I would have to buy 2" filters now as opposed to 1.25" ones.

#10 oo_void

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Posted 21 January 2013 - 10:01 AM

The T-Ring adapter connects to the lens mount, allowing you to screw on T2 thread telescope accessories. As is usually the case with this hobby, you'll need a few more items. First, you'll also something like this ...

http://www.telescope...Adapter/p/10...

Additionally, if you normally use a diagonal with your scope (you didn't mention what you have), you'll typically need some sort of extension to achieve focus such as this one ...

http://www.telescope...e/p/5124.uts...

If you can afford a bit more money, I prefer this over the simple extension.

http://www.telescope...apter/p/9964...






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