Do I need this adapter?

[hobsey]

Just been reading 'making every photon count' and there is a picture of a DSLR on an ST80 with an adapter on to achieve focus after removing the diagonal.

I already have the T ring, is this the adapter I need to achieve focus?

http://www.telescopehouse.com/acatalog/Revelation_T_Adaptor_2__.html

Cheers.

[Cornelius Varley]

The ST80 uses a 1.25" focuser so you will need a suitable 1.25" extension tube to reach focus.

[Lonestar70]

Hi Hobsey,

Yes... you will need the part in your link to go with your camera t-ring.

You will also need the following part to replace the diagonal: -

http://www.telescopehouse.com/acatalog/Revelation-Self-Center-50mm-extension-tube-2-.html

Hope this helps.

Best regards.
 

Sandy.

[datman]

Without the extension tube your telescope(s) won't have enough outward travel

[hobsey]

The st80 already has a 2" thread on it as I can screw my camera straight on to it using the t ring so I think all I need is the extension piece.

[Thalestris24]

Hi Hobsey,

Yes... you will need the part in your link to go with your camera t-ring.

You will also need the following part to replace the diagonal: -

http://www.telescopehouse.com/acatalog/Revelation-Self-Center-50mm-extension-tube-2-.html

Hope this helps.

Best regards.

Sandy.

Hi

Edit: ah there is in fact a thread on the of the ST80 drawtube... So maybe better to make use of it from a vignetting point of view

Louise

[hobsey]

So maybe better to make use of it from a vignetting point of view

Sorry, what do you mean by this?

[hobsey]

Don't worry, I know what you mean.

I was planning on using the thread on the drawtube, just needed to know if the was the right extension tube before ordering one.

[hobsey]

Thanks for the help guys.

[Thalestris24]

Sorry, what do you mean by this?

Hi

It's just that the narrower the light path between the scope and camera the more evident the vignetting. That appears as a circular gradient on your subs - lighter in the middle. I actually have a 1.25" adaptor on mine:

http://www.firstlightoptics.com/adaptors/celestron-125-inch-t-extension-93625.html

But I do get a lot of vignetting with it. As there is a thread on the outside of the drawtube it might be better to make use of it. It looks like a t-thread (M42) in which case I think you'd need a female to male T-extension tube. I guess a 40 or 50mm one would do.

Louise

[Thalestris24]

Hi

I just fitted one of these to my ST80/Canon: http://www.teleskop-express.de/shop/product_info.php/info/p4872_TS-Optics-T2-Extension-Tube---40mm-length.html

Can get equivalent from Rother Valley: http://www.rothervalleyoptics.co.uk/baader-t-2-extension-tubes.html (the 40mm option)

The only thing I would say is that it's not so convenient compared to using the 1.25" adapter because you can easily slide that in and out to remove the camera or change the camera orientation. With the t-adapter it's screwed onto the draw tube at one end and screwed into the camera at the other.

Here are some pics to make things clearer:

T-ring, Celestron t-adaptor, 40mm T extension:

Canon attached to ST80 via Celestron T-adapter:

Canon attached to ST80 via 40mm male to female T extension:

Sorry for the pic quality, I just did them quickly with a handheld webcam...

Hth

Louise