T-Adaptor / T-Ring advice?

[Brainstorm]

I bought a 48mm Canon EOS T-ring today, along with what I believe is a T-adaptor tube.. This is to fit my SW 130M eyepiece so it allow me to use my eyepieces in the T-Adaptor tube.

The adaptor tube fits the telescope, but the 48mm canon EOS T-ring does not fit either the thread of the telescope, nor the T-Adaptor tube.

When I place the camera over the T-adaptor tube (the part that fits the telescope) with my 25mm eyepiece inside, the view is blurred (I can see the image in the eyepiece, but not through the camera), it just shows the image around the outer edges of the picture.

Any ideas what's going on, or what I need to fix the problem?

Apologies if my terminology is a bit muddy; newbie alert!

[Psychobilly]

T- threads are M42x0.75... Skywatcher use a 48mm thread on some items...I guess you just have the wrong combination of parts...

Billy..

[GrantEb]

Hi

I believe you need the M42 T-ring adapter. The M48 fits the Skywatcher Coma corrector.

http://firstlightoptics.com/proddetail.php?prod=tadaptor

HTH

[Brainstorm]

Would the right T-Ring correct the issue with the picture being only visible around the edges of the frame too? I've put my camera on a similar mount on another telescope (also without T-Ring Adaptor) and can see everything clearly. I wonder why this isn't the case with this one?

[dmahon]

Camera -> T-ring -> 1.25" Tube (or 2" tube) -> Telescope

No eyepieces.

What are you trying to do?

Also you need to have enough "in-focus", which is a problem for some Newtonians. I believe that it is possible to unscrew something from the focuser of certain Skywatcher Newtonian telescopes, which allows the T-mount to connect directly to the telescope without the 1.25" tube, reducing the amount of in-focus required and allowing you to get a picture.

[Brainstorm]

Camera -> T-ring -> 1.25" Tube (or 2" tube) -> Telescope

No eyepieces.

What are you trying to do?

Also you need to have enough "in-focus", which is a problem for some Newtonians. I believe that it is possible to unscrew something from the focuser of certain Skywatcher Newtonian telescopes, which allows the T-mount to connect directly to the telescope without the 1.25" tube, reducing the amount of in-focus required and allowing you to get a picture.

I'm trying to attach the camera to the telescope, and have an adaptor tube that the eyepiece fits inside, but apart from the ring being the wrong sort and not fitting, there is no useable picture when I place the camera on the adaptor tube.

Are you suggesting I've bought something that will not work on my telescope?

If so, how are people doing astrophotography with their SW 130s?

[dmahon]

There are three methods of astrophotography

Prime focus

Eyepiece projection

Afocal

The latter two do use the eyepiece, but obviously this makes a huge difference to the F ratio and so is probably only useful for planetary and lunar photography (not deep space objects). I described the first, which is what most people with a DSLR seem to want to do. You seem to be describing the second option (the third option doesn't need a T-ring, as you use the camera lens).

What exactly have you bought (post a link) and what do you want to take pictures of?

[Brainstorm]

I'm more interested in deep space stuff, but I would like to photograph the occasional planet too. Although I get the feeling my clock drive won't be going at the right speed to track planets, so deep space stuff is all I'll be able to get with my setup. Is that right?

I guess I don't need the T adaptor tube (the left item in the photo in case I named it wrong).

These are the items I bought:

[Cornelius Varley]

The t adaptor you have purchased appears to be the Skywatcher M48-t adaptor. This one is designed for connecting various Skywatcher accessories to cameras etc. The t ring you need is this one T ring adaptor.

Peter

[dmahon]

Before you expend too much effort, have a look at some other threads - unfortunately the lack of adequate in-focus might be a problem for you to achieve prime focus with your camera:

http://stargazerslounge.com/equipment-help/128113-canon-300d-dslr-camera-skywatcher-explorer-130p-telescope.html

http://ukastroimaging.co.uk/forums/index.php?topic=49271.0

[Brainstorm]

So, basically, without modifying what I have (which I really don't want to do), I will not be able to do any astrophotography with my kit.

I think I'm going to have to send the T adaptors back and give up on the astrophotography, it's clearly not as straightforward as one would think it should be.

Oh well, it was worth a try.

[pwalsh61]

Don't give up! Where would the Bruce have gotten if he'd given up?

Where did you get the equipment from? Perhaps a quick call to them to explain what it is you want to do will help? It's in their interests to make sure you get the right equipment so you come back as a satisfied customer. From what I've see on the forums, the folks at FLO, Rother Valley Optics and Ian King Imaging are most helpful.

[Brainstorm]

Hi, I got my kit from the local astronomy shop, Paradigm Shift in Edinburgh. The ring was £12.50, and the T-Tube adaptor was £25. I mentioned a friend in Cambridgeshire wanted an adaptor for his Pentax, he offered to ship it for around £1, so he's very reasonable with pricing.

I've been thinking of sawing a bit of the focusing mount away to give me the extra few mm, if I unscrew the eyepiece mount the tube sinks in a good way beyond its normal minimum, so there's plenty room for chopping a few mm off. I'll see how it goes when I get the new ring.

Does the focusing issue apply when the tube is mounted? Because at the moment that's what I'm having a problem with.