Focusing - Newbie question

[Star Kid]

Good morning all, 

I got myself a T ring and  attached my DSLR to my skywatcher 130 last night in hope of capturing some images however hit I've hit a stumbling block. When i try to focus the canera on the moon i cant seem to wind in enough to reach focus. I thought that maybe it was a case of the moon being too close and i would need another adaptor to be able to use some eye pieces along with the camera. So this morning i tried to get a shot of a star (sorry i don't know the name) and found i couldn't focus on that either. I have since found out that its a common issue with my scope where you can't wind in enough. I hage heard you can overcome this by plugging a laptop into the camera abd use the laptop for live view but i am clueless at this point! If anyone can offer any advice it would be much appriciated!

Thanks and clear skies!

[Cornelius Varley]

This problem is common to many newtonian telescopes and is easy to fiix. If you use a barlow lens between the camera and focuser you should find that you can now achieve focus with the dslr.

[Star Kid]

I was under the impression that the t ring fits the focuser and the camera fits directly to that. I thought i would need another adaptor to be able to fit a barlow or am i being naive? Is there a way to fit the barlow without another adaptor?

Thanks for your help.

[ArmyAirForce]

My T ring has a 2 inch nosepiece adapter screwed on to it. To get more magnification, I have a x2 teleconverter which attaches to the camera bayonet fitting before fitting the T ring. The other way to do it is with a normal 1.25inch barlow, and a 1.25inch nose piece adapter.

http://www.firstlightoptics.com/adapters/flo-125-inch-t-mount-camera-adapter.html

http://www.firstlightoptics.com/adapters/flo-2-inch-t-mount-camera-adapter.html

[Star Kid]

Thanks for replies guys, looks like i'll have to invest in an adaptor with the nosepeice. Quite annoying as the guy in the shop showed me the t ring and said it would be a case of fitting and away i go. There was no mention of being able to focus the camera! I will have a look into using the laptop in the meantime.

[ollypenrice]

The use of a 2x Barlow will double the focal length and quadruple the exposure time. This won't matter on solar system targets but will be a massive disadvantage if you try any deep sky imaging. I don't know the specifics of your telescope but the other solution is to move the secondary mirror up the tube a little. In some cases it is possible to move it far enough just by using the collimation screws. As I say, I don't know the particular details of your scope but, as Peter said above, the problem is familiar.

Olly

[ArmyAirForce]

23 minutes ago, Star Kid said:

...... I will have a look into using the laptop in the meantime.

The laptop and live view won't help you. If the camera can't reach focus, it can't focus. You'll just see a blurred live view instead of a blurred image through the viewfinder. The camera sensor needs to get closer to the focusser to achieve focus; which it physically can't. A barlow moves the focus point out away from the focusser, bringing the focal point to a position where it can land on the camera's sensor in focus.

[Star Kid]

The scope is a skywatcher 130/900m. I wouldnt feel confident in adjusting mirrors etc without breaking it. I read an articke that said you could focus using the live view laptop method but im guessing I've misinterpreted that it was at half 5 this morning!

So i think i have two options:

1. Get an adaptor with a nosepiece

2. Adjust the mirrors etc (probably break the scope) 

[Star Kid]

Ive found a couple of barlow lenses, one of which is a celestron 1.25" universal barlow, T adaptor and T ring. Can this one be used with the skywatcher scope?

I also found skywatcher deluxe achromatic barlow but i'm not sure if that has the T ring part. Jessops' descriptions are vague. Gould anyone tell me if these will do the job and if so what one?

Cheers

 

 

[ArmyAirForce]

You will have to use a Barlow with the nosepiece. On its own, you still won't achieve focus, so if you don't have one, you'll need one of those too.

[Cornelius Varley]

The  Celestron barlow will work with your telescope.

[Star Kid]

Thank you i have just ordered it, should arrive tomorrow. I hope this works fingers crossed all will be well.

[Star Kid]

So the barlow turned up this evening! I've had a quick play as the clouds cleared and managed to achieve focus. I took a few pics of the moon and they are awful, but as all i wanted to do was focus I'm well chuffed. Thanks for all of the help, onto getting some better shots now!

Cheers

[cjdawson]

I'm wondering if there is some confusion on terminology that we're using, so to help clarify  let me talk you though it.

 

T-Ring.

http://www.jessops.com/online.store/products/90114/Show.html?utm_source=google&utm_medium=cpc&utm_campaign=PLA&utm_term=Canon%20Eos%20T-Ring&gclid=Cj0KEQiAz5y1BRDZ4Z_K_eGa84cBEiQAtQkeaK_YsVceblFTJNezwqO97xeF_kW-jsNVDRSKSaYytloaAvSa8P8HAQ

This is a ring that connects to your camera.  The ring has a thread on the inside which is standard.  It's known as a T-Thread.  This screw thread can then be used to attach to lots of items, old lenses, telescope parts, microscopes etc.

 

T-Adapter

http://www.tringastro.co.uk/celestron-t-adapter-universal---125-in-715-p.asp?gclid=Cj0KEQiAz5y1BRDZ4Z_K_eGa84cBEiQAtQkeaOQoKVnn8cewaZX17iCQ2-URAugP8icKVTGbavTprvEaAg9x8P8HAQ

This is a device that at one end acts like an eyepiece and at the other end has a T-Thread.  The idea is that you can screw this into a T-Ring, then it you can plug the adapter into the telescope just like an eyepiece.  As the camera is attached to the T-ring, hey presto, camera is now attached to telescope.

 

 

Why do it like this?  Different Cameras require different T-Rings.  Commonly Cannon use one fitting, Nikon uses another, as so Sony, Fuji, Kodak etc.  So, rather than needed a Whole T-Adapter for each camera, you just need a cheaper T-Ring, This is the only part that is different.

 

This also has the advantage that you can use different connection types later on...

 

Prime Focus adapters (These tend to be used on SCT scopes)  It's a T-Thread that screws directly to the focusser.

Some telescopes, namely the SkyWatcher ST-80 has a T-Thread built right onto the focusser.

Flip Mirrors has T-Threads, so you could attach a camera to one side, an eyepiece to another, and have it connect to other T-Thread devices.

The advantage of being able to connect directly to a T-Thread rather than using an eyepiece adapter is that you end up with a more secure fitting.

[nfazuk]

On 1/25/2016 at 09:31, ArmyAirForce said:

My T ring has a 2 inch nosepiece adapter screwed on to it. To get more magnification, I have a x2 teleconverter which attaches to the camera bayonet fitting before fitting the T ring. The other way to do it is with a normal 1.25inch barlow, and a 1.25inch nose piece adapter.

http://www.firstlightoptics.com/adapters/flo-125-inch-t-mount-camera-adapter.html

http://www.firstlightoptics.com/adapters/flo-2-inch-t-mount-camera-adapter.html

I've been trying to figure out how to connect my Nikon D800 to a SW 130PDS - I was under the impression this could only be done with a Coma Corrector - another £100 I didn't want to spend at this stage. Just order the 2" T Mount. Thank you. Perhaps I'll invest in a Coma Corrector when I get in to Deep Sky imaging.

http://www.firstlightoptics.com/coma-correctors/skywatcher-coma-corrector.html