Closing in on the moon

[Simon Dunsmore]

Hi Folks, 

Quick question from a newbie. So I have a shiny new Skywatcher 200pds (which I love!) I was looking at the the moon recently and thought it would be great to take some zoomed in shots with my dslr. 

I got me a T adapter and a Seben eyepiece holder so that I could incorporate the power of the eyepiece into the set up. Problem is, I can't focus enough. 

I know I can with the barlow attached but how do I achieve additional zoom so that I can photograph what I actually see through an eyepiece? 

I have Included a photo of the setup. 

Any advice greatly appreciated. 

Thanks Simon 

[Cornelius Varley]

Is there an eyepiece in the eyepiece holder ?

[Simon Dunsmore]

Hi, 

Yes there is a 15mm eye piece, but it can take any. 

[Simon Dunsmore]

Will moving the eyepiece inside the lense tube (closer or further away from the camera)  help? 

 

[Ruud]

Yes, moving the eyepiece might help. In this setup the eyepiece has to focus an image onto the sensor. See here:

http://www.astronomysource.com/2011/10/13/eyepiece-projection/

To photograph what an eyepiece shows used visually,  you should use an afocal method: eyepiece in telescope, focus for visual, move head away and camera in place. The camera needs to have a wide field lens on it if you want to capture the whole view. I think eyepiece projection gives better results than the afocal method, but I'm not certain.

[Simon Dunsmore]

Hi, 

Thank you for your help. 

Sorry if this is a silly question, still new to all of this. Why can't I get the camera to focus?  I can't wind the focuser any further in. Do I need to add anything to the set up to make it work? 

The link was very helpful. 

[Ruud]

To every position of the eyepiece in the tube belongs a range of focus distances that the focuser can cover.

Try with a strong yet distant light source (*) and use a piece op tracing paper instead of the camera. When (by turning the focuser) you can reach focus about 5.5 cm behind the adapter your are close to a good setup for your camera.

With Canon, I believe, the sensor is 55 mm behind the lens connector. You will have to experiment a bit.

(*) a poorly shaded street light, a narrow beam torch shining straight at the camera. The further the better

---

Edit: another idea. Have you tried with and without the diagonal?

[Simon Dunsmore]

Hi Ruud, 

Thanks again for your assistance. I don't have a diagonal. The set up fits directly into the focuser on the scope. 

 

[Luna-tic]

Try a different EP in the tube, one with shorter f/l (such as a 20 or 25mm). You may not have enough back focus available with that EP adapter. An alternative to using that adapter tube is to use an EP that has a threaded collar for a T-ring already on it (such as a Celestron Ultima Duo, or Baader Hyperion)

[Simon Dunsmore]

Hi, 

Thanks again, great advice, just need some clear skies here in Kent to experiment. 

Thanks again 

Simon