Focus EOS 600D with Skywatcher 200p

[sward]

I have a Skywatcher 200p Dobsonian and wanted to use my 600D to get some better shots of the moon and planets than I can with my long lens. I have bought the T and SLR Ring which I have then plugged straight into the 1.25inch in place of the eyepiece. However, I can't focus on any objects in the sky, Jupiter and Saturn just looked like fuzzy doughnuts last night. Perfectly circular which is a start but still completely out of focus. 

This afternoon I thought I'd have another go in daylight and pointed at some trees approx 100-120ft away and the leaves were in focus with the focusser wound all the way in. With it all the way out I could focus on leaves on a shrub about 60ft away. 

I assume therefore that I need to get the camera closer to the tube but how? And how much? The tube that is screwed into the part that fits into the 2inch eyepiece holder is about 1.25 inches long but can I replace this? 

Does anyone have any ideas please? 

I can focus using normal eyepieces so don't want to resort to moving primary mirrors which was mentioned in another thread. As this is primarily being used for viewing not photography.

Thanks very much for your help in this matter.

Steve

 

[Cornelius Varley]

You will need a barlow lens to move the point of focus outwards. Like this.

Or attach the t-ring to the focuser as described in the video also.

[PaulM]

I have a 350p skywatcher dob and can get primary focus with my EOS 350D not sure if its the same as a 200p in this respect and therefore should be achievable i also have a lot more room so to speak when my 2" barlow is fitted as to get focus i dont have to fully wind in  the focuser

Edited August 17, 2020 by PaulM

[almcl]

You might want to loose the eyepiece tube in order to get close enough in to reach focus.

Here's what I used to do with my 200p :

 

Hope that makes sense?

[sward]

Thanks for this. I will look into these and let you know when I get some clear skies. 

And I'll let you know in a few days I hope!

[sward]

On 17/08/2020 at 22:07, almcl said:

You might want to loose the eyepiece tube in order to get close enough in to reach focus.

Here's what I used to do with my 200p :

 

Hope that makes sense?

I knew I needed to get closer to the tube, I didn't think it would be that simple. I just tested it fits (it does) now just need the clear skies.

Brilliant thanks!

S

[sward]

On 17/08/2020 at 21:14, Cornelius Varley said:

You will need a barlow lens to move the point of focus outwards. Like this.

Or attach the t-ring to the focuser as described in the video also.

Thanks Cornelius, just got time to watch this video and I can try both of these options as we have a Skywatcher and we have a Barlow as well. Now I wait patiently for the skies to clear so I can get a glimpse of Jupiter or Saturn!

Thanks for your help in this.

Steve

[sward]

On 17/08/2020 at 21:16, PaulM said:

I have a 350p skywatcher dob and can get primary focus with my EOS 350D not sure if its the same as a 200p in this respect and therefore should be achievable i also have a lot more room so to speak when my 2" barlow is fitted as to get focus i dont have to fully wind in  the focuser

Thanks Paul, I will be trying this when the skies clear. I looked at the video suggested above and it says exactly this. It's fantastic that there is so much help out there. 

S