Unusual focus problem

[Realtimedoctor]

Hi guys, 

I've a skywatcher 200p, with the standard focuser. I've been using it with my Canon 600D at prime focus without any issues. Usually I get to the focus point with the focuser half way out. 

Now, I recently got hands on a old QHY8L, I understand it's sensor distance to flange is 20mm. Whereas on my canon it would be around 55mm with the T ring attached. So math dictates that I'll need to move the focuser out by 35mm, to get the QHY8L to focus. Seems straightforward right? 

However, it turns out that even after moving the focuser out to maximum which is just about 30mm, I can't get focus, moreover I had to add another 2" extension ~30mm to the focuser, plus a T Adaptor to the qhy which again is out by ~10mm to get to focus. 

This is confusing, as I'm now about 70mm out from my initial position of focus and my camera is sticking out like Burj Khalifa on the telescope. I wonder if there is anyway, I could reduce this? 

 

[CraigT82]

Are you trying to focus the new camera on something too close? If you're looking at a tree or something closer than infinity you will need lots of outwards focus travel

[Realtimedoctor]

6 minutes ago, CraigT82 said:

Are you trying to focus the new camera on something too close? If you're looking at a tree or something closer than infinity you will need lots of outwards focus travel

Well, yesterday I was trying to focus it on something maybe a mile or so away, a house roof. 

Because I tried it the night before, and all I was getting was a black image, no stars nothing. So I tried to see if the camera works during the day, which it seems it is, however the focus position is way out. 

 

Could be that I was getting black images because I was too close to focus any light whatsoever? 

[michael8554]

Have faith in your maths.

Set it up to your previous DSLR  focus point with a spacer that gives you some range on the focuser.

Then point at Jupiter and fine focus.

Michael