Spacing question - Is this right?

[swag72]

As I have a OSC on the way, I really do need to get to grips with spacing. So, I have taken a picture and highlighted where I think the spacing measurement should be taken to and from.

Can you good people have a shifty and see if you agree. If not, please tell me where I should be taking the measurements from.

In this example I am not using a reducer, so it's all fitting into an extension tube.

My understanding with the Atik is that I should have 56mm+/- in between the arrows I have drawn.

[Stephen]

If you are not using a reducer, the spacing does not matter

If you are using a reducer, the spacing is between the sensor (Atik flange minus 13mm) to the mating flange on the reducer.

[swag72]

Spacing doesn't matter with no reducer? I didn't realise that!

[Stephen]

Spacing doesn't matter with no reducer? I didn't realise that!

I tried to convey that the other day

"Spacing" is getting the CCD the correct distance from the optical element (the reducer) so it "changes" the light the correct amount (bad explanation I know!)

Too far or too close will result in the light being over or under corrected when it hits the sensor

[swag72]

It has to be in words of less than 5 letter for me to understand!!!

[Merlin66]

Sara,

With no reducer etc, then the telescope just acts like a big camera lens..all you have to do is bring the target star etc into focus on the CCD using the normal focuser.

That's it.

( the spacing "problem" arises when a reducer is used. It's designed to sit a specific distance in front of the final focus (ie the CCD) )

HTH

[swag72]

Perfect sense - Cheers Ken!

[swag72]

If you are using a reducer, the spacing is between the sensor (Atik flange minus 13mm) to the mating flange on the reducer.

Can I just confirm then that the measurement from the Atik flange is from exactly as I've marked it at the camera end? Or is it from the end of that sticky out bit?

[Stephen]

Can I just confirm then that the measurement from the Atik flange is from exactly as I've marked it at the camera end? Or is it from the end of that sticky out bit?

End of the sticky out bit is 13mm away from the sensor

Your spacing needs to be 55mm from the sensor to the reducer.

(Or 42mm from the end of the sticky out bit!)

[swag72]

42mm from the sticky out bit it will be then!! Thanks for clearing that up!!