Moving my primary or secondary

[lfinn]

Hi

I have been thinking of modding my dob so I can do some imaging with it but I'm unsure how to calculate how much I need to move my primary or secondary so I can do afocal imaging

Does anyone have a calculation to optimize a dob for imaging

Thanks

Liam

[Laurie61]

I have done some afocal imaging and it does not require any mod's to the scope. You use an eyepiece, focused normally, and fit the camera above the eyepiece with the camera's lens looking squarely through the eyepiece.