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Thanks Matt. The two rear elements are fixed into the main assembly. There is no adjustment for centreing nor for spacing or angular adjustment between them. Only adjustment may be rotation of the elements, but I have not seen any markings to indicate a rotational reference.
As anticipated, I have spent my time slowly changing the separation between the front elementand the two fixed elements while maintaining angular alignment for airy disc pattern and checking visually.
I am using an artificial Star I made from some fibre optic cable and a white LED. My ccd camera does not show clearly the airy Discs pattern right at the focus point. I need to use an eyepiece and view by eye. I use a Tak 3.6mm eyepiece which gives about 250 times magnification.
The adjustments are a tedious process. Less than 1/10 of a turn produces a huge affect on the airy disc pattern.
It seems adjustments to the front element have most visual affect on the airy disc pattern outside of focus, while the adjustments to the whole assembly have a most visual affect on the airy disc viewed inside of focus.
I think I am getting close to setting it right. I will continue tomorrow.
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