A little additional work since my last effort on 282.
Thought I would just share an
insight. My field is just about flat but I realized that the ASI 6200 tilt plate has three screws and a gap between the OAG and the plate. I used some feeler gauges to see what the space is between the two. It was about 0.5 mm but was not the same between the three screws… about 0.1 difference… this may give a check for adjustments, especially if I try to move the whole plate in 0.1mm as well as a locater for a screw out of whack causing a tilt.
The
feeler gauge is what is used to space spark-plugs (in the old days). $6 on Amazon.
My CPZ is 0.104 mm so careful work here can move the image circle up minutely. The screws are M 2.5 and their "pitch" is 0.45 mm, so a full turn move the screw that much , so 1/4 turn will move it 0.1125 mm.
The actual measurements of the spaces between the screws on my camera were:
0.48 0.35 and 0.38mm, given that the CPZ is 0.104, seems that this will be able to be fine tuned.
Note on this camera there is also a locking screw that is set after the adjustment. (Push-Pull)
In my Tak days I learned to make these adjustments vertically with the weight evenly adjusted over the three screws.
With the Tak 180 ED the CFZ was 0.017 mm, so even if you adjusted with a laser, you needed to look at the final result by eye. The CCDInspector image looks worse than it is since it enhances very small (possibly imperceptible) FWHM differences... 2.83 versus 3.02. This is what is called "curvature".
Finally, another topic is that this image uses a variation of Gary Imm's star masking technique to get RGB colors into a NB image. The mask uses StarXterminator rather than the PI masking procedures.
This is the recent version of 282.
Sh2 282 Field Flattening Exercise Older version of 284 with the same scope but a CCD.
Sh2 284 HA RGB
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