optics-sept-6
A montage of a full range (10mm) focus sweep- focus 0 is at bottom left, focus 9500 is at top right.
Each image along a row has a focus +500 from the one before it.
To be concrete, the images in the left most column have, starting from the bottom, foci of 0, 2000, 4000, 6000, 8000 microns.
The DES r-band. Frames 1532-1552, Object at CCD2 row,col=2721,633
The NASA r-band appears to be 2mm closer to the secondary mirror than the DES r-band.
Frames 1485-1505, Object at CCD2 row,col=2721,633
The open filter slot appears to be about the same distance to the secondary mirror as the DES r-band.
Frames 1506-1526, Object at CCD2 row,col=2721,633
Looking back at the optics data set, it seems to us that if one believes the earthquake clips are putting significant torque on the secondary and if this is the primary cause of the optics issues, then one can determine which earthquake clip is at fault.
It seems (given the assumptions) that the optics are worst on the bottom right of the secondary as seen in the picture. The two earthquake clips that would be most suspect are the the ones at 6 oclock and 4 oclock.