Hyperstar has the smallest Critical Focus Zone of them all, about 10um, so tilt has a big impact and it's very apparent once removed. Every time I assemble a "stack" of camera/connectors/spacers/filter wheel/filter drawer (any or all of the listed) for screwing onto Hyperstar, I must get the tilt out of the entire stack. And with the method I describe below, I see differences in tilt each time I change spacing anywhere in the stack. I've used this method with an ASI1600MC, ASI1600MM, ASI183M, and ASI071 cameras and never need to make any further adjustment for tilt after the camera's mounted. I know this with certainty using CCD Inspector's Real-Time Curvature Map feature to monitor every sub for correct focus. This method should work for any "stack" that can be removed and reattached to any telescope unless that attachment is optically bent in some way with the surface it rests on.
All of the camera sensors listed above reflect a regular matrix of dots from a low power red laser pointer source which I have not seen damage an unpowered camera sensor in any way. Surprisingly, this reflected matrix does not move as the camera's sensor is moved laterally for a laser that is mostly perpendicular to the sensor (This sounds like magic but that's what it does.). When the camera's sensor is moved too far latterly, the matrix of dots will disappear but it will not move which makes the adjustments described below possible. This means that if you can set up a laser that is perpendicular to a transparent surface that the entire "stack" can rest on, then the reflected matrix of dots (which has a center dot) can be used to remove all tilt from the "stack" by adjusting the camera's tilt until the center dot of the matrix is reflected back into the laser.
Step 1: build a simple laser alignment tool consisting of a laser pointer, or just its head", mounted into the approximate center of about a 14" x 12" board (plywood will do) which has some form of tilt adjusting. To adjust board tilt, I simply used 3 bolts of several inches in length going through the board and into T-nuts on the underside. The laser doesn't need to be perfectly perpendicular to this board since the tilt adjustment from the bolts will do the work.
Step 2: Mount about a 4 inch clear square of 1/4" thick Plexiglas over about a 2 inch diameter hole of a separate 3/4" x 6" wood plank about 3 feet long. This is the surface the "stack" will rest on. Make sure the Plexiglas does not bend (remains flat for a clean reflection) after mounting.
Step 3: Place the board with the laser on the floor. Above it, secure the plank onto a desktop high surface (screwed or held down with weights). Slide the board along the floor to approximately center the upward pointing laser into the desk mounted plank's hole. Then adjust the floor board's tilt until the laser reflects back into itself off the Plexiglas bottom surface. Since angle of incidence = angle of reflection, this guarantees the laser light that continues out above the Plexiglas top surface is also perpendicular to the Plexiglas top surface. You can now place the camera/connectors (i.e. "stack") on top of the Plexiglass and center it until an array of spots are reflected off the camera sensor back onto the board on the floor. All cameras I've used show these spots, ASI183mm/mc, ASI1600mm/mc, ASI071. Identify the center spot. This will be the spot closest to the laser and is also in alignment of the entire grid of dots. Other spots can appear reflected off the sensor cover glass but can be ignored by checking for their overall grid alignment. The grid's center spot must point back into the laser source to have a zero tilt on the camera sensor.
(Only, for cameras without a built in tilt adjustment) If you see tilt (and you will), add the 11mm thick ZWO tilt adjuster into your optics. In the case of Hyperstar, since the tilt adjuster mounts flush onto the camera's body, the adjustment screws must point down (toward the scope) which conflicts with Hyperstar's default filter drawer setup. So a shorter "custom" Hyperstar adapter is required. Space consuming and clumsy for making fine adjustments, I throw away the tilter's large thumb screws, replacing them with low profile flat hex bolts (just the pull screws) and insert thin strips of whatever that works to adjust tilt.
Edited by CCDer, 20 July 2019 - 10:46 AM.