If your camera is a Duo, you definitely have to use the shims (skip to the section: Where to Place the Shims?)
If your camera isn't a Duo, you have to determine whether the shims are needed.
There are two body versions used across the ZWO 2600 and 6200 series. Some units share the same body design as the Duo cameras, and depending on the version, the Z’Tilter installation may require the included shims.
How to know if your installation requires shims?
Measure approximately the gap highlighted with the question mark (?) in the image below. Depending on your camera, the measurement should be approximately 4.5mm or 7.5mm.
Here is how to decide:
If the measurement is approximately 4.5mm, don't use the shims.
If the measurement is approximately 7.5mm, use the shims.
If you don't have an instrument to measure in mm, you can compare the height of the gap with the height of the tabs inside the ring. This can give you an idea of whether the shims are needed to completely fill up the space in the image above.
Where to Place the Shims?
The shims should sit inside the recessed slots on the camera face. When placed correctly, the top of the shim ring will sit flush with the camera surface.
The image above shows the correct placement of a shim below the tab inside the mounting ring. When mounted this way, the top of the ring will be flush with the front face of the camera.
The process for installing with shims is basically the same as in the video, with the only difference that you have to place the shims in the gaps before attaching the ring.
After that, you will mount the front plate according to the instructions near the end of the YouTube video.