How do I use the Baader M68 Fine-Adjustment Ring to fix my back focus?
If you have elongated stars in the corners of your image, you likely need to adjust your sensor-to-corrector distance. First, determine if you need more or less spacing. Then, insert a Baader M68 Fine-Adjustment Ring (starting with 0.5mm or 1mm) between your corrector and camera adapter to incrementally increase the distance until your stars are sharp across the field.
Which M68 ring thickness do I need: 0.3mm, 0.5mm, or 1mm?
The choice depends on your goal.
-
For Back Focus: The 1mm and 0.5mm rings are best for making initial, larger adjustments to spacing. The 0.3mm ring is for when you are very close to perfect focus and need to make the smallest possible change.
-
For Rotation: The 1mm ring allows a full 360° turn to re-clock threads. The 0.5mm ring gives a 180° turn, and the 0.3mm ring gives a ~120° turn for framing adjustments.
Can the Baader M68 ring help orient my camera on a large refractor's M68 focuser?
Yes, this is a primary use case. If your camera threads on and ends up upside-down or at an awkward angle, you can unthread it, add a Baader M68 Fine-Adjustment Ring of the appropriate thickness (e.g., 0.5mm for a 180° flip), and re-thread it. The camera will now tighten down at the desired orientation.
Will stacking multiple Baader M68 Fine-Adjustment Rings cause image tilt?
While these rings are precision-machined, stacking several thin shims can potentially introduce a small amount of tilt. For best results, try to use a single ring of the correct thickness. If you must stack, ensure all surfaces are perfectly clean and tightened evenly.
What is the M68 thread standard on this Baader ring?
The ring uses the standard M68x1 thread, meaning it has a diameter of 68mm and a thread pitch of 1mm. This is a common standard on many high-end focusers, field flatteners, and reducers from brands like Baader, Takahashi, and Astro-Physics.
Is the Baader M68 Fine-Adjustment Ring compatible with ZWO M68 accessories?
Yes. As long as the ZWO accessory uses the standard M68x1 thread pitch, this Baader ring will be fully compatible for adjusting spacing or rotation within your ZWO imaging train.
