Nov 20, 2024 by WO Team
Applicable to all Adjustable Flattener:
- FLAT 61A (1.0x)
- FLAT 73A (1.0x)
- FLAT 73R (0.8x)
- FLAT 6AIII (0.8x)
- FLAT 68III (1.0x)
- FLAT 7A (0.8x)
- FLAT 8 (0.72x)
- Dr. Flat (0.8x)
To address the optical path shift caused by temperature variations during imaging, William Optics has designed most of our flatteners with an adjustable back focus mechanism. (Learn more about back focus.) This adjustability also allows certain flatteners to be compatible with multiple telescope models. However, each combination results in a different back focus distance. In some cases, the back focus distance may be long enough to require the use of extenders.
The table below provides information on the compatibility between telescopes and flatteners (indicated by ★) as well as the required adapters or extension tubes.
Flattener compatibility table
Flat 61A
1.0x | Flat 73A
1.0x | Flat 73R
0.8x | Flat 6AIII
0.8x | Flat 68III
1.0x | Flat 7A
0.8x | Flat 8
0.72x | Dr. Flat
0.8x | |
GS-61 | ★ | |||||||
Z-61 | ★ | |||||||
Z-73 | ★ | ★ | ||||||
Z-81 | ★ | |||||||
Z-126 | ★ | ★ | ||||||
GT-71 | ★ | |||||||
GT-81 | ★ | |||||||
GT-81 WIFD | ★ | |||||||
GT-102 | ★ | ★ | ★ | |||||
GT-153 | ★ | ★ | ★ | |||||
FLT-91 | ||||||||
FLT-120 | ★ | |||||||
FLT-132 | ★ | ★ | ★ | |||||
FLT-156 | ★ | ★ | ★ | |||||
RC Series | ★ |
How to Determine the Adjustment Distance?
You can find the adjustment distance data on the product page of your flattener.
Flattener Product Page > Spec and Compatibility > Compatibility > Adjustment Distance
How to Adjust Back Focus?
- No matter how complicated the structure of the front part is, please find the back adapter connected to the camera.
- If your setup requires additional back extender, please remove the original part and install the extender.
- Adjust the back adapter to the required distance.
- Tighten the ring against the back adapter.
Fine Tuning
According to the aberration pattern of the surrounding star points of your image, you can determine whether to extend or shorten the Flattener back focus.
▲ Camera Sensor Too Close
▲ Camera Sensor Too Far Away