William Optics 0.72x Reducer/Flattener Full-Frame: full-frame speed for large apos
The William Optics 0.72x is the reducer-flattener for the large apochromats from the WO lineup: the GT102 (with 3-inch focuser), FLT132, and GT153. It flattens the field of view up to full-frame and shortens the focal length to 0.72x: almost a full stop of speed gain and a wider field of view.
Every refractor naturally produces a slightly curved image plane; a flat camera sensor cuts right through it, causing stars in the corners to stretch into streaks. A flattener corrects that curvature so that stars remain small and round all the way to the corners.











Ohara glass optics
The triplet made of Japanese Ohara glass with FMC coating keeps stars sharp to the corners of a full-frame sensor, with maximum contrast and minimal reflections.

Adjustable back focus
You adjust the distance to the telescope by rotating the flattener, allowing you to tune it for different cameras, from DSLRs to cooled CMOS. The M48 camera side with integrated filter thread incorporates your filter directly into the train.
Featured accessories
Connect your camera with the William Optics M48 adapter or 48 mm T-ring for your mount.
For whom yes and for whom no
- ✓ Owners of a GT102, FLT132 or GT153 who shoot full-frame
- ✓ Deep-sky astrophotographers seeking a speed advantage on a large apo
- ✗ Owners of smaller William Optics apos: the Flat6AIII and Flat7A are the go-to choices for them
Specifications
| Type | Reducer-flattener |
| Reduction factor | 0,72x |
| Image circle | Full-frame |
| Optics | Triplet, Ohara glass, FMC coating |
| Suitable for | William Optics GT102 (3 inch focuser), FLT132, GT153 |
| Telescope silk | M92 |
| Camera side | M48 with integrated filter thread |
| Backfocus | Adjustable |
You can find more accessories for this merk at the William Optics merk Page.





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