On many fast refractors with larger cameras normal field flatteners reach the limit for field correction and illumination very quickly. Many modern refractors have large size focusers but till now only William Optics have had a universal field flattener of larger than 2“; that time is now past!
After several months of development and testing, the new 2.5" zero-power, field flattener is ready for the market and available from stock.
Specifications
2.5" Field Flattener - Universal Field Flattening Lens for f/5 up to f/9 refractors
2" or T2 flatteners are too small for big CCD cameras. This new 2.5" flattener has an open aperture of 62mm. It allows you to use large-chip CCD cameras (for example 24x36 mm) with fast f/5 refractors.
The distance between flattener and CCD sensor is 91.5mm - so you can continue to use accessories like filter-wheels or an off-axis-guider without any problem.
This is only a flattener; there is no reduction of the focal length.
You need a focuser that is large enough to accommodate this flattener. We offer ready-to-use adapters for the large focusers by Baader and Starlight Instruments and are working on more. We can also offer custom made adapters to your specifications.
Technical Data:
- for f/5 up to f/9 refractors
- open aperture: 62mm
- M68 male- and M63 female-thread at telescope side
- M69 female-thread at camera side
- distance between flattener and camera sensor: 91.5mm
