TOA-645 field flattener

The new field corrector for imaging with Takahashi TOA-130 and TOA-150B refractors

Takahashi has adapted its TOA-67FL super-reducer to the constraints of digital imaging, with its large CMOS sensors and small pixels.

The TOA range of refractors are high-end telescopes with amazing performance. Images are extremely sharp and contrasted. The chromatism and the spherical aberration are controlled and perfectly corrected. However, this focus on aberration correction performance results in a greater field curvature than lenses of similar focal length; the image is distorted at the edge of the field, unless a field corrector or focal length reducer is used.

Until now, there were 2 types of flatteners for the TOA refractors. The 67-FL field flattener corrected an image circle that was oversized compared to the needs of current digital cameras. The quality of the aberration corrections up to 50 mm diameter was not suitable for the sensors requirements. The 35FL corrector, on the other hand, had been designed for a mixed use, photographic and visual, with the obligation to be able to adapt a mirror diagonal to the focus. This compromise did not allow to fully exploit the optical performances of the corrector.

The new TOA-645 field flattener removes these limitations and provides an optimal optical solution for both TOA models, allowing them to be used at their maximum performance, without any compromise. It is common to all TOA refractors. The corrected image circle has a diameter of 60 mm. The optimal backfocus of each telescope is achieved by using an M72 extension ring specific to each model : #51L for the TOA-130, #51S for the TOA-150. The photo adapter with M54 thread, or CA Ring35, is also common.

The mechanical input of the TOA-645 flattener is with M72x1 female thread, which makes it compatible with the focusing system of the TOA-130NS as well as with that of the TOA-130NFB and TOA-150B but also with those of the former models.


Main characteristics

Characteristic Takahashi TOA-645 field flattener
Optical design 2 lenses in 2 groups
Input mechanical interface M72x1 male thread
Output mechanical interface M72x1 female thread
Mechanical diameter 78 mm
Total length 42 mm
Weight 265 g

Available kits

Difference between the kits including the Takahashi TOA-645 field flattener
TOA-645 Flattener kit for TOA-130
TOA-645 Flattener kit for TOA-130
TOA-645 Flattener kit for TOA-150
TOA-645 Flattener kit for TOA-150