Takahashi 645 FLT for TOA130
The newly designed TOA-645 field flattener provides an optimal optical solution for both TOA models, allowing them to be used at their maximum performance, without any compromise. 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.
The newly designed 645 flattener features two fully multi-coated lens elements in two groups and provides outstanding correction out to a 60 mm image circle. Being designed specifically for the TOA-130N and TOA-150B, RMS spot diameters of 1 micron on-axis are achieved. At a 30 mm diameter image circle, the RMS spot diameter is 2 microns, and at 43 mm it is 3 microns. Even out to the full diameter of 60 mm, the RMS spot diameter is 5 microns. With these spot sizes, images are nearly aberration on even the newest small pixel sensors
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Optical characteristics
| Characteristic | Takahashi TOA-645 flattener kit for TOA-130 |
| Focal length (TOA-130) | 990 mm |
| Focal ratio (TOA-130) | 7.6 |
| Corrected image circle diameter | 60 mm |
| Metal back distance (M72x1 thread) | 83.7 mm |
| Metal back distance from CA35 ring (M54x0.75) | 56.2 mm |
Mechanical characteristics
| Characteristic | Takahashi TOA-645 flattener kit for TOA-130 |
| Mechanical input | M72x1 male thread |
| Mechanical output (field flattener) | M72x1 female thread |
| Mechanical output (CA35) | M54x0.75 female thread |
| Mechanical diameter | 78 mm |
| Total length | 70 mm |
| Total weight | 360 g |
