TEC 0.9x Focal Reducer Corrector for APO 140 ED/FL The TEC FRC 0.9× combines field flattening with a 10% reduction in focal length. TEC specifies a 51 mm image circle, or a 36 × 36 mm square format, with approximately 10% corner vignetting.
Manufacturer model: TEC 0.9x Focal Reducer Corrector for APO 140 ED/FL · Specifications checked against manufacturer data on 2026-11-04
The TEC FRC 0.9× combines field flattening with a 10% reduction in focal length. TEC specifies a 51 mm image circle, or a 36 × 36 mm square format, with approximately 10% corner vignetting.
The current manufacturer table gives two separate spacing references for APO140FL f/7: “Back Focus Range” is 127–128 mm, while “Back Focus Real” is 118–119 mm. These are different mechanical references, so use the drawing and adapter that match the imaging train.
The FRC fits the Starlight Instruments FTF3545 focuser. With the named APO140FL f/7, applying the 0.9× factor gives a calculated 882 mm focal length at approximately f/6.3. TEC supplies the reducer configuration for the telescope specified when ordering.
TEC manufacturer documentation
Current TEC FRC table used rather than older telescope accessory prose quoting f/6.2 or 115 mm generically. Range and Real spacing columns are kept distinct. Derived focal length/ratio are arithmetic from 0.9×, not additional manufacturer measurements. ED variants must use their own adapter reference; FL spacing is not silently assigned to ED.
| Correction | Field flattening and focal reduction |
|---|---|
| Published image circle (mm) | 51 |
| Published square format (mm) | 36 × 36 |
| Manufacturer corner vignetting | Approximately 10% |
| Spacing table model | APO140FL f/7 |
| Manufacturer back focus range | 127–128 mm |
| Manufacturer back focus real | 118–119 mm |
| Derived effective focal ratio | 6.3 |
| Derived effective focal length (mm) | 882 |
Data sheet
TEC 0.9x Focal Reducer Corrector for APO 140 ED/FL The TEC FRC 0.9× combines field flattening with a 10% reduction in focal length. TEC specifies a 51 mm image circle, or a 36 × 36 mm square format, with approximately 10% corner vignetting.
Manufacturer model: TEC 0.9x Focal Reducer Corrector for APO 140 ED/FL · Specifications checked against manufacturer data on 2026-11-04
