Takahashi Back Focus Guide for CCD and Photographic Applications
| Model - Focal Ratio | Focal length - metal back distance | Reducer F-ratio · focal length · metal back distance | Flattener focal ratio · focal length · metal back distance |
| FC-50 . f/8.0 | 400mm | f/5.8 · 290mm · 55.0mm | n/a |
| FS-60C . f/5.9 | 355mm . 143.9mm | f/4.4 · 264mm · 56.0mm | f/6.2 |
| FC-60E . f/8.3 | 500mm . 173.5mm | f/6.3 · 380mm · 60.7mm | n/a |
| FC-65 . f/7.7 | 500mm | f/5.9 · 380mm · 60.79mm | n/a |
| FCT-76 . f/6.4 | 487mm | f/4.5 · 345mm · 72.8mm | n/a |
| FS-78 . f/8.1 | 630mm . 165.9mm | f/6.1 · 474mm · 72.3mm | n/a |
| FSQ-85ED . f/5.3 | 450mm . 200mm | f/3.86 . 328mm . 72.2mm | f/8.0 . 675mm . 117.5mm |
| FCL90 (SKY-90) . f/5.6 | 500mm . 170.5mm | f/4.5 · 407mm · 72.2mm | same |
| FCT-100 . f/6.4 | 640mm | f/4.6 · 460mm · 76.95mm | n/a |
| FS-102 . f/8 | 820mm . 194.5mm | f/6.0 · 614mm · 83.9mm | n/a |
| FSQ-106 f/5 | 530mm · 120mm | | |
| FSQ-106ED f/5 | 530mm . 178mm | f/3.6 . 385mm . 72.2mm | f/8.0 . 850mm . 117.5mm |
| FC-125 . f/5.6 | 705mm | f/5.9 · 740mm · 134.5mm | n/a |
| FS-128 . f/8.1 | 1040mm . 198.78mm | f/6.0 · 770mm · 83.9mm | n/a |
| FS-128F . f/8.1 | 1040mm . 218.5mm | f/6.0 · 770mm · 106.2mm | f/8.2 · 1055mm · 106.2 |
| FCT-150 . f/7.0 | 1050mm . 309mm | f/5.0· 750mm · 102.45mm | n/a |
| FS-152 . f/8 | 1216mm . 218.5mm | f/6.0 · 774mm · 106.2mm | f/8 · 1223mm · 106.2 |
| BRC-250 f/5 | 1250mm · 106.2mm | n/a | n/a |
| FRC-300 f/7.8 | 2348mm · 106.2mm | f/5.9· 1770mm · 83.7mm | |
| TOA-130 . f/7.7 2.7" focuser | 1000.0mm · 200.0mm | f/5.79 · 780mm · 83.7mm w/TOA Reducer f/5.6 . 728mm . 106.2mm w/Super Reducer | f/7.5 . 980mm . 117.5mm w/TOA-130 FN |
| TOA-130 . f/7.7 4" focuser | 1000.0mm · 200.0mm | f/5.79 · 780mm · 83.7mm w/TOA Reducer f/5.6 . 728mm . 106.2mm w/Super Reducer | f/7.7 . 1000mm . 106.2mm w/TOA-130FF |
| TOA-150 . f/7.33 | 1100mm . 214mm | f/5.7 . 860mm . 106.2mm w/TOA Reducer f/5.5 · 825mm · 106.2mm w/Super Reducer | f/7.3 . 1090mm . 106.2mm w/TOA-130FF |
| TSA-102S f/8.0 | 816mm | f/5.98 · 610mm w/TOA Reducer | f/7.84 . 800mm w/TOA Flattener |
| E-130 . f/3.3 | 430mm · 56.0mm | n/a | |
| E-160 . f/3.3 | 530mm · 56.0mm | n/a | |
| E-200 f/4.0 | 620mm · 59.8mm | n/a | |
| E-210 . f/3.0 | 628mm · 62.8mm | n/a | |
| E-250 . f/3.4 | 854mm · 84.2mm | n/a | |
| E-300 . f/3.8 | 1130mm · 122.0mm | n/a | |
| E-350 . f/3.6 | 1248mm | n/a | |
| M-180 . f/12.0 | 2160mm . 133.0mm | | f/9.8· 1763mm · 56.0mm |
| M-210 . f/11.5 | 2415mm · 162.0mm | | f/9.3 · 1961mm · 56.0mm |
| M-250 . f/12.0 | 3000mm · 150mm | | f/9.3· 2328mm · 56.0mm |
| M-300 . f/11.9 | 3572mm · 107.5mm | | f/9.1 . 2739mm . 56.0mm |
| CN-212 . f/12.4 | 2630mm · 154.0mm | f/9.9 · 2105mm . 56.0mm | |
| CN-212 . f/3.9 | 820mm · 56.0mm | | |
| MT-130 . f/6.1 | 795mm . 91.0mm | f/4.8 · 618mm · 56.0mm | *f/8.2 · 1060mm · 61.0mm |
| MT-160 . f/6.3 | 1000.0mm . 93.0mm | f/4.9 · 776mm · 56.0mm | *f/8.3 · 1330mm · 61.0mm |
| MT-200 . f/6 | 1200.0mm . 87.0mm | f/4.9· 970mm · 56.0mm | *f/8.0 · 1600mm · 61.0mm |
| EXTENDER-Q 1.6X | 125mm | | |
| EXTENDER-TOA 1.6X | 117.5mm | | |
| *Extender/Flattener The metal back distance is measured from the point at which the end of the reducer and the camera adapter come together, hence the name "metal back". Takahashi has measured these distances for optimum performance for photographic or CCD applications. |
