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