Adjustable Flattener for 80 - 155mm telescope

Starfield Optics

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Product Overview


The Starfield 1.0x adjustable flattener makes finding the correct back focus easy! Fighting with adapters is a thing of the past!


By setting the adjustment required for your telescope, achieving the correct amount of back focus is simple. If more adjustment is needed for fine tuning all that is needed is a small twist. If you are using accessories such as filter wheels and rotators you can not still get the required back focus. Just add up the thickness of all the accessories, plus the distance to your sensor and subtract from 69.87 and then set the reducer to the number that is calculated.


The reducer attaches directly to the Starfield telescope focusers. Using the supplied 1.5mm Allen key, loosen off the three screws a half turn and then unscrew the lock.

Thread the reducer onto the focuser.


This Flattener is designed for telescopes ranging from 80mm to 155mm


  • 80 mm / focal ratio f/6 - 81.2 mm
  • 90mm / focal ratio f/6 - 82.5mm
  • 102 mm / focal ratio f/7 - 75.3 mm
  • 115 mm / focal ratio f/7 - 73.0 mm
  • 130 mm / focal ratio f/7 - 69.7 mm
  • 140 mm / focal ratio f/6.5 - 68.0 mm
  • 155 mm / focal ratio f/8 - 57.0 mm



Filters can be added inside the reducer.


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