Starfield 0.8x Adjustable Reducer/Flattener for 90/102mm Refractors
 Starfield 0.8x Adjustable Reducer/Flattener for 90/102mm RefractorsStarfield 0.8x Adjustable Reducer/Flattener for 90/102mm Refractors 

Starfield 0.8x Adjustable Reducer/Flattener for 90/102mm Refractors

  (1 Review)
✓ 2 year warranty


29x in stock shipped 1-2 working days

About this product

Model:  starfield_0.8x_90_rf
Part Number:  SF-08-90

The Starfield 0.8x adjustable reducer and flattener makes finding the correct back focus easy!  Fighting with adapters is a thing of the past! 

By adjusting the reducer to achieve 55mm of back focus is simple, and 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 adjust based on the table below and then set the reducer to the number that is calculated.

The reducer attaches directly to the StarField 102mm telescope focuser by removing the Axil lock.  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 Reducer can also be used for other Telescopes from 70mm to 102mm

  • aperture 102 mm / focal ratio f/7 - 55 mm 
  • aperture 80 mm / focal ratio f/7 - 57.6 mm
  • aperture 80 mm / focal ratio f/6 - 59.6 mm
  • aperture 70 mm / focal ratio f/6 - 61.6 mm 

Filters can be added inside the reducer.

The William Optics M63 to 2" Nosepiece Adaptor can be used to convert this reducer for use with focusers that do not feature a compatible M63 thread.

Design: Corrector and reducer for refractor telescopes

Telescope connection: M63x1 external thread

Camera connection: M48x0.75 external thread

Reduction factor: 0.8x

Lenses: 3 lenses with ED element

Coating: Multi-coating and internal blackening

Working distance: Variable (adjustable)

Adjustment range of the distance: 0-13 mm stepless

Suitable for: Refractor telescopes from 70 mm to 102mm aperture with focusers from 2.0"

Mechanical Diagram

Customer reviews

Average Rating (1 Review):  
Write a Review and share your opinions!

Rating (max 5):  
Excellent reducer
30 December 2021  | 

Tried it with Stellamira 90 mm F6. correct backfocus is about 59 mm +/- 0.5 mm.
worked well. flatfield for the entire APS-C sensor. no vignetting. Image circle 40+ mm. should work with Full frame with some flats.


Please fill in the form below to ask a question.