Addendum - Optical Components

TS-Optics M90/2,5"Rack and Pinion Focuser 

updated: 2025-09-09


TS-Optics M90/2.5" Rack and Pinion Focuser - supports up to 6 kg - max. travel distance:  95 mm


The alternative to Starlight Feather Touch FTF2535 refractor focuser or the OEM Crayford  focuser


  • For refactors, RC and Cassegrain telescopes - up to 6 kg payload
  • Including telescope connection (M90 female thread) and 360° rotation
  • M63 threaded connection on the eyepiece side with 2" and 1.25" adapter
  • Draw tube travel 95 mm - perfect for refractor telescopes
  • Finder shoe already mounted
  • Important: 
    • This focuser requires the 50 mm M90 extension tube to be used with an RC205/1624 reflector telescope because the inner mirror diameter is smaller than the focuser's diameter (69 mm + 3 mm for the rack).
    • For this reason, this focuser cannot be used with the 0.67x reducer, as otherwise the focus point is closer to the end of the telescope and cannot be reached.


Telescope Express: TS-Optics M90 Rack and Pinion Focuser

Technical data

Connection on telescope side:

81 mm push-in connector and M90x1 female thread (12 mm deep) with 360° rotation

Camera side connection thread:

M63x1 mm internal thread

Eyepiece side connections:

2" and 1.25" with compression ring

Shortest overall length:

85 mm from M90 thread connection to M63 internal thread
103 mm to 2" connection

Position of the extension tube at innermost focus position:

81.5 mm behind the M90 connection thread

Focusing range(travel distance):

95 mm

Free inner diameter:

62 mm with anti-reflex thread

Outer diameter of the draw tube:

69 mm + 3 mm for the rack

Dual-speed Reduction ratio:

1/10 micro-reduction

Load capacity:

up to 6 kg

Weight with rotation adapter:

1240 g (43.5 oz.)


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