Feather Touch® 3500 Series Focusers

We are pleased to announce the newest addition to our line of focusers – the Feather Touch® FTF3515 Focuser. The 3.5 inch internal diameter focuser has a draw tube travel length of 1.375″. This large size focuser can be used to hold almost any type of viewing accessory including a 3.0″ Wynne corrector. This focuser will work on large Newtonian and larger Ritchey Chretien telescopes. This robust focuser was designed to safely lift and hold 18-20 lbs of viewing equipment without shifting or sagging.

The FTF3515 Series focuser has the same design as the FTF3545 that is used on large refractor style telescopes. It is ideal for applications which demand precision imaging while also managing a heavier weight capacity.

If you have custom requirements and/or needs, please do not hesitate to contact us with details — our precision machine shop can get your parts made to the most demanding tolerances!

This focuser comes with our Fine Focus Reduction Unit which allows very accurate focusing. It is typically a 10:1 planetary reduction assembly that makes focusing extremely precise and easy. We were the original developer of this type of system for telescope use and have been making and improving these for longer than any other manufacturer. These units have undergone continuous improvement and we believe they are, quite simply, the best in the industry.

The smooth and precise feel of our Fine Focus Reduction Unit is the key, and it allows our users to focus precisely with unparalleled accuracy, speed, and reliability.

The 3500 series focusers can be rotated easily relative to OTA via a rotating locking collar.

Our standard female locking collar allows us to design and machine almost any type of adapter to attach the focuser to almost any scope.

The rack and pinion design uses a precision fine pitch ½ inch wide Brass rack and matched hardened Stainless Steel pinion.

Our original Brake Feature is included to allow for easy load adjustment of the weight on the focuser. This feature also allows locking the pinion/draw tube when needed.

The end of the draw tube uses a 4.1×24 tpi male thread which allows for a female threaded end cap or a 2.0″ or 3.0″ compression ring end cap to be used to attach different types of viewing accessories.

And, as with our other focusers, this focuser uses internally machined light baffles for superior light-reducing.

Please click the link below to view the products from our website.


Thread:4.1 x 24 tpi M on Draw Tube (End Cap Side)
Draw Tube Travel:34.93 mm | 1.375 in
Diameter at Back Side
(Eye Piece) of Draw Tube:
92.71 mm | 3.65 in
Draw Tube Drive Mechanism:Helical Rack and Pinion 72 Pitch
Reduction Ratio:10:1 (Approximately)
Travel per Pinion Revolution:21.46 mm | 0.845 in
Lifting Capacity:8-9 kg | 18-20 lbs