16.10.2020 Starlight Instruments 2.5" x 3.5" travel, Feather Touch Focuser FTF2535HD

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The base adapter arrived today so I was able to fit the focuser to the iStar H-alpha 6" f/10. The fit and finish on this focuser are flawless on all parts. 

Ownership of a Feather Touch focuser is multifaceted. Its quality of design, appearance and function are worth every penny. It will certainly outlast me despite my almost daily presence in my home-built observatory. Apologies for the white dust. I had been sawing out a circle of polystyrene for the objective protection cap.

Here the base adapter lies in front of the focuser mechanism. It has three sturdy screws with pointed plastic tips. These points locate in the triangular groove in the base of the focuser mechanism. Providing a silky smooth, shake-free rotation of the whole focuser which has to be experienced to be believed.

Now the base adapter has been screwed into the flat base plate via their matching M95 x 1mm thread. The flared, base adapter provides a superb touch of classical design and craftsmanship. Lifting the whole design above the merely functional.

The knurled thumbscrews are exquisite. With a hint of bling in their gold finish. Which is nicely set off by gold finish on the 10:1 slow motion knob on the focuser. 

These screws are large and fine threaded to provide a lifetime of pleasure in effortless adjustment. The base adapter is lined to provide a perfect fit without friction.

Here we see the focuser drawtube at full extent. The FTF 2535HD offers 3.5" of total travel. More than generous for most users.

There is zero slop from the well designed system. The drawtube remains still under load without any creep. Turning the large focusing knobs reminds one of the quality of the rack and pinion mechanism. A fine, bronze, helical rack is matched by the polished, stainless steel, helical pinion. There is absolutely no sense of cogging, lost motion or backlash.

A delight to use and a pleasure to own such a fine piece of equipment. After years of struggling with grossly inferior focusers I am happy to have finally upgraded my focuser to the very best available. "A thing of beauty is a joy forever."

There is a clear aperture of 63mm throughout the drawtube. With incredibly flat, matt black paint on the internal baffles.

And now with the drawtube fully retracted to provide a nicely compact arrangement. I may shorten the main tube of the 6" slightly to provide a greater range of drawtube movement. At present there is only 1cm of rack protruding when the focus is correct at 200mm from the etalon's leading edge to the focal plane. For binoviewer use I may need more inward focus. I shall have to see.

Interestingly, the heavy focuser on its new backplate needed only 1" of main tube movement, up through the rings, to rebalance the OTA. I thought it would be much more.

The thumbscrew facing the camera is a nicely balanced brake. Preventing the drawtube from moving when heavily laden. The focuser has a claimed capacity up to 15lbs. 

This image shows the focuser in place on its new backplate. The etalon/filter stack is arranged correctly for the 2.6x GPC.  Previously I had double checked the 200mm focus point from the etalon. Then locked the focuser with the knurled thumbscrew. receptacle. 

I normally use a rotating, adjustable T2-1.25" eyepiece receptacle. This hold the camera close to the blocking filter. I am still trying to find a compact, T2-1.25" non-rotating, helical focuser.

Here is Starlight Instrument's own web page for the Feather Touch FTF2535HD focuser.

FTF2535HD---Feather Touch® 2.5" Diameter Dual Speed Focuser 3.5" Draw tube travel, and Brake

 

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