Best Electronic Focuser for Feather Touch 3.5" Focuser - Forums

Topic starter

Apr 18, 2024

Hello,

I'm about to purchase the Stellarvue SVX 140T refractor with a Feather Touch 3.5" focuser.

Might anyone know the best electronic focuser for this gear? I'll be imaging remotely only in a permanent observatory.
I know the ZWO EAF might work, but the bracket is machined for a flat, rather than a curved surface, so it's not ideal.

I can spend up to $500 or $600 for an electronic focuser and it must be able to be controlled through ASCOM/Windows.

Thanks!
Jerry

Well Written

Arun H

Apr 18, 2024

I'd recommend the ones made by Optec which are used with three Feathertouch focusers I have on three scopes.

Jerry Gerber

Topic starter

Apr 18, 2024

Thanks Arun, that's exactly what I am going to get.

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Reg Pratt

Apr 18, 2024 · Edited: Apr 18, 2024

I pair my FT with the Sesto Senso 2 and its been amazing. Zero backlash. Another option for you.

Scott Lockwood

Apr 18, 2024

I use the MicroTouch autofocuser by Starizona with a Microtouch motor on my TEC160FL with the Feather touch 3.5 focuser for years with no problems.

Bill McLaughlin

Apr 19, 2024

The Optec systems are very reliable. I have used them on a Tak 130, an FSQ 106, and currently on a Stellarvue SVQ 100. Nowadays there are two styles, the original that uses an external control box and a standalone USB motor. I prefer the box since it allows two scopes to connect. for futureproofing.

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Rowan Prangley

Apr 19, 2024

Hi Jerry,

Starlight Instruments make a PDMS focuser for Feather Touch 3.5". It's very sturdy and rated for higher payload weight.

Worth checking out! Though, lead times will be applicable.

If you imaging train is lighter in weight, than Optec or even Starlight Instruments FSM series (which are made by Optec) are excellent.

Hope this helps.

Best Regards,

Rowan

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Jerry Gerber

Topic starter

Apr 20, 2024

Thanks everyone for sharing your experience with me!

I ended up purchasing the PrimaLuce Sesto Senso 2 and the 37mm adapter for the Feather Touch 3.5" focuser.

Jerry

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Chris White- Overcast Observatory

Apr 20, 2024

I'm using the optec ft40 focusers with and without the integrated controller.

The only thing that you should be aware of, is that over time I've had the gears disengage. You twist the body of the focuser to disengage, which is convenient when you want to rack the focuser manually but this can be a problem in a remote setting. You may want to tape it so it can't work itself loose.

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Tom Dinneen

Apr 21, 2024 · Edited: Apr 21, 2024

+1 for Sesto Senso 2. Solid fit. Much better than EAF which doesn’t fit all that well because of the curved bottom and lack of mounting holes for the bracket. Optec would undoubtedly work great as well. With the FT you want a motor that clamps onto the focuser rather than via a bracket. In my opinion.

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Malcolm Park

Apr 21, 2024 · Edited: Apr 21, 2024

Jerry Gerber:
Hello,

I'm about to purchase the Stellarvue SVX 140T refractor with a Feather Touch 3.5" focuser.

Might anyone know the best electronic focuser for this gear? I'll be imaging remotely only in a permanent observatory.
I know the ZWO EAF might work, but the bracket is machined for a flat, rather than a curved surface, so it's not ideal.

I can spend up to $500 or $600 for an electronic focuser and it must be able to be controlled through ASCOM/Windows.

Thanks!
Jerry

Starlight Instruments Posi-Drive Motor System - I have it paired with my Feather Touch and TEC140

Ernst Arnold

Apr 21, 2024 · Edited: Apr 21, 2024

Jerry Gerber:
Hello,

I'm about to purchase the Stellarvue SVX 140T refractor with a Feather Touch 3.5" focuser.

Might anyone know the best electronic focuser for this gear? I'll be imaging remotely only in a permanent observatory.
I know the ZWO EAF might work, but the bracket is machined for a flat, rather than a curved surface, so it's not ideal.

I can spend up to $500 or $600 for an electronic focuser and it must be able to be controlled through ASCOM/Windows.

Thanks!
Jerry

Hi Jerry,

I'm using an Optec QuickSync FTX30 on my Tak TSA120 with 3.5" Feather Touch focuser. Works precise in a wide temperature range. It's controlled with linux and INDI driver. A nice feature is that it can be disengaged and used manually vor visual observation, but for only remote usage I would fix it.

Best regards
Ernst

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Riccardo Civati

Oct 3, 2025

Hi everyone

I’m bringing up this topic because i Need to install an autofocus motor on a feather touch FRF3545A-B.

I’ll Need to clarify: i’ll Need to move a moravian C3 26000 pro with 10×36 mm filters wheel and the original 1x TEC FIELD FLATTENER with and OAG.

I’m worried that if i use an HSM35 or an optec( since they attach to the micrometric pinion), i Might experience slippage in the planetary reduction gears with variable backlash.

Does anyone have experience with this COMBINATION?

The only solution would be the feather touch posi-drive motor

Bob Lockwood

Oct 3, 2025 · Edited: Oct 3, 2025

I use the Optec version (FT40) the FTX40 is just their newer version and pretty much the same as the FT HSM35. It's attached the fine-focus side of the AP focuser and will
lift my Moravian C3-61000 Pro with the 7x 50x50 filter-wheel. The image-train ( TCC-camera-CFW-OAG ) comes in at about 15lbs and the FT40 has no problem lifting it with zero slipping.

Note: As far as backlash, I don't notice any while reversing directions viewing the guide star, but there could be some, I just don't see it.

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Peter

Oct 7, 2025

Hello Gerry.

On my 3” Feathertouch I used a lakeside focuser. Unfortunately I can’t replace the control box, I’ve been looking at the Pegasus or ZWO motor focus units.

They have a good lift capacity

Riccardo Civati

Oct 8, 2025

Bob Lockwood · Oct 3, 2025, 04:37 PM
I use the Optec version (FT40) the FTX40 is just their newer version and pretty much the same as the FT HSM35. It's attached the fine-focus side of the AP focuser and will
lift my Moravian C3-61000 Pro with the 7x 50x50 filter-wheel. The image-train ( TCC-camera-CFW-OAG ) comes in at about 15lbs and the FT40 has no problem lifting it with zero slipping.

Note: As far as backlash, I don't notice any while reversing directions viewing the guide star, but there could be some, I just don't see it.

Did you notice any drift in the counts at the focus point?

To be clear: the FT40 counter was ‘X’ when you First focuser on the star. The following year, were the counts more o less the same value, or did you notice a progressive reduction over the year?

Bob Lockwood

Oct 9, 2025

Riccardo Civati:
Bob Lockwood · Oct 3, 2025, 04:37 PM

I use the Optec version (FT40) the FTX40 is just their newer version and pretty much the same as the FT HSM35. It's attached the fine-focus side of the AP focuser and will
lift my Moravian C3-61000 Pro with the 7x 50x50 filter-wheel. The image-train ( TCC-camera-CFW-OAG ) comes in at about 15lbs and the FT40 has no problem lifting it with zero slipping.

Note: As far as backlash, I don't notice any while reversing directions viewing the guide star, but there could be some, I just don't see it.

Did you notice any drift in the counts at the focus point?

To be clear: the FT40 counter was ‘X’ when you First focuser on the star. The following year, were the counts more o less the same value, or did you notice a progressive reduction over the year?

To me, drift would indicate movement, so no. The count or focus position changes over the night just because the temp changes. As for keeping track of where the scope comes to focus over a year's time, I don't keep track of that, I don't see the point.