18 replies to this topic

[AbsolutelyNot]

Hello:

 

I have a SW 80ED that I use for imaging.  The issue is that despite repeated attempts at tuning up the stock focuser I am losing nights to bad focus (N.I.N.A).  I have decided that I will upgrade the focuser as clear nights are too rare and valuable to lose to a poor focuser.

 

My existing imaging train is as follows - from the SW drawtube is threaded on the SW 80ED 0.85x reducer with  a M56 x 1 thread.  A ZWO 8 position filter wheel is attached via adaptor to the reducer and a ZWO 1600MM is attached onto the filter wheel.  Focus is achieved using a ZWO EAF.  All of the listed equipment will be used with the new focuser.

 

I'm looking at the FLO focuser here - the Astro Essentials v2 2" Dual-Speed Crayford Focuser for Sky-Watcher Refractor Telescopes.  It has a M54 x 0.75 female thread on the drawtube.  FLO's website for this focuser states "Our Astro Essentials Adapter will enable you to use Sky-Watcher focal reducers with this focuser."  The adaptor does not have its thread sizes listed although one of the comments alludes to it having an M56 x 1 thread, which means it would fit my SW reducer.  However, this adaptor would simply slide into the focuser and be held with grub screws.  It doesn't give me a warm-and-fuzzy feeling and a youtuber seemed to experience camera tilt due to this arrangement.

 

A bit of digging revealed that there is an adaptor that seems like it would allow for a solid, threaded connection between the reducer and the focuser.  A company called RAF Camera sells an M56 x 1 male to M54 x 0.75 male adaptor.  In my mind this would allow for a solid connection.

 

What I'm looking for is a second set of eyes to check my work and make sure I'm not missing a better path for focuser replacement.  Thanks in advance.

[Oldfracguy]

I had one of those "Astro Essentials" dual-speed Crayford focusers on a Meade LX85 R5 (120mm f/5.83 achromat) I used to have:

 

 

 

It was by far superior to the stock dual-speed Crayfords that come with the SW 80ED. 100ED and 120ED Evostars (all of which I've owned before).  In fact, I believe this is the same model focuser used on the SW Equinox and old Orion EON scopes.  The focuser that yu see in the photo above fits inside tubes with 97mm ID, which is the SW 80ED, 100ED and 120ED Evostars, and attaches using the existing three Phillips screws at 120° intervals.  The actual OD of the part that slides into the telescope's tube is 97mm, so it can harder to slide it it than the 96.6mm GSO Dual-Speed Crayford focusers that Agena and others sell.

Edited by Oldfracguy, 31 March 2025 - 10:02 PM.

[AbsolutelyNot]

It was by far superior to the stock dual-speed Crayfords that come with the SW 80ED. 100ED and 120ED Evostars (all of which I've owned before).  In fact, I believe this is the same model focuser used on the SW Equinox and old Orion EON scopes.  The focuser that yu see in the photo above fits inside tubes with 97mm ID, which is the SW 80ED, 100ED and 120ED Evostars, and attaches using the existing three Phillips screws at 120° intervals.  The actual OD of the part that slides into the telescope's tube is 97mm, so it can harder to slide it it than the 96.6mm GSO Dual-Speed Crayford focusers that Agena and others sell.

Thanks for the reply.

 

I did note in some of the reviews that the fit was tight, as you noted above.

 

The GSO focuser does state that it is 96.6 mm which would seem to be a no-fuss install.  I also see in the title that it has a M56 thread but there is no further discussion of the specifics - i.e. male or female, pitch, etc.  If it has a 56M x 1 male thread then in theory the SW 0.85x reducer should thread on with no need for an adaptor.

 

GSO 2" EAF Compatible Crayford Focuser for Refractors w/ Camera Rotator & M56 Thread - Dual Speed (with 96.6mm Telescope Adapter) - PAF-GS-R96-DW436.  I have submitted a product query with Agena Astro and I'll update this thread if / when I receive a reply.

[Oldfracguy]

Thanks for the reply.

 

I did note in some of the reviews that the fit was tight, as you noted above.

 

The GSO focuser does state that it is 96.6 mm which would seem to be a no-fuss install.  I also see in the title that it has a M56 thread but there is no further discussion of the specifics - i.e. male or female, pitch, etc.  If it has a 56M x 1 male thread then in theory the SW 0.85x reducer should thread on with no need for an adaptor.

 

GSO 2" EAF Compatible Crayford Focuser for Refractors w/ Camera Rotator & M56 Thread - Dual Speed (with 96.6mm Telescope Adapter) - PAF-GS-R96-DW436.  I have submitted a product query with Agena Astro and I'll update this thread if / when I receive a reply.

Those GSO Dual-Speed Crayfords tend to slip out of position with a heavy imaging load attached.  The more robust Linear Bearing versions can handle a larger payload, but they are hard to move when you tighten up the drawtube tension adjustment thumbscrew enough to keep the drawtube from slipping down when the scope is pointed upward at a high angle.  I had that problem on an 8" Classical Cassegrain, so I bit the bullet and installed one of those TS dual-speed Rack-and-Pinion focusers.  What a total improvement, and well worth the $$$ I paid for it.  I think the Astro Essentials focuser is better, and it might take a little sanding on the inside of your SW 80ED Evostar's tube to widen the ID just a little bit so the Astro Essential focuser will slide in easier.  

[AbsolutelyNot]

Thanks again for the reply.

 

I have not heard back yet from Agena regarding their focuser.

 

I have also reached out to a local shop who sells Baader and Explore Scientific R&P focusers to see if either of those would work in my situation.

[hfjacinto]

Once you go moonlite you’ll never go back.

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Edited by hfjacinto, 01 April 2025 - 12:34 PM.

[hfjacinto]

Even my stellarvue has a moonlite.

 

 

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[AbsolutelyNot]

Once you go moonlite you’ll never go back.

Thanks for the reply.  I've been looking at the Moonlite page but it's a bit frustrating as its measurements are all imperial and there is a bit of a "choose your adventure" feel to the process.  I'll keep looking, though, since they seem to work well for you.

 

I heard back from the local shop regarding the Baader R&P focuser.  See below.

 

 To fit the Steeltrack on your SW 80ED, you would need this adapter:

Baader RT-Adapter Diamond Steeltrack for Synta/Celestron Refractors - Ø97mm

The drawtube of the Steeltrack features an S58 dovetail ring, as well as an M60x1 and M55x0.75 threads. You would need one (or more) adapter that goes from one of those, to M56x1 male. There are optional adapters that can go to M42, M48 or M68 (all male).

The problem is that M56x1 adapters are rare. You would need to find one that has your M56x1 thread, and one that fits on the Steeltrack or one of its adapters. You could check the Blue Fireball M48 female to M56 male adapter, used with the Baader M48 adapter (2957204).

Otherwise, there is PreciseParts that can easily produce custom adapters, and one that goes from the Steeltrack to M56x1 should not be an issue.

We indeed sell ES focusers, but you would have difficulty to find a flange to make them fit on your SW telescope. Even though it is complicated, the Steeltrack would still be easier.

 

[Mike W]

Thanks for the reply.  I've been looking at the Moonlite page but it's a bit frustrating as its measurements are all imperial and there is a bit of a "choose your adventure" feel to the process.  I'll keep looking, though, since they seem to work well for you.

 

I heard back from the local shop regarding the Baader R&P focuser.  See below.

E-mail Moonlight

[AbsolutelyNot]

I heard back from Agena regarding the GSO crayford focuser:

 

Hello, The M56x1 thread is on the focuser drawtube and is for a camera interface. The telescope side is 96.6mm flange for connecting to the tube of a refracting telescope. Sincerely, Agena Astro

 

 

Right now the GSO focuser seems to be the easiest and logical choice - the focuser will fit into the SW 80ED tube without modifications and the drawtube is threaded with the required M56 x 1 thread for the SW 0.85x reducer.  The focuser is also designed for easy installation of the ZWO EAF that I use.

 

I have been going back-and-forth with my local astronomy store regarding the Baader focuser but it seems that the only way to connect the two will be with a pricey custom made adapter.

 

I have reached out to Moonlite and will update when I hear from them.

 

For the record my imaging train weighs about 1.1 kg so it's not overly onerous.

Edited by AbsolutelyNot, 01 April 2025 - 04:20 PM.

[Rasfahan]

Really, stay away from those GSO crayfords. They show slippage. Get a R&P.

[Oldfracguy]

I heard back from Agena regarding the GSO crayford focuser:

 

 

Right now the GSO focuser seems to be the easiest and logical choice - the focuser will fit into the SW 80ED tube without modifications and the drawtube is threaded with the required M56 x 1 thread for the SW 0.85x reducer.  The focuser is also designed for easy installation of the ZWO EAF that I use.

 

I have been going back-and-forth with my local astronomy store regarding the Baader focuser but it seems that the only way to connect the two will be with a pricey custom made adapter.

 

I have reached out to Moonlite and will update when I hear from them.

 

For the record my imaging train weighs about 1.1 kg so it's not overly onerous.

That's not much at all, only 2.4 lbs.  I have 2" diagonals and 2" eyepieces that weigh nearly as much:

 

 

 

and some other 2" diagonals and 2" wide-angle eyepieces that exceed 1.1 kg in total.

 

That GSO Dual-Speed Linear Bearing focuser with the 96.6mm OD end would be a very good starting point.  The main thing going for you is that your motorized EAF will hold the focuser in position, unlike visual observation with a diagonal and eyepiece where you have to trust the focuser to be robust enough to keep the drawtube in place with the scope pointed upward at a high angle, yet still be smooth enough in its operation where you can make fine adjustments in the focus position. I say go for it, and best of luck with your imaging  .

Edited by Oldfracguy, 01 April 2025 - 05:47 PM.

[AbsolutelyNot]

Thanks all for your input.

 

I heard back from Moonlite, copied below:

 

 

 

We make 3 models for your SW 80ED.

CF 2" crayford refractor focuser
CFL 2.5" large format crayford refractor focuser
Nitecrawler rotating WR25 format focuser

Note-all of our focusers come with a motor option, we do not make manual focusers now days.

Normally customers setting that scope up for imagining with the reducer would get the CFL 2.5" format model Go to products/ CFL model/ click on the CFL focuser thurmbnial , then scroll to the bottom of the page and pick--

Color = ?
Flange = Synta
Drawtube = 4.5" travel 68mm thread
Motor = high res stepper motor V3
Finder brackets = reg style
---------------------------------
$885 plus shipping

Qty1 68mm to Synta adapter for the reducer $59

My option so far are:

- Astro-Essentials, but I'd be on my own to find an adapter to fit my SW reducer, and the focuser may need physical modifications to fit inside the telescope tube.

- GSO, with the exact size fit in the tube and the required M56 thread for my reducer.  It also fits a ZWO EAF.  However, contributors to this thread are cautioning against it.

- Baader, with a R&P-like Crayford.  The drawback is that a ZWO EAF would need modifications and a custom adapter to fit the SW reducer.

- Moonlite, which is highly regarded, but is easily the most expensive, by a lot, and would render my ZWO EAF unnecessary.

 

I guess I'll do a bit more digging to find the best path.  Thanks again for everyone's input.

[Mike W]

Too Bad SVbony doesn't sell focusers. Two speed rack and pinion!

[hfjacinto]

The moonlites have gone up a lot in price. I paid around $350 for each of mine (with the focuser motor), I purchased mine manual and then added the focus motor at a future time, but doesn’t look like they do that now.

Having motorized focusing will make your life easier and automating the focusing as the temperate changes let’s you get tiny stars, but the cost wwwwwoooooooowwwwww! It’s higher than I expected.

Edited by hfjacinto, 01 April 2025 - 08:32 PM.

[AbsolutelyNot]

The moonlites have gone up a lot in price. I paid around $350 for each of mine (with the focuser motor), I purchased mine manual and then added the focus motor at a future time, but doesn’t look like they do that now.

Having motorized focusing will make your life easier and automating the focusing as the temperate changes let’s you get tiny stars, but the cost wwwwwoooooooowwwwww! It’s higher than I expected.

Yeah, that quote came in a wee bit higher than I expected.  I've been running the stock focuser with the ZWO EAF for a while now but the SW crayford has been slipping, despite many attempts at fixing it.

 

I think I'm going to go with the Baader.  It gets very good reviews and is rated well over my current (and projected future) load.  I can buy a printed Baader bracket for my ZWO EAF for a low cost and my local astronomy store owner has found a combination of adapters that will provide a solid connection to the SW reducer.

[chongo228]

Thanks all for your input.

 

I heard back from Moonlite, copied below:

 

My option so far are:

- Astro-Essentials, but I'd be on my own to find an adapter to fit my SW reducer, and the focuser may need physical modifications to fit inside the telescope tube.

- GSO, with the exact size fit in the tube and the required M56 thread for my reducer.  It also fits a ZWO EAF.  However, contributors to this thread are cautioning against it.

- Baader, with a R&P-like Crayford.  The drawback is that a ZWO EAF would need modifications and a custom adapter to fit the SW reducer.

- Moonlite, which is highly regarded, but is easily the most expensive, by a lot, and would render my ZWO EAF unnecessary.

 

I guess I'll do a bit more digging to find the best path.  Thanks again for everyone's input.

 

MWDastronomy.com makes a bracket to fit your EAF on a Moonlite and keep their clutch. 

[Jon Isaacs]

I heard back from Agena regarding the GSO crayford focuser:

 

 

Right now the GSO focuser seems to be the easiest and logical choice - the focuser will fit into the SW 80ED tube without modifications and the drawtube is threaded with the required M56 x 1 thread for the SW 0.85x reducer.  The focuser is also designed for easy installation of the ZWO EAF that I use.

 

I have been going back-and-forth with my local astronomy store regarding the Baader focuser but it seems that the only way to connect the two will be with a pricey custom made adapter.

 

I have reached out to Moonlite and will update when I hear from them.

 

For the record my imaging train weighs about 1.1 kg so it's not overly onerous.

 

Moonlite is out of the manual focuser buildness. 

 

If you want the best, that's Feathertouch. Astro-Physics, TEC, they use Feathertouch focusers.  The Feathertouch design is superior to other Crayfords.  They also make rack and pinion focusers.

 

 

 

I use the standard GSO two speed Crayfords with an eyepiece plus diagonal weighing 1.45 kg.  I do rework them by slipping a thin strip of Teflon between the pinion and the plastic pressure block.  The Teflon reduces the friction required to turn the focuser so higher preloads are possible while retaining a light, easy touch.  It is tricky... 

 

In the long run, it might be better to just buy an 80mm with a modern rack and pinion focuser.  The Kunming United Optical telescopes have two speed rack and pinion focusers of near Feathertouch quality.. 

 

Jon

[Oldfracguy]

Moonlite is out of the manual focuser buildness. 

 

 

In the long run, it might be better to just buy an 80mm with a modern rack and pinion focuser.  The Kunming United Optical telescopes have two speed rack and pinion focusers of near Feathertouch quality.. 

 

Jon

I'm of the opinion that the reason Moonlite is out of the manual focuser business is that people do not see the need to replace the focusers on these KOU-made ED scopes.  They really are that good.  A couple years ago I sold an AT125EDL to a long-time CN member who also has a Tak FS-128 with a Feathertouch.  One family member told him they liked the Astro-Tech AT125EDL's dual-speed rack-and-pinion focuser better than the Feathertouch on the FS-128.  

 

These KUO dual-speed rack-and-pinion focusers will literally hold up a brick:

 

 

 

With a 2" diagonal, a 28mm UWA eyepiece, and the brick hanging from the focuser, it did not slip down out of position, and the fine-focus knob still raised and lowered the load smoothly.  The scope is a William Optics Zenithstar 81.

Edited by Oldfracguy, 09 April 2025 - 11:26 AM.