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Focuser Upgrade - Synta ED100/ED80

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#1 zakry3323

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Posted 23 December 2018 - 05:59 PM

Hi all!

I'm looking into replacing the stock focuser on my Skywatcher ED100- the tension bolt hole is kind of stripped out. Sometimes it's fine, sometimes it simply falls right out. 

I replaced the stock focuser on my Orion ED80 with the Orion dual-speed crayford. It works as intended but there can be just a little slippage when I'm imaging near zenith unless I really crank the tension knob, which usually means that I have to re-focus all over again. It also appears identical, sans paint job, to the stock dual-speed crayford on the ED100. 

One thing that I like about the Synta focusers it is that my Baader Clicklock threads right onto the draw tube. I'd like to continue being able to re-frame my shots after having focused by rotating the image train. 

 

I'm considering the GSO Linear Bearing Crayford, and the Moonlite focusers as a replacement. I'd really appreciate it if you might share your experiences with me if you own either of these focusers, especially if you've got them on one of the ota's I'm using. 

 

Something else to consider is that I'm eventually going to autofocus, probably with JMI or Rigelsys, and I'd like to be confident that the focuser can be easily adapted for autofocus use in the future. 

Feathertouch is out of my budget, and I'd feel funny if my focuser was nicer than my telescope smile.gif

Cheers, happy holidays! 


Edited by zakry3323, 23 December 2018 - 06:02 PM.


#2 petert913

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Posted 23 December 2018 - 07:19 PM

The Orion 2-speeds are not great.  Slippage as you mentioned, and just kind of a crude design IMO.

 

I bought the GSO for my 120mm f/8.3 Orion refractor and it works very well.  Smooth and stable.

Their linear one is even better. 

 

Moonlight or  Feather Touch if you have the budget. 


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#3 zakry3323

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Posted 23 December 2018 - 07:41 PM

The Orion 2-speeds are not great.  Slippage as you mentioned, and just kind of a crude design IMO.

 

I bought the GSO for my 120mm f/8.3 Orion refractor and it works very well.  Smooth and stable.

Their linear one is even better. 

 

Moonlight or  Feather Touch if you have the budget. 

Thanks for replying! I don't like yucking on anyone's yum, so I'll say that the Orion 2-Speed was a definite improvement over the stock single speed crayford that came with the ED80, at least! I'm sure it would be great for most applications in visual use, I've got a lot of weight hanging on mine, probably more than specs allow. 

How do you rotate your diagonal or imaging train with your GSO? I see on the website that they say this about the 360 rotation feature: "However, please note that this is a relatively weak feature of this otherwise excellent product." 

I'm guessing that if GSO is covering their butts about it upfront, it's probably a little less than "robust". But I'd love to hear your experience with it! Would you say that it's at a minimum, more efficient to use than say, typical 3-point set screws? 


Edited by zakry3323, 23 December 2018 - 08:27 PM.

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#4 hfjacinto

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Posted 23 December 2018 - 11:26 PM

Only issue with getting a moonlite is that it will ruin it for you. You’ll find the current focusers lacking. All my scopes have moonlites or feather touch except for the APM as that one has a 3.7” focuser and moonlite/ft focusers in that size cost lots. I did get Ron at moonlite to motorize my APM so it’s still usable for imaging.
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#5 25585

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Posted 24 December 2018 - 02:34 AM

Moonlites are rotatable. If the OE is not, it's a good reason to buy one.

 

I wish Moonlite did 3 inch focusers.


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#6 russell23

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Posted 24 December 2018 - 08:09 AM

I tried a GSO linear bearing and had some trouble with it. 

 

Now I have a Moonlite which is outstanding.   I think eventually I would like to go with a Feathertouch, but I do not regret moving away from the stock focuser that came on my SW120ED.


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#7 hfjacinto

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Posted 24 December 2018 - 08:12 AM

Moonlites are rotatable. If the OE is not, it's a good reason to buy one.

I wish Moonlite did 3 inch focusers.


You can get the nightcrawler in 3”, but it costs more than the 153

#8 RadioAstronomer

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Posted 24 December 2018 - 08:27 AM

Moonlite all the way! It's an incredible piece of engineering. 

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#9 zakry3323

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Posted 24 December 2018 - 11:01 PM

Moonlite all the way! It's an incredible piece of engineering. 

Beautiful setup, thanks for the advice! 


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#10 zakry3323

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Posted 24 December 2018 - 11:28 PM

Overwhelming vote is for the Moonlite! Thank you all so much for your help, now to decide if the 2" is enough, or if I should go for the 2.5". 

 



#11 Jon Isaacs

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Posted 25 December 2018 - 03:49 AM

Overwhelming vote is for the Moonlite! Thank you all so much for your help, now to decide if the 2" is enough, or if I should go for the 2.5". 

 

It depends on what you are looking for.  As Dave said, he has his eye on the Feathertouch but likes the Moonlite.

 

Have you considered just retapping the "tension" bolt to the next size up?

 

Jon


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#12 zakry3323

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Posted 25 December 2018 - 08:48 AM

It depends on what you are looking for.  As Dave said, he has his eye on the Feathertouch but likes the Moonlite.

 

Have you considered just retapping the "tension" bolt to the next size up?

 

Jon

I've thought about it, perhaps I will once I have its replacement. It's standard Synta, so I can always use it on another one of my OTA's. 

 

Thing is when it was functioning at nominal, it wasn't robust enough to rack in the imaging train at 50 degrees, let alone near zenith. Not bad at all for doing visual, but I need an upgrade to handle all the weight I put on it. 



#13 BarrySimon615

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Posted 25 December 2018 - 10:36 AM

Try beefing up the tension bolt on your current focuser with some white Teflon pipe tape and see if that solves your problem.

Barry Simon
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#14 25585

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Posted 25 December 2018 - 12:35 PM

Overwhelming vote is for the Moonlite! Thank you all so much for your help, now to decide if the 2" is enough, or if I should go for the 2.5". 

 

Moonlite does not make both sizes for all telescopes. Some scopes only 2 ins, others only 2.5 ins.  



#15 BKBrown

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Posted 25 December 2018 - 02:10 PM

I'll cast my vote for the Moonlite focuser as well...it will spoil you! It also looks very good on the SW100ED, much more aesthetically pleasing to me than the white stock focuser (which actually works perfectly well IMHO) smile.png  

 

Clear Skies,

Brian

 

 

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#16 zakry3323

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Posted 25 December 2018 - 02:12 PM

Try beefing up the tension bolt on your current focuser with some white Teflon pipe tape and see if that solves your problem.

Barry Simon

Will do, thanks!



#17 barbie

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Posted 25 December 2018 - 05:50 PM

I haven't experienced any problems with the stock focuser on my ED100. In fact, it's the best Crayford I've used to date and see no reason to upgrade since I don't do imaging any longer, nor do I have any intention of doing so again in the future!!  In the first place, if I were to image, I wouldn't use a Crayford style focuser!!   The last ED100 I had five years ago had an excellent focuser too!!  I've not encountered any problems with slippage(on either of my ED100's) even at zenith with a 2" Diagonal and heavy eyepiece and they BOTH had proper amounts of tension right out of the box.  I've also extensively used Feathertouch and Moonlite focusers and really didn't experience much if any difference in performance versus the Skywatcher units.  Other than cosmetic appearance, I don't think there is much to recommend either the Moonlite or the Feathertouch so I won't spend the extra $$$ to upgrade.  As I already said, if I were to do imaging again, I wouldn't even consider a Crayford style focuser, only a rack and pinion.grin.gif


Edited by barbie, 25 December 2018 - 05:56 PM.

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#18 russell23

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Posted 25 December 2018 - 09:00 PM

I haven't experienced any problems with the stock focuser on my ED100. In fact, it's the best Crayford I've used to date and see no reason to upgrade since I don't do imaging any longer, nor do I have any intention of doing so again in the future!!  In the first place, if I were to image, I wouldn't use a Crayford style focuser!!   The last ED100 I had five years ago had an excellent focuser too!!  I've not encountered any problems with slippage(on either of my ED100's) even at zenith with a 2" Diagonal and heavy eyepiece and they BOTH had proper amounts of tension right out of the box.  I've also extensively used Feathertouch and Moonlite focusers and really didn't experience much if any difference in performance versus the Skywatcher units.  Other than cosmetic appearance, I don't think there is much to recommend either the Moonlite or the Feathertouch so I won't spend the extra $$$ to upgrade.  As I already said, if I were to do imaging again, I wouldn't even consider a Crayford style focuser, only a rack and pinion.grin.gif

I wouldn't say your experience is unique, but a lot of people have not had great experiences with the Synta stock focusers.  When I received my SW120ED it was a mess.  There was grinding and the fine focus did not work at all.  When I tried the online instructions for fixing it I had zero luck.  I could not get it to hold any weight without slipping.

 

So Skywatcher took the entire scope and fixed it at no charge to me.  It worked nicely after that but the first time I put a heavy eyepiece in it I started having some issues with slippage.   So I replaced it with a 2" Moonlite - which is much smoother on the fine focus and much more rugged. 

 

So my thoughts with the stock focusers on these scopes is run with them until you have a problem with them.   Then upgrade to a Moonlite or Feathertouch.   I have a FT adapter for that time when I finally decide I want to upgrade further to the FT focuser. 


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#19 Jon Isaacs

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Posted 25 December 2018 - 09:28 PM

Other than cosmetic appearance, I don't think there is much to recommend either the Moonlite or the Feathertouch so I won't spend the extra $$$ to upgrade.

 

I have a fair amount of experience with a number of focusers, never owned a Moonlite but I have three Feathertouch's, a couple of JMI's, some GSOs, a ED-100 two speed plus a variety of others.  I also work on focusers for others on an informal basis.  

 

The Skywatcher 2 speed is a good enough focuser and does a reasonable job if not loaded too heavily.  But the Feathertouch is quite a different design than other Crayfords, it is very clever and it more robust and handles heavy loads with authority.  For astro-photography, upgrading the focuser may not only be desirable, it may be necessary.

 

Jon


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#20 barbie

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Posted 25 December 2018 - 11:15 PM

I have a fair amount of experience with a number of focusers, never owned a Moonlite but I have three Feathertouch's, a couple of JMI's, some GSOs, a ED-100 two speed plus a variety of others.  I also work on focusers for others on an informal basis.  

 

The Skywatcher 2 speed is a good enough focuser and does a reasonable job if not loaded too heavily.  But the Feathertouch is quite a different design than other Crayfords, it is very clever and it more robust and handles heavy loads with authority.  For astro-photography, upgrading the focuser may not only be desirable, it may be necessary.

 

Jon

I also have a fair amount of experience with many focusers and still would not use a Crayford style focuser for heavy cameras or other astrophoto gear!  Only an excellent rack and pinion like my former A-P focuser would be good enough!!



#21 barbie

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Posted 25 December 2018 - 11:18 PM

I wouldn't say your experience is unique, but a lot of people have not had great experiences with the Synta stock focusers.  When I received my SW120ED it was a mess.  There was grinding and the fine focus did not work at all.  When I tried the online instructions for fixing it I had zero luck.  I could not get it to hold any weight without slipping.

 

So Skywatcher took the entire scope and fixed it at no charge to me.  It worked nicely after that but the first time I put a heavy eyepiece in it I started having some issues with slippage.   So I replaced it with a 2" Moonlite - which is much smoother on the fine focus and much more rugged. 

 

So my thoughts with the stock focusers on these scopes is run with them until you have a problem with them.   Then upgrade to a Moonlite or Feathertouch.   I have a FT adapter for that time when I finally decide I want to upgrade further to the FT focuser. 

lol.gif lol.gif I've NEVER had any problems with any of my Synta focusers so I won't be replacing them anytime soon.  In fact, in over 15 years of owning and USING Chinese scopes, I have yet to get one with a bad focuser.  I can't say the same for some of the American made ones or those made in other countries beside China/Taiwan!!


Edited by barbie, 25 December 2018 - 11:33 PM.


#22 zakry3323

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Posted 25 December 2018 - 11:34 PM

I'll cast my vote for the Moonlite focuser as well...it will spoil you! It also looks very good on the SW100ED, much more aesthetically pleasing to me than the white stock focuser (which actually works perfectly well IMHO) smile.png  

 

Clear Skies,

Brian

Your upgrades really do make a huge visual improvement! Thanks for sharing! Can I ask you what kind of rings you're using for your ota on the Sirius mount? I find the stock rings for the 100ED less than a joy to use. I've swapped over to the ES102 rings and a losmandy dovetail that I use with my achro, but it doesn't fit exactly right, and I'd prefer to have more than a single point at which to fasten the rings to the plate. 

IMG_20181111_155807.jpg


Edited by zakry3323, 26 December 2018 - 12:23 AM.

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#23 zakry3323

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Posted 26 December 2018 - 12:11 AM

I haven't experienced any problems with the stock focuser on my ED100. In fact, it's the best Crayford I've used to date and see no reason to upgrade since I don't do imaging any longer, nor do I have any intention of doing so again in the future!!  In the first place, if I were to image, I wouldn't use a Crayford style focuser!!   The last ED100 I had five years ago had an excellent focuser too!!  I've not encountered any problems with slippage(on either of my ED100's) even at zenith with a 2" Diagonal and heavy eyepiece and they BOTH had proper amounts of tension right out of the box.  I've also extensively used Feathertouch and Moonlite focusers and really didn't experience much if any difference in performance versus the Skywatcher units.  Other than cosmetic appearance, I don't think there is much to recommend either the Moonlite or the Feathertouch so I won't spend the extra $$$ to upgrade.  As I already said, if I were to do imaging again, I wouldn't even consider a Crayford style focuser, only a rack and pinion.grin.gif

Thanks very much for sharing your experience! I'm happy to say that the stock crayford on the 100ED and the replacement on the 80ED (same focuser, different color) perform just fine when I don't have a big load on them. As for the bolt hole on the tension lock stripping out, I can't really speak to whether or not my experience is representative of the majority of the focusers paired with the 100ED, I got it used and can't complain for the price I paid. At my focal length, I've been happy to learn on the crayfords. 

I hadn't considered any more alternatives to the Moonlight besides the GSO with linear bearings. The R+P's that I can find within my price range include the Stellarvue and the newer Primaluce Hybrid-Drive. If you know of others that you could suggest, keeping within my $400-500 budget, please let me know. An A-P focuser is out of my range....and probably a bit more than my humble 100ED deserves smile.gif

 

I have a fair amount of experience with a number of focusers, never owned a Moonlite but I have three Feathertouch's, a couple of JMI's, some GSOs, a ED-100 two speed plus a variety of others.  I also work on focusers for others on an informal basis.  

 

The Skywatcher 2 speed is a good enough focuser and does a reasonable job if not loaded too heavily.  But the Feathertouch is quite a different design than other Crayfords, it is very clever and it more robust and handles heavy loads with authority.  For astro-photography, upgrading the focuser may not only be desirable, it may be necessary.

 

Jon

It's gotten me this far, so I really can't complain! Slippage can be an issue, but carefully racking in with some gentle hand support gets me in focus, and once it's where it needs to be, the tension locks keeps it there. There is occasionally some shift if I'm overzealous, so it's been all about finding that "sweet spot".  Now with the fastener randomly popping out, I decided that I need to move onto something better- something that can rack in and out with some weight on it and can easily incorporate with a motorized focus controller (currently this is impossible).

 

Manually having to refocus and deal with the slippage in between filters is doable, but it sure isn't fun. On top of that, refocusing throughout the night to account for temperature change manually with my current focuser... well I would call myself lazy but I just don't think that's a reasonable way to spend my time, and to be sure my images suffer for it. Motorized focusing will be a future upgrade when I can afford it- for now I just want to be able to trust my focuser with the weight I've got on it, and don't want to make a mistake buying something that is precise but lacks easy adaption to motor focus control. 

A Feathertouch...maybe someday, but it's out of my budget for now. Thanks for sharing your experience with me, I really do appreciate it! 


Edited by zakry3323, 26 December 2018 - 12:14 AM.


#24 Redbetter

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Posted 26 December 2018 - 02:36 AM

I have an 80ED and two of those rotatable GSO's now (sold by Lunt, but same focuser) on two other 80mm scopes.  I only do visual.  I prefer the GSO's so far.  The GSO's don't seem to be finicky and they seem to handle 2" with 41 Pan or 31T5 well.  I have had to adjust the Synta 2-speed a few times to get it working well.   Seasonal issues? 

 

The 1.25" Synta rack and pinions for refractors have been more problematic, requiring degreasing (removing Synta glue) to work well in anything but warm weather, and periodic tweaking to keep them working. 

 

One of the reasons for trying the GSO refractor focusers was the 2" GSO on the Z10.  It works a lot better than what I recall experiencing on others' Synta made Dobs. 

 

My experience is the opposite of barbie's.  The Synta focusers have nearly all been problematic at some point and I have replaced two of them with GSO's (to be fair, one of the Synta's was a plastic 1.25", the other was the same metal one as used on the ST80 and I didn't even bother to degrease it or tweak it before pulling it since I had experience with another.)


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#25 Jon Isaacs

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Posted 26 December 2018 - 07:54 AM

I also have a fair amount of experience with many focusers and still would not use a Crayford style focuser for heavy cameras or other astrophoto gear!  Only an excellent rack and pinion like my former A-P focuser would be good enough!!

There is a lot of difference between Crayfords.  I avoid lumping them together.  

 

This is what you wrote:

 

"Other than cosmetic appearance, I don't think there is much to recommend either the Moonlite or the Feathertouch so I won't spend the extra $$$ to upgrade

 

There are major differences between a Synta Crayford and a Feathertouch.. The Feathertouch supports the drawtube with a robust dovetail, the bearings ride on steel.  The pinion drives on steel that is attached to the dovetail. It is very stiff and compact.  This is what separates the Feathertouch from other Crayfords. 

 

In the the standard Crayford design like the Synta and Moonlite, the bearings that support the draw tube are on the opposite side of the pinion so the drawtube is under the load of pinion drive force, this limits the amount of force that can be applied and therefore the weight that can be supported.  

 

An important difference for astro-photography is the design of the focuser brake.  With the standard design, the lock pushes on the drawtube which disengages the pinion drive so it is not possible to focus with the lock engaged. The Feathertouch design uses a loading screw that pushes against the pinion shaft.  This actually increases the pinion drive force and so it is possible to focus with heavy loads without slippage.

 

I just tested the Feathertouch on my Starsplitter.  I positioned it so it was vertical.  I tightened up the brake and placed 11 pounds of weight on the drawtube. It didn't slip and I was able to operate both the coarse and fine focus adjustments without an issue.  Yes, the action was not as light and easy as when using it with a few pounds of eyepiece but no focuser lifting 11 pounds vertically is light and easy, you have to do the work..  

 

So, there are advantages to rack and pinion focusers but the Feathertouch Crayford has a lot to offer and obviously is a world apart from the GSO and Synta Crayfords when it comes to handling heavy loads.  

 

Jon


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