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Are Hex focusers really bad?

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#1 Neinball

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Posted 22 April 2020 - 09:11 PM

I'm considering getting either a TS Photoline 107 with a 3" focuser, or a ES127 for a mid to widefield imaging setup. I like the ES because its got just enough reach to give me some galaxy capability and if I ever need service I won't have to ship it halfway across the world, but while I have the budget for the scope I don't have the budget for the scope and a moonlite. I've been told by several people including the owner of a 115CF that the Hex focusers are unusable for imaging and that if you get an ES scope the first thing you need to do is replace it. On the other side I have yet to see any real complaints about the the TS focusers but again I'd like something I won't have to ship across the pond for service/warranty. So for those of you who have used the Hex focusers, particularly the 2.5 model, are they really as bad as I'm hearing and warrant immediate replacement for imaging work?  



#2 TOMDEY

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Posted 22 April 2020 - 10:51 PM

I got the ES 3-inch hex focuser and Star Diagonal; very first thing I noticed is that the mechanism is traditional helical rack and pinion and exhibits severe backlash, even though the knobs include regular and fine focus. Other aspects of the build are similarly sloppy... poor choice of screws and placement, knurled thumbscrews that are sloppy loose and heads that interfere with other structure... a real amateurish cob-job. The advantage is that it is el cheapo. I'm just using it for visual use on my 6-inch APO Refractor Triplet at low power... actually as a modest finder telescope on my 36-inch scope. Quite grandiose, as a finder scope. I'd say that for imagery, a big fat Moonlite or Feathertouch upgrade would be... almost essential. I'll do my usual mods on this thing, and enjoy it... for what it is... cheap!

 

I actually like Chinese Stuff, and will continue to buy it. Good value if you're OK with ~good value for the price~ and have the skills to modify or replace ill-conceived and executed mechanicals. When it comes to screws and fasteners... the Chinese seem to have never really figured it out and/or simply don't care. Just push it out the door.    Tom

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#3 Neinball

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Posted 23 April 2020 - 07:24 PM

I got the ES 3-inch hex focuser and Star Diagonal; very first thing I noticed is that the mechanism is traditional helical rack and pinion and exhibits severe backlash, even though the knobs include regular and fine focus. Other aspects of the build are similarly sloppy... poor choice of screws and placement, knurled thumbscrews that are sloppy loose and heads that interfere with other structure... a real amateurish cob-job. The advantage is that it is el cheapo. I'm just using it for visual use on my 6-inch APO Refractor Triplet at low power... actually as a modest finder telescope on my 36-inch scope. Quite grandiose, as a finder scope. I'd say that for imagery, a big fat Moonlite or Feathertouch upgrade would be... almost essential. I'll do my usual mods on this thing, and enjoy it... for what it is... cheap!

 

I actually like Chinese Stuff, and will continue to buy it. Good value if you're OK with ~good value for the price~ and have the skills to modify or replace ill-conceived and executed mechanicals. When it comes to screws and fasteners... the Chinese seem to have never really figured it out and/or simply don't care. Just push it out the door.    Tom

They're R&P focusers? then why does ES call them Crayfords in all their literature, just being lazy?



#4 TOMDEY

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Posted 23 April 2020 - 08:44 PM

They're R&P focusers? then why does ES call them Crayfords in all their literature, just being lazy?

The two aren't necessarily disjoint/mutually-exclusive. Rack and Pinion refers to the longitudinal geared driving mechanism / traction provision, Crayford refers to the longitudinal linear bearing provision. I haven't dismembered it enough to scrutinize the bearings... just complaining about the fasteners and backlash, which appears to reside in the ... pinion/rack interface (?) Helical is supposed to prevent that. Maybe it's in the knobs and how --- heck, I don't know... thankful that I'm only using it for low-power visual. Anyway, I pretty much replace all of my OEM focusers with FeatherTouch or Moonlite.     Tom



#5 tjz

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Posted 24 April 2020 - 08:33 PM

Perhaps I am lucky, but I have no issues with my ES127 FCD100 or my ES80 FCD100 with the 2.5" Hex focuser. I use a ZWO EAF and set the backlash to 200 steps inwards in SGP and I get nice looking repeatable V curves. My stars are as sharp as I can expect with Rocky Mountain seeing conditions. The only issue I have is that you really need to adjust the set screws somewhat firmly and the focuser rotation lock screw very firmly to eliminate any wiggle and tilt. You might do better with a different focuser, but then you have the issue with getting the ES one unglued from the OTA.


Edited by tjz, 24 April 2020 - 08:34 PM.

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#6 TOMDEY

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Posted 24 April 2020 - 11:38 PM

Perhaps I am lucky, but I have no issues with my ES127 FCD100 or my ES80 FCD100 with the 2.5" Hex focuser. I use a ZWO EAF and set the backlash to 200 steps inwards in SGP and I get nice looking repeatable V curves. My stars are as sharp as I can expect with Rocky Mountain seeing conditions. The only issue I have is that you really need to adjust the set screws somewhat firmly and the focuser rotation lock screw very firmly to eliminate any wiggle and tilt. You might do better with a different focuser, but then you have the issue with getting the ES one unglued from the OTA.

Cool; so far - so good! The funny thing, in contrast, with the 3-incher on my ES 152mm --- the thing actually FELL OUT! The only thing barely holding it on were these three microscopic set screws that contacted at the very innermost part of the focuser (those little dents marked in this image below >>>) Clearly, the proper location to attach the adapter to the focuser should have been to provide substantial screws going into that big groove farther up the focuser. All I can figure is that the factory floor-boss told the assembly workers to ignore the problem and get the things out the door. So, I will remove the adapter that mates to this, and drill and tap screw holes in the proper locations, and provide good English screws. Honest, anyone else with this same make and model --- check out yours else the entire focuser + Star Diagonal + Eyepiece/Camera --- just decide to drop right off, some otherwise perfect night!    Tom

 

~click on~ >>>

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#7 WxMan

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Posted 24 May 2020 - 12:36 AM

Cool; so far - so good! The funny thing, in contrast, with the 3-incher on my ES 152mm --- the thing actually FELL OUT! The only thing barely holding it on were these three microscopic set screws that contacted at the very innermost part of the focuser (those little dents marked in this image below >>>) Clearly, the proper location to attach the adapter to the focuser should have been to provide substantial screws going into that big groove farther up the focuser. All I can figure is that the factory floor-boss told the assembly workers to ignore the problem and get the things out the door. So, I will remove the adapter that mates to this, and drill and tap screw holes in the proper locations, and provide good English screws. Honest, anyone else with this same make and model --- check out yours else the entire focuser + Star Diagonal + Eyepiece/Camera --- just decide to drop right off, some otherwise perfect night!    Tom

 

~click on~ >>>

I'm considering the 152. Is it worth the extra cost above a 127? I know focuser is 3" on 152 and 2.5" otherwise, but was looking for the optical opinion if you have that experience.



#8 RichA

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Posted 24 May 2020 - 01:16 AM

I'm considering getting either a TS Photoline 107 with a 3" focuser, or a ES127 for a mid to widefield imaging setup. I like the ES because its got just enough reach to give me some galaxy capability and if I ever need service I won't have to ship it halfway across the world, but while I have the budget for the scope I don't have the budget for the scope and a moonlite. I've been told by several people including the owner of a 115CF that the Hex focusers are unusable for imaging and that if you get an ES scope the first thing you need to do is replace it. On the other side I have yet to see any real complaints about the the TS focusers but again I'd like something I won't have to ship across the pond for service/warranty. So for those of you who have used the Hex focusers, particularly the 2.5 model, are they really as bad as I'm hearing and warrant immediate replacement for imaging work?  

I owned a cheap 4" achro briefly, I bought it to test it.  It had a hex focuser and it wasn't too bad.  It had a very slight "click-click-click" feel as you focused, almost like fine detents, but it wasn't objectionable unless you are used to  things like $600 Crayfords or TeleVue focusers. 



#9 TOMDEY

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Posted 24 May 2020 - 05:10 AM

I'm considering the 152. Is it worth the extra cost above a 127? I know focuser is 3" on 152 and 2.5" otherwise, but was looking for the optical opinion if you have that experience.

Hi, WxMan! I haven't critically-critiqued the visual imagery yet.

 

Six inches is way bigger than five inches, in every respect; so, in the context of ~aperture rules~, the 6" is a magnificent bargain at ... the few thousand dollars entry fee. I'm using mine visual only, on the back deck in a convenient, high-end yoke mount on heavy duty Manfrotto crank tripod, and/or as a finderscope on my 36-inch scope. So, that low-power/rich-field use doesn't stress the scope at all. I'll also crank up the mag to see how it performs on the moon, planets, clusters, etc. --- but haven't done that yet.

 

For a refractor, six inches is at that threshold where hauling it around becomes a consideration. The carbon fiber build is light weight, very nice! For the price, this thing is extravagant. It is not Premium Grade, which would cost several times as much.    Tom



#10 YAOG

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Posted 25 May 2020 - 09:06 PM

I'm considering getting either a TS Photoline 107 with a 3" focuser, or a ES127 for a mid to widefield imaging setup. I like the ES because its got just enough reach to give me some galaxy capability and if I ever need service I won't have to ship it halfway across the world, but while I have the budget for the scope I don't have the budget for the scope and a moonlite. I've been told by several people including the owner of a 115CF that the Hex focusers are unusable for imaging and that if you get an ES scope the first thing you need to do is replace it. On the other side I have yet to see any real complaints about the the TS focusers but again I'd like something I won't have to ship across the pond for service/warranty. So for those of you who have used the Hex focusers, particularly the 2.5 model, are they really as bad as I'm hearing and warrant immediate replacement for imaging work?  

All of the ES Hex focusers are R&P focusers regardless of what you think you read, ES lit. is misleading and frequently wrong. The Hex focusers are not high quality focusers suitable for imaging, they are okay for visual use if carefully adjusted and thread adhesive applied to the small grub screws to hold adjustment. The Hex focusers are more about having a marketing feature to sell their products. For imaging buy a 2.5" Moonlite Crayford or Starlight Instruments FTF R&P both are excellent and work well with many different ASCOM autofocusers. 

 

The truth is that if you for some reason feel you must buy an ES telescope for imaging use you will need to buy the FCD100 series scope to get a reasonably well corrected lens to reduce the blue halos the FCD1 lenses have. You will also need to replace the focuser realistically if you are serious about imaging due to sag, and drawtube shift. If you do the math and import a scope from TS Optics in Germany you can afford to buy a better scope with much better mechanicals and probably slightly better optics for about the same money. But don't take my word for it, do your due diligence and read the optical test reports from people doing DPAC and Zygo testing and the user reviews of these scopes when used for imaging. This is the scope to buy, TS 130mm f/7 FPL-53 triplet with 3.7" R&P focuser, delivered for about $2,200 or so. 


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#11 John Fitzgerald

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Posted 31 July 2020 - 01:27 PM

Cool; so far - so good! The funny thing, in contrast, with the 3-incher on my ES 152mm --- the thing actually FELL OUT! The only thing barely holding it on were these three microscopic set screws that contacted at the very innermost part of the focuser (those little dents marked in this image below >>>) Clearly, the proper location to attach the adapter to the focuser should have been to provide substantial screws going into that big groove farther up the focuser. All I can figure is that the factory floor-boss told the assembly workers to ignore the problem and get the things out the door. So, I will remove the adapter that mates to this, and drill and tap screw holes in the proper locations, and provide good English screws. Honest, anyone else with this same make and model --- check out yours else the entire focuser + Star Diagonal + Eyepiece/Camera --- just decide to drop right off, some otherwise perfect night!    Tom

 

~click on~ >>>

Tom,

I just did the modification you suggested, after some obsessing about it.  I used three #8-32 x 5/16 set screws in addition to the three supplied screws that bear near the outer edge of the flange.  The focuser is rock solid now, and cannot fall off because the new set screws are behind the inside flange, down in the groove.  The additional screws make it a decent focuser now.  Granted, it's not a FeatherTouch, but it's plenty good for visual, but IMO, it does need this modification, unless it is checked for looseness often.  The grub screws supplied bite into the flange only about 1/8 inch from the edge, and if they are not tight, a little bit of slippage could lead to a "fall out" condition.  The original grub screws were still holding fine, but after buying a Delos, I wanted insurance.


Edited by John Fitzgerald, 31 July 2020 - 02:55 PM.


#12 TOMDEY

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Posted 31 July 2020 - 04:19 PM

Tom,

I just did the modification you suggested, after some obsessing about it.  I used three #8-32 x 5/16 set screws in addition to the three supplied screws that bear near the outer edge of the flange.  The focuser is rock solid now, and cannot fall off because the new set screws are behind the inside flange, down in the groove.  The additional screws make it a decent focuser now.  Granted, it's not a FeatherTouch, but it's plenty good for visual, but IMO, it does need this modification, unless it is checked for looseness often.  The grub screws supplied bite into the flange only about 1/8 inch from the edge, and if they are not tight, a little bit of slippage could lead to a "fall out" condition.  The original grub screws were still holding fine, but after buying a Delos, I wanted insurance.

Thanks, John~Superb! I gota get off my duff and do exactly that. Yes, that placement is perfect. I actually put this mod on my ~To Do List~ today... might get to it tomorrow...    Tom



#13 John Fitzgerald

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Posted 31 July 2020 - 06:40 PM

Thanks, John~Superb! I gota get off my duff and do exactly that. Yes, that placement is perfect. I actually put this mod on my ~To Do List~ today... might get to it tomorrow...    Tom

Please let us know how it goes.  Thank you again!




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