BobH
super member
Reged: 01/03/08
Posts: 143
Loc: PA
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I'm looking for a gadget to attach to the focus knob of an ETX-125 PE that would allow manual fine focus and have a flex extension cable. All I can find is the motorized type.
Any suggestions?
Thanks,
Bob
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"Wise men learn more from fools than fools from the wise." - Cato the Elder
Meade 8" LX200 GPS
ETX 125 PE
Tasco 50mm x 600mm
StellarVue 115ST on MiniTower
Orion Astroview 100
Celestron 8x42 Outland LX
'03 Harley FXDL (oops, wrong forum)
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rmollise
Post Laureate
Reged: 07/06/07
Posts: 4557
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Quote:
I'm looking for a gadget to attach to the focus knob of an ETX-125 PE that would allow manual fine focus and have a flex extension cable. All I can find is the motorized type.
Any suggestions?
Thanks,
Bob
It's not clear to me exactly what you want. If just a flex-focus extension, they are available from numerous vendors. Those sold on Ebay work fine...or as well as this sort of thing can. As for "fine focus" AFAIK, nobody makes a replacement focuser knob that provides fine focus.
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Uncle Rod
Rod's New Book:
Choosing and Using a New CAT
Available now!
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BobH
super member
Reged: 01/03/08
Posts: 143
Loc: PA
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I guess I'm looking for something like the JMI Motofocus, only without the "moto." Something with reduction gears to allow for much slower turning of the focusing knob, only controlled manually rather than by an electric motor.
Bob
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"Wise men learn more from fools than fools from the wise." - Cato the Elder
Meade 8" LX200 GPS
ETX 125 PE
Tasco 50mm x 600mm
StellarVue 115ST on MiniTower
Orion Astroview 100
Celestron 8x42 Outland LX
'03 Harley FXDL (oops, wrong forum)
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jgraham
Postmaster
Reged: 12/02/04
Posts: 6751
Loc: Dayton, Ohio
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I thought about designing a lever I could clip onto the focus knob of an ETX (and onto my StarBlast), that would make it easier to make tiny changes in the focus.
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-John
================================================
Homebuilt scopes from 4.25-16.5"
Meade LXD75-N6/SN6/SC8, DSX-90, ETX-60BB, ETX-125PE, DS-2130
Orion StarBlast, BinoViewers, Coronado PST
Rebel XT/XTi, DSI Pro (I, II, & III), DSI, LPI, Electronic Eyepiece, Phillips SPC900NC
Tasco 60mm Refractors
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blb
sage
Reged: 11/25/05
Posts: 214
Loc: Piedmont NC
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A clothespin on the focus knob works well for fine focus 
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C-11, C-6, XT10i Dob, ETX125PE, TV102, & AT66
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rmollise
Post Laureate
Reged: 07/06/07
Posts: 4557
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Quote:
I guess I'm looking for something like the JMI Motofocus, only without the "moto." Something with reduction gears to allow for much slower turning of the focusing knob, only controlled manually rather than by an electric motor.
Bob
IOW, like a Feathertouch focuser for the ETX. Alas, ain't one or I'd have one. 
I get along OK with the flexifocus (which I only use when the knob is inaccessble. Works OK.
--------------------
Uncle Rod
Rod's New Book:
Choosing and Using a New CAT
Available now!
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jgraham
Postmaster
Reged: 12/02/04
Posts: 6751
Loc: Dayton, Ohio
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Perfect! I'll have the try the clothspin idea. 
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-John
================================================
Homebuilt scopes from 4.25-16.5"
Meade LXD75-N6/SN6/SC8, DSX-90, ETX-60BB, ETX-125PE, DS-2130
Orion StarBlast, BinoViewers, Coronado PST
Rebel XT/XTi, DSI Pro (I, II, & III), DSI, LPI, Electronic Eyepiece, Phillips SPC900NC
Tasco 60mm Refractors
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BobH
super member
Reged: 01/03/08
Posts: 143
Loc: PA
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Well, I couldn't find a clothes pin lying around the house, so I ordered a flex cable.
Bob
--------------------
"Wise men learn more from fools than fools from the wise." - Cato the Elder
Meade 8" LX200 GPS
ETX 125 PE
Tasco 50mm x 600mm
StellarVue 115ST on MiniTower
Orion Astroview 100
Celestron 8x42 Outland LX
'03 Harley FXDL (oops, wrong forum)
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BobH
super member
Reged: 01/03/08
Posts: 143
Loc: PA
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I do have another question, though.
In searching for a flexicable, I ran across some comments about keeping the OTA pointed upward while installing the cable to avoid having the focusing shaft fall into the housing.
I looked at my ETX, and pushed and pulled on the focusing knob and it doesn't move in or out.
Was that caveat for earlier versions of the ETX?
Thanks,
Bob
--------------------
"Wise men learn more from fools than fools from the wise." - Cato the Elder
Meade 8" LX200 GPS
ETX 125 PE
Tasco 50mm x 600mm
StellarVue 115ST on MiniTower
Orion Astroview 100
Celestron 8x42 Outland LX
'03 Harley FXDL (oops, wrong forum)
|
Joe Lalumia
Post Laureate
Reged: 01/24/07
Posts: 3600
Loc: Rockwall, Texas, USA
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There is a tiny set-screw on the side of the focusing knob-- which you need to loosen to remove the knob.
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LX90 8" LNT, SV Nighthawk & TelePOD, SV 80/9D & M4 mount, ETX 90, Orion XT10i, 20x80 binoculars, SV-BV3s-- www.texasastro.org
"Great minds discuss ideas;Average minds discuss events;Small minds discuss people." Unknown
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yock1960
professor emeritus
Reged: 06/22/08
Posts: 976
Loc: SW Ohio, USA
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ETX's certainly don't have 'fine' focus! The flexible focusers do make it more accesible, especially when the OTA is pointing near the zenith, but it really doesn't change the fineness of focus. Maybe the larger diameter knob helps a little? I've wondered about something like this:
http://www.sciencecenter.net/hutech/borg/parts/html/7315.htm
maybe overkill and maybe there isn't enough focus travel on the ETX to use it anyway.
Steve
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LXD75 GEM
Orion Starblast 4.5" Imaging Reflector
William Optics Zenithstar 66 SD APO
Meade DSI II OSC
Meade DSI III OSC
Orion Starshoot Autoguider
Televue Powermate 2.5x
Discovery 6" Dobsonian
Nikon Action Extreme 10x50's
Gallery
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nytecam
Postmaster
Reged: 08/20/05
Posts: 5744
Loc: London UK
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Quote:
ETX's certainly don't have 'fine' focus! The flexible focusers do make it more accesible, especially when the OTA is pointing near the zenith, but it really doesn't change the fineness of focus. Maybe the larger diameter knob helps a little? I've wondered about something like this:
http://www.sciencecenter.net/hutech/borg/parts/html/7315.htmmaybe overkill and maybe there isn't enough focus travel on the ETX to use it anyway.Steve
Will it cope with the backlash that I've found common to my ETXs 
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Nytecam 51N 0.1W
Meade 30cm LX200+ETX-70+e-finder+C8+Ha+CaK PSTs SBIG SGS+homebuilt spectrographs
Starlight SXVF_M9+Lodestar CCDs/Canon 300D DSLR/Fuji E550
My observatory build-ETX-70 imaging-my videos
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rmollise
Post Laureate
Reged: 07/06/07
Posts: 4557
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Quote:
I do have another question, though.
In searching for a flexicable, I ran across some comments about keeping the OTA pointed upward while installing the cable to avoid having the focusing shaft fall into the housing.
I looked at my ETX, and pushed and pulled on the focusing knob and it doesn't move in or out.
Was that caveat for earlier versions of the ETX?
Thanks,
Bob
AFAIK, this is a potential problem with any ETX once the knob is off.
--------------------
Uncle Rod
Rod's New Book:
Choosing and Using a New CAT
Available now!
|
jgraham
Postmaster
Reged: 12/02/04
Posts: 6751
Loc: Dayton, Ohio
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For a cheap fine-focus thingy I tried the clip idea on my StarBlast last night and it was very effective. To grib the focus knob on the StarBlast I used a small shop clip rather than a clothes pin, but the idea is the same. I'll have to try it with my ETX. Another possible benefit of the clip is that if you install it right it might be easily accessible with the telescope pointed near zenith.
--------------------
-John
================================================
Homebuilt scopes from 4.25-16.5"
Meade LXD75-N6/SN6/SC8, DSX-90, ETX-60BB, ETX-125PE, DS-2130
Orion StarBlast, BinoViewers, Coronado PST
Rebel XT/XTi, DSI Pro (I, II, & III), DSI, LPI, Electronic Eyepiece, Phillips SPC900NC
Tasco 60mm Refractors
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nighty
sage
Reged: 12/31/06
Posts: 344
Loc: 75w39n
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Check this link for the vernier mechanism (second item). Some multi-speed focusers use similar parts.
http://www.oselectronics.com/ose_p101.htm
Here is a link to a ATM design using this part.
http://www.bedair.org/Focus/focusproject.html
I use one on my 5" refractor with homemade knobs from radio shack.
Terry
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Stuff to look at stars and things
Scopes For Kids Project
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BobH
super member
Reged: 01/03/08
Posts: 143
Loc: PA
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Terry,
That's exactly what I have been looking for!  Unfortunately, making my own is beyond my talents.
Thanks, at least now I know there is/can be such a gadget.
--------------------
"Wise men learn more from fools than fools from the wise." - Cato the Elder
Meade 8" LX200 GPS
ETX 125 PE
Tasco 50mm x 600mm
StellarVue 115ST on MiniTower
Orion Astroview 100
Celestron 8x42 Outland LX
'03 Harley FXDL (oops, wrong forum)
|
nighty
sage
Reged: 12/31/06
Posts: 344
Loc: 75w39n
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I was sure I could not make one, but just drilled a hole through a large plastic knob and attached it to the tabs. This version required holding the large knob and turning the small knob. Second version attached the tabs to the bottom of the focuser via an aluminum strip and both knobs attached to the shafts. Each application took much planning and fiddle time but only about ten minutes of work.
I think the shaft on the ETX will fit directly so an adapter is not needed. You should be able to make it work for around $20.
Terry
--------------------
Stuff to look at stars and things
Scopes For Kids Project
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DMRandall
newbie
Reged: 12/25/08
Posts: 4
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I could sure see a marketable product in that fine focuser. Wish I had the ability to build a dozen or so to test market them. Esp if they were as easy as a "replacement focuser knob for ETX"...
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Jason Rader
member
Reged: 12/06/08
Posts: 50
Loc: Douglasville, GA
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Thanks for the clothes-pin idea. I'll give it a try when the skies clear up!
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ETX-70AT(For the kids)
ETX-125AT(Delivered 1/7/09!)
Meade 26mm 400 Series Plossl
Meade 25mm MA
Meade 9mm MA
Criterion A.R. 18mm(No idea what this is except it's an 18mm)
Criterion Ortho 6mm(Ditto)
Criterion A.R. 9mm(Ditto)
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BobH
super member
Reged: 01/03/08
Posts: 143
Loc: PA
|
|
Quote:
Quote:
I do have another question, though.
In searching for a flexicable, I ran across some comments about keeping the OTA pointed upward while installing the cable to avoid having the focusing shaft fall into the housing.
I looked at my ETX, and pushed and pulled on the focusing knob and it doesn't move in or out.
Was that caveat for earlier versions of the ETX?
Thanks,
Bob
AFAIK, this is a potential problem with any ETX once the knob is off.
Now my problem is how to get the knob off.
Scoptronix flex focuser arrived today. Supplied hex key does not fit existing focuser knob set screw. No key I have fits. Appears to be stripped. I've never had it off, but the scope was returned to Meade once for repairs.
What to do? 
--------------------
"Wise men learn more from fools than fools from the wise." - Cato the Elder
Meade 8" LX200 GPS
ETX 125 PE
Tasco 50mm x 600mm
StellarVue 115ST on MiniTower
Orion Astroview 100
Celestron 8x42 Outland LX
'03 Harley FXDL (oops, wrong forum)
|
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