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poodle
sage
Reged: 01/21/05
Posts: 254
Loc: Breckenridge, Texas
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I have an old Meade LX5 that I swapped my Dob for. I love the tracking but hate the focuser. I was wondering if you can use a Crayford style focuser on this scope. I cannot in my mind see how one would hook up. Would it go between the diagonal and the eyepiece holder or between the diagonal and the eyepiece? Also would one have room to swing the scope vertical with a focuser on it? Or would it replace the eyepiece holder? I know this sounds like a stupid question but I also know on CN there are no stupid questions.
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Steve
10" Lx5
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Lane
Carpal Tunnel
Reged: 11/19/07
Posts: 1515
Loc: Frisco, Texas
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I really doubt there is enough room on a fork mount to install this focuser and a diagonal but here it is anyway:
You can buy a crayford focuser that has standard SCT threads, so it screws to the back of the scope in place of your visual back. Then on the other end is has a standard 2" opening for a 2" diagonal or you could use a 1.25" diagaonal with a 2" to 1.25" standard eyepiece adapter. The part that screws to the back of the scope in this picture is that silver ring. You can't see the threads because this is a really bad picture but they are there. The bolt on top allow you to swivel the focuser around in a circle to any angle you want.
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Mounts: CGEM, ORION SIRIUS, AT Voyager/motorized
SCTs: C6, C8, C9.25, C11,
Refractors: TV Pronto, Orion ED80
Edited by Lane (11/01/09 06:04 PM)
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Lane
Carpal Tunnel
Reged: 11/19/07
Posts: 1515
Loc: Frisco, Texas
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What exactly do you not like about the focuser on the SCT? Because you may be able to replace the focuser knob with a feathertouch microfocuser if they make one for that model. I put the feathertouch on all my SCTs and it is definitely much nicer to use that the standard knob.
You could also attach the meade electric focuser or the JMI electric focuser, then you just push buttons to focus.
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Mounts: CGEM, ORION SIRIUS, AT Voyager/motorized
SCTs: C6, C8, C9.25, C11,
Refractors: TV Pronto, Orion ED80
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poodle
sage
Reged: 01/21/05
Posts: 254
Loc: Breckenridge, Texas
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Thanks for the replys Lane. I had a crayford on my dob, it was smooth and it did not have all the slop. I guess that is what I hate most is the slop. It is a big old game of back and forth trying to land on just the right spot. I also got a moto focus with the scope but I dont use it, I prefer the feel and control with my fingers.
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Steve
10" Lx5
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Lane
Carpal Tunnel
Reged: 11/19/07
Posts: 1515
Loc: Frisco, Texas
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Then you may want to look into a feathertouch microfocuser. It replaces the existing knob with a big course focus knob and smaller fine focus knob. Very nice to use and silky smooth.
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Mounts: CGEM, ORION SIRIUS, AT Voyager/motorized
SCTs: C6, C8, C9.25, C11,
Refractors: TV Pronto, Orion ED80
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SteveC
Carpal Tunnel
Reged: 06/15/06
Posts: 1775
Loc: The Garden State
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Quote:
Thanks for the replys Lane. I had a crayford on my dob, it was smooth and it did not have all the slop. I guess that is what I hate most is the slop. It is a big old game of back and forth trying to land on just the right spot. I also got a moto focus with the scope but I dont use it, I prefer the feel and control with my fingers.
Is the mirror stationary in the LX5 or does it move up and down on the fucusing tube? If it's the latter then your problem is more that just the the fucuser knob and the gears attached to it. Your mirror may be flopping around.
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SteveC
TEC 140
Intes Micro 715 deluxe
TEC 110 (on order)
SolarMax 40
Losmandy G-11 w/Gemini, DM-6 w/Sky Commander on SV wood tripod, Vixen Skypod
TEC EP Turret, TMB Supermonos, ZAO II, Naglers, 32mm Konig, 24mm Panoptics, 14mm Meade UWA
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Stew57
member
Reged: 05/03/09
Posts: 84
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Sounds like focus shift, an inherent problem in sct designs. Individual ota's have it to a greater or lesser extent. How much does the image move when chasing focus?
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SteveC
Carpal Tunnel
Reged: 06/15/06
Posts: 1775
Loc: The Garden State
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Quote:
I really doubt there is enough room on a fork mount to install this focuser and a diagonal but here it is anyway:
You can buy a crayford focuser that has standard SCT threads, so it screws to the back of the scope in place of your visual back. Then on the other end is has a standard 2" opening for a 2" diagonal or you could use a 1.25" diagaonal with a 2" to 1.25" standard eyepiece adapter. The part that screws to the back of the scope in this picture is that silver ring. You can't see the threads because this is a really bad picture but they are there. The bolt on top allow you to swivel the focuser around in a circle to any angle you want.
Just a word of caution concerning that WO focuser. I owned one for a couple of months and had to return it. I may have been the one in million, but that small screw at the 10 o'clock position, well there are four of them. They fit into a groove and hold the focusing portion onto the SCT screw in portion. Well, spinning that focuser will cause the small screws to catch in the groove and lossen up, then they begin to wiggle. Then the threads begin to wear out, not on the screws that can easily be replaced, but on the focuser housing, which can't. Like I said, I may have been the one in a million with this problem, but I was not happy with the design.
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SteveC
TEC 140
Intes Micro 715 deluxe
TEC 110 (on order)
SolarMax 40
Losmandy G-11 w/Gemini, DM-6 w/Sky Commander on SV wood tripod, Vixen Skypod
TEC EP Turret, TMB Supermonos, ZAO II, Naglers, 32mm Konig, 24mm Panoptics, 14mm Meade UWA
Edited by SteveC (11/02/09 11:37 AM)
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jason_milani
Carpal Tunnel
Reged: 09/03/04
Posts: 1737
Loc: Northeast Ohio
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You've got excessive image shift from mirror flop. A Feathertouch micro will not get rid of that. An aftermarket Crayford may work but as stated it may not fit with the fork mount. You might want to try and re-lube the baffle tube which may tighten things up a bit and lessen the shift. It's an LX-5 so it's fairly old and the original grease on that baffle tube might need to be replaced.
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Celestron C-14
Celestron C-8
Celestron C-5
Orion/Vixen ED114SS APO
William Optics Megrez 72mm ED
Celestron CGE mount
Discmount DM-4
Mallincam Hyper Color Plus
Baader UV/IR Modded Canon 40D
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poodle
sage
Reged: 01/21/05
Posts: 254
Loc: Breckenridge, Texas
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Thanks for the replys. Jason that sounds like a good place to start, do you know of a place with instructions for doing such a thing? You are right ,this is an old scope. It is in really good shape. Other than the focus the scope and the electronics seem to work fine.
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Steve
10" Lx5
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Ouranos
sage
Reged: 11/07/06
Posts: 427
Loc: Illinois
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What is mirror flop/slop? Does that cause image shift when focusing? How is it corrected?
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East/Central Illinois
Orion XT10
Celestron C8
AstroTech 102ED
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Rick Woods
Postmaster
Reged: 01/27/05
Posts: 5684
Loc: Inner Solar System
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There are two things, defined by me thusly:
Mirror flop = when you slew across the sky, the mirror changes position a little bit and you have to refocus. I don't know what you can do about that.
Wait, yes I do - Meades (and newer Celestrons, I understand) have mirror locks that will prevent flop. You just have to be careful to loosen the lock when you want to refocus.
Image shift = when you focus, the image shifts a little to one side or the other. If you run the focus out to the ends in both directions several times, is can distribute the grease a little better and reduce this effect.
My M14 has very slight image shift - about 8-10 arcseconds. However, the mirror flop is pretty large, and I definitely have to refocus after slewing a long way.
It doesn't bother me, just part of the hobby.
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poodle
sage
Reged: 01/21/05
Posts: 254
Loc: Breckenridge, Texas
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Using your definition Rick, my problem would be image shift. I guess I will try running the focus all the way out a few times and see if that helps. I always run it all the way in when I am finished with it for the night.
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Steve
10" Lx5
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Brian L
super member
Reged: 11/17/08
Posts: 119
Loc: The garden paradise of Pittsbu...
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I have one of those WO focusers on my 10" LX200 and I really like it. I keep the mirror locked most of the time and use the crayford for focusing. I've had it for three or four years and I have had no issues with it at all. The only problem is that with a 10" SCT at least, the focuser+diagonal limits the altitude range. You can only get to within 10 degrees or so of the zenith before your diagonal bangs into the fork mount. There's no warning, of course- so you have to pay attention when declination slewing using the mount's GOTO function. Might not be a problem on 12" and larger SCT's and certainly not on equatorial mounts. It's a good value for $200.
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WO FLT-110 f/6.5, TEC optics
Losmandy G-11 Gemini
Meade 10" LX200 GPS/UHTC
Questar 3.5" Standard
Vixen VMC-110L
Canon 450D, unmodified
Assortment of TV Panoptic, TV Radian, Vixen LVW, and WO eyepieces
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