Jump to content


Photo

Trouble in Paradise

  • Please log in to reply
16 replies to this topic

#1 Lew Chilton

Lew Chilton

    Surveyor 1

  • -----
  • Posts: 1742
  • Joined: 20 Oct 2005
  • Loc: SoCal

Posted 03 August 2014 - 08:41 PM

I just purchased a slightly used Takashashi TSA-120 from a well-known over-the-counter retail and mail order telescope emporium in my area. I mounted it on my Tak EM-200 mount.

First light - for me - came Saturday nite at my favorite high-altitude star party site.  The optics are superb. No complaint there. The mount is solid and tracks smoothly. No complaint there. But, whoa, that Tak Micro-Edge focuser has a problem.

 

It focuses much like the older Celestron and Meade SCTs.  As the image is fine-focused in and out to achieve sharpest focus, the image shifts laterally back and forth in the field of view. The higher the magnification, the greater the shift. At 180X, Saturn was moving back and forth about 2 or 3 times its own diameter as I was trying to bracket sharpest focus.  Any idea(s) what the problem could be? Thanks for your help.

 

 



#2 GJJim

GJJim

    Apollo

  • -----
  • Posts: 1333
  • Joined: 09 Sep 2006
  • Loc: Western CO

Posted 03 August 2014 - 11:52 PM

Sounds like a spacer pad is worn or shifted in the mechanism. You may have to send the focuser to Texas Nautical for refurb.



#3 WesC

WesC

    Vanguard

  • *****
  • Posts: 2006
  • Joined: 06 Feb 2013
  • Loc: La Crescenta, CA

Posted 04 August 2014 - 12:18 AM

That definitely doesn't sound right. 



#4 WesC

WesC

    Vanguard

  • *****
  • Posts: 2006
  • Joined: 06 Feb 2013
  • Loc: La Crescenta, CA

Posted 04 August 2014 - 12:20 AM

BTW we have the same last name, pretty cool!



#5 bobhen

bobhen

    Viking 1

  • -----
  • Posts: 668
  • Joined: 25 Jun 2005

Posted 04 August 2014 - 11:48 AM

Lew,

 

I have a Tak 120.

 

Turn the scope over and look at the focuser. Check to see if the small silver disk is tight against the focuser cover. If not tighten it up. Try using a ballpoint pen or something sharp to place in one of the notches and turn the disk. If the disk is already tight, remove it and then remove the green focuser cover and tighten or adjust the stiffness of the focuser to your liking. Replace the cover and the disk and then tighten up the disk.

 

Hope that helps. If not, call Texas Nautical. The views delivered by a Tak 120 are definitely worth getting that focuser right!

 

Bob



#6 tomcody

tomcody

    Surveyor 1

  • *****
  • Posts: 1688
  • Joined: 06 Jul 2008
  • Loc: Titusville, Florida

Posted 04 August 2014 - 12:20 PM

I just purchased a slightly used Takashashi TSA-120 from a well-known over-the-counter retail and mail order telescope emporium in my area. I mounted it on my Tak EM-200 mount.

First light - for me - came Saturday nite at my favorite high-altitude star party site.  The optics are superb. No complaint there. The mount is solid and tracks smoothly. No complaint there. But, whoa, that Tak Micro-Edge focuser has a problem.

 

It focuses much like the older Celestron and Meade SCTs.  As the image is fine-focused in and out to achieve sharpest focus, the image shifts laterally back and forth in the field of view. The higher the magnification, the greater the shift. At 180X, Saturn was moving back and forth about 2 or 3 times its own diameter as I was trying to bracket sharpest focus.  Any idea(s) what the problem could be? Thanks for your help.

If the image is shifting as you rock the focus knob back and forth? the draw tube is loose in the focuser! To confirm this just slightly tighten the focuse lock knob on the top of the focuser until you feel some resistance when adjusting focus. If that fixes your issue? Then the next step is to adjust the pre-tension on the drawtube. To adjust pre- tension do the following:

1. Remove the pinion cover on the bottom of the scope by loosening and removing the flat chrome screw.

2. Loosen the two phillips head screws for the pinion shaft until you feel some play but can still adjust the drawtube.

( Why loosen the pinion shaft? the pre- tension screws on the top of the focuser press the drawtube down and you don't want that downward pressure to bind against the pinion shaft).

3. allong the top of the focuser are three 1.5mm allen head screws , they are set in a clear sealer that looks like clear nail polish. Use a small drop of acetone ( nail polish remover ) on each screw until it turns then:

4. adjust the three screws starting with the center one while you move the draw tube in and out untill you are happy with the smooth movement and feel that you have removed any play in the drawtube.

5. adjust the two pinion screws for smooth movement and no backlash.

6. replace the pinion cover

Done, note the three pre- tension screws should harden up as the acetone drys, if not a drop of clear nail polish will lock them in place again.

Good luck

Rex


Edited by tomcody, 04 August 2014 - 12:24 PM.


#7 AustinAstronomer

AustinAstronomer

    Mariner 2

  • -----
  • Posts: 236
  • Joined: 04 Mar 2010

Posted 04 August 2014 - 04:08 PM

Lew,

 

I have a Tak 120.

 

Turn the scope over and look at the focuser. Check to see if the small silver disk is tight against the focuser cover. If not tighten it up. Try using a ballpoint pen or something sharp to place in one of the notches and turn the disk. If the disk is already tight, remove it and then remove the green focuser cover and tighten or adjust the stiffness of the focuser to your liking. Replace the cover and the disk and then tighten up the disk.

 

Hope that helps. If not, call Texas Nautical. The views delivered by a Tak 120 are definitely worth getting that focuser right!

 

Bob

 

 

That "small silver disk" is a spanner screw.  Without the proper tool, it is difficult to remove.  I guess Takahashi uses them so folks won't mess around with their focusers.  :-)


Edited by AustinAstronomer, 04 August 2014 - 04:15 PM.


#8 Lew Chilton

Lew Chilton

    Surveyor 1

  • -----
  • Posts: 1742
  • Joined: 20 Oct 2005
  • Loc: SoCal

Posted 04 August 2014 - 04:38 PM

Thanks everyone!  I will do as you suggested. I already have the proper spanner tool which Texas Nautical sent to me a few years ago when I had to swap out a Micro-Edge from one TOA-130 to another. I no longer own the TOA-130s because they were too heavy for me. That's why I bought the TSA-120. I will duly report if the adjustments you suggested remedy the problem.

 

Cloudynights is such a great site because of you guys.

 

Lew



#9 LewisM

LewisM

    Vostok 1

  • -----
  • Posts: 187
  • Joined: 23 Jan 2013
  • Loc: Australia

Posted 05 August 2014 - 05:12 AM

 

Lew,

 

I have a Tak 120.

 

Turn the scope over and look at the focuser. Check to see if the small silver disk is tight against the focuser cover. If not tighten it up. Try using a ballpoint pen or something sharp to place in one of the notches and turn the disk. If the disk is already tight, remove it and then remove the green focuser cover and tighten or adjust the stiffness of the focuser to your liking. Replace the cover and the disk and then tighten up the disk.

 

Hope that helps. If not, call Texas Nautical. The views delivered by a Tak 120 are definitely worth getting that focuser right!

 

Bob

 

 

That "small silver disk" is a spanner screw.  Without the proper tool, it is difficult to remove.  I guess Takahashi uses them so folks won't mess around with their focusers.  :-)

 

A pair of circlip pliers - either conventional or reversed - works perfectly. I disassembled my FC-100 focuser last night with nil problems.



#10 Pete-LH

Pete-LH

    Messenger

  • *****
  • Posts: 414
  • Joined: 25 Mar 2009
  • Loc: Wilmington, DE

Posted 09 August 2014 - 09:15 AM

NOTE: I followed tomcody(Rex)'s directions for my FS-102 and they are perfect.

I've also found the adjustment is similar for some older Vixen focusers and an olde AP Superplanetary focuser that I had.

To remove the chrome disc and cover I am ashamed to admit that I used an adjusted paper clip. The disc and cover are just cosmetic. It's the two philips screws and 3 small allen screws on the top that control the tension.

I still find that with time the two philips scews loosen enough that the focuser will slip with a heavey load and need to be adjusted. I've contemplated putting a drop of epoxy on the screw where it meets the plate but I think the tension can be somewhat temperature sensitive in the Winter at temperature extremes. I find I need to adjust it then as well.

I love the Tak optics but I am less than thrilled with the focuser they offer on such a high end refractor. Doesn't cure my case of TAKITIS however.



#11 crazyqban

crazyqban

    Vanguard

  • *****
  • Posts: 2082
  • Joined: 16 Dec 2008
  • Loc: Miami, Florida

Posted 10 August 2014 - 11:03 PM

Do what I did, replace it with a Feathertouch.



#12 Pete-LH

Pete-LH

    Messenger

  • *****
  • Posts: 414
  • Joined: 25 Mar 2009
  • Loc: Wilmington, DE

Posted 11 August 2014 - 12:37 AM

"Do what I did, replace it with a Feathertouch."

 

Sergio ... that is in my plan down the road. Right now I am having fun evaluating some smaller refractors and making some other upgrades.

 

Its a balance of funds and priorities.



#13 Lew Chilton

Lew Chilton

    Surveyor 1

  • -----
  • Posts: 1742
  • Joined: 20 Oct 2005
  • Loc: SoCal

Posted 17 August 2014 - 04:01 PM

Thanks everyone for your advice. After removing the little silver disk cover and disconnecting the Micro-Edge link, I removed the green focuser cover which exposed two small phillips head screws. They were pretty loose so I snugged them up a little to adjust the focus drag, and then reassembled everything. I tried it out last night at a star party and everything is as it should be. No image shift. Thanks for giving me the confidence to mess with the focusing mechanism. Here's a picture of my setup at last night's star party.

 

All the best.

Attached Files


Edited by Lew Chilton, 17 August 2014 - 04:02 PM.


#14 blueman

blueman

    Photon Catcher

  • *****
  • Posts: 5294
  • Joined: 20 Jul 2007
  • Loc: California

Posted 17 August 2014 - 08:53 PM

Boy that place sure looks familiar! I only wish I had been the one to paint the white lines. Mine are, well, less than artistically done. ;^)

Glad you found the problem, now you have the Tak working tack sharp.

Maybe I will see you there next new Moon. I plan on being there and would love to look through the TAK. Just look me up setup next to Larry.

Blueman


Edited by blueman, 17 August 2014 - 08:55 PM.


#15 Lew Chilton

Lew Chilton

    Surveyor 1

  • -----
  • Posts: 1742
  • Joined: 20 Oct 2005
  • Loc: SoCal

Posted 17 August 2014 - 11:46 PM

Blueman, last nite was 3rd quarter, so most of us left by midnite. Everything was great except for the red ants! I went 2 weekends earlier to Mt Pinos, but we got clouded out Sat. nite and Sunday it rained. This was my first star party at the LAAS Lockwood Valley site since about 1983. Hope to run into you sometime soon.  All the best.

Attached Files



#16 blueman

blueman

    Photon Catcher

  • *****
  • Posts: 5294
  • Joined: 20 Jul 2007
  • Loc: California

Posted 18 August 2014 - 12:17 AM

The little ants are not so bad, but look out for the BIG red ones, they do leave a mark.

Conditions may be good for the new Moon, come up if you get a chance.

Blueman



#17 Balok

Balok

    Explorer 1

  • -----
  • Posts: 85
  • Joined: 18 May 2009
  • Loc: Alberta

Posted 19 August 2014 - 03:10 PM

Your set up looks fantastic Lew.

Love that Tak green.








Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics