Jump to content

Banner.jpg.b83b14cd4142fe10848741bb2a14c66b.jpg

Hello...and a few questions straight away.

Nona

By Nona
in Welcome

Recommended Posts

Nona

Nona

Posted
Posted

Hi all...just registered and I have a few questions about accessories for my OMC140. I like virtually everything about this scope...except the focuser. Basically it's $hite and I'd like to upgrade. Anyone else out there upgraded their focuser?? I also want a pair of binos after looking through some Denk's. I can't afford Denk's yet but would consider Burgess or WO binos...has anyone had any problems focusing with these? (this applies to Mak-Cass owners). Soon as I'm fully setup (waiting for a new mount...EQ6 goto), I'll start posting some pics. :lol:

Link to comment
Share on other sites
  • Replies 26
  • Created
  • Last Reply
Kaptain Klevtsov

Kaptain Klevtsov

Posted
Posted

Welcome to SGL Nona. I've got an OMC140 and have no bother with the focuser at all. What specifically is it doing that it shouldn't?

BTW mine came to me via Ambermile Engineering and therefore might have been tweaked / optimised in some way. My 'scope has what looks like a piece stolen off a micrometer to work the focus, is your's the same?

Captain Chaos

Link to comment
Share on other sites
lunator

lunator

Posted
Posted

Hi Nona

Welcome to SGL

I have an OMC140 and haven't had any issues with the focusser.

What is the issue with it?

I know I have to let the scope cool properly before the image looks it's best and this can appear to be a focussing problem at 1st.

Cheers

Ian

Link to comment
Share on other sites
  • 1 month later...
Nona

Nona

Posted
  • Author
Posted

Hi everyone...thanks for the replies and apologies for not getting back sooner...What a nightmare few weeks! :D

I've had to take a new job in Bristol...I live in Kent. :shock:

My home pc blew up and it's taken a few weeks to source a new motherboard. :shock: :shock:

Soon as the pc is up and running, I get tonsillitis!! :)

However, I'm back to full health etc and will answer some of your replies. The focuser is the same as Captn Chaos ie. looks like the end of a micrometer sticking out. However, it feels REALLY loose...I can detect virtually no resistance when turning. Could this have become detatched in some way?? Needless to say, I can't get the scope to focus accurately...it seems like half a turn out of focus (if that makes sense).

If anyone replies, I promise to get back within a day at worst!! :)

Link to comment
Share on other sites
Nona

Nona

Posted
  • Author
Posted

I've mailed OO before and they quoted me £35 for a service...with P&P I'm looking at £50. That's not bad, but I'm hoping someone will say, 'what you need to do is...blah, blah'...and save me £50!! :)

Link to comment
Share on other sites
GazOC

GazOC

Posted
Posted

The Meade LX series has a similar focusing mechanism to the OMC, maybe the below will help.....

Elevate the optical tube so that it is pointing slightly above the horizontal and lock down the declination lock. Rotate the focus knob counter-clockwise as far as possible without forcing it. This will put the primary mirror all the way forward on the baffle tube and extend the focus rod all the way to the end of its travel. Remove the three hex screws that mount the focuser assembly to the rear cell of the telescope. Slowly draw the focuser assembly out of the hole in the rear cell. You will be drawing the primary mirror back down the baffle tube as you pull the focuser out. Pull gently until the primary mirror slider stops against the rear cell.

At this point, its a good idea to familiarize yourself with the focuser assembly and how it engages with the primary mirror mount. The focus rod has a hole in its end through which a pin from the primary mirror mount passes. Rotating the focus knob threads the focus rod in and out, pushing or pulling on the pin, which in turn, moves the primary mirror. The rod is not fastened to the pin and may detach during this procedure. If this happens simply slide the threaded rod over the pin to reinstall.

Gently push and pull the primary mirror up and down the baffle tube, using the focuser assembly ten to twelve times. This will even out the lubrication on the baffle tube and allow for the smoother movement of the primary mirror. If the travel seems stiffer or more loose in certain areas, repeat several more time to further even out the lubricant.

Then push the mirror back into the rear cell, making certain that the pin from the primary mirror mount is through the hole in the focuser rod. Thread in the three hex screws to remount the focuser assembly to the rear cell, but do not tighten. Wiggle the focuser assembly to make sure that the mounting plate is flush and centered with the opening in the rear cell and that the holes are centered around the three hex screws before tightening.

Now turn the remounted focuser assembly focus knob all the way clockwise until it stops at the end of its travel. Release the two hex head set-screws on the sides of the shiney aluminum focus knob. Continue to turn the focus knob clockwise until it feels snug (this will remove all of the backlash in the focuser mechanism).

With the set-screws still released, turn the focus knob counter-clockwise about 1/16th of a turn. At this point you are making an adjustment for the smoothness action of the focuser.

Reset the focuser knob set-screws, first by turning in one of the set-screws until it just bottoms out. Turn in the second set-screw tight (if necessary rotate the focus knob a little so that you can gain access to the second screw), then tighten the first set-screw. This method will insure that you do not tighten the focus knob off-center.

Test the focusmechanism to see if the backlash and/or image shift has been eliminated to a large degree. It should be recognized that it is impossible to eliminate it entirely, as it is normal to have some of this effect in this system due to the fact that the mechanism moves the primary mirror on a slider that is mounted on the main baffle tube of the optical tube assembly (a design that allows the greatest range of focus possible for a variety of accessory attachments). At this point you may find that you have resolved the problem, or you may now experience that the focus knob is either too tight, or that the backlash/ image shift has become worse. The counter-clockwise adjustment of the focus knob of 1/16th of a turn is a starting point. If the backlash/ image shift has become worse, then turn the focus knob clockwise again and repeat the procedure using a counter-clockwise turn of 1/32nd of a turn, etc. Should the focuser be too tight to turn smoothly, you can skip repeating the procedure, and simply loosen the set screws of sides of the focus knob and turn slightly counter-clockwise. Then retighten the set-screws as described above.

This is a proven method of getting the best performance of the focusing mechanism from your Meade SCT. If you have more questions regarding adjusting the focuser, please contact the Meade Customer Service Department at (714) 756-2291.

Link to comment
Share on other sites
Nona

Nona

Posted
  • Author
Posted

I'm going to have to wait until the morning to see if I have an allen key to undo the allen bolts that fix the back of the scope onto the main tube. It looks like a 6 or 7mm which I have...just not sure where. Thanks for all the comments guys...very helpful. :)

Link to comment
Share on other sites
Brass n glass

Brass n glass

Posted
Posted

Hello and welcome Nona. Captain Chaos is right; the three black Allen screws under black plastic caps at the back of the ptimary are for collimating. I've never taken my OMC140 apart, but I checked how to do it on an Italian website showing how it's done. That was three years ago, and I can't find the site any more. But I remember it showed how the primary and focusser assembly could be pulled out in one piece through the back by undoing the small chromed screws round the end of the tube. I would have thought the Orion Optics people would be able to take you through it on the phone.

If you have the micrometer screw and your OMC140 has a white tube, you will have one of the later ones where focusser problems were supposed to have been sorted out. Owners of some of the early versions reported problems with image shift and failure to move the primary.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.