Subscribe to BackyardAstro
Select Addendum Post :

The documentation and inaccurate information supplied by the manual and in newsgroups across the internet has many people confused when attempting to use the polar finder scope. There have been a few postings in the newsgroups that document how to use the finder but the subject is still confusing. I’ve documented and illustrated the correct way to use the polar finder in an attempt to help LXD55 owners. This procedure is more difficult to perform with the scope and counter weights on the mount. I recommend polar aligning the mount without them, but it’s not absolutely necessary.

At this time if you have not aligned the polar finder scope to the mount itself, it would be a good idea to do so. If it’s not aligned, you be wasting your time performing the procedure I describe below. The manual does not instruct you how to align the polar finder scope to the mount, but fortunately I have written an article on aligning the polar finder scope also.

Find out your longitude and latitude. No precision is necessary at this time. You just need the number in degrees. In my case it is 31N and 97W for Round Rock, TX.

  • Level and eyeball the mount to point north at Polaris.
    Use the altitude adjustment to raise or lower the altitude to match your
    latitude. Move the tripod to align the azimuth. You may move the tripod right
    now because it’s easier and faster then turning the knobs.
  • Determine the longitude of the meridian in your time zone. To do this, multiply the number of hours you are offset from Universal Time (UT) by 15. For Central Time Zone in the U.S. it is 6 hours. So…. 6 X 15 = 90. The meridian for Central Time Zone is 90 degrees.
  • Calculate the difference from the meridian you just
    calculated and your longitude In my case, 97 degrees. 90 – 97 = -7
    or 7 degrees west. Had my longitude been 87W degrees, the calculation would be
    90 – 87 = 3
    or 3 degrees east. A positive number means you are
    east of the time zone meridian and the negative number means your are west of it.

 

  • oct_10_1_20ampolar_finder_pattern_smallNow let us deal with the silver dial, and the reticle
    pattern. Unlock and rotate the RA axis
    until the pattern matches the diagram on
    the right and lock the RA axis. Turn the
    silver dial so OCT 10 lines up
    with 1:20 am. This date and time are specific to the time
    which Polaris will best match the reticle pattern as viewed through the polar
    finder scope.

 

  • Now concentrate on the Meridian scale on the dial.
    It has markings E  20  10  0  10  20 W.
    Mark the position of 0 on the mount before you do anything else.
    I used a white out pen to mark mine. Now adjust the dial to properly set your meridian offset. This is the number we calculated above. In my case it was 7 degrees west. The graphic represents my proper offset with respect to the mark we just made.
  • Finally, we have performed the proper calibration of the reticle pattern
    and the setting circles scales. We are ready to go!I’m polar aligning
    my scope on Aug 7 at midnight. Since the finder was calibrated against
    UT time, I’ll need to adjust for the difference. There is a six hour offset
    from Central Standard Time so midnight is 6am UT. I unlock the RA axis
    and rotate the mount until Aug 7 and 6 am UT line up. Then lock the
    RA axis.

 

  • Now look through the polar finder scope and use the
    alignment knobs to place Polaris in the single circle. The Earth’s wobble means that Polaris will not always line up with this reticle pattern. The diagram shows it’s position through the end of the decade.    

 

 

 

The image to the right is a screen shot of what Starry
Night Pro shows to be the location of Polaris and the celestial pole on
Aug 7 at midnight Central Standard time (6 am UT). It’s been adjusted to
show the view as seen through the finder scope.
Now that Polaris is lined up in the circle, you should be polar aligned close
enough for short exposure astro photos. I’d estimate you can get two to three minutes at prime focus using film.

Meade LXD 55 FAQ

Posted by Jason under Addendum

Q: What side should the declination motor be on in relation to the Optical Tube Assembly (OTA)?
A: According to Meade the declination motor should be on the west side of the OTA, assuming the OTA is in the polar home position. I however have used it on the opposite side for months without any problems.

Q: What type of battery does the polar finder illuminator use?
A: The polar finder uses two silver oxide batteries. (Energizer 392, LR41, or Radio Shack 23-022)

Q: Is the mount capable of being auto guided?
A: Speculation exists stating future versions of the firmware will enable this function, but not at this time no one has demonstrated a working CCD auto guided.

Q: Can I take astrophotos with the telescope?
A: Yes. All of the telescopes in the LXD55 line are capable of having cameras attached to them. The quality of the photos will vary depending on your location, film used, camera used, and your determination to work hard and produce good results.

Q: How long does the battery pack last?
A: Meade’s answer is about 40 hours. I find that I get 20-30 hours on the pack. Less when learning how to use the Autostar, since the scope is moving at its highest speed more often.

Q: Can the mount handle the weight of the 10″ SN?
A: At this time not many have the larger Optical Tube Assemblies (OTA) but so far so good. The mount seems ;to be adequate for the larger tubes. The tripod however is the weak link here. It’s rather stable as long as the legs are not extended but flexes otherwise.

Q: Do I have the latest version of the Autostar software?
A: In the past I’ve made a futile attempt to keep this answer current. Meade makes updates available quite often so I’ll simply provide a link: Autostar Update

Q: I’ve aligned the Autostar but after I GOTO a target its not centered.
A: Imperfection in the drives, initial alignment, and especially the time entered in during setup can all be factors. Press and hold [Enter] on the paddle for 3-4 seconds. The display will show “Sync”. Now center the target and press [Enter]. This will help make the Autostar GOTO a bit more accurate. I use this more often when I’m viewing objects in the same area of the sky.

Q: Does Autostar actually work as advertised?
A: Yes. The Autostar is not new to Meade telescopes. It’s been used for years on some of their other product lines. The ETX and DS series come to mind. Don’t expect it to be perfect. It’s not. Experience using the system will improve its usefulness.

Q: What does training the drives do for me and do I need to?
A: Training the drives teach Autostar how much to compensate for backlash or slack in the gears. You should train the drives before when you first get the telescope and it’s wouldn’t be a bad idea to periodically train the drives to help maintain it’s accuracy.

Q: What is cord wrap and should it be on or off?
A: Cord wrap is a feature that when set prevents Autostar from performing complete circles and wrapping the cords around the mount. Some people prefer to turn it off to save their batteries. This allows Autostar to move shorter distances, wrapping the cords, but saving the batteries. Conversely Autostar will move the opposite direction in a near 360-degree turn, using up batteries, but not wrapping the cords.

Q: Why do the star move after a GOTO completes?
A: There is most likely slack in the gears. “TRAIN DRIVES” is a menu option in the Autostar. It will help eliminate some backlash in the gears. Also check and make sure the gears are not loose of the shaft. This is a problem that plagues this mount. See Post “Loose Gears” for details.

sn6_focuser_assembly

Many people have experienced problems reaching focus with the SN OTAs. In some cases collimation is the problem, but not always. Generally speaking with 1.25″ eyepieces most users with be using the extension and adapter. (Shown assembled on the right in the image) When a Barlow is added some find it no longer possible to reach focus. In these cases, you’ll need to remove the extension. If you are using 1.25″ eyepieces, remove the 1.25″ adapter from the extension tube by turning it counter-clockwise. Then attach it to the focuser tube. Having removed the extension you should now be able to reach focus.

The real problem is working with eyepiece and Barlow combinations that requite both setups. Switching between the screw on adapters takes to long and isn’t all that easy to do in the dark. My solution was to scrap the Meade 1.25″ adapter and extension tube. Now I use the 2″ adapter (shown above middle), and a 1.5″ extension and 1.25″ adapter I purchased from Moonlite Telescope Accessories. They slip in just like eyepieces and secure into place with nylon set screws.

dec_motor_bolt_remove

Hold the motor and remove this bolt with a 3/16″ hex wrench. Meade supplies this wrench, its the largest of the three that shipped with the mount. Once the bolt has been removed slide the motor down and remove it from the mount.

dec_motor_gear_set_screw
If the set screw is not visible rotate the gear until you can reach it with a .050″ hex wrench and tighten it up.

dec_gear_set_screw
Now tighten the gear set screw on the worm gear shaft. Again use a .050″ hex wrench

gear_mesh
After tightening the set screws up, replace the motor on the mount.
Make sure the gears mesh as in the photo and tighten the hex bolt that holds the motor on.

The polar finder scope was not perfectly aligned from the factory. The manual did not include instructions on aligning the polar finder scope to the mount, so I’ve written this guide to help. There are three hex set screws that affect the alignment of the scope. Adjusting them requires a perfectly orchestrated task of loosing one or two while tightening the hex screws. This took me nearly a hour and thirty minutes to get right. Be patient, make small adjustments, and if you start getting aggravated, quit and try again later.

  • Setup the mount without the OTA, without the counter weight, and without the shaft.
  • Point the mount towards a ground based target, far away or more than a mile.
  • Rotate the Ra axis to one side and the Dec axis so you can see through the polar scope.
  • Center the target on the cross hair of the polar finder using the altitude and azimuth adjustment knobs.
  • Rotate the Ra axis to the opposite side. If the cross-hair moves off target, it needs adjusting.
  • Adjust the finder using the three hex screws. Adjust only half way back to the original location.
  • Center the target again, using the altitude and azimuth knobs.
  • Rotate the Ra axis to the opposite side, adjust again if necessary, and center the target.

Perform this last action until the object no longer moves when you rotate the Ra axis from one side to the other. After you make a couple of adjustments, the movement will begin to decrease and therefore you must be really careful when loosening and tightening the hex screws. Too much and you’ll set yourself back and need to spend more time on this procedure.

Once this task is complete, alignment of the OTA axis and mount axis can be performed.
The manual describes two different methods to accomplish the axis alignment and descibes it well.
Look at pp. 51-52 for the procedures.