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Meade LX200 new focusing
#Forever  #Love  #Photos

New focusing device for Meade LX200 telescope

Made in Budapest, on 23.12.2018 ​ Invention – Ferenc Hollósi  - Hungary

Antecedents:                                                                                                                                                                                                          

4 years ago I bought a Meade LX200-type telescope, which optical properties are excellent.                                                              At the beginning, I took quite tolerable photos of constellations – objects with it, but over the years, this property has constantly deteriorated.

The error was that, on the photos taken with the telescope, not round but oval starts appeared with longer exposure. This could primarily be seen when I made a larger right ascension or declination motion with the telescope. The tests revealed that with the fourth – fifth 5-minute exposure, quite round stars could be seen already, but ovality errors became visible with magnification. I admit only the perfect is acceptable for me!

For a long time, I thought that the pole position was causing the fault. Therefore, with the method invented by me, named “Pole position is easier with measurement” by Ferenc Hollósi, I made the pole setting perfect.                                                        Or it is about a conductivity error.                                                                                                                                                                  The Fornax – 152 mechanism by Pál Sári performs conduction perfectly and it is made more accurate by TDM.                        Another tip was that the attachment or other fastening element is shaking.                                                                                        But we excluded these errors by thorough work. 

​As the optics of Meade LX200 worked well, sometimes I was able to take good pictures, as well. 

A new idea was needed to eliminate the error.                                                                                                                                               I started a new experiment to determine the cause of the error, so that I perfectly aligned a green laser beam with the Meade telescope on a reference star, and I examined that if I make a large motion in right ascension or declination direction, whether the star remains or not in the center in the telescope, while the aligned laser beam points exactly to the star.                          The result of the test showed that the laser beam was always pointing precisely to the star, even in any movement, but in the Meade telescope, the star moved from the center almost to the edge of the test image.                                                                  This movement proved to me that positioning to the pole and star tracking are good, but the 370 mm mirror of the Meade telescope moves. So I found the cause of the error.

It is not enough to find the error – you have to solve it!                                                                                                                            The main mirror moving, mounting and moving mechanics caused the error. 

I disassembled the Meade LX200 telescope into pieces (please see the disassembling of the telescope​), because it has become unusable even for taking photographs. I found that the tube holding the primary mirror, moves back and forth on a central tube. The two tubes move 0.3 mm against each other; it was sealed with a special grease, but the lateral primary mirror displacement was not retained by this grease, only it was slowed down. This is why the photographed stars were oval. If there was no grease between the tubes, it would have been a better solution, because then the mechanics of the mirror would have just tipped over.                                                                                                                                                                                                      The primary mirror lock proved to be ineffective, it did not eliminate the tilting of the primary mirror, only slowed it down. The photos taken have confirmed this.

I have been thinking for a long time to find a solution, and, as a result, I figured out, designed and created a completely new main mirror moving mechanism by Ferenc Hollósi.                                                                                                                                       I have it manufactured, and the Meade LX200 telescope assembled in this way has been behaving particularly good already during the assembly, it moved the heavy-weight main mirror in parallel with the mechanical axis without any shaking.            The first experimental images did not indicate any main mirror displacement even in case of large movements, and finally, the starts have become round even during a long exposure (5 minutes - 10 minutes).

The principle and method of my created main mirror moving equipment is suitable for all mirror telescopes, the main mirrors of which can be moved and focused, e.g.: the Meade, Celestron and Schmidt-Cassegrain types.

The new MEADE LX200/355 focusing apparat made by Ferenc Hollósi (december 2018)

The replaced parts of Meade LX200 

The empty tube

The new optic holder and the threaded guide structure of Meade LX200

The structure pushed in and installed

Meade LX200 external optic guide and focusing part

The threaded optic guide and cogged belt system (4 pcs.) of Meade LX200 

The complete installed optic guide and focusing device Meade LX200 

The picture was made with original factory MEADE LX200/355 telescope, photo details - 25.10.2017, 300sec, ISO1600

The picture was made with new MEADE LX200/355 telescope, photo details - 18.02.2020, 300 sec, ISO 1600, focus: 3556mm

The picture was made with new MEADE LX200/355 telescope, photo details - 26.12.2019, 300 sec, ISO 400, focus: 3556mm

The picture was made with new MEADE LX200/355 telescope, photo details - 18.02.2020, 300 sec, ISO 1600, focus: 3556mm

The picture was made with new MEADE LX200/355 telescope, photo details - 26.12.2019, 300 sec, ISO 800, focus: 3556mm