Last update 98-6-20

Experiences with the Meade LX10


On the 31 of October 1997, I bought an 8 inch Schmidt-Cassegrain telescope, the Meade LX10. The LX10 is my third telescope. My first telescopes where an 4 inch Newton made in China and a Meade ETX (3,5 inch telescope). The ETX was bought in march 1997. The ETX is a very fine telescope but after a few months I was thinking of buying a bigger telescope. Two telescopes where within my budget. The Meade LX10 and the Celestron, Celestar 8. As far I understand both telescope are very similar in quality. Based on availability and some conflicting advice, I decided to buy the LX10.

My first impression of the LX10 is that it is a very solid piece of equipment. It is a lot bigger then the ETX. With the telescope a simple 18 page instruction manual is supplied containing some basic information.

The LX10 was packed in two big boxes (Optical tube and the optional Field tripod) and a few small boxes. The mounting of the telescope is straight foreword. After carefully reading the brief instruction, a quick meal and a few coffees, my telescope was in two hours ready for observing.

Meade is normally providing together with the telescope a simple 25 mm MA eyepiece, but till my surprise the telescope was supplied with a type 3000 plössl eyepiece.

The LX 10 electrical circuit can be powered from 9 volt battery or 4 R6-penlights of 1.5 volt (Type AA). It has also a 12 volt connection for an external supply. E.g. from a car battery. The installation of the 9 volt battery is easy and can be done with using any tool. The installation of the four penlights was a little more complicated. For this the drive compartment has to be opened on the bottom of the drive base.

Opening of the drive gave me also the possibility of inspecting the internals of the drive. The drive looked for me, mechanical very solid and robust. It is big improvement compared with the ETX. The worm gear is driven by a tiny electrical motor similar as in the ETX. Meade calls this the DC servo motor. The supplier tolled me the RA speed was very accurate and should be correct as a clock. A quick test learned me that Meade used a very simple DC motor with no speed control. The speed is purely controlled by the motor supply voltage and not with something advanced like a quartz controlled step motor. The same principle as in the ETX but this time adjustable with a small potentiometer. (The electronic circuit has a small potentiometer so that is what I expect). The 9 volt or 6 volt battery voltage is in that simple electronic circuit of two transistors and some other components converted to a stable voltage of about 3,5 volts. With the additional supplied keypad hand controller the RA motor speed can be doubled or stopped. To double the speed, the motor voltage is roughly doubled to about 6,2 volt (my battery voltage) . The electrical power current consumption was about 23 mA. With this consumption a standard penlight batteries would last about 50 hours and a 9 volt battery about 17 hours. With alkaline longer.

The LX 10 is standard prepared for a 9 volt battery. To change this to the second battery pack of 4 penlights of type R6 / AA, inside the LX10 the two plugs of the battery pack's has to be swapped.

The first night I the it was a little wet. Nevertheless I was impressed by the easy installation and control of the telescope. Within a minute the telescope was set-up in my garden and after the cooling down ready for observing. The viewfinder has a pleasant wide field and after targeting on Saturn, I locked the RA drive and DEC. I switched on the drive and is was direct following Saturn. Operation of the telescope is easy in the dark. The fork arm is great and any object is easily targeted. After locking the RA and DEC it was easy to get the target in the middle of the view by using the manual slow motion of the DEC and the keypad hand controller for the RA. This was for me a great improvement compared with the ETX.

The first night the wetter was not so good, but the view of Saturn was better then ever compared with the ETX. Only focusing was not so easy. The focus knob is moving smooth but a little stiff. Secondly when reversing. I noticed the mirror made a little jump and Saturn was moving about half of its diameter.

My first impression is that the mechanical part of the LX10 is very good and solid. I'm not impressed by the way Meade controls the RA speed. For the optical part, I need more time to judge.

Han Kleijn , 97-11-2

Due to the cloudy wetter here, I did some thinking and testing on my LX 10. First I checked the accuracy of the RA drive on the test bench. After 30 hours running it was reading on the RA scale 30 hours and 5 minutes. The sky is going round in 23 hours, 56 minutes and 4,09 seconds. The so called sidereal time (24* 365,2421/366,2421). That means that in 24 hours a telescope should run 24 hours, 3 minutes and 57 seconds. For every 6 hours about one minute more. Till my own surprise, my LX10 is spot on.

So I expect the telescopes are well tuned before leaving the factory but I'm still a little worried how it will react on cold or on ageing. The problem is that it has no closed loop speed control like the LX50, LX200. The old SCT's had an synchromotor which by definition was correct as long the net frequency is 50 or 60 Hz and constant. A good modern drive has a step motor driven by pulses derived from a quartz controlled oscillator.In my manual Meade claims that the LX10 is well suited for long-time exposure astrophotography. Meade also says that for long-exposures, more then 5 or 10 minutes, guiding is required. For this the drive should have the following accuracy (please let anybody tel me if I'm wrong) The telescope has a focal length of 2000 mm which results on a 35 mm film in a field of about 60 x 40 arc minutes. ( I make a picture at the equator) Let's say I'm not critical and accept guiding errors of 1/480 of the film equals (1/480)*60 arcmin equal 0,125 arcmin. In 5 minutes the sky moves 75 arcmin. That means the drive should have an error less then 0,125 / 75 equals 0,15 %. Maximum 2 minutes in 24 hours. That's purely the error in the motor speed and not the additional failures in the worm drive or optical effects in the night sky.

Last week there where some clear nights.Trying out my LX 10, I became very enthusiast about its RA-scale. Due to the fact that the RA scale itself can be rotated and set, it becomes a very powerful tool. After setting well, it is just point and shoot directly to any object which co-ordinates are known. It works as follows. 1) First as usual, the telescope is polar aligned. After this the DEC scale should be correct. 2) Then the telescope should be pointed to an easy know target, such as the star Vega or Capella. After setting the adjustable RA scale to that of the know star, the RA reading will is correct in any position as long the motor keeps on running. Finding any object is just to turning the telescope fork to the right RA & DEC and the object will be in most cases within sight of my 40 mm Plössl. After this calibration procedure, I found from my garden within 10 minutes more Messier objects then ever before. Much easier then with my ETX or Chinese Newton telescope. Wonderful, so simple and so effective. I don't think digital scales are required as long the above procedure is done with some precision.

Objects seen:

- M92, I could dissolve only a little. Condition where not so good.. 
- M57, Interesting planetary ring
- M81
- M82 
- M1 Interesting cloud
- M31

Dew became a big problem. A few days ago, the air was so wet, that the telescope was within an hour covered with dew water. I did not own a dew cap, but I was surpriced how effective a simple dew cap was made of newspaper paper. After heating and therefore drying my telescope inside my car, a 30 cm's long cap of newspaper paper saved my telescope for hours against dewing up. The water was running from the windows of my car but the telescope kept dry and clear.

97-12-23 The wetter is still cloudy....cloudy.....and cloudy. The months November/December have a bad name in being cloudy. Only one night it was clear, but I was too tired and a little ill, so I missed it. Today I fixed a new second hand camera. Till now I was using my old Minolta X300. Also the new one is a Minolta from 1985. They are both electronic cameras. I would like to have a fully mechanical camera but with a additional set of two penlights it is easy to power the camera for hours. The big advantage of again a Minolta for me is that my two 30-70 and 80-210 mm lenses fit on the camera. Nice for piggy-bagging on the main telescope. With my first camera I always connected with some sellotape two electrical wires to the battery compartment. Secondly to keep the camera open in B position, a small piece of aluminium paper with sellotape was used to push the release button down. With the new modified second hand camera it became easier. The 3 volt supply is supplied via the second flash connector. With some sellotape inside the camera button it is always down. In B position the camera will stay open as long the supply is there. Much easier and no fiddle around with a lot sellotape.

I also measured the electrical consumption of the Minolta camera. With the camera shutter open, it uses only 30 mA. This means that the camera (supplied from two penlights) could stay open for more then 24 hours. Very long. I think I will stick to my Minolta. The advantage of a electrical shutter is that it can be controlled remotely. I normally leave the camera in its self-portrait position. After making the connection to the electrical supply, the led will start blinking for about 25 seconds. This will give me time to cover the telescope.

And now waiting for clear skys

March 1998, Experiences with the Celestron off-axis guider

Radial guider

Yes finally my Off-Axis guider has arrived. Ordered directly from the States, it arrived here in January. Unfortunately Customs did not sleep and I had to pay an additional 18% tax. I have bought an Celestron radial guider. First trials showed me that the LX10 motor is running steady but a little to slow. I had to adjust every 40 seconds to keep track with M31 and M42. Secondly I also had some major problems with Off-Axis guider.

1) Problem with the prisma adjustment. The Prisma was locked and could not move. After opening the guider and some pushing, the mechanism came free. Did happen a few time in the next weeks before it stays away.

2) Focusing. With the separate ordered illuminated eyepc 12 mm from Orion, I could not get in focus. Probably depending on type of camera. As soon the focus of the telescope was set to a sharp image in the camera, I was not able to focus the stars with the eyepc. Terrible. just spend another $ 300 and it did not work. The combination eyepc, guider and camera did not mach. I solved it by mounting an old negative lens inside the Eye PC.

3) Then the prisma was not in the right position. It is fixed an rotating around two small screws. These these two screws are pointing into two holes of the prisma holder. These holes in my guider are unequally drilled. Intended ? I do not think so. I have more the feeling that it is a manufacture failure. The two screws have a machined sharp point. By screwing one screw to the maximum inside and the other more out, the prisma was turning a little till it desired horizontal position.

4) The screw to fix the radial movement was too short. I could not fix the radial position. By forcing some more tread on that screw with an old nut, it could move the screw an additional 1 or 2 mm more inside. This was enough to reach the end and the problems was solved.

The focus is still not perfect. I'm not sure if it the prisma quality or something else.

Somehow I did receive at guider made on a blue Monday. This is a Dutch saying. (The makers where still suffering a headache from the Saturday/Sunday house party)

Finally, After these problems I could make my first pictures. The weather was cloudy again and I had to wait and wait. Somehow this year it is terrible. After a week the night was clear and moonless. Played around with the equipment for an hour of two and then just when everything was ready for my first pictures, new clouds where drifting across the sky. Terrible, live is not easy.

After an other cloudy week, the sky cleared. This time everything worked out well. The only problem was that the LX10 was running a little to slow, so I had to adjust RA every 30, 40 seconds. Mechanical the LX10 seems to be very steady. Every 8 minutes I could notice a slight change in the speed. A very small one. The drive is running very steady. I'm still very happy with the concept of the LX10. Only the motor should run on quartz driven.

Finding a guide star is not always easy. Only a small portion of the light is reaching the prisma. I can see stars till about mag. 7.5 I did find two guide stars close to M31 and one should be SAO 36618. The design of the Celestron guider is good. Adjusting the prisma and rotating it radial makes much possible. The only problem is that not all positions are comfortable for long guiding. I still can not focus the stars till a point. Bright stars look like small comets. Is this normal. Can anybody tell me ?

Illumintated eye pc

Then the problem of the illuminated guider. I bought one from Orion, 12 mm MA. Nice design but somehow the LED is to bright. So bright that I could not see the faint stars. Strange. The eyepc has an adjustable button to dim the light. On it lowest position the light was still too bright. Are my batteries to strong ? How to solve this additional problem ? I finally solved it by putting a small part of a broken solar cell between the batteries. That created enough voltage drop to reduce the light till a acceptable level.

My first pictures look good. Here are two examples scanned with my Artec scanrom 4E:

M31 shot made with the LX10

M42 shot made with the LX10

That's all. The next months I will try to write something more. Clear Skies Han. 98-3-15

98-6-2. Last week I had some time to have a closer look to the illuminated eye-pc. I opened the metal battery holder containing the led, batteries and potentiometer. The potentiometer had a value of 500 ohms, which in my opinion is too low. I put a small resistor of 1,5 Kohm in series. This reduced the light level till an acceptable level and also reduces the power consumpition with a factor of three.

The next night was one of the few clear moonless nights this year and showed me that the resistor had the right value. The only disadvantage is the that the light level is only adjustable over a 30%. As long the light level is ok it does not matter.

Also the adjustment of the prisma in the off-axis guider payed off. The stars where nice points instead of the original comet shape like of look. I made 2 pictures till the wetter became bad again.