LIDL, Tuning the SkyLux

Background Story

The German discounter market offers regularly bugdet gadgets, such as telescopes and microscopes. In December 2004 we customers were blessed with one microscope and two telescopes within just two weeks. Lets forget about the microscope for the moment (nice pice though, guess what, I bought one).

Two telescopes? Yes, two different ones. First the (for LIDL legendary) 70mm f/10 Fraunhofer refractor on an equatorial mount made it's way to the supermarkets. Later, maybe even better, the MEADE ETX-70 was provided in a very nice bundle for a more than competitive price...

This blabla though shall be about the first of the two mentioned; infos about the ETX-70 are to be found on other places on this webpage.

De-/ Greasing the Mount

The mount appears to be similar to the Chinese „Astro3“-mount sold in various places. A motor is available for this mount, thus, a motor is available for the LIDL-mount too. Two different versions even, I went for the more expensive „hand-box“ controlled one for about €100.- at my favorite telescope shop.
Having a motor driving your right ascension axis you certainly would prefer that the mount moves smoothly by a thumbs twist, preferably w/o any major forces when the telescope is nicely balanced.

When the mount came out of the box, it did not really want move at all. Sticky grease was literally gluing the axis to the bearings. Taking everything apart is not a big deal. Thus removing the grease and replacing it with precision mechanics oil is not very difficult either. In fact I more or less soaked all gears and bearings in oil, resulting in a very well lubricated and nicely moving equatorial mount. Actually I even cared about the declination axis, even though this appears not be very important, it still is nice to have a smooth DEC-handling too. So, taking apart the RA-axis requires just to loosen the hex-nut in the mount's base (see image). Be careful, all sorts of washers are involved, e.g. a spring-washer is waiting just behind the bolt, waiting to fall off and get lost.... Anyway, if all important parts are lost, you can easily pull out the axis, having a good chance to even loose more parts such as washers ;-) Cleaning all the re-found parts from itchy grease shall not be a problem, applying the appropriate oil neither... you should watch out to use lube which is suitable for the materials used in the mount.

RA-Handle mod

Lets talk about the declination axis. Sure, the lube is applied by now, but what is about the DEC-handle? Terrible, isn't it? Yes, terrible! Tracking in RA causes interaction between the DEC-handle and the rest of the mount, i.e. bocking all tracking. What can we do to solve that sort of problem? Lets dismantle the worm-gear of the DEC-drive. Two hexagonal bolts are to be removed (left photo), you will have the worm and it's bearings removed from the mount. Next step: loosen the hexagonal bolt of the bearing (right photo). Everything taken apart, it is no problem to assemble everything with the worm in a reversed orientation (after cleaning off all sticky grease and applying appropriate oil).

Please note that the photographs below show the already modified mount.

Optics

Mechanics are one part, but also the optics design is not yet ideal for astronomical purposes. Why? The LIDL scope, according to many publications on the Internet (especially in German language), the optics are designed to also serve the purpose of terrestrial observations w/o the use of the diagonal which is somewhat standard to astronomical observations. In astro-obs, using a diagonal, the focuser is retracted almost completely into the telescope tube. The design of the scope actually prefers terrestrial observations; an aperture stop is inserted in the focuser, even the focuser tube cuts a portion of light out itself, when retracted into the scope whilst the use of the diagonal.
First one would like to remove the focuser by removing the two Phillips-screws, trying to find back the spring which certainly dropped to the ground somewhere... With having removed the handle, so that the sprocket does not engage with the cograil anymore, the focuser-tube can now be pulled out easily. BTW, the sticky grease is also present in the focuser, here it is welcome, so, do not remove it... otherwhise the focuser will defocus by the weight of the eyepiece when moving to easily.

Remove the two screw to dismount the focuser.	This spring waits below...

The aperture stop can be removed by pushing it out towards the objective direction of the focuser tube, this will not affect the optics for astronomical observations i.e. using the diagonal mirror.

The surplus part of the focuser tube beyond the cograil of the focuser is arbitrary per se and can thus be removed, e.g. sawed off.
Painting the inside of the focuser tube with non-reflective black paint could possibly improve the contrast of the scope. This, however, I have not done yet.

Last modified Jan. 9th 2005