Product Review: Bresser EQ3 and 70mm f/10 Refractor

Keep the telescope. Throw away the mount.

 

This instrument is an embarrassment to the tradition of German engineering. Like very many other sellers of consumer optics – telescopes, binoculars, microscopes -- Bresser GmbH, Gutenbergstraße 2, 46414 Rhede, buys much of its production from China. This telescope, and especially its mount, betrays its Chinese origin with cheap engineering and poor production. The optics are fine. This telescope works as well as the other 70mm refractors that that I have from Meade and Celestron and the National Geographic label (all of them also made in China). Within the range of consumer goods, the optics are a given. It is the mechanics that fails. 

 

The first clue is the grease. Chinese routinely apply thick grease that hobbyists remove and replace with machine oil. 

 

I bought the telescope and mount from Explore Scientific on 31 March 2022 and it arrived on 7 April. It was easy to assemble but I also could see that it had basic design problems. First and foremost, there was no way to orient the setting circles for Right Ascension and Declination. 

With the telescope aligned correctly to North,
the Right Ascension is wrong by 48 minutes.
The circle would not move, glued into place
with heavy grease.

When set to my latitude (30 degrees North) and aligned on Polaris the setting circles read 23 hours Right Ascension and 70 degrees North Declination. Polaris is at 2 h 31 m RA and 89° 15’  

With the telescope set correctly,
the declination is wrong by 20 degrees.
The circle could be hard-set at the factory
to 90 degrees. (89.25 degrees is more exact.)
But the circle should still be adjustable.

Regardless of any other movements or settings, the setting circles were fixed in place as if they are glued there. Indeed, they were: with grease. 

After several sessions over two months of taking this down and setting up and trying this and that, I finally pried the setting circles loose and washed them off with rubbing alcohol. (I have GooGone, but I did not want to risk damaging the circles.) Also, the axes would move some distance and then stop. If I slewed the telescope manually, I could get more motion and move easily some short distance in the opposite direction.

 

After the first failures on the first afternoon, I remounted the telescope on an Explore First Light Nano altitude-azimuth mount and tested its optics. I alternately used both the 25 mm and 9.7 mm Plössl oculars. After aligning the finder with Sirius, I quickly found the Messier 41 open cluster and then Messier 42 the Great Orion Nebula and its Trapezium asterism. I also split the binary Mintaka (delta Orionis). I located another asterism that I know, sigma Orionis. I was pleased with the result. The easier of the two binaries was distinct. The smaller pair gave only some hint and only because I knew what I was looking for an looking at. They are much clearer in my larger Explore Scientific 102mm achromatic doublet refractor. Viewing the waxing crescent Moon I also was happy to find that the focus did work well with two filters screwed into the oculars. I ended the test with Mizar-Alcor (zeta Ursae Majoris), easily and clearly revealing Mizar’s visual companion. The optics of this telescope are good. 

 

Problems with the Mount

 

The right ascension (RA: hours-minutes of arc from the peripoint of Aries) axis would move a little in one direction and then move back more in the other. If I rotated the telescope manually, the slow motion cable would move the RA axis more in one direction and then less in the other.

 

Five days later (12 April 2022) I set the telescope up again in my office so that I could work indoors during the day. The gears locked. With all clutches open, the counterweight shaft with the Dec scale 0-9-0 would not move. Using the motion control knob, the RA moved a little and then quit. This happened often when I first set up the telescope. At other times the declination axis (Dec) would behave the same way, not moving the axis while turning the knobs, though in those cases, the RA would move. Before it locked up the RA would alternately respond with large movements in one direction but only small motions in the opposite travel.  

• I disassembled the Dec axis. 
• I removed the three hex pins holding the collar. 
• I removed the counterweight and its shaft. 
• I removed the cover with the worm gear. 
• I was able to turn the axis freely through several rotations. 
• Using a locking pipe wrench, I was able to move the Dec axis.

I put it back together, noting that the shaft must be somewhat loose, looser than hand-tightened, in order for the circle to move relative to its pointer.

  

15 April 2022 18:30 I watched half a dozen YouTube videos and read four articles online. Most of them were useless, very basic, not at all mentioning any of my problems. One stood out. How to use setting circles on a small telescope (and why they don't work!) Astronomy and Nature TV here: https://www.youtube.com/watch?v=geQszAVWMok

 

At the 2:35 mark, he gives a “Bluffer's Tip” for setting the polar alignment. It was the missing piece of the puzzle. In reality, I have to do the same thing I have done for a computerized “go-to” mount: star alignment. After setting up the telescope mount in Latitude and Direction (with a compass or your cellphone, for example), use a reference to identify a known bright star and its Right Ascension and Declination. In this video, he uses Dubhe, alpha Ursae Majoris. 

 

That solved one basic problem. So, I hauled out the telescope again (in daylight this afternoon). I found that with all of the movement back and forth, assembly and disassembly, the setting circles are now loose enough to move by hand. 

 

The remaining problem is that after traveling in one direction, the setting circles RA and Dec stop moving. The slow motion cables do turn but the axes stop traveling. One or the other will turn and then not, but then travel in the opposite direction when the cable turn is so turned. The cables turn; the telescope does not travel.

 

7 May 2022 Before going out I made a table of prominent stars in my early night sky and continued testing the mount. 

 

The axes would not hold their settings.

I aligned on magnetic north with a compass, then re-aligned on True North with my cellphone.

1.     I located Polaris. The readings were 19h 30m and 0 instead of 02h 31m and 89 degrees. I set the Right Ascension wheel to 2h30m.

2.     Next, I turned to Arcturus. The readings were 9h 50.5m and 50 degrees. I reset the circles to 14h 15m and 19 degrees. 

3.     Finding Spica the readings were 15h and 10, close to the actuals of 13h25m and -11d  (11 South). The declination setting circles do not differentiate the two halves of the circumference.

4.     Locating Regulus the setting circles showed 6h 30m and 0d 20m, far from the actual values of 10h (10h 08m) and 12 degrees (11d 58m).  

I gave up for the night and viewed with an Explore Scientific 102-mm f/6.47 achromatic doublet on an Altitude-Azimuth mount.

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