Skylux 70mm f/10 Refractor

Skylux 70mm F/10 refractor

With all the cheap telescopes coming from Asia these days the market for beginners telescopes has exploded. In almost every big store you can buy a cheap telescope. Some of them are all right, most of them really bad. I occasionally place an advertisement on the "Dutch Ebay" website www.marktplaats.nl filled with some advices about buying a beginners telescope. This because I always get irritated by all those advertisements promoting a "professional 76mm telescope with 525 power". As a result of this I get e-mails from people interested in buying a cheap telescope asking me which telescope they should buy. This got me interested in the quality of nowadays beginners telescopes. Recently I got the chance to borrow a well known beginners telescope in Europe: the Skylux 70mm F/10 refractor. For me a nice opportunity to review this telescope and perhaps even win a nice telescope myself!

The Skylux 70mm F/10 refractor is sold only once or twice per year in big low budget supermarkets all over Europe. In the Netherlands the price of the telescope is 90 euro, which is about 110 US dollars. This is a relatively low price in Europe as competing telescopes by manufacturers like Skywatcher are sold here for approximately 180 US dollars. Although the telescope is sold only once or twice a year, it is easy to get your hands on a copy. It can be found frequently on websites like www.marktplaats.nl.

The Skylux refractor is also sold named "Bresser Mars Explorer" for the much higher price of 160 euro, which is about 190 US dollars. Nevertheless, the box of the Skylux tells us the real manufacturer: Meade, USA. Knowing this, I get even more interested in the quality of this telescope: what quality products does the big Meade sell to newbies? Does Meade invest in these future Meade customers or do they deliver them inadequate material?

First look

Time to take a first look at the telescope. The Skylux telescope comes as a package including: the Optical Tube Assembly (OTA), a 6x30 finderscope, a German equatorial mount, a 1.25" diagonal, three 1.25" Kellner eyepieces (20mm, 12mm and 4mm), a 2x Barlow lens, a 1.5x erecting lens and a CD-rom including planetarium software called "Cartes du Ciel".

The Optical Tube Assembly (OTA)

The tube looks not bad at all for such a cheap telescope: no rattling parts, no parts which will break of easily, a nicely moving focuser, 2 baffles inside the tube, 1 baffle inside the focuser and a coated primary lens. The primary lens cannot be collimated, but I didn't expect this from a beginners scope. And if the lens is well collimated on purchase, I'd say a beginner can only ruin the collimation instead of improve it.




On the left hand side the primary lens is shown. The lens has a blue coating. Inside the tube three baffles are placed as shown by the arrows. On the right hand side the all-plastic focuser is shown. Only the screws are made of metal.

A discussion point is the use of plastic in almost every part of the tube: only the screws are made of metal and everything else is made of plastic. Even the focusing tube is made of plastic covered with metal looking paint. The biggest disadvantages of the use of plastic are:

1) Plastic parts are sensitive to temperature changes which can result in misalignment of the lenses.
2) Making the telescope incapable of observing the sun using the projection method. If an objective solar filter is not used, plastic parts will melt and damage the telescope or even the eye of the observer.

Of course the big advantage of using plastic is the lower costs of plastic parts compared to metal parts. I can personally understand the manufacturer's decision for using plastic parts. The only other options for reducing costs would be using less quality lenses or a less quality mount. Especially the option for using less quality lenses would not be acceptable. When using plastic, it will still be a good telescope as long as temperature sensitivity is acceptable and as long as the telescope is not used for solar observing without an objective solar filter.

Optical accessories

A first look at the eyepieces won't make me enthusiastic: all black parts are made of plastic. I'd assume making these parts "all metal" (and glass) wouldn't raise costs too much while reducing the melting risks when observing the sun without an objective solar filter. Also, the eyepieces are not blackened on the inside. This will slightly reduce the contrast of the images, but I personally think this is a minor disadvantage. A positive fact about these eyepieces are the threads inside the eyepieces allowing you to use filters (including those really dangerous little black solar filters, of which a copy was fortunately not delivered with this telescope).



As the primary lens has a focal length of 700mm (F/10), the three eyepieces of 20mm, 12mm and 4mm will deliver magnifications of 35x, 58x and 175x. Using the delivered Barlow lens also magnifications of 70x, 117x and even 350x are allowed. Because magnifications of twice the primary lens diameter in mm (in this case 140x) are useless, the 4mm eyepiece is a bad choice. Also the Barlow lens is of little use. Only the 117x magnification is a nice addition, which could also be delivered by a 6mm eyepiece with probably a much better image quality. So, in my opinion, this telescope could perform better when supplied with a 6mm eyepiece instead of the 4mm and the Barlow lens.

The telescope comes with a low budget all-plastic 1.25" diagonal. Inside this diagonal a surface mirror is placed. In my opinion, a prism would have been a better choice. A prism has a better resistance to inexperienced users: polishing a prism could make it cleaner while polishing a surface mirror can only result in damaging the coating covering it.

For use during daytime, the telescope also comes with a 1.5x erecting lens. I have tried to focus on a distant object using this lens and any eyepiece which failed. Let's just throw it in the trashcan and never talk about it anymore.

The finderscope is a 6x30 version. I have tested this little scope during daytime and found it adequate. Inside the tube of the finderscope one baffle is placed which does not stop light from the primary lens. I have seen much worse on different beginners telescopes.

The German equatorial mount

The big bonus of this telescope: the heavy equatorial mount. This mount is really nice. I have seen this mount before loading heavier tubes and I have to say it does a fine job holding this 70mm refractor. The sensitivity to vibrations is fine and the tripod is doing a good job. The mount is equipped with 2 handles for doing fine adjustments, which is uncommon for a beginners telescope. And in contrast with all the other parts of the telescope the mount is almost completely made of metal! In my opinion, this mount is superior to the "EQ1" mount delivered by numerous well known telescope manufacturers.

On the other hand you can discuss the choice of a German equatorial mount for a beginners scope. An alt-azimuth mount is easier to operate by an inexperienced user. Of course you can always simulate such a mount with a German equatorial mount, but unfortunately (as with most mounts) the polar axis cannot be pointed al the way to the zenith to do so.

Testing and comparing in the field

In order to test the Skylux beginners telescope, I think a good procedure is to compare it with a telescope that is affordable and is of well known good quality (the perfect beginners telescope?). To do so, I have compared it with a 68mm F/14.7 Mizar achromatic refractor. I think the Mizar telescope has been build during the late 70's and is of good quality. The quality of its primary lens will probably be not as good as the APO refractors reviewed here at Cloudy Nights frequently, but the price of this Mizar telescope was also a fraction of the typical price of those premium quality telescopes. If offered 2nd hand, I assume a 68mm Mizar telescope will have a price of approximately 200 US dollars.

Unfortunately the weather conditions have been very bad lately in the Netherlands, but I have been able to do some observations on Mars and do a star test using this telescope and compare it to the Mizar 68mm refractor. During these observations, both telescopes were cooled down extensively. The seeing conditions were very good, which is highly unfamiliar in the Netherlands.

The Skylux telescope was borrowed from a friend and I was not able to take the whole telescope to my home. So, during testing in the field, I used the EQ1 mount of my old travelscope. This mount is shown on following picture.

Primary lens

For testing the primary lens I have loaded both telescopes with my 7mm Nagler type 6 eyepiece (I am a proud owner). Loaded with this premium quality eyepiece any disappointing image must be caused by an inadequate primary lens. And of course, a beginners scope loaded with an eyepiece priced three times the scope must be captured on film. :-)


Left: the Skylux 70mm refractor
Right: the Mizar 68mm refractor

As first a star test was done using the Skylux/Nagler combination. During moments of very good seeing at least 3 nice round Airy rings were visible with no interruptions. So I presume the instrument was collimated well.

When looking at Mars trough the Skylux/Nagler, I saw a nice orange globe, not pinpoint-sharp, a little bit of chromatic aberration, but no details on the surface. I think those details were on the edge of visibility. So not a spectacular sight, but I have seen much worse. I was quite satisfied about the sharpness of the image and the chromatic aberration. As next, I tried the Mizar/Nagler combination. The sight trough this combination really made me nuts! A very sharp globe, no chromatic aberration at all and details visible on the planet without any difficulty.

The Mizar/Nagler showed me how good the seeing conditions actually were. I have owned this Mizar telescope until some years ago (it now belongs to my father) and had never done high magnification observations using a good quality eyepiece like the Nagler. I have never known the Mizar telescope was of such good quality.

My conclusion about the primary lens of the Skylux refractor: not bad at all. Sufficient for a beginner. Nevertheless, the Mizar telescope was the big winner.

Eyepieces

As mentioned, the Skylux refractor comes with three Kellner eyepieces and a Barlow lens. To test the eyepieces, I have compared them to some old eyepieces that came with the Mizar telescope and some of my own. I have tested them by comparing the sight of Mars through the Skylux and the Mizar telescope.



In the centre row the three Skylux Kellner eyepieces are shown. The other eyepieces shown are: a Tele Vue 7mm Nagler type 6, a Meade 20mm Super Pl?ssl series 4000, an old Ganymedes SR 4mm and an old Mizar HM 12.5mm.

After comparing the Skylux Kellner eyepieces with the eyepieces shown above I come to these conclusions:

The 20mm eyepiece is a nice eyepiece. The Meade 20mm eyepiece gives just a slightly better view.
The 12mm eyepiece is a little less nice eyepiece. It gives a better view compared to the 12.5mm Huygens eyepiece, but slightly worse compared to the Skylux 20mm eyepiece.
The 4mm eyepiece is a terrible eyepiece. Its view can be compared to the old SR 4mm eyepiece. Experienced observers know that's really bad publicity. The view of the eyepiece is all blurry and no details can be shown using this eyepiece.
As expected, the Barlow lens is terrible too. I presume the only reason for including this Barlow lens is to promote the telescope by saying it can magnify 350 times.

Things to like about this telescope

1) A nice price for a beginner.
2) A primary lens of sufficient quality.
3) Two eyepieces of sufficient quality.
4) A very nice German equatorial mount with 2 handles for doing fine adjustments.
5) A nice 6x30 finderscope.

Things to dislike about this telescope

1) A terrible 4mm eyepiece.
2) A terrible Barlow lens.
3) A German equatorial mount can be difficult to operate.
4) Lots of plastic parts.

Final conclusions

The Skylux 70mm F/10 refractor is not a bad purchase as a first step into astronomy for a beginner. All major objects will be visible and may encourage the observer to move a step further into astronomy and finally buy a more expensive instrument. Nevertheless I do have some comments on this telescope: the 4mm eyepiece and the Barlow lens are of inferior quality. A 6mm eyepiece would have been a better choice and it may be wise for people who own this telescope to buy a 6mm Pl?ssl eyepiece themselves. I also have to say the telescope is not of bad quality, but by spending a little more money much better scopes can be found. For example a 2nd hand Mizar or Vixen refractor.

Jeffrey Bout is living in the Netherlands. He uses a Skywatcher 10" Newton telescope for visual observing, mostly on Deep Sky objects. Typical sky conditions are: limiting magnitude 6, seeing bad till moderate, high humidity.