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Skywatcher 102mm f/10 Refractor



Introduction

In spite of having experienced the 'delights' of a junk warehouse refractor back in the days when I was a kid, I always kept looking up and 'wonder why'. Better yet, at the age of 32 I thought the time was right for the fulfilment of my long cherished childhood dream by buying a telescope for watching the heavens. After weeks of comparing systems, thinking about needs and observing priorities, transportability, location, etc. this highly motivated newbie with no experience (that would be me) repeated the following conclusions to succeed in his quest for the holy scope: 'I will spend money on decent optics and a sturdy, fast set-up, so I will pass the Goto's. I will have a good scope, pure and simple, maintenance-free with crisp images at a moderate budget.' And so the blue tube of the Skywatcher102/f10 achromat kept wondering through my head…irresistibly, constantly,… it was predestined. Note that the Skywatcher 102/1000, the Celestron 102HD and the Helios Evostar 102 are the exact same Chinese made achromats (Synta), only different brand names.

I chose for a slower scope (f10) because it would do a better job in correcting the chromatic aberration and take higher magnification well and…because it looks cool! Chromatic aberration and false colour are noticeable but not an issue really and very good corrected for an achromat. (please note that I've got nothing to compare my optics to though) Some CA was what I expected anyway, but it's far from intrusive. The fact that I observe from my light polluted Belgian backyard (magnitude 4 on most nights) in the northern hemisphere was another plus for a refractor and it's still a 'grab 'n go' scope.

Getting the holy box

I purchased mine at Lichtenknecker Optics in Belgium and was thrilled to get the box at the store. While the owner was explaining some technical stuff to a customer about a very expensive mount (one could tell that right away), heartbeat increased knowing that my inner child was about to get fed. Some moments later (seemed endless at the time), I finally got it (after having paid 629 Euro) and rushed home to set it up.

Unpacking the holy box

Everything was well packed in the box and all tools required for assembling the scope were there together with an instruction manual. Take it from the double left-handed guy (that would be me again), the scope is easy to set up, it took about 25 minutes to finish the job. Enthusiasm increased while it stood there quite impressive on its sturdy mount.

Technical dates

The original tube in the box was a Helios Evostar 102 which I later exchanged for a Skywatcher tube with adjustable lens cell. The optical performance of the 2 scopes is identical (I can tell because I used the Evostar for about 3 weeks). I only liked the blue tube better, that's all, there were none in stock at the time. So, all accessories came in the Evostar box. The mount is a sturdy EQ3-2 (CG4) with worm gear for slow motion control when locked. The tube has a 2" focuser, 1.25" adaptor included and a dewcap. Further included were:

  • 1.25 stardiagonal (decent quality, no junk)
  • 2 eyepieces of decent quality 20 and 10 mm silver plossls
  • 6x30 finderscope with bracket
  • polar alignment scope for the EQ mount
  • aluminium tripod
  • accessory tray (metal)
  • shorty Barlow (again of good quality)

Additional pieces bought separately:

  • 40 mm super plossl
  • 12.5 mm super plossl
  • 7.5 mm super plossl (traded for the 20 mm plossl as the Barlow performs well)
  • Baader skyglow filter

Observing dates

** In average seeing conditions (original dates)

At the moment of writing this it has only been 6 weeks since I bought the scope and I've been out on every night that's clear enough, even when it's not cloudless! I must admit that I haven't been able to view the planets since I'm not an early morning kinda guy. 'yeah well, but you bought a planetary scope, right?' Right, I will update later, this gives us the opportunity to show what other things a moderate refractor is capable of. Quite a lot actually…

The moon is of course very impressive in all eyepieces with every magnification. Razor sharp images to the edge of FOV, with very little chromatic aberration up 100x which is only noticeable when you really want to look for it. I couldn't resist to push the magnification way beyond the useful value of 200x (50x per inch of aperture) on this object to see what it could do. At 266x (7.5 EP + 2x Barlow) still razor sharp (this is about the maximum useful value in good seeing conditions in regards to maximum detail resolution not only on the moon but also on doubles and planets too probably).

And then just to fool around, at 300x (10 mm EP +Barlow in front of diagonal) still quite sharp but focussing becomes a nerve test, not to mention the damping time and at the ridiculous 400x (7.5 mm EP + Barlow in front of diagonal) still 'sharp' although air turbulence becomes distracting and focussing is hard but it can be done. It's important to say that these last magnifications did not contribute to better detail resolution at all. Here is where APO- guys 'n gals start to laugh as their babies can easily take these magnifications and more in good seeing conditions. Here is where I have to shut up.

Deepsky: the DSO's are at their best at the lowest magnifications (25x 40mm) only the brightest take higher magnification. M57 looks like a donut and takes higher magnification fairly well. M56 is fuzzy (not resolved), M71 is also fuzzy and more difficult to see. M13 is fairly bright, but cannot be resolved, M92: same story. M31 shows up even in the finderscope, but detail is elusive. That's what I tried on DSO's so far and the skywatcher seems to be a legitimate deepsky scope at lower powers. I'm just thrilled to track these objects and watch 'em 'live'. Haven't been to a dark sky area yet, so all this observing is done in a light polluted backyard. With street lights near to me, there's no chance for dark sight adaptation. Stars are pinpoints by the way and I enjoy looking in the Cygnus environment for hours as it's near zenith (and less affected by light pollution) at this time especially with the 40 mm eyepiece. Roaming it every clear night. I can't wait to see the Pleiades, spot the Sagittarius region, Orion…I just enjoy what I can see from my backyard right now.

Doubles: Albireo (Cygnus) is simply wonderful at 25x. Stunning! Rasalgethi (Hercules) is easily split at higher magnifications, Epsilon Bootis takes more effort (magnification) but is very rewarding (the diffraction ring of the brightest component is visible, but the split is nevertheless clean and sharp), Eta Cassiopeiae is also stunning. Double double in Lyra cleanely split, Mizar (Big dippers tail) cleanely split. The hunt for doubles is open now, I didn't know that it would bring me so much joy, especially the ones with their companions and colour differences. Unsuspected treasures actually, accessible for smaller apertures.

That would be it for now. I especially recommend a decent 40 mm eyepiece as it fills your FOV with pinpoint sharp stars. When objects are bright enough, I go to higher magnifications (example: doubles, open clusters (e.g. double cluster between Cassiopeia and Perseus) to 'zoom in' on interesting area's. It should do an excellent job on Jupiter and Saturn as the optics take high magnifications very well.

**Under dark skies (addendum)

Just after I wrote this article I was able to get the scope to a dark sky site and now I'm completely in love with it! Seeing conditions were excellent. The milky way was clearly visible naked eye all the way in the sky and so was the double cluster in Perseus (slightly averted vision). Ok, here it goes:

All the fore-mentioned DSO's stood out much more clearer and were easier to catch. Even M71 was quite easy this time. Seeing conditions were so good that I easily could use 80x magnification (12.5 mm EP) to get lots of stars in the FOV and to view at fainter DSO's. The brightness of the Dumbbell nebula (M27) f.i. blew my head off (please note that it's still bright grey and won't be spectacular to people who expect 3-d images).

Although the double cluster always gives me goose-bumps, this time it looked like someone had forgotten to clean up scattered glass in the sky. WOW! At 25x little colour nuances were visible and it was fun to 'zoom in' on both of 'em.

Globulars M13 and M92 showed quite a few resolved stars at the outer region by 160x and 200x by slightly averted vision. M26 appeared as a fuzzy patch in Scutum, but showed its true nature at 160x when there were some individual stars resolved through the 'mist'. This is just to show you what a huge difference a dark sky makes as in light polluted area's this wasn't possible.

M29 (in Cygnus) showed up without me realising that I was looking at it as it's located in a very rich star region. A drawing of this open cluster at www.belmontnc.org (awesome site with lots of realistic beautiful drawings) made me recognise its geometrical shape.

Eta Perseus is now my favourite substitute for Albireo, although most people think that Almach Andromeda should take the honours, I found 2 beautiful rich open clusters (approx. 3 or 4 degrees separated from each other) somewhere between Ophiuchus and Aquila with the 40mm EP which frames the entire magnificent Pleiades(M45) and the funny 'coat-hanger' cluster , and…

I really could go on for hours, but my final update will be one of watching Jupiter and Saturn, I promise.

Verdict

This is one helluva scope for the moderate price. I'm very pleased with it. Although it's a planetary scope, it's a good all-round instrument (but get a 40mm or/and a 32mm EP!).

Pro's:

  • Rigid equatorial mount, no play on both axis and smooth enough, not top of course, locks well, slow motions work fine. Can be upgraded with motor.
  • 2" focuser feels sticky and takes some effort to turn, but gets into focus every time. Suitable for professional accessories (photography).
  • Usable finder that keeps alignment well.
  • Good optics, even excellent considering the price.

Drawbacks

  • Alu tripod: every move on the focuser or slow motion controls cause vibrations that dampen within some seconds (especially at high magnification, it takes patience, at 266x the object viewed at will have crossed approx. ¾ of the FOV before vibrations have dampened). It's to short to look at zenith in an elegant way but helps one to keep in shape. Duh.
  • Tube is top heavy, so you'll need some tricks (e.g. brass focus knobs) for balancing the scope more up front.
  • Some plastic parts (focus knobs, slow motion gear).

Suggested improvements

  • To reduce damping time: weight between the middle of the legs (thankx Al), vibration suppression pads (thankx Tom), fill the legs with sand, get a wooden tripod. These will make a dramatic improvement on damping time (1-2 seconds, now 5-6).
  • To balance the scope more up front: massive brass focus knobs, other focuser, weight belts on rear, heavier and better 2" diagonal (e.g. Televue Everbright) (although my original 1.25" diagonal is very satisfactory).
Yes I will upgrade to a 6" achromat some time (since it seems great for DSO too), but till then I will enjoy this fine little brother. I won't sell it then, this is a keeper.

Something to think about:

even if you think that Mike Patton is a vocal genius, even if you love Hooverphonic, adore Tori Amos, play in a thrash-band, ride motorcycles, practice athletics and are a romantic,…astronomy is cool and most of all…it's LOADS OF FUN!! Strange? Just look up and 'wonder why'. Maybe it's written there, somewhere .....

Jacques

Update Feb, 2003

And then there were the planets…

The fun continues as the constellations dance on the rhythm of the seasons. Many more deep sky treasures have been found and then there were the planets…

Mr. Ron B – a most helpful and gentle individual in several yahoo astro groups – predicted a shock experience when looking at the planets with this instrument. The truth of his words echoed through my head when looking at Saturn for the first time. The following observing reports consist of averaging seeing conditions. One thing that I learned in this regard is that altitude is a VERY important factor. The higher in the sky, the better the views of these gems. Please do note that no colour filters were used (I don’t have any).

Saturn: Cassini division noticeable at 80-100x together with 3 of its moons. One equatorial banding, and shadow at the planet (of the rings?). A fabulous sight indeed! Most used mag. is 133x when Cassini division is very evident together with the mentioned features. When seeing permits it is no problem to bump up mags off 160x to 200x to clearly see Cassini all around the rings and a darker shade on the edges of the inner ring. In those rare excellent seeing conditions Saturn tolerates 266x with satisfying results; at this mag the image is somewhat soft, but still most enjoyable without adding detail though.

Jupiter: What a stunning sight this gem makes together with its 4 moons. 2 bands are always there as well as the darker zones at the poles. It is worth to mention that the longer one looks at this gem, the more detail one will see. Observing is a skill and a matter of patience as I found out. The reward is more detail. It seems to me that Jupiter is more critical to seeing conditions as in moments of steady seeing a lot of impressive detail (like structure in cloud bands) makes its way to the eyepiece. Most used mags are 133x and 160x. 200x is a little overkill on Jupiter with my instrument and without filters (no extra detail is seen). The (very bright) planet suffers somewhat from chromatic aberration which is a non-issue on Saturn. A moon transit is a delight to experience as the shadow is ink black. Wow! The famous red spot is also well within reach of this refractor, although it looks rather pale to me. (No filters remember).

I do enjoy looking at these planets at lower powers too to see ‘em float into space surrounded by many stars and then bump up the volume to have a closer look. To conclude: this instrument is most capable of great planetary images. I should consider motors though as I’m always busy turning the slow motion controls to keep the objects into view. At high powers this is not very comfortable, but I don’t really care. The views are just too stunning!

Final thoughts

As I’m getting familiar with the night sky, I find myself loving all aspects of astronomy: planets AND deep sky. 4” of unobstructed refractor apurture – even achromatic – will show you a lot more than one might think. Especially on deep sky which is not its real forte, I’m pleasantly surprised by its performance.

Open clusters are a delight to look at and are a pleasure to resolve. 160 to 200x on the fainter ones are no exception to pick out the very faintest stars within reach of this instrument. Most look stunning at low to mid magnifications (25-100x) (M37, M36, M38, M35, M52, M103, M34 and lots, lots more, NGC’s included).

It shows some galaxies as well like M33(detectable) and M81/M82 (stunning) and more to find out.

It shows planetaries like ‘the blue snowball’, ‘the blinking planetary’, ‘the Eskimo nebula’ and again more to find out ?. Higher powers are needed for not mistaking them for a star (at least without filter).

It does a great job on splitting doubles.

It shows globulars with granulation (some with individual stars resolved).

After 7 months into the hobby, I’m still thrilled by what’s up there…and it’s all for free; it almost feels like coming home…at last.

Clear skies

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