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BRESSER 4 Inch f 4.5 AR 102XS Refractor visual observers’ REVIEW

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BRESSER 4 Inch f 4.5 AR 102XS Refractor visual observers’ REVIEW

Tim Versteegen.

Why did I buy?

It was a golden moment, lifting the snug cardboard top off the big long box that held so much wonder and suspense in the days before Christmas.

Under a clear plastic window, Styrofoam cradled a Tasco 3½ inch reflector.

My first glimpses of shimmering jewel-like clusters around the Southern Cross were revelations that sparked a lifelong interest.  

That was 1980, proper refractors were way out of budget and out of reach, but over countless, cool carefree Australian backyard nights, in my element, in the days when streetlights extinguished at11pm, I didn’t care.  

Too many years on my passion is undiminished, and I’ve been blessed to own and use a variety of instruments;

Meade 8-inch f5.6 SCT / ETX 90 / Celestron 9.25 inch f10 SCT / Vixen 120 NA Achro / Skywatcher Equinox 120 Apo / Skywatcher 6-inch f5 Achro.

I’m also into nightscape photography at dark-sky sites, which typically involves flying from my light polluted home.

I’ve developed a streamlined kit that fits perfectly into carry-on luggage - there’s even room for a couple of spare pairs of underpants. 

I’ve been searching for a travel ‘scope to go with it - an affordable, four-inch aperture refractor with decent glass, compact enough to take on board a plane.

I spotted the Bresser AR 102 SX amid ebullient German sales blurb that made much of its ‘amazing’ little-more-than 2.5 kilo featherweight build.

I’ve never bought brand-new – always ‘open box’ or pre-owned. The Tasco 3 ½ inch was new – but Dad shelled out for that one.

Now I’m a father. On occasion this apparently unstable and ephemeral world scares the hell out of me. I try to be nice to people. At just £222.50 including delivery - I reckoned I owed it to myself.   

Out of the Box

Secured in double-layered cardboard, another Styrofoam cradle, and a familiar, nostalgic tinge of excitement.

The ‘box opening’ became an event as I shared the unveiling with fellow Astro-nerd Rory, who is more Astrophotographer than observer.

Everything looked neat and securely packed.

After a frantic battle with endless tabs of hidden sellotape, the instrument was out for handling. 

First reaction – Wow this tube is short.   

Wrestling the lens cap off was a mission (more on that later), but when it was finally uncorked, humms of approval greeted first glimpses of a clean, greenish tinted objective which suggested decent coatings.

I’ve seen robust on-line discussion about whether the objective is indeed ED glass.

The retailer certainly sold it to me as an ED scope – but there is no mention of it on the tube livery, or in any of the non-specific manual / warranty paperwork tucked in the box. 

I’ve got no idea exactly what type of glass it is … but I’m an uncomplicated amateur observer.

As long as the views are good and the optics collimated, I’m happy.

The oversized ‘hex’ focuser was a nice surprise – rotatable, with three sturdy securing screws and the widest ‘rack’ and focusing pinion I’ve ever seen.

In this case 'hex' means the inner draw-tube is hexagonal, rather than cylindrical. I'm assuming one has to be careful to store it with the focuser fully racked in, to prevent dust or dirt seeping into the tiny gaps. 

The king size brushed aluminium focusing knobs looked and felt solid, as did the focusing lock.

Astrophotographer Rory was smitten – pointing out the obvious features that suggested this was a scope aimed more at snappers than observers.

Even the Vixen / Synta dovetail is designed like a telephoto-lens foot.

There’s a steel strip that makes the dovetail that little bit thicker – and protects the paintwork underneath from holding-screw marks. Nice touch.

Now, to the so-called ‘accessories’ – which also suggested this was a package for photographers – mainly because photographers wouldn’t bother to use them.

The supplied chrome-painted plastic diagonal and 26mm Plossl were flimsy, even for a beginner. For the price I wouldn’t expect anything more.

I do recall a useful post that advised saving such cheaper items for shared public viewing sessions – but I wouldn’t bother.

The flexible and brittle-looking plastic finder and mounted shoe also seemed barely fit for purpose. BUT again … what can one expect for an alleged ED refractor for a couple of hundred quid? I couldn’t wait to find out.

First views – mid summer city suburban twilight

The sky was clear, but at a Northern Hemisphere latitude and time of year when summer nights don’t really get dark – just a deep turquoise-blue.

I love my big city suburban home – but the light pollution is significant.

My permanent backyard mount is mainly for lunar and planetary observing, but on went the spanking new Bresser for an all-round test.

The first ordeal was removing the protective cap from the fixed dew shield extending from the objective lens.

No buttery-smooth, metallic retractable dew shields here folks.

Removing that dust cap from a vinyl-lined rim is like extracting a compliment out of the mother-in-law. Tough.

One starts delicately, gradually increasing applied force until in my case – prizing away with an oversized screwdriver - the cap shot away with a rifle-like crack over the neighbors’ fence.

Looking on the bright side – there is no way this formidable cover is going to slip off in storage or transport. (It survived re-entry - flung back over the pickets to my backyard by the way...)

Front cap removed, trying to align that flexi-plasticky-finder was the next mission. The flimsy finder-tube actually bends - and the plastic holding screws popped out of their housing with another crack when tightened past a point that seems to defy alignment with the main scope. After some frustration I was able to align on one of the crosshairs at a recognizable point. That would have to do.

Bright planets and stars generally bring out the worst in fast achromatic refractors – the dreaded violet-blue halos and flares of Chromatic Aberration.

I decided to subject the alleged ED glass to the sternest test.

Under a relatively bright, semi-moonlit, light polluted sky, I didn’t have much choice.

Cooling the stubby tube to ambient temperature was as quick and easy as expected.

Set with objective pointing down, and a (dust-free) nylon sock over the open focuser end pointing skywards, warmer air could escape. I gave it 45 minutes – I later found out that around 30 minutes is good enough.

Jupiter was past its best, approaching the murk of the South Eastern horizon, but still bright, winking in less than steady air.

I put a proper diagonal in the back and began with an ultra wide angle 13mm eyepiece.

The semi ‘aligned’ finder worked OK, and the wide-field of the f4.5 objective makes bright objects pretty easy to find - even with higher magnifications.

I centred the Jovian blob in the field of view, twisted the smooth oversized focuser wheels, and was amazed. Yes, there was a violet halo that sometimes extended flare-like more than a planet-diameter beyond the disc … but the equatorial belts were there, the major moons were clear and now and then, intriguing mid-hemispheric detail could be glimpsed through a good quality 5mm eyepiece. The wide field view was so pleasing I forgot about the CA. 

I tried a Baader fringe-killer filter that I bought for my Vixen 120 NA long ago, but still preferred the more natural-looking CA-drenched view.

Given the low altitude and somewhat unsteady twilight sky – I was really impressed. Yes, the sharpness and detail were nowhere near what I’ve seen in the 120 Equinox, but I had to keep reminding myself this was a relatively cheap, 4-inch, wide-field 4.5 scope. Overall the contrast was pretty good.

The next target was another traditional no-go for a short refractor – a quarter moon.  

Once again, the violet-flare of CA was evident, but once again, after a few seconds at the eyepiece, I forgot all about it.

Tiny sunlit peaks over black shadow-lands were obvious along the terminator in a 5mm eyepiece. The relatively sharp views from this intriguing, ultra-fast f4.5 compelled me on my rebellious ways to yet more unsuitably bright targets.

I swung (actually the tube is so short it defies swinging) … tilted … the stubby ‘scope in the direction of Arcturus.  

Wow. Again, I’m not sure what’s in that glass objective – but whatever it is – to my eyes - it delivers a kind of metallic sparkle on stellar targets, like tin baubles on a Christmas tree.

The burnt-orange hue was wonderful to behold – and no CA that I could see. But the sky wasn’t truly dark, perhaps the late summer twilight was masking false colour.

Vega was a brilliant white-blue … a thin violet edge evident … but not enough to spoil the view.

Racking in and out of focus showed a neat circular blob – although crisp ‘Airy dics’ eluded me – it was enough to prove to me the ‘scope was relatively well collimated and free of any ‘pinched’ optics.

I moved on to Albireo – the impressive colors of the main yellowy star and its tiny sapphire-like companion sparkled through. 

I slotted an ultra-wide 21mm eyepiece into the diagonal. The added height meant I couldn’t comfortably look into it without bumping into that *&%! plastic finder.

Here’s where the rotatable focuser was handy. With a heavy eyepiece it can be a real pain to keep shifting and re-clamping a diagonal holding screw.

In this case – I found it much easier to move the entire focuser around.

The only slightly disconcerting factor was a grinding-sand like sound when the holding screws were tightened in a new place around the ‘hex’ tube. Perhaps one isn’t supposed to do this.

Anyhow, back to the wide field view.

Even in light polluted skies, dim star fields around Cygnus were evident, but there was a tiny bit of curvature evident around the extreme edge.

A 30mm eyepiece extended this curvature more noticeably – to an extent that began to spoil the vista. I’m assuming there’s a field flattener for this ‘scope, but as a visual observer I’m not that bothered.

Swapping back to a 13 mm eliminated the problem – and the field of view was flat to the edge.

A final look through a 9mm at M57 ended a memorable first session with the 102XS. A vaguely greenish ovoid smoke ring glowed dimly among pinpricks of faint yet well-resolved stars. Lovely.

I was impressed and pretty happy with my impulse purchase.

It was time to plan a trip to dark skies to test this super-short, super-fast ‘scope on the wide field views it was designed for.          

First Views – Rural Skies

Packing the AR102XS for a family holiday was a breeze. The scope, my own quality diagonal and eyepieces, and some separate camera gear all fitted neatly into a medium-sized backpack.

As we were travelling by car I could take a solid Porta-mount style Alt-Az set up with a robust tripod.

The weather in southern France was pretty good – the two nights I ventured into the fields were very different; one warm and dry with a little hazy high cloud, the next cold and dewy.

The moon was approaching first quarter phase – which meant I had to wait 'till midnight for the interfering glow to slip behind the horizon.

I left the ‘scope outside for 30 minutes – the views after this time were steady – suggesting the short cool-down time was sufficient.

After another struggle aligning that flimsy finderscope – and searching for plastic holding screws that kept popping out into long grass – I vowed to replace the finder before the next observing trip.

But the main attraction of this refractor – the (apparently) ED f4.5 objective – soon shone through, and the finder-fight was forgotten.

Catching M13 before it drifted too far West, the view through a wide-field 13mm eyepiece was beautiful, showing a tight, clearly stellar ball with a smatter of outer pin-points clearly resolved.

M27 was crisp. The unmistakable hourglass peeping out amid surrounding stars, I thought I might have detected a vague green-red tinge, but I’m never convinced about ‘seeing’ colour in such objects, and suspect that it might have been wishful thinking.

A huge advantage to such fast optics was quickly apparent.

Operating on a non-driven Alt-Az mount, the combination of a wide-field ‘scope and eyepieces meant targets stayed in the field of view longer.

M33 was easy to find. Alternating between wide angle 13 and 9mm eyepieces, averted vision showed glowing clumps beyond the main hub. No obvious spiral structure – but knowing what it looks like in long exposure photos - it’s tempting to imagine one has glimpsed such things.

Seeing objects in wider fields-of-view was also something special – as was the experience of relatively large objects – such as Andromeda.

Just stunning. In the wide-angle 13mm, the main companion was obvious, and detail could be teased out with averted viewing. I’m not claiming to have seen spiral arms – but it was far more than just a big elliptical glow. Very different from any view I’ve seen in other, larger aperture ‘scopes. It was hard to stop gazing and move on … but when I got to the Pleiades rising in the East, I was glad it did.

Wide-field star clusters like these must be the reason for this ‘scopes’ existence – the thrill takes one back to that first time at the eyepiece.

Under genuinely dark rural skies (I was momentary spooked by a deer) I’m pretty sure I glimpsed faint blue filaments of gas-glow around the brighter stars.

The Hyades were equally amazing – Aldebaran a glittering, crimson jewel.

The slight curvature around the edge of field I’d noted in the 21mm ultra-wide field eyepiece seemed less bothersome under a darker sky, probably down to the enhanced, immersive spectacle before me. I tried to count individual stars, but gave up when I got past 60.

Free-styling across the summer Milky Way without GoTo - or kneeling in the damp grass before that flimsy finder  - was a delight.

Even something vaguely interesting like the ‘Coathanger’ asterism in took on a new character through the 102SX.

The tell-tale pattern filled the field of view, along with many other faint, yet sharp pinpoints of light.

It was on the second, cooler, dewy night that another, eminently treatable shortcoming of the ‘scope in its original form became apparent.

The fixed lens hood is too short for long viewing sessions when the dew sets in.

There was no power source for a hairdryer handy in the remote farm paddock, but it was half past four, and I was expected to perform the usual family duties with those who had drifted into dreams under stuffed quilts at 9pm.

No matter – I’d had my kicks. Those scintillating star-clusters were burning in my mind.

For me, the 102SX is a solid, wide/rich-field travel scope.

I’ll pimp up the finder-scope and dew shield, making this one a keeper.  


  • NGC007, Traveler, sonny.barile and 15 others like this


Jul 22 2018 11:03 AM

I think it is only AR127 and AR152 in Bresser line that use Petzval design.


I have got AR102S and it is certainly not a Petzval design. AFAIK AR102XS is basically a shortened AR102S and in order to reduce the chromatic abberation they used ED glass on one of the doublet lenses. It is definitely not a ED scope though.

You're right. Only the Bresser Messier AR127 and AR152 have a Petzval design. 

    • morden8uk likes this
Aug 26 2018 11:01 AM

Good stuff thank you for your time and efforts in sharing this with us in the interwebs.

Looks like a good scope for the price.  Thanks for sharing the info.

The first thing I did when I received my AR 102XS was install a Synta/Vixen-style finder base.  Here is the base I used:




I really detest the proprietary, non-standard finder bases that some companies put on their telescopes.  The Synta/Vixen-style base is really the de facto standard now.  All the companies should accept it.


I chucked the supplied base, bracket and finder into a box in the closet. 


I put a Z-Bolt laser finder in the base.  That's the best finder for an RFT.  



This refractor could be a good instrument for framing deep sky objects with low magnification, but within its context?

For example, if we use the Bresser with a good 30mm 82º wield field?



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