Long Focus Redux: A Spell with the Orion SpaceProbe 3 Reflector.

The Orion SpaceProbe 3 altazimuth reflector in British racing green. In a word: awesome!

















Dedicated to Lars Filipsson


Tuesday December 5 2017

The Orion Spaceprobe 3 reflector package arrived in the early afternoon in perfect nick. It was purchased from amazon.co.uk deliberately so as to test whether such a company would deliver the product in good condition. The telescope was double boxed and each of the components were further packaged away safely in separate smaller boxes.  All items received looked fine.

The product arrived well packed with no damage.
















The optical tube assembly was protected with bubble wrap.
















The tripod had foam between the legs to prevent their movement during travel.

















All in, the instrument cost just over £70 delivered to my door. I could have opted for an even cheaper rendition of the ‘scope but I went with Orion USA because they have the telescope made to their own specifications, and that includes the addition of quality accessories; namely two good 1.25″ eyepieces; a 25mm and 10mm (probably modified achromats) with good antireflection coatings applied to their lens components, delivering powers of 28x and 70x, respectively.

Two superior quality oculars came with the Orion SpaceProbe 3.

















There were no junk Barlows with this package (a great relief compared with other entry level telescopes). I also received a collimation cap, a Philips screwdriver, a red dot EZ finder, an excellently written instruction manual and leaflet to enable me to download Starry Night software. The telescope also came with a one year limited warranty, so I could return it were I to find any of the components to be defective.

The telescope was easy to assemble and took just about 20 minutes of my time.

My first test was to see if the telescope delivered sharp images out of the box. A newcomer would be very disappointed if he/she found that it did not work as advertised. To my great relief (and joy too), the instrument delivered very sharp images with both eyepieces, so all was well.

One especially neat feature of the telescope was that the primary mirror came centre spotted, which greatly facilitates with accurate collimation. That was another reason I opted for the Orion model; some youtube presentations of other incarnations of the telescope did not appear to show this feature on the primary but carefully studying this video allowed me to glimpse this important feature, and I thereby reasoned that there would be a good chance of finding one on my model. My luck paid off.

Inserting a laser collimator into the eyepiece holder showed what my sneak peek observations confirmed; the telescope was quite well collimated in the factory and only needed slight tweaking of the primary and secondary mirrors (using the supplied screwdriver) before it was absolutely perfectly aligned. The entire exercise took just a minute or two and was easy to conduct.

The well written instruction manual has instructions on how you can tweak the collimation on the telescope using the screwdriver and collimation cap supplied with the ‘scope.

The telescope was found to be nearly perfectly collimated, as evidenced by the position of the red dot near the centre of the mirror.


















The fact that the instrument was well collimated didn’t actually surprise me, as the system has a larger relative aperture. At f/9.2, good collimation ought to be easily held.

Fine collimation is rendered very easy using the protruding screws on the primary mirror cell and the supplied Philips screwdriver.


















I elected to use the telescope using my own 6 x 30mm achromatic finder as well as not engaging the altitude bevel. Simply adjusting the altitude tension on the knobs on the mount head was good enough to provide just the right amount of tension.  I did check to see if both of these worked, by the way; and they did as advertised. I also chose not to attach the accessory tray, as this would enable me to collapse the tripod at a moment’s notice and store it away when not in use.

The telescope atop its altazimuth mount is very lightweight and can easily be lifted with three fingers. I moved the instrument to my back garden and gave it a few minutes to acclimate more fully in the cool, overcast daylight. Although lightweight, the aluminium tripod is quite strong and stable; a good match to the featherlight mass of this telescope. Motions in azimuth and altitude were smooth and hassle free, even using higher powers. Mechanically, I was very impressed at how well the instrument was shaping up.

The simple rack & pinion focuser  operated smoothly and can be adjusted so as to tighten or loosen it as desired. Applying the laser test showed that collimation remained stationary throughout its travel; neat!

The telescope has a good rack & pinion focuser that operates smoothly and accommodates 1.25″ eyepieces.


















As previously stated, I chose not to use the supplied EZ finder as they are pretty useless for anything dimmer than 1st or 2nd magnitude stars. I quickly found a 6 x 30mm unit that attached easily to the telescope and which did not clash too much with the colour scheme of the rest of the instrument. This is a much better option going forward, as it allows me to aim in on much fainter stars from my dark, rural sky.

Close up of the finder I mated to the ‘scope; note the matching colour and texture of the finder bracket with the focuser and rim of the optical tube assembly. Schmokin’ !

















Preliminary Optical Testing

The supplied oculars delivered extremely sharp views of distant trees at 28x and 70x. Contrast was excellent. I decided to push the telescope using the supplied 10mm ocular and a 2.25x Barlow. The result was truly astounding! But to be specific; the image remained razor sharp at this power (that’s 158x for your information) across the entire field. To be honest, I was a bit shocked and called a few of my neighbours to have a look. They agreed with me; the images were unreasonably excellent!

But I went even further; I attached my 7.5mm Parks Gold eyepiece to the 2.25x Barlow which increased the power still more to 210x. Amazingly, though the image was fast running out of light, owing to its small aperture, it was still tack sharp and full of detail!

This telescope appears to have astoundingly good optics for the very modest price I paid to acquire it!

This agrees with the findings of Lars Filipsson et al, who kindly alerted me to this ‘scope, as well as those of the American gentlemen on the youtube presentation highligted above. It also jibes well with the findings of the veteran observer(a Newtonian specialist) and Sky & Telescope reviewer, Gary Seronik, who gave the same instrument a 4 star rating. Former S & T associate editor, Tony Flanders, also liked the telescope.

Based on this preliminary testing; I can confidently recommend this telescope to beginners on a tight budget. Here’s a link to the amazon site I purchased it from.

How did they do it? What’s going on?

A perfectly shaped 76mm spherical mirror forms the heart of this instrument.

















Nae chance of starlight or moonlight this evening; very cloudy unfortunately

Wednesday December 6 2017

It is noteworthy that in his field tests, Seronik rated the SpaceProbe 3 reflector above that of a classic 70mm refractor. Indeed, concerning the former, he wrote that it was just a “nice telescope. It provided sharp images and was a joy to use.” What is more, only the larger aperture 4.5″ reflectors rated higher than the little long focus 3 inch reflector. As explained in a previous post, a mirror with a parabolic shape is the ideal form for a Newtonian, as it effectively negates the effects of spherical aberration. But for small mirrors (less than 5 inches or so), a spherical mirror can generate good images if the focal length is made sufficiently long. We need not enter into a technical consideration of these tolerances only to say that at f/9.2, the differences between a parabolic and spherical mirror are negligible, especially for a 3 inch aperture.

Of course, there are other advantages of long focal length systems. All aberrations get smaller as the f ratio increases, allowing even inexpensive eyepieces to work well. Traditional aberrations considered in Newtonians, such as coma and field curvature, are vastly reduced at f/9.2 compared with say, a comparable f/4 system. That’s why inexpensive eyepieces won’t work well in the f/4 Starblast but will perform admirably at f/9.2. Needless to say, I’m very much looking forward to testing this telescope under the stars but that can’t happen until conditions improve.

With a focal length of 700mm, the instrument can deliver pleasingly wide fields with inexpensive eyepieces of long focal length. One obvous choice is my 32mm Plossl, which should serve up a power of 22x in a 2.3 degree field. That’s perfectly adequate for the vast majority of larger deep sky objects, so the instrument should give very pretty views during low power sweeps.

Thursday, December 7 2017

The Spaceprobe 3 telescope set up for more daylight tests.

















After a very wet and cloudy day yesterday, I was able to resume more daylight testing of the SpaceProbe 3 telescope this afternoon in much colder and brighter conditions.

I have been enjoying the two eyepieces that came with the instrument, both of which are labelled as “Explorer II” oculars. Conducting more tests at high powers, I can reaffirm that the optical quality of the telescope is excellent; noticeably sharper and brighter than a typical long focus 60mm achromat or shorter focus ED apochromat of the same aperture( 60mm).

The supplied oculars are very good but could do with a Barlow lens to extend powers when required.





Because the maximum magnification yielded by the supplied 10mm ocular is only 70x, I would recommend that users consider the purchase of a decent Barlow lens to increase the range of magnifications one can achieve in the field. For example, a 2x Barlow inserted ahead of the eyepiece(see the above image) will boost the power to 140x when used with the 10mm eyepiece and a 3x Barlow will give 210x. The higher powers, of which this small telescope appears eminently capable of, will come in handy when viewing the Moon, planets and close double stars. A 2x Barlow will also boost the power of the 25mm Explorer II eyepiece to 56x.  I would avoid the cheapest models though; try to go with a multicoated Barlow that will cost £30 or more new. Alternatively, you can always search the buy/sell websites in your country where you can pick up decent second hand models for not a lot of money.

With the tripod fully extended, the SpaceProbe 3 reflector is raised quite a bit off the ground allowing comfortable standing viewing for an adult, but the legs can be collapsed to allow a child or a seated adult easy access to the eyepiece. Newtonian reflectors are much more comfortable to observe with compared with refractors or Maks, especially when viewing objects at greater altitude above the horizon. And greater comfort means that one can engage better with the images garnered by the instrument so that they can be studied for longer.

Time: 21:45 to 22:15 UT

Seeing: III, clouds clearing gradually leaving a clear sky, more sleet and snow showers due overnight, waning gibbous Moon rising in the east.

Temperature: 0C

I enjoyed my first light under a dark sky with the Orion SpaceProbe 3 altazimuth reflector and it continues to impress. I inserted my lowest power ocular (a 32mm Plossl) and aimed it at Capella now high up in the eastern sky. The telescope focused this creamy white star down to a tiny, brilliant pinpoint. The first thing I noticed was how the astigmatism that is present in my observing eye did not manifest itself as it does with my faster reflectors (with focal ratios of 5 and 6) using the same eyepiece. I did not need my glasses to correct it. Moving the star from the centre to the edge of the field I was deeply impressed with how the focused stellar image did not become distorted. It reminded me very much of the views I grew fond of in my classical refractors. F/9.2 is a great place to be in a reflector!

From there, I moved to the Pleiades, now becoming more prominent in the sky as the hazy cloud dissipated. The image was just charming! A host of blue white fireflies glistening in the frosty winter sky. Increasing the power to 70x using the 10mm Explorer II eyepiece supplied with the instrument, I examined the 70x images of Albireo, now low in the west. The Airy disks were round and rich in natural colour; golden and blue. From there, I visited Almach much higher up and once again the lovely colour contrast pair was well resolved. Lifting the telescope with one hand, I moved from the back garden on to the front lawn and focused in on Castor A and B; a beautiful sight in this little telescope. I then tested the high power perfomance of the telescope by coupling my 2.25x Baader shorty Barlow to the 10mm Explorer II eyepiece delivering 158x. Both the A and B components focused down to hard, round Airy disks. I could not see any distortions in the image. Just beautiful round disks surrounded by a faint diffraction ring. The image remained equally sharp at 210x when I exchanged the 10mm with my Parks Gold 7.5mm.

Though the tlescope on its mount is very lightweight, I was still able to track this star system quite easily at the highest powers. I’m learning how to adjust the tension in the altitude axis so as to keep the system in the field of view for prolonged periods of time as I do with my other telescopes on their respective mounts.

So far, so very good! Now waiting for the Moon to rise higher in the sky; pretty excited with the prospect of seeing our natural satellite in this fine little telescope.

Friday December 8 2017

Time: 00:30UT

Just got in from a spell of Moon gazing with the SpaceProbe 3. I can confirm what the American gentleman said about this telescope in his youtube video clip and associated review; it’s an awesome lunar telescope! The 10mm Explorer II eyepiece with 2.25x Barlow produced a wonderfully sharp image of the lunar regolith at 158x. I pushed it some more using my Parks Gold 7.5mm (so 210X) and the image remained very sharp and with excellent contrast!

Isn’t modern mass produced technology wonderful!

Time: 12:30UT

I ventured outdoors again this afternoon to enjoy the high power views of the SpaceProbe 3 reflector. On these short and cold days, sunlight is a precious commodity and I especially savour the images of the tree tops that catch the rays of a feeble Sun. 210x is worth seeing in this telescope!

Based on what I’ve witnessed so far, there is another group of amateurs that would greatly benefit from experiencing this telescope; those that profess ‘advanced’ telescope knowledge and/or insist on procuring gear of the highest quality. For a fraction of the cost of one high end eyepiece, you can experience for yourself the virtues of this little telescope. I dare say, it would do you the world of good to do so!

We’re away for another short vacation this weekend. Hope to resume my observations with the Orion reflector upon my return.

Sunday December 10 2017

Tayside panoroma on an idyllic winter day. Shot taken from outside our hotel, shortly before midday, local time. The picturesque Kingdom of Fife lies just across the water.

After a great weekend of leisure and Christmas shopping in the city of Dundee in the northeast of Scotland, we arrived home at dusk (about 4pm local time) and after setting the fire, I ventured out on what proved to be the coldest night of the year so far to conduct more tests with the Orion SpaceProbe 3 reflector.

TIme: 16:40 UT

Temperature: −7C

Seeing: III, a tad below average, despite excellent transparency and a cloudless sky.

Left: the 130P Newtonian and right, the little 3 inch Orion SpaceProbe spying Epsilon Lyrae.

















Fielding both my 130P and SpaceProbe 3, I turned them on Epsilon Lyrae and charged them with a power of about 150x (10mm Explorer II ocular and 2.25x Baader shorty Barlow. Both telescopes resolved the four stars of this famous test multiple star system. The split was much more convincing in the larger 130P, as expected, but it was also well resolved in the 76mm reflector.

From there, I swung the telescopes eastward into Cassiopeia and centred Iota in the instruments. Again, I was rewarded with good results; the little Orion SpaceProbe 3 did manage to resolve all three components at the same magnifications but, as I expected, the image was brighter and more effectively resolved by the larger 130P telescope.

Time: 23:00 UT to 23:40UT

Temperature: −6C

With the Pleiades near the meridian by now, I tested the 32mm Plossl out in the same instruments. The 130P, with its shorter focal length, served up the larger true field (2.5 degrees) but the SpaceProbe also framed the entire cluster well using the same eyepiece (the Pleiades subtends a true field of about 2 angular degrees), albeit in a slightly smaller field of view. This time, I looked for vignetting at the outer edge of the field in the 76mm Orion reflector and felt that although a small amount was present at the extremities it wasn’t a big deal. The telescope certainly provides a generous maximum true field of view for beginners and more experienced individuals too.

By lowering the back leg of the Orion tripod, greater altitudes can be reached.

















By now, the Double Cluster (Caldwell 14) in Perseus was nearly overhead. Others have reported that the little 3 inch reflector cannot quite reach the zenith because the tube bumps into the tripod. Although this is true, I did find that lowering one of the legs of the tripod allowed me to increase the pointing altitude of the telescope a wee bit more, and I was finally able to view these magnificent objects using both the 32mm Plossl and the supplied 25mm Explorer II ocular. The view in both eyepieces was very beautiful in the little telescope but I did find the latter to be more compelling, as it delivered the slightly higher power and framed the clusters that little bit better.

Left, my 80mm f/5 achromat and right, the Orion SpaceProbe 3 trained on Rigel, now near the meridian.

















Next I fielded my 80mm f/5 achromatic against the Orion SpaceProbe 3, comparing the view of Rigel (Beta Orionis) now approaching the meridian. Though there was quite a bit of turbulence at this lower altitude, I was able to just resolve the faint companion at 166x in the ShortTube 80 using my 2.4mm HR eyepiece and at 158x (10mm Explorer II and 2.25x Baader shorty Barlow) in the 76mm reflector. The 80mm refractor image was that little bit brighter though, which didn’t present as too unexpected.

These results show that the inexpensive Orion telescope can resolve higher resolution systems when pushed to higher powers. Adequate cooling and careful collimation are always your friends in this endeavour.

Monday December 11 2017

A snow covered Ben Lomond, as seen on the morning of December 11, just a few miles from my home.

Time: 12:50UT

The icy weather continues.

I conducted a daylight test with the 32mm Plossl on the SpaceProbe 3. Aiming at some trees in the distance (150 yards) in bright, winter sunshne, the eyepiece gave a very nice, sharp, flat field. I did not notice any dimming at the edges of the field.

The rather thick vanes holding the secondary mirror in place.

















The secondary is held in place by three vanes that are rather thicker than in my other Newtonians. This gives rise to a more prominent diffraction pattern around high magnification stellar images. Although I find this perfectly acceptable for an entry level telescope, it could have been designed better. Such a small secondary mirror could easily be supported by thinner vanes.

One other issue I have with the telescope is that there is a clip on the right edge of the secondary mirror (as you look down into the eyepiece holder), which appears to shave off a small amount of light that could come to the telescope (see below). I have no idea why they used such a clip but, again,  it’s something I can live with.

The right side of the secondary mirror (seen here in this off centre image) has a clip which does cut off a small amount of light reaching the eyepiece.

















As mentioned previously, the two eyepieces that come with the telescope are of good quality. I believe they are two of a larger set of Explorer II oculars which originally came in focal lengths of 6mm, 10mm, 13mm, 17mm, 20mm and 25mm. I found a short review of them here. It makes interesting reading. Both the 25mm and the 10mm are apparently Kellners, while the rest are Plossls.

Time: 23:15 to 23:45 UT

Seeing: II, an improvement over last night, remaining clear and very cold.

Temperature: −3C

My adventures with the little long focus reflector continue apace. Tonight, I set the telescope up to have a look at some favourite seasonal deep sky objects. I began with M35 in northern Gemini, which looked like a storm of faint stars haphazardly strewn across the face of my wonderful 25mm Explorer eyepiece. I enjoyed a spellbinding tour of the Sword Handle of Orion, and was particularly impressed by the images served up of the Great Nebula in Orion (M42 & M43) using both the 25mm and 10mm oculars. The companion to Rigel was beautifully resolved in the improved seeing at 93x using my 7.5mm Parks Gold.

Beta Monocerotis as seen through the 3″ f/9.2 reflector at 210x.

















When I turned the telescope on Eta Orionis, I cranked the power up to 210x using the 10mm Explorer II Kellner and 2.25x Baader shorty Barlow, focused carefully, and was greeted by two kissing Airy disks; a very good result indeed for such a modest optical accoutrement! But the corker for me this evening was the sight of Beta Monocerotis triple system. At 210x the view was awesome! This telescope produces wonderful images of very delicate targets and with excellent contrast. No wonder seasoned observers and beginners alike are drawn to its considerable charms.

Wednesday December 13 2017

I have spoken before of the very high contrast of the images generated by the oculars that came with the Orion SpaceProbe 3. On the evening of Monday December 11, I was comparing the view of the Sword Handle of Orion seen with this 3″ reflector with that garnered by my 80mm f/5 ShortTube refractor. The SpaceProbe 3 had the 25mm Explorer II eyepiece and the 80mm refractor was used with the Mark III Baader Hyperion zoom eyepiece, which was set to approximately 14mm focal length, so as to show the region at the same magnification as the reflecting telescope. What I noticed but did not report at the time was that the contrast of the image in the Spaceprobe was much better than that served up by the Baader zoom in the 80mm f/5 glass. The difference was very striking; the sky was much darker and the nebulosity within the M42/3 complex more strkingly presented in the reflector image. I noted this result as very odd, as one would expect the refractor to have the better contrast. So last night, I dodged the showery weather and ventured out again to conduct more experiments.

Between 23:00 to 23:45 UT on Tuesday December 12, I decided to deploy my 130P reflector to observe the Orion Sword Handle and included the two Explorer II eyepieces  together with the Baader zoom  to compare and contrast the images. Since the 25mm Explorer II eyepiece gives a magnification of 28x, I first compared the view in the 130mm reflector using this eyepiece and the zoom set to the same magnifiation (so setting the zoom to near the lowest poewer setting at 23 mm). The result was remarkable: the 25mm Explorer II eyepiece produced a much more contrasty image than the zoom did, despite showing more in the way of off axis aberrations!

Switching then to the 10mm Explorer II ocular which delivers 65x in the 130P, I moved the zoom to near the 10mm setting (so delivering the same 65x power), I again compared the images. The 10mm Explorer II eyepiece produced a much more contrasted image in terms of sky background and how well the M42/3 nebulosity stood out in comparison with the Baader zoom!  Indeed the view through the 10mm Exploer II eyepiece on axis was truly excellent! What’s going on here?

My working hypothesis is that the number of lens elements in the eyepieces had a bearing on this very striking result. The Explorer II eyepieces are simple, 3−element Kellners ( modified achromats), while the zoom has 7 elements. The minimalist design of the latter oculars produced a dramatic difference (to my eye) in terms of how much contrast the images were producing at the same magnification. What an interesting finding! I shall conduct further experiments as soon as conditions allow.

Are minimalist eyepieces the way to go?

















A quick google search on this topic revealed some interesting results. Check out what the OP says here about the same eyepieces, together with the various responses.

Time: 22:45 UT to 23:40 UT

Temperature: 0.5 C

Seeing: II, very good between snow showers. Windy at times, sky noticeably brighter.

Classic 3 incher.

















If it wasnae fur yer wellies, where would ye be?


Got a fair good spell later in the evening after a couple of snow showers. I was comparing the view through the Orion Explorer II Kellners and my Baader zoom. Turning on two targets; M42/3 and the Pleiades, I studied the images in the 25mm Exlorer II and compared them to the 24mm setting on the Baader zoom. The result was quite compelling: the simple Kellner was noticeably more contrasty than the zoom set to 24mm. The field of view was also larger in the Explorer eyepiece too; and that’s consistent with what others have said; it gives a nice 50 degree field, quite comparable to a Plossl. In comparison, the Baader is more like 40 degrees at this setting. The 25mm Explorer produced an absolutely draw dropping view of the Pleiades high up in the south, with pinpoint stars set against a jet black sky. Again, it reminded me of the views I enjoyed through my classical refractors, using simple eyepieces. The Explorer II 25mm was made to be used with an instrument such as this! It just rocks with the small aperture and long native focal length.

The same tests carried out on the 10mm Explorer II eyepiece (and the appropriate setting of the zoom) produced slightly less striking differences but they were there nonetheless. What is more, the larger field of the zoom complicates the situation at this focal length.

I ended the evening looking at the same objects in both the 3″ SpaceProbe and my handy 80mm f/5 achromat. Again, I can report that the 25mm Kellner produced a darker sky background than the zoom set to 24mm in the refractor. Light grasp in both instruments was quite comparable though, with the edge going to the 80mm glass.

So, the little SpaceProbe 3 Altaz revealed a weakness in my trusty Baader zoom eyepiece. Though very satisfying, it does not offer up the very best contrast when it comes to eyepieces. That being said, I would never dream of parting with it. It’s still very good and comes quite close to what you’d get with a quality, simpler, fixed focal length ocular. Its zoomability keeps you reaching out for it.

Friday, December 15 2017

Small Newtonians in the snow.

















Because I wish to keep this little gem of a telescope( what would the point in selling it be?), I have bestowed the name Oona( a ‘she’) upon it.That’s what I’ll call the SpaceProbe 3 any more.


Oona: a ‘scope that offers delightful images.

















To sum up, the Orion SpaceProbe 3 represents tremendous value for money. It’s just a very honest ‘scope, just as ‘Rocket Roberts’ stated in his review. By that, I mean that you get exactly what it says on the tin. It’s easy to deploy and use, even if you live in an apartment with limited space. It is very lightweight so it can be carried around very easily, yet strong enough to allow you to follow objects even at higher powers. It gives very pleasing views of deep sky targets, as well as solar system objects (I personally cannot wait to aim this ‘scope at Jupiter in the new year) and can be enjoyed by all the family. I highly recommend this telescope to a budding young stargazer or more experienced observers wishing to enjoy the considerabe optical benefits of using an old school, long focus Newtonian.

This is where this review ends. My sincere thanks again to Lars Filippson for recommending this telescope for testing.

Thanks for reading.


Neil English is the author of several books on amateur telescopes. If you like this work and wish the author to continue, please consider purchasing one of his books.


Postscriptum: Former Sky & Telescope Contributing Editor, Gary Seronik, who is a Newtonian specialist, wrote a wonderful article on his website on this little 3″ f/9.2 Tasco reflector. You can read what he says about it here.


De Fideli.

14 thoughts on “Long Focus Redux: A Spell with the Orion SpaceProbe 3 Reflector.

  1. Hello Neil.

    I’m so happy you like it!
    Your report corresponds very well with what I have seen and noticed.
    Your tripod seems to be better than mine though..
    Do you see any vignetting with the 32mm?


  2. Hi Lars,

    Doing very well so far.

    The tripod is the weakest link alright but I can deal with it OK. It takes a little getting used to at very high powers.

    Regarding vignetting: I have noticed that when I look down at the secondary mirror it appears to pick up a small rectangular shadow at the edge, which shims off a small bit of the light. Where does this derive from? I’m tempted to remove the secondary structure for a closer look but I’ve been too impressed with the raw images from the scope to attempt anything too daring at this stage.

    Best wishes,


  3. Evening Lars,

    I tested the 32mm Plossl on the SpaceProbe 3 this evening when I got back home. As a control, I fielded the 130P, which delivers a clear 2.5 degree field. The test object was the Pleiades cluster which encompasses about 2 angular degrees from side to side. The 130P did give a wider field, as expected. But the 76mm SpaceProbe also framed the entire cluster well but with a slightly smaller field. I think there was a small amount of vignetting at the edges of the field but it wasn’t too bad to my eye.



  4. Hello Neil,

    It works with the 32mm, but like you I think it “frames” better with a 25mm Plössl.
    Evidently, the optical quality of this little telescope is very consistent and it should definetely be on the list of choices for anyone looking for a first, second (or third) telescope.
    This gem gives very good images and takes high powers. It would be fun if more (experienced) observers dared to give it a try. In the hands of someone who knows what he/she is doing it is very capable and much more than just a “toy”.

    Thank you for the informative, in-depth reports you do Neil!


  5. Hello Lars,

    It’s definitely a keeper! I’m amazed at the images it serves up. In a world where there is heavy peer pressure to spend spend spend, it is reassuring to know that some of the finer things in life still cost very little.

    With best wishes,


  6. Hello Lars,

    I’m very grateful to you for pointing out the little 3″ f/9.2 reflector to me. It will take pride of place in my personal telescope collection, and like all my telescopes, will get plenty of use.

    Tonight, I’m taking my 12 inch f/5 Dob for a grand tour of Orion; so something completely different!

    Have a very blessed Christmas and all the best for 2018!

    Best wishes,


  7. Hello Neil,

    I knew it was a very good telescope that represented great value. Thank you for testing it.
    Now you know it too.
    Your article will help someone new to astronomy and maybe raise an eyebrow or two on those who would benefit from it..

    High quality optics does not have to cost a small fortune.

    I wish you a Merry Christmas and a Happy New Year!

    Best wishes,

  8. Evening Lars,

    I stumbled across a formula that computes PV wavefront error (w) for a spherical mirror:

    w = 22.5 D/F^3

    Where D is the diameter of the mirror in inches and F is the focal ratio of the same.

    Doing the sum with a 3″ F/9.2 Newtonian such as this gives:

    w = (22.5 x 3)/ 9.2^3 = 0.086 so about 1/12th wave PV!

    Best wishes,


    • Hello Neil.

      Yes, the math tells us the mirror is very good, but it gets even better when it’s confirmed at the eyepiece. It really is a honest telescope as you stated.
      We’ve had a long spell of ‘bad’ weather here=no skygazing for me for many weeks, so I have really enjoyed reading your articles and posts even more!
      I’ve been thinking about giving my little homebrewed 3″ a better tube.
      It has a cardboard tube and it is not the best material for it.
      It deserves something better, so maybe a hexagon wood tube with elements of other kinds of wood and gold inlays would do .?

      Best wishes,

  9. Afternoon Lars,

    I can certainly empathise with you concerning the abysmal weather we have been enduring in the “frozen north”. We may not be Scandanavian but we sure share much of its climate lol.

    Anyway, I made up for it last night; the skies cleared in the late evening and stayed clear for much of the night; I was at it until after 2am lol. Seeing was very good too and I feasted myself on about 20 double star targets and even made a sketch of M51 as seen through my 130mm f/5. I was very surprised how well this galaxy showed up in a brighter than average sky owing to the reflection of ground snow from the landscape. I can’t wait to turn my 12 inch Dob on that target!
    The 3″ Spaceprobe has a been a godsend and I am still very grateful to you for pointing me towards it. What I am amazed about is the relative lack of exposure this telescope has received from the amateur community. I suppose it’s the same ole same ole: they mistakenly equate cheapness with bad quality and as we know, nothing could be further from the truth with this little telescope! It’s profile ought to be raised several notches so that more people can explore its many charms. I have a few more projects to conduct with this telescope in the foreseeable future to flag up its potential. I think I might just dedicate it to solar viewing in my own case.

    Hope you get the time to make that gold inlayed tube for yours!

    With best wishes,


    • Neil,

      Not much to do about the weather, it is what it is where ever it is.
      Still, the weather with all those persistent clouds is a drag.

      The 130 f/5 is a very nice allrounder, and M51…!
      I remember the first time I saw M51 many years ago thru my, then new 10″GSO, DARK site and excellent seeing. I sat there for about two hours. I’ve never seen it that good to this day. Fantastic!
      Those rare moments when everything goes your way..

      I recently bought a grimey looking Synta 102/1000 refractor with a eq3/2 mount on a auctionsite here for about 50 pounds total delivered.
      With a little dedication it cleaned up really well and I tried it on my AZ4 which turned out to be a good match. Nice refractor actually!
      The eq3 is a bit lightweight for it, but I think I will try it together with the 130 f/5, which is both shorter and lighter. I’m not very fond of eq-mounts, but now that I have it I will give it a go anyway.

      It warms my heart that you liked the little 3″!
      Lovely little telescope that can bring joy back into observing!
      Like you I’m a little confused it hasn’t gotten more attention, it’s been around for many years in different colours and brands.
      If image quality is what matters it should definetly have been recognized by now.

      Yeah, gold inlays may be a bit too much.. haha!

      Have a great weekend Neil!


  10. Good morning Lars,

    The weather is not so hot here either at the moment but at least it’s turned milder. I missed a clear spell yesterday evening while I was fitting the 130 f/5 into its new case lol. That’s what you call putting the cart before the horse! Never mind; there will be other nights.
    I’m very glad to hear that you got that little achromat working. Those 4 inch f/10s are amongst the best ‘scopes for outreach and quick excursions and represent a true bargain in the hobby. And they are especially good on double stars. I spent quite a long time enjoying an old Tal 100R. I preferred its images to my old 4″ f/5 Genesis refractor on high power targets like Mars and Jupiter. I bet you’ll get some great images from that telescope.
    I’m going to take a closer look at M51 with my 12″ f/5 later in the week. More cold weather on the way, so there will be a good chance of a clear sky. I was actually quite surprised how well the 130mm showed it up; the cores of both M51 and NGC 5195 showed up well and with a little more concentration and averted vision, I was able to trace out something of the steamer linking the two.
    I have grown very fond of the 10mm Kellner that came with the Spaceprobe. It’s throughput is excellent being such a simple, 3 element design and produced very high contrast images. As long as I keep the galaxy near the centre of the field, it’s very sharp and contrasty. Indeed, when Barlowed I have enjoyed using the same eyepiece to pick off the very faint companions to Delta Geminorum and Alula Borealis.
    I would like to do more experiments to see how the little SpaceProbe 3 compares with small refractors. I have an old 60mm classic achromat I can ressurect as well as a 90mm Apo that I can make aperture masks for; could try 60mm, 70mm etc and compare the daytime views on high magnification targets. That should keep me entertained for an afternoon or two!

    Big rugby weekend ahead; but there can only be one overall champion in the six nations!

    Have a great weekend,


  11. Yeehaw! The Irish juggernaut secures yet another win over Scotland in Dublin!

    6 Nations champions 2018!

    Going all out for the Grand Slam on Paddy’s Day at Twickenham!

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