Wednesday, February 3 2016: SkyWatcher has established a solid international reputation for producing high quality Newtonian optics for the modern amateur astronomer, and at prices that won’t break the bank. Having been thoroughly satisfied with a 8″ f/6 Skyliner Dob, I became very curious about a smaller, model – the Heritage 130P (a 5.1″ f/5 Newtonian with a parabolic primary) tabletop Dobsonian – which promises to provide decent light grasp and resolution in an ultra-portable package for take anywhere travel and short grab ‘n’ go excursions to the back garden.
The telescope was purchased new from Rother Valley Optics on Tuesday morning, February 2, and arrived in the mid-afternoon today. The price, inclusive of postage, was £129.
The telescope came double-boxed and involved no assembly. The optics looked clean and streak-free. A neat instruction manual accompanied the instrument.
The ‘scope, weighing about 6 kilos with the mount, has a built-in carrying handle for swift transport into and out of the house.
Following along the same lines as their extremely successful flextube line of larger Dobs, the Heritage 130P can be extended to reveal the upper tube assembly, lengthening the tube from just 38cm to about 61cm. The lower assembly is adorned with the names of time-honoured astronomers, celebrating four centuries of telescopic astronomy. While some folk might find this ‘tacky,’ I rather liked it.
Remarkably, the telescope was almost perfectly collimated out of the box, as evidenced by the just slightly offset red dot from the centre-marked spot on the primary mirror. That’s a nice touch, as one can imagine the reaction of a complete novice were he/she to discover that the optics were delivering iffy views as a result of mis-aligned optical components. It might be enough to put someone off the hobby for good.
Once the collimation was tweaked, I investigated retracting and extending the tube assembly several times to investigate the rigidity of the structure. I am pleased to report that the collimation held quite well but might still require last-minute tweaking for more demanding tasks, such as obtaining the best lunar and planetary views, as well as double star work. Overall though, this is a very well thought out piece of kit and certainly better than I had anticipated.
The telescope primary and secondary mirrors are fully adjustable and can be aligned in a matter of minutes. Unlike the three ultra-thin spider vanes on larger models, the secondary mirror on the Heritage 130P is affixed to a single vane, which is a good bit thicker than the latter; a necessary design compromise to maintain that little bit more stability to the optical train.
The focuser is unusual. Unlike standard rack and pinion or Crayford type focusing mechanisms, the Heritage 130P employs a simple helical focuser which involves rotating the eyepiece either clockwise or ant-clockwise to bring objects to a sharp focus. In addition, the length of the upper tube can also be adjusted to accommodate cameras and other equipment. In short, any eyepiece will reach focus using a combination of these procedures. Only 1.25″ oculars can be used with the instrument, however.
Some observers may find reaching precise focus a little fiddly, but with a bit of practice, it works smoothly and accurately.
The Heritage 130P also came with a simple red dot finder (RDF) to aid in locating objects quickly under a dark sky.
A particularly attractive feature of the instrument as received is the dovetail mounting of the optical tube assembly which enables one to remove the tube assembly from the mount proper for even easier storage.
In addition, the dovetail plate allows the user to mount the instrument separately on other types of mounts such as this author’s ergonomical Vixen Porta II alt-azimuth for an alternative style of observing. What a nice touch!
Optical testing: Although the instrument suffers from the introduction of considerable amounts of stray light during daylight use without employing some sort of light shroud, I set the instrument up in the late afternoon, aiming the instrument at a roof top about 100 yards distant. I didn’t wait around to use the supplied oculars (which are adequate but not great for testing) but instead decided to push the ‘scope as hard as I could. To that end, I ran inside and affixed a good quality 6mm orthoscopic to a 2.25x Baader shorty Barlow lens, which would deliver a power of 244 diameters. Inserting these into the helical focuser, I carefully rotated it until best focus was achieved. Although the view was a bit drowned out with extraneous light, I am happy to report that the image of the terracotta roof tiles came into very sharp focus; a great initial sign that the optics were of potentially high quality.
After dark, more cloud encroached, but I waited for the odd sucker hole and was rewarded by a clear spot corresponding to Auriga, then high in the eastern sky. Relocating the instrument in a dark spot in the garden, I centred the bright star, Capella, using my multi-coated 32mm SkyWatcher Plossl in the field (yielding a true field of 2.5 degrees!) and was delighted to observe (with my eye glasses on) a beautifully sharp vista, with pinpoint stars across most of the field. Then, I investigated the high power view of Capella at 244x and after refocusing, was thrilled to see a tight white Airy disk with diffraction rings a shade more prominent than what I have observed in my work horse telescope, a larger 8″ f/6 Dobsonian. This could be explained by the larger central obstruction of the Heritage telescope (~29 per cent by aperture) as compared with 22 per cent for the larger 8 inch.
On a whim, I moved the instrument north-eastward from Capella and centred the star, theta Aurigae. Focusing as accurately as I could, I was able to steadily hold its very faint companion at 244x, some 4 arc seconds away from the primary. Very encouraging to say the least!
It wasn’t long before the skies completely clouded over, and the drizzle came back, ending my first light vigil under the stars. Needless to say, the instrument performed surprisingly well under admittedly dodgy observing conditions.
More testing in the pipeline though.
Thursday, February 4, 2016
Having collimated the telescope in situ and placed a makeshift light shround around the upper telescope assembly (UTA), I am happy to reaffirm that the telescope delivers tack sharp images of distant willow tree branches at 244x.
Friday, February 5, 2016
The Heritage 130P has a parabolic primary mirror, that is, it is figured into the shape of a parabola. Why is a parabolic shape responsible for such sharp images in a Newtonian reflector? It’s an interesting question, yet many amateurs accept it as a given. But we can do considerably better than that. We can analyse the properties of the parabola, one of the conic sections beloved to the mathematicians of classical antiquity, and thereby gain a deeper appreciation of why this shape, over all others, is chosen by opticians in the fashioning of high quality primary mirrors. Our analysis will borrow from the approach of the great French mathematician, Rene Descartes (1596-1650), who developed a way of investigating geometry using algebra.
A parabola is the set of all points which are equidistant from a given point called the focus and a given line known as the directrix.
The image below outlines the basic features of a parabola drawn on a x-y axis.
Let the focus be the point S( a,0) and the directrix be the line x=-a, as shown in the diagram. Consider any point on the parabola, P(x,y).
Thus, by definition, the length of SP = length of PM
So [(x-a)^2 + y^2]^0.5 = x + a
Therefore, (x-a)^2 + y^2 = (x+a)^2
Thus, x^2 -2ax +a^2 + y^2 = x^2 + 2ax + a^2
From which y^2 = 4ax ( Eq 1)
This is the standard form of the equation of a parabola.
Consider next the parametric equations x = at^2 and y = 2at.
Substituting the expression for x into equation 1 we obtain;
y^2 = 4a^2t^2 = 4a(at^2) = 4ax
So, x = at^2 and y = 2at represents the parametric coordinates of any point on the parabola y^2 = 4ax.
We can use this to derive two more equations that will enable us to arrive at the result we want. Consider the diagram drawn below.
y^2 = 4ax
Differentiating implicitly with respect to x we obtain;
so f'(x) = 2a/y, which is the gradient of the tangent at any point.
Now since y = 2at, the gradient becomes 2a/2at = 1/t
And so the equation of the tangent to the parabola at the point P is given by:
y – 2at = 1/t(x-at^2)
Multiplying across by t gives;
ty – 2at^2 = x-at^2
or x – ty + at^2 =0 ( Eq 2)
Also, the gradient of the normal at P = -t and so the equation of the normal will be:
y – 2at = -t(x-at^2)
or tx + y – 2at – at^3 = 0 ( Eq 3)
Now we are ready to obtain further information from the parabola under discussion.
Let the tangent at P intersect the x-axis at R and the y-axis at U, and let the normal to the parabola at P intersect the x-axis at V, as shown in the diagram below:
The coordinates of R are obtained by setting y = 0 in equation 2
x – ty + at^2 =0 and so if y = 0 then x = -at^2 and so the coordinates of R are (-at^2, 0)
The coordinates of U are obtained from setting x = 0 into equation 2, from which it is easily shown that y = at i.e. U(0, at).
The x-coordinate of V can be obtained by setting y = 0 in equation 3;
tx + y – 2at – at^3 = 0 and when y = 0 we obtain:
t(x- 2a – at^2) =0,and since t cannot equal zero we have
x = 2a + at^2 and so the coordinates of V are given by (2a + at, 0).
From these results it is possible to verify the following:
(i) U is the midpoint of PR
(ii) length of SR = length of SV = length of SP
(iii) US is parallel with PV and that PU is perpendicular with SU
I will leave these as exercises for the interested reader.
Now, to the meat of the analysis. Consider a line PZ drawn parallel to the axis of the parabola as shown in the diagram below:
Since length SP = length SV so too must angle SPV = angle SVP
But angle SVP = angle VPZ since PZ is parallel with RV
So angle SPV = angle VPZ
But ZPV is the angle of incidence of a ray of light incident upon a reflective parabolic surface and so the law of reflection requires that the angle of reflection be the same i.e. angle VPS.
But since P is independent of S, the result implies that any ray of light parallel to the axis will be reflected through the focus, S.
This is the reason why parabolic mirrors work so well, as they completely avoid a phenomenon known as spherical aberration, which can can plague other kinds of optical designs.
That’s enough math for one evening eh.
After a day of more or less constant rain, the sky appears to be clearing up and so I’ll get some more time under the starry heavens using my little parabolic Newtonian.
Thank goodness for small mercies!
Saturday, February 6 2016
The telescope was collimated perfectly before use and left to cool in a dry, unheated shed. Initially, I had intended to use my Baader zoom and dedicated 2.25x Barlow to observe Jupiter, now 31 degrees above the horizon. To my chagrin, I discovered that this combination failed to reach focus. Due to the constant interruptions from clouds and with the rain never far away, I did not want to retract the UTA enough to get it to focus. Instead I chose a 7.5mm Parks Gold ocular and 2.25x Barlow yielding 195x.
Though the helical focuser is a bit fiddly and takes some getting used to, I am happy to report that the Jupiter images were wonderful in this telescope, with lots of nice detail showing up under moderate scrutiny. The planet’s enormous equatorial belts were seen in their faithful colours and many shades of tan were observed. A Baader Neodymium filter took away a little bit of glare surrounding the planet, helping to bring out more subtle details. Although I felt 195x was a little too high, and would have been happier with 160x, I was most impressed by what this inexpensive Newtonian was delivering.
Turning then to some brighter stars appearing from behind the clouds, I was equally impressed by how well the instrument focused them down to tight round Airy disks at the highest powers pressed into service (244x). The telescope seems quite immune to atmospheric turbulence as judged by the calmness of the images. Returning to a 32mm Plossl, I enjoyed a spell binding few minutes drinking up the famous Double Cluster (Caldwell 14) in Perseus. The 20x delivered by this eyepiece provided a very generous field of view, allowing both star clusters to be easily framed in a most beautiful portal.
This is certainly not a toy telescope! It is impressively powerful with high quality optics. Indeed my initial impressions were very similar to this assessment made by Ralph Bell back in 2009.
Monday, February 8 2016
Time: 18:30-45 UT
I enjoyed another brief vigil under the stars with the Heritage 130P Newtonian. Charging the telescope with a 32mm Plossl (20x), I first visited the Pleiades, now high in the southern sky. Its constituent stellar components focused to fine points of light, pure white as the driven snow, with excellent contrast. Though I did not do a side by side comparison with my 80mm f/5 shorttube refractor, I was immediately aware of the Heritage’s significant advantages in light gathering power, with many more fainter members coming through at a glance. Then, I moved the instrument southwards, where majestic Orion was just about to culminate. The view of M42, the Great Nebula, was a sight for sore eyes. Cranking up the magnification to 81x with my Baader Zoom, I enjoyed a sumptuous field of view dominated by the emission nebula and Trapezium stars at its heart. The hinterland of the nebula was jewel encrusted with brilliant white stars set against a jet black sky.
Before packing up, I examined three higher resolution targets; first Rigel, just a few degrees to the southwest of M42. Using a power of 108 diameters, I was delighted to see the faint companion to this brilliant giant star cleanly and steadily. Then I swung the telescope over to Cassiopeia, now high in the northwestern sky. First I centred eta Cassiopieae and keeping the power at 108x I was able to easily split this pair, consisting of a beautiful yellow primary of magnitude +3.5 and its ochre companion some 13 arc seconds away, shining considerably more faintly at magnitude 7.4. Finally, I moved the Heritage 130P over to iota Cassiopeiae and could make out two of the three components of this system at a glance at 108x. The third member remained somewhat more elusive though, so I attached the Baader 2.25x Barlow yielding a higher magnification of 244x, refocused, and was overjoyed to see all three components clearly and precisely!
The imminent arrival of another student meant that I had to end the short vigil there, but it was very rewarding nonetheless. The telescope has great potential as a deep sky instrument and appears to be no slouch on moderately difficult double stars.
Tuesday, February 9 2016
Time: 19:00-30 UT
After a cool but crisp day, I continued my Newtonian education by fielding two telescopes; the Heritage 130P and a high quality 90mm f/5.5 ED doublet on loan for a a magazine review. Both instruments were given plenty of time to thermally acclimate and placed in the darkest spot in my garden to minimise stray light flooding into the open tubed reflector.
The sky after sunset was clear but the stars were corruscating fairly wildly. Transparency was excellent though, so I decided to assess the seeing conditions some more by turning the 130P on Castor, now quite high in the eastern sky. Charging the telescope with a power of 195x, both the A and B components were resolved but there was quite a bit of turbulence which made the stars bloat significantly from their calmer appearances under better seeing conditions. Comparing the same target in the ED90 charged with a power of 188x, both components were also resolved but there was still noticeable turbulence. It was not quite as unsettled in the refractor though, a consequence I suppose of its smaller aperture. This demonstrated to me that poor seeing can (though thankfully rarely at my location) adversely affect small telescopes. I judged the image in the refractor to be slightly more aesthetically pleasing under these conditions.
The reader will also note that the refractor comes equipped with a state-of-the-art 11:1 dual speed micro-focuser and so was considerably easier to focus finely than with the comparatively crude helical focuser on the Heritage 130P. This may also have contributed to my conclusions regarding Castor A & B. Accurately focusing f/5-ish instruments is never a walk in the park.
Turning to M42 once again, I compared and contrasted the images in both telescopes matching their image scales as best I could (~100x). Both telescopes delivered good images but the superior light gathering power of the reflector gave it a distinct edge. More nebulosity was seen and the stellar images were noticeably brighter in the reflector. This was despite the fact that the refractor had superior contrast, with a blacker sky background.
I am hoping that conditions will improve by the time Jupiter rises in the sky in a few hours from now.
The sky has completely clouded out and the forecast predicts that it won’t clear again until the wee small hours. I am very tired though, so will leave further testing for another night.
Thursday, February 11 2016
I fielded the same two instruments tonight as last night; the 130P reflector and the ED90 refractor. I finally found a good eyepiece to optimise the 130P’s capabilities on Jupiter; a 4mm Plossl delivering a power of 165x.The ED90 was charged with a power of 150 diameters.
Seeing was only marginally improved over last night (Antoniadi III-IV) but it was nonetheless a good test of what both instruments could deliver on Jupiter under these sub-par conditions (we have a north westerly air flow here which almost invariably brings more turbulent conditions but with excellent transparency).
I fitted a Baader Neodymium filter (with very high light transmission and virtually no colour shift, more a moon and skyglow filter than anything else) to the 130P to reduce the glare a little.
Comparing the images in both telescopes over a period of about half an hour, I gathered my thoughts.
Both showed some nice details in the equatorial belts. The ED90 image revealed hints of more subtle details at higher and lower latitudes but in the end I felt the 130P showed that little bit more. In particular, it was easier to see those details at temperate latitudes, as well as the more delicate polar shadings. One very striking difference was the colour of the Jovian disk presented in the telescopes. The ED90 was noticeably yellower in overall hue – a consequence of its imperfect achromaticity in comparison to the perfectly achromatic reflector. The latter presented a brighter disk in its true colour; much more creamy white than yellow. The Neodymium filter showed that the colour in the ED90 remained the same but with a little more light loss.
In retrospect, this should not have come as a surprise; while the refractor has a low dispersion element, which improves colour correction, it still can’t deliver perfectly achromatic images. Yes, it’s a sizeable improvement over the traditional achromat but still not perfect. Only a reflector image – which brings all wavelengths of light to the same focus – could really reveal this. In addition, a brighter image can also help the eye see finer details. You need light to see such details.
That being said, I do know the ED90 is capable of showing more on better evenings ( data not communicated) but so must the 130P, as they were both compared under the same conditions. I am eager to conduct further tests in this capacity as soon as the seeing conditions return to normal.
This was an instructive vigil. The 130P should give very decent images of Jove when the seeing is fair to good.
SkyWatcher has also brought to market a related telescope called the 130PD-S, which, as far as I can tell, features the exact same optics as those possessed by the Heritage 130P but retails for about £30 more. The optics are housed in a closed tube and the spider vanes are akin to what is seen on a traditional Newtonian. It also features a low profile 2-inch dual speed focuser for precise focusing and the secure mating of a CCD camera to the instrument. The 130P-DS has proven a huge hit with astro-imagers who have used it to good effect to capture stunning views of the night sky. Featured on this link is a plethora of deep sky objects captured by this modest telescope, but the reader will also take note of the lunar and planetary images captured by the same instrument.
Although not a visual assessment, I hope you will agree that the unlying camera shows just how good the optics are in these telescopes.
Friday, February 12 2016
The seeing was vastly improved tonight, frosty but no wind. I only had time for one target; Jupiter. Like last night I fielded the same telescopes and employed the same magnifications etc.
Both telescopes served up some excellent images, but this time there was a clear winner – the 130P.
Though the image flitted somewhat between perfect focus and slightly out of focus in both telescopes, both instruments revealed excellent details in the equatorial and temperate belts. Details in the more prominent NEB were more finely resolved in the Newtonian than in the ED90. But what clinched it for me was the sighting of the Great Red Spot (GRS) near the western limb of the planet (at 00:01UT) that was picked off in the 130P but was not seen clearly in the ED90.
As always, I would be very grateful if someone could repeat these observations if you have the 130P and a good 90mm refractor.
The 130P is turning out to be a fabulous little telescope and I am overjoyed to have made its acquaintance!
I have noticed that the price of the ED90 has been bumped up by £48 in the short time since I acquired it for review. It now retails for £868?! I don’t know why this was done (it was £820 just last week, remember?), but I can tell you I do not consider these telescopes good value for money and do not understand some people’s obsession with them. Under good conditions the Heritage 130P will outperform it and for 1/6th of the price. And if the classical achromat is the prince of telescopes, Newtonians are the ruling monarchs.
I would like to keep this telescope and learn how best to maximise its potential. I have bestowed a name on her; Plotina.
After another beautiful, crisp day, the firmament was glorious after sunset, with a gorgeous crescent Moon adorning the western sky. I set up Plotina at the side of the house and trained her on our life-sustaining satellite. She cools super quick, faster perhaps than the ED refractor that now sits in its case. The view of Luna at 20x was simply breathtaking, with razor sharp crater fields and the most wonderful earthshine from its dark side. Cranking up the power to 165x, the image remained razor sharp with excellent contrast and without a trace of chromatic aberration.
After that, I headed over to eta Orionis, a fairly tricky double star and was rewarded by a good clean split of the A and B components, the primary shining about a magnitude brighter than the secondary (3.8 and 4.8, respectively) and separated by a mere 1.7 arc seconds. Because of its f/5 relative aperture, it is very important to examine such high resolution targets at the centre of the field. This can be achieved by placing the system at the eastern edge of the field and letting it drift into the centre. The procedure is repeated several times until one is certain that the duplicity has been unveiled.
Some haar moved in a short time ago but hopefully it will clear later. I hope to field my most powerful telescope, Octavius, to continue my study of the Giant Planet.
Saturday, February 13 2016
My luck ran night overnight, as instead of clear skies, we got a fall of snow.
The final step in keeping anything in my family is to get my wife’s approval. For that, I had to get all my facts together to make a convincing case lol:
The optical tube assembly weighs just 3.2 kilos
The little lazy Susan weighs 2.8 kilos
The telescope can be collapsed to half its length.
The tube assembly can be used with a variety of other mounts.
The telescope is easy to tweak; involving a couple of minutes with a laser collimator.
The telescope is easy to carry about using one hand, so even when I’m feeling lazy it will not overtax me.
The telescope cools rapidly, so no waiting around or extensive pre-planning involved. Just set it out 15 or 20 minutes before use and you’re cooking with gas.
Because the tube is open, the optics can be accessed to remove dust and other grime easily.
The telescope gathers a very decent amount of light to go that little deeper than my short-tube refractor; very good for deep sky viewing.
The telescope takes high magnification well; images remain sharp and well defined up 244x (higher powers not yet tested) when conditions are average to good, so will perform well on lunar, planetary and double star targets.
The telescope can be improved in a number of ways; for example, the mirrors could be re-coated to give both higher reflectivity and increased durability, the secondary size re-assessed, ways could be found to refine the helical focuser, a permanent light shroud can be installed etc. Any amount of tomfoolery is permissible!
The instrument exudes charm and is popular with the kids.
The entire package cost only £129.
I think these points will be enough to win her over. Fingers crossed eh!
Improving the Focuser:
As mentioned earlier, the focuser on the Heritage 130P is of the simple, helical variety. One simply twists it one way or another to attain a good focus. But in the field at night, it can be a little frustrating to focus precisely, especially when using high magnifications. Manhandling the focuser almost always causes the telescope to move a little, necessitating re-centering of the object under study.
Fortunately, I was able to find a very simple solution; about six inches of string!
The string is tied in a single knot around the focuser, gripping the top thread, and leaving two overhanging ends which can be pulled in either direction causing the focuser to move inward or outward, as desired. This enables both course and fine focusing with much less vibration or annoying image shift. I tested it out during the day on a variety of targets at various distances from about 40 yards to infinity and it worked really well! This will allow more quality time observing and more precise focusing from moment to moment.
I’m well happy with the improvement!
Sunday, February 14 2016
St. Valentine’s Day and the first Sunday of Lent.
Last night I fielded Plotina just before midnight. After snowing for much of the day, the late evening sky cleared up to reveal the hosts of the second heaven. Seeing was very good but bitterly cold(-4C), but I was rewarded by quite an extraordinary view of Jupiter and its magnificent satellite system. I watched the planet for about 40 minutes, beginning at 23:50UT and ending at about 00:35UT.
This instrument continues to humble me in many ways. The optics are unreasonably excellent in this telescope; something I was not really prepared for, but hand on heart, it has thus far given me the finest views of Jupiter in any small telescope that has passed through these parts. I made a quick sketch depicting the planet’s appearance at 23:50UT (CM II 217 degrees), when it was 33 degrees above the horizon. The Great Red Spot (GRS) was plainly seen in the eastern hemisphere of the planet. The magnification employed was 165x and a Baader Neodymium filter threaded to the 4mm Plossl.
Indeed, I was able to use this telescope to establish the most accurate longitude of the GRS during this apparition. The GRS was observed transiting the centre of the planet at 00:32 UT where the system II longitude was 243 degrees. Not bad eh?
In the immortal words of Alexander Pope;
Nature and nature’s laws lay hid in night;
God said “Let Newton be” and all was light.
Monday, February 15 2016
I subjected the 130P to a high magnification test on the first quarter Moon, at an ambient temperature of -1C. I am very happy to confirm that it handled 244x without flinching, with the craters, mountain ranges, maria and valleys remaining tack sharp and colour free throughout. This is about as high as one would like to go with this telescope in the vast majority of applications and a testament to the quality of the underlying optics.
I would warmly encourage other individuals to test each and every one of the claims I have made about this telescope. Test everything; hold fast to that which is good.
Sound Biblical advice that!
Way hay! I found me an online thread about the same telescope; Enter the One Sky Newtonian from Astronomy Without Borders .
250K+ hits ……..Crikey!
Seems like I don’t need to say anymore, eh.
Tuesday, February 16 2016
What a thread! The things they say about this telescope warms my heart.
That thread has saved me months of blogging; Laudate Dominum!
Gary Seronik of S&T also found the telescope a joy to use; see here.
And yet another independent review can be read here.
Here my story ends.
Thank you for viewing.
Thursday, February 18, 2016
Having just acquired the latest issue(March 2016) of Astronomy Now (pp 63), I read with interest that the current longitude (system II) of the GRS is 238 degrees. That’s just 5 degrees shy of my best estimate made with the 130P shortly after midnight on Sunday February 14 (see above). I’m thrilled to bits to have gotten so close with this nifty little travel Newtonian.
Monday March 14, 2016
I have found that the Televue bandmate planetary filter is a great match for the 130P whilst studying Jupiter.This filter will be used in all future observations of the planet with this telescope.
The primary and secondary mirrors of the Heritage 130P have been despatched to Orion Optics UK. Both mirrors will be re-coated with Hilux enhanced aluminium reflectivity coatings and a slightly smaller secondary (35mm @27% linear obstruction) is to replace the original flat.
Will report back on progress.
Tuesday, March 22 2016
The mirrors arrived back from Orion Optics UK this afternoon and I immediately set to work putting it all back together again.
Out came the matt black paint to darken the periphery of the new secondary mirror to further reduce stray light and increase contrast.
The primary mirror had to be re-spotted at its centre but this can easily be done by placing the mirror shiny side down on a sheet of paper and tracing round its circumference. Next, the 130mm diameter circle was carefully cut out and folded first in half, and then once again into quarters. When the paper is unfolded the centre is marked by the intersection of the two crease lines. A scalpel (lol!)was used to excise a very small hole at the centre of the unfolded paper and then it was placed over the mirror, being secured in position with some cellotape. Finally, a doughnut shaped sticker was placed on the spot exposed by the hole. Job done!
The optics were then rehoused in the tube, collimated using an inexpensive laser collimator (SkyWatcher) and briefly tested with an eyepiece. Everything looked dandy!The telescope should now deliver brighter, more contrasty images on all celestial targets. And those special coatings will last at least a quarter of a century!
Surely now Plotina will be as durable as any high quality refractor nay?
All I have to do is wait for a decent clear spell to see how well she performs under the starry heaven.
Wednesday, March 23, 2016
Beginning about 20:30 UT this evening, I took advantage of a clear spell after a few hours of light rain. Jupiter was about 34 degrees above the horizon and rising, and I continued observations through to 21:15 UT before more cloud rolled in. I captured some beautiful detail on the Jovian disk, including the appearance of the GRS at the planet’s eastern limb. As the minutes passed, the view of Jupiter got ever better as it gained in altitude. The 130mm f/5 performed flawlessly. The planet was brighter, crisper and cleaner than I had ever seen it before with this instrument under these conditions (Ant II). To say that I’m pleased with the modifications would be an understatement, but we’ll leave it at that.
I heartily recommend this telescope to my amateur friends across the world.
Wishing you all a very blessed Easter.
March 31, 2016
I enjoyed a half hour with the Heritage 130P this evening after I had observed Jupiter. After spending some time in Leo hunting down some spring galaxies, I started looking at some double stars. Gamma Leonis was easy, Castor A and B just as easy, iota Cassiopeiae triple lovely and all three components resolved. Mizar & Alcor were glorious at 150x as was Polaris A & B. Izar (epsilon Bootis), a summer favourite, was high enough in the east for me to split it. These were all seen at 183x save for Mizar & Alcor. I then decided to try a pair of stars I haven’t visited in a while; Alula Borealis and Alula Australis in Ursa Major. They are high overhead this time of year. Aiming is quite difficult using just the RDF but with my 32 mm Plossl delivering 20x, I was able to frame them both in the same field. Starting with the orange star Alula Borealis, I employed 183x using my most comfortable ocular; the Mark III Baader Hyperion zoom set to 8mm with its 2.25x Barlow. Although this does not show the highest contrast views (but only by a surprisingly small margin!!), I was able to see the very faint spark of its companion. The primary is magnitude 3.5 but the secondary shines at magnitude +10.1 and only 7.4″ separating them! I was chuffed to see this in such a humble little reflector. Then came the icing on the cake; I moved south to Alula Australis (Xi UMa) and could see that the star looked ‘entangled’ but I knew I needed a little more power to get a clearer view. So I ran in and fetched by 6mm orthoscopic and coupled it to the little 2.25x Barlow yielding 244x, centred and focused carefully: Voila! The pair (1.6″ split) were beautifully resolved (magnitudes 4.3 and 4.8), the components round as buttons, with a kind of diffraction halo encircling them; kind of like an ‘aura’ encasing two luminous eggs in a wafer thin handkerchief lol.
If no one bothers, how can one ever discover the truth? The Heritage 130P is unreasonably excellent on everything; a great little bundle of joy!
April 7, 2016
Mr. Adam Blake from Pennsylvannia USA, was kind enough to share some video footage of Jupiter he captured with his One Sky Newtonian, as seen on the evening of April 5, 2016 during a spell of good seeing. He used an inexpensive 5X GSO Barlow and standard UV/IR filter on the camera at prime focus to capture the images, which have only been very lightly processed to show the telescope’s potential. See below.
I aimed the Heritage 130P at iota Leonis, now high in the south. Using 244x I was able to quite easily resolve A-B. The primary shines with magnitude +4.06 and the secondary +6.71 with 2.1″ separating the components. I would warmly encourage others to try this system, as well as the aforementioned star systems with this telescope.
A Portable Dew Buster: Are you concerned about dew building up on the open tube of the Heritage 130P? Nae worries! I never let any heating devices within a country mile of my telescopes, just like my forebears. I bought a portable three-speed fan for about £10 that zaps dew in seconds from the secondary and primary using cold air. Now you can enjoy the telescope under the stars for as long as you like!
April 28, 2016
At an ambient temperature of -1C, the Skywatcher Heritage 130P worked flawlessly to bag epsilon 1 and 2 Lyrae, eta Bootis (with its 10th magnitude companion), pi Bootis ( AB: 4.9, 5.8 separation 5.4″ and AC: 4.9,10.6, separation 127″), alpha Herculis ( AB:3.5, 5.4, separation 4.6″ and a corker, AD: 3.5, 11.1, separation 79″)
For lunar and planetary studies, I can also recommend the Baader single polarising filter to use with this adorable little telescope. Retailing for £32.00, it significantly enhances belt detail on Jupiter, reduces glare and presents the planet in its natural colours.
Sunday, May 15, 2016.
During a relaxing weekend away with a group of old friends in the picturesque and historic village of Luss, on the western bank of Loch Lomond, I took the little SkyWatcher Heritage 130P along with me, as it was so easy to transport and set up. After long sunny days outdoors, I set the instrument (on its Dob mount) up on the garden table for a look at Jupiter and the first quarter Moon, which were perfectly positioned in the evening sky.
As this was an annual event away, the crew were expecting me to bring along a telescope, but it is usually of the short refractor variety. I got some odd looks from the gang as I extended the upper stage of the ‘strange’ reflecting telescope, but I was sure glad I made the effort; they were all mightily impressed by the images the little portable reflector served up:- and even more gobsmacked when I told them how relatively inexpensive an instrument of this quality cost to acquire!
July 21, 2016
My collegaue at Astronomy Now, Steve Ringwood, has independently reviewed the New Meade Light Bridge 130 Mini Dob for the August 2016 issue of Astronomy Now (now in the shops) on page 108-10. Although a slightly different design to the Heritage 130P featured in this blog, the optics are essentially the same but features a solid tube and a more traditional four spider-vane secondary support for even more rigid collimation maintenance in the field. Steve found that the optics were very good indeed, being capable of powers in excess of 200x, in agreement with my findings. At $200, it is priced at the same as the One Sky Newtonian from Astronomy Without Borders, discussed above.
So more choice for the discerning amateur.
Brian Schultz, from his YouTube channel Cool Space, describes how the One Sky Newtonian can be fitted to an inexpensive go-to mount for added versatility. See here for a video clip.
August 8-9 2016
Our family ventured to the remote Isle of Skye, a place of outstanding natural beauty, for our summer vacation. My trusty 130mm f/5 Heritage Newtonian travelled with us. Though the weather was mostly damp and windy, I did enjoy a bout of observing with the instrument during brief clear spells on the evenings of August 8 and 9. The sky is truly glorious at this location, presenting some of the darkest and most transparent skies in all of Europe. And the (not so) little 130mm did not disappoint, serving up jaw-dropping views of the northern Milky Way high overhead, once the crescent Moon fell out of the sky. Deep sky objects were a joy to behold, including M31,Caldwell 14, M57, M13 and M92. The North American Nebula in Cygnus was as plain as the nose on the your face, as were the eastern and western Veil nebulae nearby.
I can also report that high resolution targets – including a batch of close test double stars – presented very well indeed. Images of systems such as Izar, delta Cygni etc, were calm and well resolved at high powers (243x), showing that this island has good seeing conditions for such work. Scotland has many such places(as I continue to discover) if one is intrepid enough to find them out!
September 30, 2016
My experiments with the Skywwatcher Heritage130P continue apace. A while back a kindly gentleman from the USA alerted me to a potential issue with the instrument; the loss of precise collimation as the instrument is pointed to different parts of the sky. In a series of experiments conducted over the last six weeks or so, I discovered that while tightening the shaft that holds the secondary mirror in place seems to solve this problem for lightweight eyepieces, it doesn’t always hold collimation for heavier oculars such as the rather bulky, Baader Hyperion zoom.
As a consequence, I have reassessed the suite of oculars I use with the instrument and have switched entirely to smaller, more lightweight units. Below is an image of my current experimental set up; a 32mm Plossl, delivering a power of 20x and a 2.5 degree true field. Using the tiny, screw-on 2.25x Baader Barlow, I can couple the 32mm ocular to give a power of 45x and a true field of ~1.1 degrees – just large enough to frame the entire Double Cluster in the field!
For higher power work, I use a Parks Gold 7.5mm delivering 87x, a 6mm Baader classic orthoscopic yielding 108x, and a 4mm Revelation Plossl (fully multicoated) giving 163x. Finally, using the 2.25x Barlow I can achieve 243x and even 366x when mated with the 6mm and 4mm oculars, respectively. I also have an old 1.6x screw-on Barlow made by UK Astro Engineering, which gives me still more options to play with.The Barlows will increase the eye relief of the short focal length of the short focal length eyepieces too.
Over the winter I hope to fine tune this set up some more, but I am very happy with the range of powers available to me and the relatively low cost of its operation.
I also intend purchasing some Bob’s Knobs collimating screws to fit to the secondary assembly in order to make collimation even more easy to achieve.
I will report back later in the year to tell you how I got on!
The instrument continues to inspire in so many ways and needless to say I have grown very fond of using it.
Thursday, October 13, 2016
Plotina received her new set of Bob’s Knobs secondary screws to make fine adjustments to collimation easier. I consider these to be a quality acquisition going forward.
Monday, October 17, 2016
Upon further investigation, I have been able to tighten up the stalk holding the secondary mirror in place by inserting a small washer, as shown below.
This increased rigidity allows the instrument to maintain precise collimation even after moving the telescope wildly in altitude and azimuth. This was verified using a laser collimator. The telescope can now use larger oculars once again, including the Baader zoom.
Monday & Tuesday, October 18 and 19, 2016
A break in the wet autumnal weather over the last two nights has allowed me to conduct further tests with the SkyWatcher 130mm f/5 Newtonian. I fielded a 90mm apochromat (retained for further testing) side by side with the instrument and studied how both performed on a variety of high resolution targets located in different parts of the sky.
Yesterday evening, shortly before midnight, I compared and contrasted both instruments in respect of their ability to maintain crisp, bright images of a waning gibbous Moon. Once our satellite achieved a decent altitude, I cranked up the magnifications on both instruments and examined the cratered terrain along the day-night terminator. Both instruments performed well but the larger aperture of the Newtonian allowed me to employ significantly higher magnifications (in excess of 300x) before the image became unsatisfactorily dim for my liking. The 90mm refractor, in contrast, maxed out about 200x.
Tonight, with better seeing but in colder(+4C) and hazier conditions, I ran the two telescopes to a variety of double star targets at various altitudes; gamma Delphini, theta Aurigae, Iota Cassiopeiae and delta Cygni; these systems were deliberately chosen so as to test how the 130mm Newtonian would hold collimation as it was adjusted in altitude and azimuth. My results show that the insertion of the washer in the stalk supporting the secondary mirror (described above) worked perfectly well, the stellar images remaining crisp, round and tiny. In every case, the Newtonian produced brighter, more convincing splits of these systems under equivalent magnification regimes – 200 to 250x.
These results show that the Newtonian is a wonderful, cost-effective and versatile instrument for all celestial targets and is noticeably superior to a much more expensive 90mm refractor, which quickly runs out of both light and resolving power in comparison.
I continue to highly recommend this instrument to those who are looking for excellent performance on a limited budget.
Nothing more to say really.
Thanks for following this blog.
Update: February 15 2017
My colleague at Astronomy Now, Ade Ashford, is helping to change culture by writing an excellent four page article on how to tune up the SkyWatcher Explorer 130PDS, mentioned in the blog above, and essentially the same telescope optically as the Heritage 130P (but with a closed tube) for better visual and photographic use. You can read this VERY interesting article in the March 2017 issue (page 98 through 102), out now.
Update: July 17 2017
Time: 00:09 BST
Location: Wigtown, Southwest Scotland.
Seeing: ( I to II): generally excellent, very calm
Instrument: 130mm f/5 Newtonian
Comments: A fabulous bout of double star observing. See notes below.
Update: July 18 2017
Time: 00:45 BST
Comments: Just in from another excellent session with the 130mm Newtonian. Highlight of the night was tracking down and resolving the lovely Mu Cygni. Tight pair, even at 244x and a fainter ‘companion’ wide away making it seem more like a triple system. Generous aperture and solidly good optics made very light work of this system. Like I said, this is arguably the best grab ‘n’ go ‘scope on the market today. Details below;
Update: July 21 2017
Time: 00:35 BST
Instrument: 130mm f/5 Newtonian, aka ‘Plotina’
Seeing: Excellent (I); very clear before midnight. Some cloud moved in after midnight.
Comments: Still in Wigtown. Third night where conditions have been excellent.
Some very tricky systems resolved once again this evening with this modest telescope. Textbook perfect results!
Update: April 4 2018
The Astronomers Without Borders, One Sky Newtonian thread has now exceeded 300,000 hits!