First Light and Star Testing: Ostara 102ED Refractor

[Stratis]

Ostara 102ED

First Light + STAR TEST Update!

Finally the clouds cleared for about 30 minutes tonight and I was out like a shot with the new scope. The fast-moving cloud made it tricky to get reliable tests and cut short the high-mag component, but good views were had and conclusions hinted at. Please forgive the poor image quality, these were taken with my mobile phone flash camera but as it's near-impossible to show the results of these tests without making it an imaging run I thought it would be better to show off how well the monochrome colour schemes match

Mounting and Setup

This scope has the easiest setup I've run through since the ST80, easier in some respects as the tube rings are very much more solid on this scope and the focuser can rotate to match the orientation. Total setup time was under 5 minutes from opening the flight case to first light, MUCH faster than my SCT and actually even faster than some of my smaller scopes due to the minimal faffing around with accessories. A sharp eye will notice the lack of a finderscope, I simply didn't find one necessary with the HEQ-5's excellent GOTO. Five minutes and here we are;

The scope is totally at home on the HEQ-5, barely stressing it at all (as the single counterweight attests) and leaving plenty of weight available for imaging equipment. Even with a heavy (~1kg) DSLR and autoguider you will have loads of payload remaining. I am planning to start imaging on my Canon D5 Mk II weighing in at 900g, so it's nice to know I've got the spare weight; I was able to lift the scope and HEQ-5 mount together and with some effort carry the whole lot up a narrow flight of stairs single-handed.

There is no flexure, no balance shifting and no unwanted rotation even when slewing both motors at maximum rate. Slewing with focus way out with the 2" diagonal and EP loaded up yielded zero focus shift or focuser rotation; even the dew shield didn't move a milimetre. Mechanically, the entire scope may as well be carved out of solid onyx.

Star-field Testing: Astigmatism/Spherical Aberration

The gap in the clouds visibly shrinking around the patch of clear sky overhead, the first test had to be the field curvature and optical quality assessment. Popping the HEQ-5 into Rate 6 and panning across the familiar lanes of the Milky Way revealed, without hyperbole, the single finest view of the sky I have ever witnessed. I very nearly fell off the observing stool at the clarity, the sharpness of focus, the colour reproduction on the pinpricks falling through the view of the Ostara 32mm SWA bundled EP. I could make out close doubles I didn't even know the name of while panning at Rate 6, faint asterisms jumped out of the starfield with an enthusiasm unknown to my Schmidt or Maksutov. The ST80 produces a similar view, but is awash with colour, distortion and has an odd colour cast compared to the bang-on neutral white pouring down the Ostara tube. Simply stunning.

Paying close attention to stars at the edge of the EP, a minor curvature is apparent and the ghost of astigmatism at the absolute field edge; swapping for a 2" Meade 30mm QX yielded MUCH worse distortion with 'seagull' stars near the field edge but brighter, sharper images on-axis. Overall I'd support Ostara's claim that these scopes are hand-finished in the UK before sale by OpticalHardware, the field was flat, bright and optically flawless from a visual standpoint. A Ronchi test may reveal some minor undercorrection and the field was not perfectly flat edge-to-edge; a Field Flattener might be a good idea if professional imaging is in the cards.

DSO Testing: Light Grasp/Transmission

Traditionally a borderline case for the 102mm class of refractors, DSO performance tends to lean on optical quality and transmission as aperture is obviously not available. At f/7 image brightness should fall slightly against the f/5.9 APO crowd; CA shouldn't be an issue for any refractor on these dim objects, instead we are simply looking to pick the faint fuzzies out of the background sky. This is traditionally the province of big Newts and SCTs, but we may estimate the performance of the frac as an AP platform. Lens shielding and baffling also play a large role here, as even a hint of stray light can cost us a whole viewing magnitude and the ace card that refractors bring to the table is contrast.

The HEQ-5 GOTO was given a list of common and uncommon Messiers to go hunting for with the widefield Ostara EP;

• M13: The classic target was easily visible, with a broad structure and sparkling core. Individual stars did barely resolve at 32mm and I have no doubt a Barlow would reveal fine detail.
  
• M31: Heaving nicely into view, Andromeda and companions glowed a soft pearl blue, with a trace of circular structure and unlike my SCT, a smoothly defined luminance gradient to velvet-black.
  
• M71: A lesser-known Mag 8, this cluster came into view surprisingly easily but with little detail at this low magnification as a dirty grey snowball
  
• M101: The Pinwheel Galaxy can be tough to resolve and today very little was on offer; averted vision revealed something, but no shape or structure came through the high-altitude cloud layer
  
• M27: A hard target for any small-aperture scope, the Dumbell proved too faint for the misty sky to reveal; only a grey smudge. Worsening conditions called a halt to this stage of testing.
  
• C14: The famous double cluster was briefly rendered for a few seconds before the orange sky-sludge overtook it; both clusters easily visible, well worth a look next clear sky night.
  

The general result of this trial was that the 102mm can faithfully reproduce the performance of my 127 Mak and then some, beating the MCT handily on image quality, focal accuracy and contrast. Having viewed through the 102mm I do not look forward to a return to the cramped FoV and somewhat blurred image of the Maksutov... I never felt the Mak had any optical problems at all before today, but cannot deny that the 102mm beats it on this small selection of DSOs. With reach down to Mag 10 visually under light-polluted and weather-ridden skies, the 102ED is a great choice for deep sky logging if not for actual visual detail viewing which remains the province of big-aperture. Good, maybe even great, but ultimately bound by the laws of physics.

Star Testing: Optical Figure/Chromatic Aberration

The clouds gathering for a final push, I resolved to get at least one round of decent star testing, only to find my 1.25" EP set was not in the bag.... spectacular. Oh well, time to improvise. While CA testing is best done at high mag (in fact a 4mm EP will reveal colour fringes in almost any APO), the results of lower-mag EPs are still relevant if observed with a carefully positioned eye.

1-Star aligning on Vega gave solid, accurate tracking while numerous EPs were swapped in and out; results below.

• 2" Ostara 32mm SWA (Bundled)
  Vega was a beautiful, pin-sharp diamond in focus, I do not think I've ever seen this star so stunningly defined in any of the ten scopes I've used. Out of focus either side we see concentric, well-defined diffraction rings with deep dark interference fringes between; zero detectable CA either side of focus, the defocused star is like a puddle of pure white light.
  
• 2" Meade QX 30mm UWA
  This premium EP boasts greater transmission on-axis than the Ostara, but again shows no CA. Diffraction rings are slightly less defined in this EP, presumably owing to its greater FoV. The Ostara has therefore acquitted itself well again such well-known competition, and if I am honest I would trade the wider field of the QX for the sharper star-images of the Ostara any day. Bravo.
  
• 1.25" Reticle EP (22mm)
  Lacking the time to run back to the house and clouds closing in, I threw in the only other EP I had to hand, the 22mm reticle from the finderscope. This too showed a glorious ink-black sky where clouds did not pollute the colour-free image. Vega showed no discernable CA out of focus, inside focus the glimmer of a violet fringe began to present but honestly a technicality
  

At this point the clouds called time before I could get a 15mm or a 10mm in the scope, this test I'll relay as soon as it can be done.

Basic report of this test; no visible CA and a notably 'pure white' star image both in and out of focus; 22mm yielded the barest hint of a violet tinge to Vega, but no red fringing of any kind has presented at any time. Furthermore, all diffraction rings were beautifully round and symmetric out of the box, and much more crisply defined than in my (optically very good) C9.25. Each star point looked like a tiny perfectly white raindrop, not the blaze of colour I see in achromats.

The question has been raised if this is a 'true APO' or not... from these results I have to conclude a firm YES. I will conduct further tests and post as many images as I can over the coming months, but from first light I can attest to my complete satisfaction with the scope and fittings. I can't see any troubles on the horizon with using this as an astrophotography base, and if an enterprising individual can pick up the OTA for a three-digit price I'd say it was definitely worth the money.

Clear skies to all!

~Paul

[lardy]

Very nice and comprehensive report Paul.

Enjoy that Ostara

Regards

Mark

[astrokoma]

Thank you for your star test review.

After many OTA's, i became a refractor observer and i believe that if you try a premium refractor, there is no return...

[PARTY MARTY]

That's brilliant review Stratis!

Again after reading on your findings, I compared similar results with my TS 115 Triplet, and my were very similar results I've built confidence on my new Triplet now!

And thanks for hard work and time to but this review and star test together, this review as built a strong case that you can find cheaper alternatives which are out there in the market, ok not all well branded scopes, but will offer good quality views and performance for the money. Ok not all Apo's are good but that's the problem finding the right Apo is like find fine art. They are vary the same and performance. But paying a lot of money for an Triplet is not even 1700 euros but that's nothing compared to similar very high quality one which costs around 2600 euros, stil I felt that I was taking a big risk and thought that I've made the wrong choice. But imaging with my triplet she's produce some staggering images, which again stop my doubt once again!!!

Now I love my triplet and she give my years of enjoyment of viewing and imaging pleasure!!

[Nibor]

Paul, Many thanks for the "first light" - seems like you have got yourself a really great scope!!

[John]

Sounds a cracking scope Paul

I will be interested to hear how it does when you use some higher magnifications.

[Newfie]

Great review Paul here's hoping for a long clear sky to enjoy your new scope.

[Stratis]

Ostara 102ED

High-Mag and Torture Test Update!

So, hot on the heels of last night came another brief 2hr window of clear sky and I pounced on it. This session gave me a full raft of Messiers to add to my kill list, a new appreciation for the wonders of 2" EPs and quartz diagonals, and the final verdict on this controversially-named 'ED' refractor. Is it an achro? Is it an APO?? No! It's..... sort of between the two (although MUCH closer to an APO...). Read on!

Setup and Viewing

This time I was determined to get the star test right, although having four times longer under the sky certainly helped. I came prepared with a full range of 1.25" EPs... although as you will find out, even this turned out not to be enough at first. I installed my premium Revelation Quartz Dielectric diagonal as it was a chilly night and quartz holds wavefront integrity better than glass does in the cold, I wanted to eliminate all possibility of interference. Scope cooldown was about ten minutes, the tube was ice-cold to the touch by this time which firmly beats the 30-40min cooldown of my SCT, which will display visible tube currents when defocused. This was my first run with the supplied finderscope attached also, and I found it to be a splendid little instrument with bright views and a well-defined (but not intrusive) illuminated crosshair. The helical focuser was rock solid, didn't shift a millimetre without permission.

Tonight's viewing was a bit of a Messier Marathon, hemmed in as I am by three houses, a line of trees and a streetlight . The scope did well down to Mag 12 under fairly poor seeing before it began to struggle, darker skies would have helped immensely but the star testing took priority this time so clouds were present by the time I got around to the faint fuzzies. The missed objects I spent time searching for manually and simply couldn't locate; all were located in the NE/E quadrant of sky which generally has both haze and light pollution in it from my location.

Hits: M13, M92, M103, M31/32, M34, M52, M39, M29, M27, M71, M56, M57, M15, M2, M51, Double Cluster (for the girlfriend )

Misses: M72, M110, M76, M33

Overall this scope makes light work of DSOs in the M catalogue, most Caldwell objects will demand a dark site however and a number will simply lie beyond its capabilities. I found myself barely using the finderscope, popping in the 32mm 2" gave enough clear field of view to starhop without leaving the eyepiece.

High-Mag Star Test

So in continuation of the original star test, I aimed at Vega and threw in the Celestron E-lux 25mm Plossl; no CA, no nothing really just perfect sharp views. I love this eyepiece by the way, well done to Celestron for making it a bundled piece. FoV isn't the best, but what you can see is sharp and bright. Next step down for me is my 15mm SkyWatcher UWA; this EP can stress some faster scopes as it starts picking up spherical aberration but nothing of the sort visible here. Now; the in-focus image of Vega did show a ghost of violet at 48x and when defocused the barest fringe was visible. There certainly IS colour in this scope, but we may have to go hunting for it.

At this point I am actually OUT of high-power EPs; I do most of my high-power observing with an f/10 SCT that needs little boosting to achieve high mag. A short EP has been on my shopping list for a long time, unfortunately I can't decide which to go for (if anyone can point out a good planetary EP please let me know!) so the position remains unfilled. At this point I can confirm that there is colour, but not enough to call. Slewing to Deneb yielded no CA whatsoever, off to Albireo and same story, no CA.... but dammit I'm out here and it's cold and I am finding some colour!

Torture Testing the Ostara

I had a think, out there in the dark; what do I have in the cupboard that would ruin any scope's day? What pieces of optical gubbins can magnify CA and lay it bare for all the world to see? How many of them can we use on top of one another to really [removed word] up the image coming out of this otherwise fine and innocent telescope? Well, three things in my kit bag came to mind....

And here they are, the Three Horsemen of the Telescopalypse.... cheap single-element Barlow, 10mm Modified-Achromat EP, and Revelation Binoviewer.

All three of these items rarely leave the kitbag except on special occasions, and none of them are recommended for use in a refracting telescope of any kind outside of controlled situations. So let's review the terrible trio and see what effect they have on Vega's colour.

First up the Barlow.... my god is this a thing of ruin and despair. This wretched single-element plastic-lensed catastrophe was thrown into an order for free by UK Hobby Stores as an 'apology' for delaying an order, which to me is like apologising for keying your car by torching it and leaving it in a field. This hateful lens ruins the view in whatever configuration you dare employ it, it even introduces colour into my SCT somehow. Jupiter becomes a pale orange featureless disc and double stars look like eggs frying in a pan. HORRIBLE.

Next, the amusingly titled 'Super 10' modified-achromat from SkyWatcher. Now to be fair this is a bundled EP with a lot of SW scopes and it isn't exactly awful in a Cassegraine or Newtonian.... but in a refractor, CA appears in abundance. My ST80 cannot bear this eyepiece as you might imagine, Jupiter gains an in-focus colour flare twice the diameter of the planet itself like some awful 360-degree Santa's Beard. It's not bad as a starter for lunar viewing but falls apart in other roles.

Finally, an odd choice. What could possibly be wrong with a binoviewer? Surely they are a well-respected addition to anyone's setup for perceiving planetary details and brighter DSOs? Well, as the image clearly shows, lurking inside these things are...

...prisms, the worst thing for magnifying CA! A prism adds further diffraction to the system and will enhance any fringing that is present; this is a highly controversial point I know, but in my experience it holds true. I rarely attempt binoviewing with a non-CT optical system.

Worst Case CA Results

So Vega lined up and tracking, let's start torturing this poor thing;

• 10mm Achromat EP
  Amazingly, the scope bore this bump up to a 72x achromat very well, I have minimal CA to report here. Extrafocal image did show a faint violet fringe, but intrafocal remained pure and in-focus was lovely. Oh well... a trip to Albireo and then Alcor showed clean separation with no fringe even in this cheap glass.
  
• 10mm EP + 3x Barlow
  Hah, my god I HATE this Barlow why do I even keep it around. Boosted to around 214x the star image is awash with violet at the extremity and green fringing within, the same effect it has on my SCT but admittedly magnified by the inherent CA of the scope. Here, for the first time, we can say we have verifiable aberration, the image in-focus is affected although still star-shaped and quite sharp. The addition of the cheap plastic element brings this scope back into line with a medium-fast achromat.
  
• EP + Barlow + Bino
  Ok we're really cooking on gas now. The addition of multiple refracting surfaces produces a hideous, unfocusable mess that barely resembles a star at any focus. Green and violet flares predominate with an oddly diffracted central mass; dark concentric fringes inside brightly coloured frills like some exotic blossom. Finally we have defeated the 102ED! The useful result of this test is to define the CA spectrum of the scope, hard violet and green, no red is visible even at this extreme so I can only conclude the coatings are working hard to exclude it from the system or there is further optimisation at longer wavelengths with this design.
  

Final Thoughts

Ok so it wasn't the most scientific test, if anyone wants to loan me a super-short eyepiece I'll be delighted to give it a whirl. What I have determined is that at medium powers we do begin to see a hint of chroma, this is not something you'd expect out of a fluorite lens so we can definitely conclude that Ostara have not produced some sort of TV-killing superscope. It is what it is, a reasonably fast ED doublet, and suffers slightly for it. This said, even at 72x in a cheap EP the aberration is invisible while in focus and, sincerely now, fails to affect the image produced in any meaningful way. This lands it head and shoulders above any refractor I'd previously used; the ST80 is a forgone conclusion, but even a slow achromat like the Celestron SLT 102 shows a lot more sparkling colour even at low powers.

If anyone has a short EP under 10mm they would consent to give me, lend me or sell me for a few bits of silver I'd love to hear from you.

Overall, this scope is a keeper, at a time when I am actually selling off five scopes simultaneously. It doesn't meet the standards set by the big-brand APOs like TeleVue and Vixen, but it sets a new standard for a three-digit fast refractor both in build quality and in image colour. The vestigial CA could be completely eliminated with a Fringe Killer or even a simple light Minus-Violet; a chap I spoke to yesterday had viewed through a 152 achro and had pushed the boat out for a Baader Semi-APO filter and relayed that it didn't really clean the image that much even when stacked with a minus-V; I am confident only minor filtering would be necessary to bring this scope's upper power limit into line.

Thanks all!

~Paul

[John]

Another interesting report Paul. The colour correction of your scope seems to match what you might expect from a nice ED doublet of that aperture, ie: for visual use, completely acceptable and no consequence whatsoever. The high power options you were using were not of the best optical quality (as I'm sure you realise) and might well have been bringing aberrations of their own to the party !

If you really want to get rid of CA then a reflector is the way to go of course !

[Stratis]

Another interesting report Paul. The colour correction of your scope seems to match what you might expect from a nice ED doublet of that aperture, ie: for visual use, completely acceptable and no consequence whatsoever. The high power options you were using were not of the best optical quality (as I'm sure you realise) and might well have been bringing aberrations of their own to the party !

If you really want to get rid of CA then a reflector is the way to go of course !

Well we shall see if this scope serves as an AP platform, at the levels of CA so far detected I see no issue with prime focus with a Canon 5D.

I have the SCT for short-exposure planetary work, anything too bright to properly resolve at high-mag in the ED I'll fall back to the big CAT. My only issue with the CAT is finding a guide camera.

[Stratis]

An update for the curious; seems this scope has been on SGL under other guises before, mostly sourced through Ian King Imaging who don't seem to offer the scope any longer. They do offer a 102mm in the same body but it is a triplet for three times the price!

This scope has appeared reviewed and unboxed (minus all the accessories I got) under the 'Ikharus' brand; here and here, I like my photos better though . Both owners seem very happy with their scopes, noting as I did that it is basically an Orion/Megrez but with a super-solid 3" focuser that almost any serious AP setup demands and thus seriously good value. The Ikharus version included a field flattener as well, something I've been keeping an eye out for.

I bring it up for this reason; one of the threads includes some imaging done with this scope! I trust I shan't be flogged for linking without permission but I can't resist...

All credit naturally goes to the original photographer but the first thing I have to say.... how flat is this field?? Would this image be taking advantage of a flattener or not? The original accreditation simply states the telescope itself and makes no mention of a flattener.... either way, an image I can only aspire to at the moment but here's hoping!

[Stratis]

I have one more update to add here, and some interesting information to pass along.

Since taking ownership of this scope, the lack of detailed information regarding the glass used has bothered me, as has the apparent variability of the brand names involved. Some investigation has yielded that the tube design is the handiwork of Altair Astro, but the focuser and lens cell can be interchanged quite freely. The Altair Astro branding of this scope is 'StarWave' and includes Ohara FPL-51 glass and a custom-engineered 3" focuser for which Altair are directly responsible. The Ostara/Ikharos brand as sold via OpticalHardware and (formerly) Ian King Imaging comes with the 2" focuser shown previously and an as-yet unknown ED lens glass.

Having spoken to both Nick at Altair and a nice chap at OpticalHardware I can confirm that the Ostara/Ikharos branded ones, despite their inferior focuser, actually use 'FPL-53 equivalent glass'; the actual FPL-53 reference number can only refer to Ohara glass which these brands do not include, but strictly speaking ED glass is rated by the Abbe value rather than which company churns it out. Further questioning reveals Hoya HKD-61 as a likely candidate, sporting an Abbe value between that of FPL-51 and FPL-53; an interesting point as it would put this scope well in the true APO range as my earlier testing did suggest.

Now with a clear night, a full moon and a Jupiter on the rise I felt it was a good final test of the Ostara 102ED on the brightest objects in the sky.... 

Jupiter

Stunning view of the gas giant at all the mags I have, it even Barlowed reasonably well (remember that cheap plastic-lens Barlow? Yeah.... still rocking it...) without colour of any kind. I had to blink a few times to reassure myself it wasn't my imagination, but up to 180x this scope gave fantastic views with cloud bands visible even in a 32mm Plossl. Interestingly these no-brand 32mm Plossls showed colour when no other EP did, demonstrating that they are not properly corrected EPs; these EPs gave me broad-spectrum 'rainbow' smearing when Jupiter reached the field edge, so clearly cannot be as a result of the scope (which would not show such a range of wavelengths even in an achromat...) and were not seen in any other EP. Those 32mm EPs are up for replacement then

In general, a perfect score on Jupiter, no halo, no fringes, no loss of contrast on planetary detail and I felt I was limited only by altitude and seeing quality. Aside from fluorite and 5-element designs, I can't see any reasonable improvement in the view that could be wrung out of 4" of aperture. 

Luna

Ok I thought, the brightest full moon of the year high up in a clear sky.... the moon was so bright tonight I could read my engraved EP lettering without a light. Turning the scope onto Luna I was genuinely shocked at the clarity and whiteness of what I saw.... light years beyond my ST80. The slightest violet hint was found at 10mm but only when I moved my eye around like a lunatic looking for it; the disc itself was the finest view I've ever had, so contrasted and crisp. I could count craters at 40x, and observe craters within them at 100x with a contrast and accuracy of shade unknown to my SCT or Newtonian. It's times like this that I am humbled by the availability of this sort of optical perfection to the average backyard astronomer, and I don't think I had truly appreciated the scope until the moment that glorious powder-white disc hove into view. With the exception of the 32mm producing field-edge lateral colour again (SO throwing these out.... ) on the lunar limb, all my EPs gave memorable views exceeding any scope I've ever used.

This scope is a true apochromat and I challenge anyone to prove conclusively otherwise.... other than a slight undercorrection in the blue region (Altair Astro tell me this is actually a deliberate design choice to improve visual performance at the expense of photographic.... they have an unreleased 'phototropic' design which corrects blue better but red less well). The lunar disc was near perfect edge-to-edge unfiltered and at its fully refulgent brightness at ideal elevation. It doesn't get any better than that.

This concludes my testing and evaluation of this scope, hope it's been reasonably helpful for everyone! I was recently contacted by an SGL member asking if he should shell out the £900 for the Premium package and a I had to advise against it as that sort of money can net you a used TeleVue, but if you can grab this for under £700 I can guarantee you won't be disappointed.

All the best, clear skies, good hunting.

~Paul

[John]

Nice report Paul 

I have to say though that, for visual observing the Skywatcher ED100 offers comparable viewing though for a lot less than £700 on the used market. That one uses an Ohara FPL-53 element too  

[Clockwork_Orange]

Hi Paul

Thanks for taking the time and effort to produce this in depth review. I'd been watching your results with great interest as I've been on the look out for an Apo. I did manage to find a Megrez 72 on ABS which I'm very pleased with.

Regards

John

[Stratis]

Nice report Paul 

I have to say though that, for visual observing the Skywatcher ED100 offers comparable viewing though for a lot less than £700 on the used market. That one uses an Ohara FPL-53 element too  

Ahh now this was an interesting question to me too.

The SW ED100 was a contender for my cash, until I began to compare the dimensions and characteristics. Physically the SkyWatcher tube is significantly longer and heavier, more like an achro, the Ostara feels a very great deal more solid, as well as more portable and easier to handle in the shorter length. The lockable, rotatable dual-speed Crayford on the Ostara is also a nice bonus. When you can get the 3" focuser version from Altair for nearly the same price with Planostar flattener, it seems a bit better value.

Optically they are great scopes with CA entirely under control so no worries there, but the ED100 is after all an f/9 scope. Even with the matched FLR it only gets down to f/7.2, slower than the Ostara/Ikharos is natively; applying the same FLR/flattener to the Ostara gets you f/5.6 which is solid DSLR imaging territory. While of course you can image at longer f/ratios (SCT owners will testify to this) it's a fact that faster is faster, and as long as edge sharpness is retained there's little disadvantage. Barlowing the ED100 gives you (in the typical 2x case) a challenging f/19, the same in the Ostara a more managable f/14. 

For visual use the SW is brilliant, but for dual-use photovisual I'm a lot more comfortable at f/7 native 

I may sound like I'm singing the praises a bit, no offense intended to the thousands of happy ED100 owners out there, but the extra couple of hundred do get you a more compact and versatile product 

[John]

No offense taken here Paul

I'm not an imager but I understand why a faster scope than F/9 is needed for that pursuit. I moved from the ED100 to my Vixen ED102SS which is a more compact and lightweight scope at F/6.5, to get wider field views but I guess it would also be a more suitable for imaging than the ED100 was.

Thanks for posting the in depth feedback on your 102 ED - it will be very useful for prospective purchasers   

[Nibor]

Paul,

Thank you for an interesting and informative review on the Ostara - I shall keep tabs on this thread should funds become available for an upgrade of my Orion ED80 !!!