Tele Vue Delos 10mm

[Qualia]

Tele Vue: Delos 10mm

AFOV: 72º

FL: 10mm

Eye-Relief: 20mm

Barrel: 1.25"

Weight: 408g

Length: more or less between 125mm - 140mm

As soon as I looked through the Delos eyepiece, Saturn jumped onto my face. The breath whooshed out from my body and everything froze for a split second, as though the world and the ringed planet had come to some silent agreement and they paused for that tiny span of time of absolute wonderment.

It was a fabulous effect, Saturn had been captured perfectly and for the following evenings I searched for that moment time and time again. Saturn was always going to be unbelievable and drew gasps from myself and non-observing girlfriend and even at this lowish magnification many subtle atmospheric bandings were clearly noticeable as were the six faint moons; tiny spheres of dimly sparkling light, beautifully contrasted in the eyepiece’s night of black velvet.

Using the Delos as a backdrop against which to explore the joys and complexities of the past was turning out to be a joy. Under the stars, under the canopy of dark skies, it is a great eyepiece with which to understand and celebrate what matters to us in this hobby. On anything I decided to view the image was always outstanding, skipping from object to object there were nights when I didn’t need to bring out another eyepiece. Deep space is incredible and the Delos is perfect for detailing the matted starlight and glittering sphere of suns within many globular clusters, especially at this time of year around Hercules, Bootes and Coma Berenices, the dark background and wide-field only enhancing the globulars' brightness.

In comparison with the 9mm Baader Genuine Ortho the difference was surprising. In the 10” f/5, the BGO 9mm has been the most used, the most celebrated and revered eyepiece whose outstanding performance on globular clusters, galaxies, planets and the Moon had driven me to buy the 10mm Delos in the first place. Image quality in both eyepieces is as sharp and crisp as it is going to get, yet I found the Delos offering a more neutral, significantly brighter and aesthetically pleasing view. The difference in AFOV and glass is simply staggering. During normal viewing, there came the stage where the Delos just disappeared, no longer peering through a peep hole but out of window on the side of some space craft.

Galaxies in Virgo and Coma Berenices were a real telescopic treat, well defined stellar patches of soft light that with concentration often revealed more of their inner secrets. Beginning a tour at M 61, I began galaxy hopping, field of view by field of view along a cosmic stream of galaxies with their dense cores of billions and billions of stars. M 88 took on a faint, spiral affect while the bright M 104 was elongated, punctuated by a soft, stellar core appearing to be - but not clearly separated at this magnification of 125x - at the edge of a dark lane.

This week the evenings have had the company of the waxing, waning and full-moon which brightened up the night sky and I figured would make quite a challenging condition for the Delos. Framed adequately within the AFOV, the eyepiece brought out sharp and crisp details across the entire Moon’s surface, giving it a three dimensional quality. As the Moon slowly drifted by it felt as if you were orbiting close above its surface. There was neither aberration nor flare and once out of sight, there was no evidence that the Moon was lurking just outside the FOV – except for the sky being brighter. The quality here was as good as any branded Ortho I’ve looked through.

And even though the heart and mind are probably the true lens of stargazing, evening after evening, aberrations on any object was zero as far as I could tell, no curvatures, no astigmatism, nothing. The Delos 10mm is a medium power, wide-field show-piece where objects can slowly drift from one side of the FOV to the other without a hint of distortion or loss of resolution. Every object was just as perfect at the field stop as it was when on axis in the centre; no flare, no scattering of light, no ghosting, no elongation of stars at the edges.

Physically, the Delos 10mm is large. It offers a 72º FOV, weighs in at about 408 grams and is about 140mm long when fully extended. Eye-relief is exceptionally comfortable at 20mm and the eye-lens is huge, giving a sense of augmented immersion while observing, especially after being accustomed to 40 to 60 degree eyepieces.

As would be expected the Delos’ build quality and attention to detail is exquisite. At an angle in the light, the coatings give off a kind of purplish-burgundy frac like tint and peering into the eyepiece itself reveals complete darkness. The sliding mechanism is a technical wonder which is used to find your own exact eye-relief comfort. It seems to be essentially a metallic sleeve with locking rings incorporated to prevent any slipping but even when loose the eyepiece remains firmly in place until you physically slide it. There’s even an engraved scale to mentally note where you like the eyepiece’s position and if you decide you can lock the rings and everything remains solid. These rings also double as a nice grip when handling the EP, even when wearing gloves.

There is something quite pleasant about having engraved green lettering in your eyepiece case, but as with all new technical wonders, it might be necessary to practice a while with the Delos until it becomes the perfect instrument for observation. Although there is certainly no kidney-beaning, at first, at odd moments, I found there was blackout which simply highlighted my own inexperience when dealing with an eyepiece of this type but with practice and careful adjustment of the eye-relief mechanism everything was righted in no time and whether you wear glasses or not, you will more than likely find your own eye-relief position that perfectly tunes itself to your own personal sweet spot for viewing.

The Delos 10mm, then, is a majestic wide-field. It has excellent sharpness, outstanding eye-relief and is a beautifully built, high-contrast, ghost-free, flat-field, eyepiece. It is simply a joy to handle and optically superior to anything else I have ever used. However, there is one significant problem with an eyepiece like the Delos. Once used you cannot ever go back to the night before you owned one, because you were a different person then, and like Alice, you’ve gone through a looking glass and have entered a new world of visual wonder, opened up a celestial window onto the universe from which you can never return.

[John]

What a write up !!!

I do understand your sentiments about "no going back"

[Naemeth]

I know the fault, albeit a small one!

It's too heavy for the focuser on my scope! (At least that thought can save me a lot of money, for now at least!)

Great read and write up Qualia, I'm sure there is a fault (well, not really fault, more like small flaw or something that isn't as good as it could be) somewhere, there must be!....

[alan potts]

Very nice report and somewhat better written than mine I feel, this could be love.

Alan

[DirkSteele]

Excellent review and could not agree more. Delos EPs are starting to fill my EP case and I find I rarely use anything else at this point.

[Stu]

Carry it safely Alan :-). Not long now, bet your suitcase is heavy!!!

Stu

[Stargazer_00]

Brilliant write up mate. You blend the cold facts and the warm emotions very well. It's clear that these sorts of purchases as much about seeking technical and optical perfection as they are about stirring those inner feelings of joy and a sense of wonderment. You are on the "slippery slope" now, and what a ride it's going to be!

[Damo636]

Fabulous report Qualia!! I suspect anyone on the fence about purchasing one of these has now hit the "Add to basket" button!

[michael.h.f.wilkinson]

Very good write up. I am definitely tempted to get a Delos or two to fill the gap in my XW planetary range. An 8 and a 6 seem the best candidates (and the 14 perhaps to replace the 12mm T4?)

[Qualia]

Thank you all for your kind and supportive comments. I realise it was not exactly the most 'objective' and critical review out there but I hope it offers some kind of insight into the eyepiece. As Stargazer susgests these purchases do indeed stir 'inner feelings' and it is probably the heart and mind which is the true lens being reviewed here.

At the moment I can't really find anything not to like about the Delos but when making a purchase of this kind I would strongly suggest using the eyepiece in person, something I just couldn't do here in Spain (I couldn't find any outlet selling them).

Other than that, for you guys in the UK with FLO, you're probably going to get a better deal with the Pentax XW 10mm. Out here the Pentax is a fair bit more expensive and I figured that if it has taken Tele Vue a decade to catch-up with that kind of eyepiece, at least they're going to make it on par.

As Naemeth has voiced, weight is also a consideration. With just under half a kilo of eyepiece on your dob, it may nosedove unless correctly balanced or counter weighted. In my own case, nothing happens until I put the truss-dob at an angle of around 20º and below and then there is a slight, gradual movement downwards. To counter this, if I really do need to be working around the horizon, I do nothing more than slide off the 9x50 viewfinder. Obviously, when used with the frac along with the AZ-4 or CG-5, weight is not an issue and even when drawing the Tal to the hoizon, there isn't too much fear that the focusser is going to slip.

Another feeling I have on this is that Tele Vue and Pentax are probably producing the same quality in all their eyepieces and when compared, differences will be very slight at the most. As such, I feel the similarities are greater than the differences and any differences there are will be just a case of emphasis; wider-field Vs eye-relief etc.

Finally, as much as the jump was between using a 4" frac and then a 10" newt, by analogy so too with using second-division EPs and then jumping to the premier league. But, I wonder if that difference would have been so noticeable if I had gone from a 4" to 5" frac, or from an 8" to a 10" newt and by analogy from an ES 82º to a TV. I really don't know what I'm talking about here, but I get this gut-feeling from reading reviews and the forums that the difference may be only very slight and noticeable under the best of atmospheric conditions.

Once again, thank you to all

[John]

I think the differences at this level are slight but, if you can, there is satisfaction, and a degree of confidence perhaps, in being able to use the best there is, or at least the best that is readily available. As someone said in another thread, "your only live once"

From all the reports I've read the Delos and Pentax XW's are very, very closely matched in all aspects. As Michael says, you can build a fantastic eyepiece set that will last a lifetime in all manner of scopes with them.

[swamp thing]

What a great write up. Thanks for sharing your thoughts

I, (like you by the sound of it) want kit to just "get out the way" and let me get on with observing. This is what truly great kit does IMO.

After all eyepieces, scopes etc are just tools to do a job. I don't wanna be fiddling with tools I wanna be doing the job.

The more a scope/eyepiece combo allows me to do this, the happier it makes me.

[Stargazer_00]

For me the two big attractions of the Delos range, and the reason I intend to get a few, is the comfort of their use and the orthoscopic quality of the view.

I am also attracted to the 72 degrees AFOV. I think a slightly narrower FOV than the 82s will be a little more comfortable too. I appreciate its all personal preference. Comfort is very important to me.

also, and this is a bit odd maybe, when I held a Delos in a shop I was simply amazed at the size of the eyeglass end. It really was a stark contrast to the 15-18mm on the ES eyepieces. Something about a giant eye glass end is really appealling to me. I'm definitely going to get a 10mm Delos I think, and probably an 8, 12mm too. I dont intend to sell off the ESs as they would offer a slightly different string to the bow.

[Qualia]

Yes, that's it John and exactly how I feel about it. We only live once and if there is the opportunity to use the best on what we love and value and to gain that peace of mind and confidence, then it makes sense to go for it.

The real shame I feel here - and this is mainly directed at Stargazer - is that we physically can't all get together and share our gear for the night. I think it would help a lot, and perhaps avoid us making mistakes - if we do. My only suggestion - and you would know this already - is before buying and whilst you're saving, is perhaps to work out what EP focal length you use more often than any other. In my own case, with the f/5, I was too often jumping from 25mm plossl straight down to the BGO 9mm. I found this was giving me the best views on globs, galaxies, given nebulae etc and was the reason I went for the 10mm over something like a 14mm for my first purchase.

In my own case, I figure I only need 3 EPs with a focal length of 10mm and longer to cover what I like to be doing, but the next tricky installment to building a small but decent kit is to work out what should be the next purchase. It is my b/day soon and my girlfriend has asked me what I fancy and I can't decide if it should be a Delos or Nagler around the 13mm to 14mm range or something like a Panoptic 24mm.

Steve, thank you for your kind words and I fully appreciate that sentiment of gear 'getting out of the way'. It really does add to viewer comfort and enjoyment.

[Stargazer_00]

It would be great to meet and compare kit, it really would. I know I would benefit alot from actually trying some of these products in my own scopes. If we had more clear skies you could do a sort of try before you commit buy buying eyepieces and then send them back if you aren't happy (and some retailers are fine with this practice anyway) but we cant rely on the weather to provide a vgood night of viewing inside the accepted 7 days of distance selling anyway.

I know you're in Spain which makes things harder perhaps but I'm certainly planning on going to SGL9 next year and will be taking the 14" dob I hope to have by then and every eyepiece I own at that point which should be all the ESs I have now plus whatever TV/Pentax/other eyepiece I have accumlated in the mean time. I'd be more than happy to let people there use my eyepieces in their scopes to get a feel for what they deliver.

Hope to see you there if you can make it, and all the other guys in here who regularly chat about this facet of the hobby

[Bart]

I have accumulated the ES 82*s and a couple of ES 100*s. I've told myself I can hang up my Eyepiece buying boots for a long time. I should really stick my fingers in my ears and stop reading TV related threads as it creates an element of curiosity and a feeling I could get an 'even better' view, albeit small I reckon. Not having looked through a TV makes it worse as you wonder what it would be like. One thing I wonder about is having had the 100* experience and enjoyed it, would I be happy going back to 72*. While everyone raves about the TV experience, I must tell myself to leave them alone for the moment at least. On the other hand I can understand the feeling that while looking through the TVs, you can feel content that it can't get much better, as someone previously said, and there is merit in that.

Don't know what I'm trying to say here really!

Enjoy the new eyepiece, lets hope we all get a few more clear nights to appreciate them.

Barry

[alan potts]

Bart,

I have already said what a great write up this is, I think my English teacher, and yes I did have one would have called this a piece of Prose. I will give you an example of Televue, and I don't know if anyone else has seen this as well but I am sure this is down to the EP and nothing else. I am open to the real reason if there is one.

My F 10 SC was out a little, it needed a touch of collimation which it got and after all was well with both eyepieces. What I saw was the Meade 40mm SWA, a very good eyepieces, showed stars that were distroted at the egdes getting worse as you got nearer to the very edge. The Pananoptic showed nothing just sharp stars. After collimation all was fine.

Anyone have an explanation for that other than a better eyepiece.

Alan.

[John]

Anyone have an explanation for that other than a better eyepiece.

Alan.

Alan,

All Tele Vue eyepieces have a small pixie living inside them who's job it is to correct the optical flaws in the host scope before the image reaches your eye ball.

50% of the cost of the eyepiece covers a lifetime contract with the Pixie.

If you listen carefully to your eyepiece case in the early hours you can sometimes hear the Pixies arguing with each other.

But I'm sure you knew that

[Stargazer_00]

TeleVue products come from discworld?

[Moonshane]

I thought you'd like it. reading between the lines I get the sense you are slightly happy? it's subtle but it's there

[alan potts]

John,

That makes me happy, I will bring you some extra clear sky. You can tell I am off tomorrow the seeing is awful here tonight, too hot.

The story about the two eyepieces is absolutely true I was able to double up on it when I had the 34mm SWA and the 35mm Panoptic for a short while they showed the same.iI am off back out to see my 9mm pixie.

Alan

[RikM]

Lovely writeup The 10mm Delos is still the only one of that range that I have used but it was very nice indeed. I compared it with my 10mm XW over a few nights in a few different scopes from ST80 to 250PX and the view was, to my eyes, almost indistinguishable.

[ramstar]

I asked you guys last week to leave bragging up these eyepieces and now look what you've done! Anymore nonsense like this and I'll have to send the boys round for a quiet word! You have been warned!

Seriously, you have at the very least made me re-think my current buying strategy. My interests at the moment are as simple as seeing what I can see - so far mainly planets, the moon and open clusters. I have a 32mm Panaview, 24mm ES82 & x2 FE arriving this week, Bst 5mm and a newly acquired 6mm BGO. On backorder I have 2 Es82 at 6.7mm & 14mm. Should I be tempted to cancel these and invest in either the Pentax or Delos 10mm? What would you do in my position - more cash upfront but with the eps on order am I duplicating what I have?but he

[swamp thing]

1367264708[/url'>' post='1918205']

I asked you guys last week to leave bragging up these eyepieces and now look what you've done! Anymore nonsense like this and I'll have to send the boys round for a quiet word! You have been warned!

Seriously, you have at the very least made me re-think my current buying strategy. My interests at the moment are as simple as seeing what I can see - so far mainly planets, the moon and open clusters. I have a 32mm Panaview, 24mm ES82 & x2 FE arriving this week, Bst 5mm and a newly acquired 6mm BGO. On backorder I have 2 Es82 at 6.7mm & 14mm. Should I be tempted to cancel these and invest in either the Pentax or Delos 10mm? What would you do in my position - more cash upfront but with the eps on order am I duplicating what I have?but he

Blimey! You've more eyepieces than me

My advice, whoah! Buying kit isn't a race. Take your time. You don't need to have all the gear straight away. Take some time to appraise the gear you've already bought before ordering any more. This will also give you a better idea for yourself on which direction you wanna go eyepiece wise.

[Qualia]

I have a 32mm Panaview, 24mm ES82 & x2 FE arriving this week, Bst 5mm and a newly acquired 6mm BGO. On backorder I have 2 Es82 at 6.7mm & 14mm. Should I be tempted to cancel these and invest in either the Pentax or Delos 10mm? What would you do in my position - more cash upfront but with the eps on order am I duplicating what I have?

I'd say premium eyepieces is never a waste of money, especially if you buy them used. These EPs might even become 'lifers', so you never have to upgrade again or you could always re-sell them without losing much - if any - money, especially if you buy them already secondhand. Premium eyepieces, then, generally hold their value more than cheaper ones.

Again, for whatever the reason, many of us start out buying new and cheaper-end stuff but soon arrives a day when we want to upgrade, we jump a level, spend some more cash, are quite happy with what we have, but then soon enough comes another day when we want to itch-that-itch and try one of these Tele Vues or Pentaxes that everyone-else-but-me is raving about.

So logically and with the bias of hindsight, we could just skip this whole process, tell ourselves that buying premium is never a waste of money and go straight into buying EPs that are worth more than our telescope.

But I feel that although a rather rational proposition in itself, it is perhaps not one entirely suited to stargazing. Let me try and explain.

Imagine someone setting out on a guitar with a year of practice under their belt, they could now just as well buy themselves a Les Paul, SG or top-range Ibenez, for after all, buying premium is never a waste of money. But what at that stage do they feel they were lacking? Do they think they are going to be playing better? That learning is going to become easier? Or that they will now achieve that magical tone that makes folk sit up and listen?

And by analogy, I feel the same can be said in stargazing. That is, one ought not to upgrade on anything in astronomy until one knows they are missing out on something that is essential to their observing sessions and just as importantly when one knows how it can be improved upon and bettered.

I feel this is exactly the same argument Swamp Thing is saying. Take your time, appraise and praise your gear and then you'll have a better idea of where you want to go and how exactly you want to get there.

In terms of practicality, you've got a lovely 8" f/5 and your EPs are going to offer you quite a range. If I were you, I'd start using a little journal, or mental notes on what you like viewing and with what EP. For each EP, I'd also jot down what magnification and exit pupil it offers.

By way of example, my own journal has a good number of observations on exit pupil (EP's focal length / telescope’s f/ratio) which conclude:

• 6mm - 4mm - nice wide field, handy for star hopping, really nice for star fields and large open clusters
  
• 4mm to 3mm - good on star-fields.
  
• 2.5mm to 1.5mm - nice for most DSOs and general planetary viewing.
  
• 1.6mm to 1mm - nice contrast and resolution on planets, Moon and globs.
  
• 1mm to 0.5mm – possible finer detail on planets tweaked, Moon work, tight doubles split.
  
• 0.4mm – not any occasion to justify an assessment.
  

In terms of my 10" f/5, we're talking general magnifications between:

• 40x - 60x
  
• 60x - 85x
  
• 90x - 170x
  
• 150x - 250x
  
• 250x – 500x
  
• 625x
  

And in terms of EP focal length for a 10” f/5, we’re looking at:

• 30mm to 20mm
  
• 20mm to 15mm
  
• 14mm to 7mm
  
• 8mm to 5mm
  
• 5mm and less
  
• 2mm
  

In practical, everyday terms, on most evenings I'm not pushing 200x. I may - on occasion - use 250x for the Moon and Saturn, but not on anything else. In fact, I have never observed over 250x on anything. I’m not saying it isn’t possible, it’s just that I haven’t had cause to do so, and probably will never buy an EP at this focal length unless one comes up cheap.

From this pattern, a number of observations can be made:

Personally, I only need one decent long focal length EP which offers a good AFOV, something around the 50x mark and with something like 1.3º AFOV. And that really small focal lengths are not going to be used that much.

However, the range of possibility between 2.5mm to 1.5mm exit pupil is huge. What looks relatively tiny in terms of exit pupil is in fact a wide range of magnification dependent on the given object being observed, the atmospheric conditions, and so on. That tiny 1mm covers most DSOs and a good general level of planetary viewing.

From this, I worked out that if I took my telescope's aperture, say, the 250mm, and divided it by 2 , I ended up with 125. If I looked at that in terms of magnification I would require a 10mm EP. I then divided that 10mm by my scope's focal ratio and ended up with an exit pupil of 2mm. This I figured would be the general work-horse for the 10".

To put that idea into practice, I just kept playing about with a 9mm and a 12mm. Night after night after night until I was certain this was what I now required. It is really just a happy twist of fate, then, that I have the Delos 10mm, for after all, if I was doing this just a couple of years ago, it could well have been a Nagler 11mm, for example, or Pentax. The reason that I went for a 10mm rather than a 11mm was that I prefered the views offered by the 9mm than the 12mm and was using the 9mm a whole lot more.

From this reasoning, I figure little steps could now be made on a 1.3 or 1.4 ratio.

So, for example, from the hypothetical 125x mag, or 10mm workhorse EP, I'd divide the mag or multiply EP's focal length by 1.3 and 1.4. So, I end up with 96x to 89x, or an EP of around 13mm to 14mm, or an exit pupil of between 2.6mm to 2.8mm. This is my next project, saving for this kind of EP.

With a 2x Barlow which I think you own (I don't get along well with them), that would give a useful range of magnifications: 90x, 125x, 180x, and 250x (weather and atmospheric conditions permitting). Sure, there is room for improvement but you get an idea of what is possible with just 2 EPs and the supplied 25mm for star hopping. So, as you can appreciate, so long as planets or close Lunar inspection isn't you thing (in my own case it is), a lot of folk really don't need so much gear.

I'm not sure if this helps, but I feel the numbers offered do help getting a general gist of what is possible and some kind of map to work around. Being a fast scope, I'd stick with good quality plossls and orthos, and slowly work out what you love observing and what EPs you reach for more often. In the end, I figure you'll notice a pattern, and may, like me, conclude you're not really using all your EPs with the same percentage of time or enthusiasm.

On a personal account, I ended up selling all my EPs except the BGOs, Tal and TV plossls and bought myself into my first premium EP. I figure, following the pattern of observation sessions, I only need two more and I'm more or less done.....for now