Dream Eyepiece Collection - At Last !

[Ben Ritchie]

That's almost exactly the line-up i'm working towards, for much the same reasons (including a move to a 16" Dob at some point).

The 6E will be really nice for high-power lunar/planetary, although if you have servocat then you could have some smaller-TFOV (and less expensive!) options instead as the constant nudge-nudge-nudge of an undriven Dob isn't an issue. The missing option here looks to be a 5mm to span the gap between the 6mm and barlowed-6mm for "good but not great" seeing. The 8E + Antares 1.6x/2" barlow would fill that.

Depending on the f/number of your Dob the only issue I can see is the exit pupil of the 31T5 (and overall cost, I guess!). The 31T5 is fine in my f/5, but faster may be an issue. In that case there's some logic to stopping with the 21E, as the true field of view isn't that much less than the big Nagler anyway.

So with my current 12" i'm probably going to have 6, 8, 13E, 31T5 and a 1.6x barlow for higher powers, once I upgrade i'll swap the 31T5 for the 21E.

[calibos]

Hi Ben,

Last night I booted up Starry Night pro + and updated my equipment list with the new scope details, the details of all the Ethos including the ones I probably wont be getting and thus was able to use the FOV indicators to do rough visual comparisons of the TFOV of the Ethos line and my Hyperions in the same scope.

What I gather is that the TFOV of my selections nicely matched a lot of the Hyperions but with the benefit of the 100º AFOV spacewalk factor and the Higher mag/higer contrast 'Majesty' factor. So for instance, a 100º 21mm Ethos gave almost an identical TFOV to the 68º 32mm Hyperion but with the spacewalk effect and the much darker sky background because of the higher mag.

I also found that with all the proposed Ethos FOV indicators turned on, there was a nice graduation of TFOV down through the focal lengths with them obviously bunching up a bit at the high mag end. So in terms of DSO viewing, when I turned on the 17mm and 10mm indicators, they seemed to fill gaps that didn't need to be filled.

However, I've been looking at the mag spread again. Although the 10mm isn't really needed because I don't see a FOV gap for DSO viewing, in terms of Lunar and Planetary, I do kind of see a MAG gap between the 13E and 8E and the 8E and 6E.

I know the Ethos TFOV is moot at Planetary mags and especially so in a driven dob, however the Spacewalk effect is still a plus as are the well corrected optics. I know I could get more specialist planetary Ep's and there are compromises with a 'do it all' Ep like the Ethos but I actually would prefer a minimal Ep collection despite high cost per EP and with some compromises. ie I'd prefer 5 or so multi purpose Ep's with minimal swapping in and out of components in the optical train than 10 or 15 specialist EP's with lots of swapping of this adapter or that and with lots of thought needed to decide which of the 10 or 15 Ep's is the perfect EP to use for the job at hand.

I've been looking at the Paracorr settings for the different Ethos and Nagler too. I think I read that there are adapters that can be used so that even the 1.25" Ethos can be used in the paracorr in 2" mode without the 2-1.25" adapter while maintaining their optimum Paracorr setting. The oprimum settings for my selection seem to be setting 4 and 5. This to me would be perfect. Leaving the paracorr in the focuser permanently. Not having to remember a load of different paracorr settings, not having to swap in and out the 2-1.25" adapter all the time and crucially, the possibility of being able to use the Supreme Barlow element on the 10E,8E &6E even with the paracorr in place. Obviously this is predicated on the height of the end of the 1.25" barrels above the paracorr lense at settings 4 & 5 and the length the Supreme barlow element adds to the ends of the 1.25" barrels.

So John, could you tell me how 'Tall' is the Supreme Barlow element?

And Ben, in terms of the 31mm Nagler. My SNP+ FOV tests showed a worthwhile jump in TFOV from the 21mm Ethos. Would I be correct that Exit Pupil = EP FL / Scope FR. The FL of the scope is 1828mm. With the Paracorr changing the FL by a factor of 1.15x, the new FL is 2102mm. If so the Focal Ratio of the scope with the Paracorr in place is 2102/406 = F 5.17. Thus the Exit pupil of the 31mm Nagler would be 31/5.17 = 5.99mm. Thats within the acceptable range isn't it?

So the re-appraisal last night would be:

Paracorr permanently residing in focuser giving the scope an effective FL of 2102mm

DSO Magnifications:

• 31mm Nagler - 68x
  
• 21mm Ethos - 100x
  
• 13mm Ethos - 161x
  
• 10mm Ethos - 210x
  

Planetary and Lunar Magnifications

• 10mm Ethos - 210x
  
• 8mm Ethos - 262x
  
• 6.6mm Ethos - 318x (10mm/1.5x Element)
  
• 6mm Ethos - 350x
  
• 5.3mm Ethos - 396x (8mm/1.5x Element)
  
• 4mm Ethos - 525x (6mm/1.5x Element)
  

So with the inclusion of the 10mm and assumption that Barlow Element can be used in conjunction with Paracorr, I think I'd have the Minimal EP collection, with the least compromises bar going for specialist Ep's, with the least swapping in and out of Optical/adapter elements, with a nice TFOV spread for DSO's and a nice magnification spread to suit any seeing for Lunar and Planetary.

[johninderby]

The AC710 barlow element adds 20mm. When I had the Paracorr I found that to use the barlow element with it a standard 1.25" to 2" adaptor was needed.

If you had the 13E you could leave the 8E out as the 13E+barlow would be 8.6mm.

John

[Ben Ritchie]

At f/5 or more the exit pupil on the 31T5 is fine - i'm extremely happy with it in my f/5 Dob, awesome widefield eyepiece.

It's only at faster speeds that the exit pupil becomes problematic - at that point the 21E makes sense as a 'lowest power' eyepiece as there isn't really a sensible alternative for max-TFOV (neither the 21T5 Nagler or 28mm UWAN offer significant TFOV gains, the 31T5 does but the exit pupil becomes significant).

[John]

What I gather is that the TFOV of my selections nicely matched a lot of the Hyperions but with the benefit of the 100º AFOV spacewalk factor and the Higher mag/higer contrast 'Majesty' factor.....

Don't get too hung up on the "spacewalk" and "Majesy" stuff - that was just Tele Vue's advertising hype

I love my Ethos and Naglers but I really think the above terms are OTT - they provide very nice, sharp views that are wider than most other eyepieces ...... but are not life changing items !.

John

[calibos]

John, I forgot to bracket Spacewalk like I did with Majesty. Don't worry, I am under no illusions. I am sure I will be very pleased with the Ethos and Nagler but do not expect them to totally 'Rock My World' I'm well used to being cynical of the hype about anything. Apeture is actually one of those things. I had heard that a 20" Premium dob would 'blow away' a 12" Chinese Dob. When I actually got a chance to compare I was definately not blown away. It'd probably take a 25"+ to blow me away. A 20" Premium is already exponentially more expensive than a Chinese 12 or 16" dob as is the weight and size increase without the commensurate Wow factor for me. A 25", more again, and the WOW I would get just doesn't seem worth it. I've resolved to max out in apeture at 16" with Chinese scope and optics. Thats why I am spending a fair bit on accessories, because this scope is my 'Keeper'. I've resigned myself to the fact that the real WOW views will only come rarely when I grab a peek through someone elses big Dob at starparties.

My rationale with the EP's was a bit different. I found myself in broad agreement with TakMan(Damiens) musings in his recent Ethos thread. I want a minimal EP set and a set that will be 'for life'. The Ethos line, though expensive has the least compromises for what I need them to do and how I want them to fit into my set-up.

So no, I am not believing the hype. I bracketed majesty and intended to bracket Spacewalk to hightlight those terms so people knew the benefits I liked were the darker sky background for a given TFOV and the wide wide AFOV where the scope almost disappears, but using the shorthand of the Televue terms for those optical effects, hyperbolic as they might be.

[albedo0.39]

Keith, both Mick (Doc) and I got to spend a lot of time under good skies with a 13mm Ethos [many thanks for Owen] and the LB's and yes, the FOV is huuugggeeee but (and for me it's a big but...) the effect was not always entirely pleasant. I felt (as did others around our scopes as the time) that the observing experience was marred somewhat by having to move your entire head to see the edges of the field.

Now, I freely admit that this is a feature of the EP that a lot of people crave, but it left me a little cold. Of course, the stars were pin sharp to the edge (as well they should be) but there wasn't the life changing experience I had so wanted.

By way of contrast, when I plugged in the Skywatcher Nirvana / William Optics UWA Clone (less than half the price but "only" 82degree FOV) I felt that the view was much more comfortable - and importantly just as sharp at the edges. [thanks for Steve & James at FLO for lending this to us].

In no way can I criticise the Ethos, it's a stunner and if I had the ££ I might well buy the entire set, but now having spent a couple of unpressured hours working one would certainly think hard about justifying the expense when the Skywatcher Nirvana / Explore Scientific are both in the frame at a fraction of the price.

Have you considered any of these EP's ?

[Doc]

I would have to agree here.

The Ethos that Steve and I looked through showed fanntastic sharpness and contrast. And from what I could see no coma through almost the whole FOV. But I found myself moving my eyes continually around trying to envelope the whole field of view. I could not spend the whole night doing this.

[calibos]

Many thanks for your thoughts my LB16 brothers

I read your Salisbury postings a few days ago. Initially I thought you guys were not WOWed by the Ethos because you didn't feel it was worth the price premium over the cheaper but also well corrected 82º EP's you got a chance to look through.

I now see its more of a comfort thing. What you describe seems to be one of the main reasons why a lot of people who don't like the Ethos went back to 82º and even 68º EP's. People who wanted to see the Field stops, or felt they should see it couldn't help but look around. I can understand why this would be tiresome. However, there is also a significant amount of people who also initially didn't like this EP for those same reasons and whom had thought they had made a mistake in buying the EP. Eventually though they trained themselves to just look straight ahead and resist the urge to look around and just let themselves be enveloped by the spacewalk effect with stars to the periphery of their vision. Only occasionally looking to the extremes of the FOV when they noticed something interesting in their peripheral vision, whereupon they would centre the interesting object and resume looking straight ahead at the new object.

Like I said to John, I am under no illusions about the Spacewalk or Majesty factor hype, nor am I unaware of the fact that there is a significant percentage of Astronomers that just don't find this EP comfortable to use. Don't worry, I won't be jumping into the Ethos Pool with both feet... arms..torso and head first I'll probably buy the 13E on its own to try it out and only if I find it comfortable and worth the expense will I invest in the rest of my proposed collection. Unfortunately, I don't know of any guys on our Irish Astro forum that have an Ethos never mind any guys in our regional observing group. I'll have no choice but to buy one sight unseen. At least these EP's hold their value very well, so if I don't like it I won't lose too much on my little experiment.

[calibos]

Another Quick Question for JohnInDerby.

What effect did the barlow element have on the Paracorr setting as opposed to the setting without the barlow in place. ie did the barlow element require you to raise the adjustable top of the paracorr or lower it in relation to Televues recommended setting. Lowering might be a bit of a problem on the 10E & 13E because in 1.25" mode their recommended Paracorr setting is already at the lowest setting of 5.

That said, I believe I have read that although there are ideal settings for each EP, that these are to achieve maximum coma reduction, but that there is significant worthwhile coma reduction at any setting. After all, the Paracorr Mark I had no adjustable top at all.

In terms of enabling hassle free swapping in and out of 2" and 1.25" Ethos and keeping in mind the necessity of using a 2-1.25" adapter especially with the barlow element in place, I think the easiest and cheapest solution for me will be to purchase some accurate, excellently made, attractive Moonlite Compression Ring 2-1.25" adapters for each of the 1.25" Ethos. Instead of the compression ring Thumbscrew, I will get Ron at moonlite to supply flush fitting headless hex screws,(Ron uses these screws on his focusers anyway so should have the correct size at hand) so as to permanently affix the adapters to each 1.25" Ethos while allowing them to sit flush in the paracorr with proper registration. These are very reasonably priced at about €20 each.

While the top surface of these Moonlite adapters is about 5mm thinner than the Paracorr adapters head, I think I should still be OK. If the barlow element requires the paracorr head to be raised from its recommended setting, they thinner adapter head will probably mean going one setting further. If the barlow element requires the paracorr setting being lowered, well then the thinner head of the moonlite adapter probably accomplishes this without changing the paracorr head setting at all.

I'll be able to test and work out the best setting regardless using Televues instructions and I think I am OK in terms of the barlow element not hitting the paracorr lense. I attached an identical Moonlite adapter to those I propose to a 1.25" Hyperion, inserted in the paracorr at its lowest setting of 5 and reckon I still have about 5mm to play with even after taking account of a 20mm barlow element attached to the 1.25" EP barrel.

[TakMan]

I'll probably buy the 13E on its own to try it out and only if I find it comfortable and worth the expense will I invest in the rest of my proposed collection. Unfortunately, I don't know of any guys on our Irish Astro forum t

'Calibos', I think the 13mm Ethos is a great first eyepiece for you and think you'll be smitten! (that was my first also). The quality is fantastic and Televue obviously knew what they were doing when this was the first to be released.

You're correct in thinking that if you should not be pleased, that at least you can recoup a good percentage of the cost if you sell it on... My advice would be to wait 'till Telescope House do another 10% off, and before VAT and inflation go up next year...! It all helps... I've seen 13mms going second hand on UK Astro Buy and Sell for £310-330.

Perhaps having such a wide field just takes time to learn, or perhaps I'm not bothered in trying to find the edge.... i just enjoy the sharp views - fading out to my peripheral vision, without some sharp edge (ie the scope) - as we see normally in our day-to-day lives. If I should glimpse something at the edge (and my appetite of what I'm viewing has been sated), than I'll 'move the scope' to that!!!!

I just can't understand this idea that 'unless you can see the edges of the view' you won't be comfortable.....? Surely the whole point of a wide field eyepiece is (be that 82º or whatever), is so that the scope disappears and it's just you floating around the stars (unless you think that you may be prone to motion sickness - I know some mates who get this when playing first person shooters...)

Lets just think about that statement for a second....

I spend £7 (and upwards these days) on going to the cinema, and rather than sitting in the middle so that my view is fully encompassed with the on-screen action, I'll take an edge seat so that I can see the end of the screen... or

I'm off on the Switzerland Glacier Express train... and rather than sit slap bang in the middle of the panoramic window, I'll let someone else take the seat and sit at the window edge.... yeh, right...!

Or perhaps I spend my days trying to squeeze my eyeballs to the far edges of their sockets so that I can see the edge of my face because I'm not comfortable with the field of view that my two eyes give me.....

You can see where I'm coming from...

Damian

[johninderby]

I never actually used the barlow element with the Paracorr as I got the MPCC just after I got the barlow and had only checked to see if the barlow element would clear when used with the Paracorr and sold the Paracorr before I had the chance to test it.

I agree with the previous post. You don't have to try and take in the entire FOV when looking through the ETHOS. Just look straight through and then if something catches you eye off to one side just look over in that direction. To me it's more natural and more like normal vision without a telescope as if you see something out of the corner of your eye you just naturally look in that direction to see what it is.

John

[calibos]

The Cinema analogy is a good one and ironically is used by those on both sides of the arguement.

Those on the other side will say that 'rare is the person whw likes sitting right up the front where one has to scan from one side of the screen to the other the whole night if one wants to take in the whole view. ie they liken the Ethos to sitting up front at the cinema. If one keeps the analogy going, plossls and up to 68º Ep's is akin to sitting near the back.

To my mind, the analogy is good except where they imagine the Ethos sits in the cinema. From what I have read they Ethos sits in the middle of the auditorium which funnily enough is where the THX certification scheme says is the best place to sit in the auditorium. Maximising the screen size so it stretches into your periperal vision, but not requiring you to scan left and right just to take in whats happening in the outer thirds of the screen like you would sitting at the front. For the rare times when something happens right at the edge of the screen, one only has to turn the head slightly. You don't have to turn your head at all if you sit at the back with your Plossl or 68º but now you know you are sitting in a Cinema watching a big screen and aren't as enveloped by the action on the screen with the sense that you are in a Cinema auditorium disappearing.

So the Ethos isn't about sitting up front at the cinema, its about sitting in the middle.

[TakMan]

You got it - and unlike the cinema experience the 'action' in the eyepiece is pretty much static so you can focus on a particular area of interest, that is you don't have objects coming into/going out of the action for you to need to scan quickly to catch it!

If you should feel that the view is too close (like sitting at the front of the cinema - not good), then you'll need to 'pull back a bit' - that's what the 17/21mm Ethos are for!!!

Surely the whole point of such an eyepiece is for the field stop to disappear and the object you're looking at to be 'framed' by the incomprehensible vastness of space, not a man made parameter...?

The other great experience I've found in looking through a wide field eyepiece is the fact you have more chance of seeing a satellite or meteor pass by due to the extra percentage of sky that such an eyepiece affords... and that's when you realise it was worth paying that 'bit extra'.

When I'm out viewing, I think the best way to describe it, is to think of sticking your head through an imaginary membrane that separates us from the void of space... your head pops through, and as your eyes come to focus, all you can see is a mass of stars and blackness as far as you eyes can see with no 'black frame' to break that immersion.

I don't know if you're into gaming(?), but a 'black border/edge' while viewing to me is the same as a cut-screen coming in and breaking the action whilst gaming - it breaks the immersion and disbelief.....

Best of luck with your decision!

Regards,

Damian

[TakMan]

What I wanted to add was:

The Cinema analogy used by the critics breaks down due to the fact that the 'cinema screen' of the universe is all encompassing (think IMAX).

The eyepiece need only be wide and corrected enough to encompass the widest human vision so as not to break the concentration/engagement/captivation.

There, argument won - now go and buy the thing!

Damian

[Ben Ritchie]

The "is the Ethos worth it" debate has been going on for aeons on CN (at least, it feels like it) so we're not going to resolve it here - but suffice to say the Ethos only really makes sense if you value extremely wide apparant fields of view. Sure, the optics in the Ethos are excellent too, but i'd offer the subjective view that the Pentax XW is better optically, if only slightly, and comes at a considerably lower (but far from cheap) price. The UWAN and Skywatcher UWAN-clone clearly offer a much better price/performance ratio for an ultrawide, albeit at with lower-AFOV and less-good (but very respectable) optics. The ES100 range also looks like delivering a better value-for-money ultra-ultrawide too.

Personally, I like the field stop to disappear into peripheral vision but can easily see it in 82-degree AFOV eyepieces, so the extra field of the Ethos is worth it to me - but that's a very personal thing. Unlike the ES they're readily available now, and mine are used (but mint) so - rightly or wrongly - the strength of the TeleVue brand means I can sell out at cost if I need to. So works for me.

[calibos]

We're not bashing Mick or Steves POV either. Their impressions of the EP are valid too. I may find I will ultimately be of the same opinion and thats why I am only going to purchase one Ethos first but I am going to give it a trial period of a few weeks to see if I enjoy the immersive abberation free AFOV and if I can control the urge to keep scanning around the EP for the field stop.

[Doc]

We're not bashing Mick or Steves POV either. Their impressions of the EP are valid too. I may find I will ultimately be of the same opinion and thats why I am only going to purchase one Ethos first but I am going to give it a trial period of a few weeks to see if I enjoy the immersive abberation free AFOV and if I can control the urge to keep scanning around the EP for the field stop.

We only tried the Ethos for a couple of hours so maybe having the eyepiece for a few weeks our view would change.

[johninderby]

I think that one factor that is often left out of these discussions is the differences in peoples vision. What is the best eyepiece for one person may not be for someone else. Nearsightedness or farsightedness, astigmatism etc. may mean that one eyepiece design is uncomfortable for them to use and so a supposedly inferior design may actually work better for them.

I suppose you could say that "No one eyepiece fits all".

John

[Macavity]

I think it interesting that Mr. N has decided to use the rather venerable series 8, 13, (17) 21mm. But I imagine that the Vixen LVW series (and albeit less obviously) the Lanthanum series were based on some... "Golden Ratio", as being the most suitable for a (~50 deg) eyepiece series? I do sense some of AN's "plugging the gap" etc., might be overkill. <G> Indeed, eve I may yet e.g. "prune" my Hyperion set, around the rather amply-filled 17 - 24 mm region.

And, should I ever decide (be able!) to buy an Ethos 8mm, it could effectively replace both my 13 and 17mm Hyperions. The 21mm Ethos could then replace any (circa) 21mm Hype, which would then render redundant a rather mottly collection of 30-something mm eyepieces. So... "job's gooddun" with but TWO eyepieces! But I'm sure it doesn't work like that... Or Teleview might need a better business model?

But, perhaps the debate is another version of (a perennial) "intuitive" versus "scientific". <G> And, coming from either extreme can only be reconciled with AGE (LOL). Me? I'm reassured by field stops! I am more intrigued by the rectilinear versus angular distortion stuff. For some reason, pin-cushion distortion has always driven me MAD. <G> I might eventually ditch e.g. my 31mm "Aspheric" for a "Teleview", if I could be sufficiently confident re. an exclusively astro purpose. (And anyway owned better scopes!)

[John]

I think that one factor that is often left out of these discussions is the differences in peoples vision. What is the best eyepiece for one person may not be for someone else. Nearsightedness or farsightedness, astigmatism etc. may mean that one eyepiece design is uncomfortable for them to use and so a supposedly inferior design may actually work better for them.

I suppose you could say that "No one eyepiece fits all".

John

John - having tried loads of different eyepieces over the years and read loads of reviews and opinions on eyepieces this is the conclusion that I've come to as well

What suits one person won't be right for another - this goes for cost as well as the eyepiece characteristics.

It's just as well there are so many choices available

John

[Doc]

Correct John but the flip side to this is because there is so many choices it's very hard for one person to try all eyepieces to make a valid choice.

[The Warthog]

That is a fabulous collection, in all senses of the word! Hey, why am I drooling?

[Rossco72]

John,

Silly question really, but how did you cut out all those perfect spaces to keep the EP's in? I've been looking at one of these cases myself.

Cheers

Stuart

[Doc]

John,

Silly question really, but how did you cut out all those perfect spaces to keep the EP's in? I've been looking at one of these cases myself.

Cheers

Stuart

The B&W cases come with pre cut pluck foam. You just pluck out the shape you need.