Delos v Nagler

[FaithJ]

I am looking to replace my 15mm and 11mm Televue Plossls, and one or all of my 8mm, 5mm and 3mm Radians, with either Naglers or the new Deloses. I am using an 18" f/4.3 Dob, currently without a Paracorr (but I am looking to get a Paracorr some time). What I am aiming to do is probably replace all 5 eyepieces with just two or three new ones.

Would you go for Nagler or Delos? Ethos eyepieces are beyond my price range, at the moment, each one costing twice as much as a Delos.

[Adrian R.]

Faith,
The Deloi, and well as the Ethoi, are the next evolutionary step in eyepiece design. Having said that, they completely outperform all Nagler eyepieces, especially in areas of contrast, sharpness, and most importantly, (for me anyway) neutral color balance. Their uncanny, really..The shorter focal length Ethoi routinely outperform longer focal length Naglers on planetary subjects rendering a sharper, more contrasty view of which, seems to buck common logic that increased magnifications lead to softer images due to primarily atmospheric conditions. Stars are truly white, not off white..planetary color and hue is far more detectable. Deep sky objects are sharper/well defined, and the background sky is BLACK..allowing you to see faint color in DSOs. The Deloi is essentially a more affordable Ethos with a smaller field, and greater eye relief and imo, and from preliminary testing of one Delos eyepiece, even FURTHER outperforms an Ethos EP in areas of contrast and sharpness.

If you can live with the smaller field, yet appreciate the longer eyerelief, and greater performance in areas aforementioned..by all means pick up a few Deloi..they are fantastic!

[Don Pensack]

Faith,
Having done field comparisons, I agree with Adrian. The Delos eyepieces, if you can afford them, would be "lifetime" eyepieces. You now will have 17.3, 10, and 6mm to pick among. Alvin Huey, a consummate observer, says they even slightly outperform the Ethos eyepieces when it comes to seeing faint targets.
Whereas there are other characteristics of eyepieces that are as important as the pure ability to see faint targets, that certainly speaks highly of them.
Add to that the fact you will almost never have to clean them because you will never get close enough to the eye lens to accidentally brush your eyelashes on the lens, and they would appear to be the nearly ideal eyepiece type. [For me, a little narrow of field, but compared to your mentioned eyepieces, quite wide of field].
You will also find that, as I did, as the eyepiece field gets wider, you don't have to do as much changing of eyepieces to frame the objects. An eyepiece that has a high enough power to examine the object also has a wide enough field to find it. I've often said to friends I observe with that I could be reasonably happy with just one eyepiece--the 13 Ethos--for that reason.
As for the Paracorr, since star images at the edges will be essentially the same as in the center when using one, you will be able to identify all sorts of faint targets at or near the edge of the field that you now have to bring to the center to identify. Close double stars look like doubles at the edge instead of small planetary nebulae. And very faint stars will be more visible in the outer 50% of the field because they will not be smeared to invisibility. Countering intuition, adding the extra lenses of the Paracorr seemed to make fainter targets easier to see instead of harder. Plus, the Paracorr essentially parfocalizes your eyepieces, which is a convenience. Recommended. But remember, it's the price of an expensive eyepiece, so I can understand the budget issues.

[FaithJ]

Thank you Adrian and Don. :)

[kemer]

I am using an 18" f/4.3 Dob, currently without a Paracorr (but I am looking to get a Paracorr some time). What I am aiming to do is probably replace all 5 eyepieces with just two or three new ones.

I think we convince ourselves that we need those "tack sharp" stars to the edge without considering the job our brains do at integrating the image. I would consider carefully whether you really need the Paracorr, which is expensive, very heavy and awkward, and extra glass. Even at f/4.3. Perhaps this is heresy, but the wide fields available these days are wider than you real can focus on, so that the periphery provides "context," but not detail. The brain fills things in...

I have a f/4.2 18" with which I use 8mm/13mm/and 21mm Ethos. I use a Paracorr on the 8 & 13 only because it balances them with the 21mm and brings them closer to parfocal. I don't use the Paracorr with the 21mm because then I don't have enough inward focus and I don't want to cut my tubes. Nor do I feel the loss, at least with the 100º FOV.

If the Deloi function like the Ethoi, but with the smaller FOV, I'd say they were well worth saving up for. I'm afraid I hardly every use my Naglers anymore.

Kemer
Obsession 18" UC f/4.2
Please, God, give us some clear, dark skies to use it!

[Don Pensack]

It's obvious Kemer is using a Paracorr 1, which is no longer in production. The current, Paracorr II, has greater tunable top adjustability, and all 3 of the Ethos eyepieces he mentions focus at the same point.
Coma is more visible the wider the apparent field of view, so the use of narrower fields (Delos vs. Ethos) may make the Paracorr somewhat optional at f/4.5-f/5, but, shorter than f/4.5, not using one just means you are putting up with less-than-sharp star images.
The coma-free fields of view in telescopes are as follows (remember, 2" = 50.8mm)[.01778mm x f/ratio cubed]:
f/6---3.84mm
f/5---2.22mm
f/4.5---1.62mm
f/4---1.14mm
f/3---0.48mm
Now, coma doesn't spring into being at that point--it's a linear function that grows steadily worse with increasing distance from center. The above figures represent the central areas of the fields of view wherein the comatic image is still smaller than the Airy disc, and so, invisible.
It does point out how little of the field of view of that 21 Ethos (36.2mm field stop) is free from coma in Kemer's f/4.2 scope (1.32mm coma free field).

I like to look around the field of view a lot and see what's there. I don't really appreciate it when the stars in the outer half of the field look like small Perek-Kohoutek planetary nebulae.
The Paracorr is expensive, and certainly adds weight (you need counterweights on a dob anyway, so this is a red herring). Awkward? Not so much. Extra glass? Surely, and it probably causes a loss of 2-3% of the light in the scope, which is a profoundly lesser amount of light loss than occurs with the accumulation of 3 months of dust. And do you clean your mirror every 3 months? [If you saw the statistics, you might]. Probably not. Well, worrying about the light loss in a Paracorr (which I did prior to using one) seems to be one of those things in life not worth worrying about since the fainter stars that became visible in most of the field because the Paracorr was there overcame any objection I may have had over whatever light loss might be there.
A driven scope looking at planets centered in the field of view? Don't need a Paracorr, even at f/4.
A non-driven scope looking at objects bigger than planets? Definitely worth consideration.
Don Pensack
Los Angeles

[rmollise]

Depends on you. I still like my Panoptics, but the Ethoses have somewhat spoiled them for me. Some folks like lots of apparent field, for some it just doesn't matter as much.

[FaithJ]

Thanks for all the input, folks. I'm going to have a look through a Delos or two at TSP next month, thanks to Alvin who's bringing his along, and depending if I like what I see, I might be visiting the vendors... :cool:

[FaithJ]

With the popularity of the Ethos and Delos designs, there are probably plenty of bargains to be had with people replacing their Naglers and Panoptics, etc, so I've ended up buying a couple of second-hand Naglers at TSP. I bought Jimi's 9mm Type 1, and a 12mm Type 4 which was for sale at CCTS's stand at TSP. I liked the Delos EPs very much that Alvin lent me but CCTS had sold out of both the 10mm and 6mm (note to self: in future, get to vendors' on Monday and don't leave it until Wednesday afternoon!).

I tried out both Nagler EPs during TSP and am very pleased with them (I've not had a chance to try them out on my 18" here at home yet, thanks to some unseasonably wet weather). I will still get a Delos in future, probably the 6mm or maybe 4.5 and 3.5mm when these two come out in the Fall.

[bearkite]

Sorry Faith... You can blame me for snagging up those Deloi... :idontknow:

I bought both Monday afternoon. The 10 spent A LOT of time in my scope for the remainder of the week. I can't wait to get the 14. As soon as that happens, both my 13 and 9 T6 Naglers are getting sold off. I'll probably end up with the entire line (with the probable exception of the 17.3).

The reason I'm making the change is two-fold. My favorite EP is my 17mm T4 Nagler. I absolutely love the fact that I see the entire FOV as soon as I put my eye to the EP. I've never had the same views with the T6's or Ethoi. I get that view with the Delos. And that comes down to eye relief. The other reason is contrast. And the Delos definitely out performs the Naglers. That was my first reaction when looking through them. Fantastic contrast. I took them up for Bob Kepple to try on Friday and that was his reaction too. Very dark background...

The reason I won't be doing the 17.3 Delos is I love my 17 Nagler and there just isn't enough of a difference to make me jump. I borrowed the 17.3 from Scott Ewart so I could do an A-B comparison. We chose NGC 4565 as the target and had three sets of eyes doing the test. Robert (Doc) Werkman and I thought the 17.3 gave marginally better views of the dark lane. Josh (Skyraider) Wright thought the 17 Nagler was a little better. There you go... Just not enough of a difference to make the jump. I will say that the 17.3 was noticeably lighter. But that's an 1.25" EP being compared to a BIG 2" EP.

Sorry for buying those up before you had the chance.

I'm blaming the vendors... He should have brought more... :rolleyes:

[FaithJ]

First come, first served, I guess. Still frustrating though. He should have brought more with him and I'm surprised he didn't, if that's the case. Next time I want to buy something at TSP, I will try and remember to email CCTS and ask Jeff if he would bring the item along and keep it to one side. That way, I can be sure of actually getting hold of the item I want to get.
Chalk this one up to experience.

We get totally ripped off for astronomical stuff in the UK (huge mark ups by dealers, 20% sales tax and taxes on shipping, etc, and even worse in other EU countries - a Delos eyepiece, not including the 17.3mm, comes to nearly $500 here) and I'm sick of being ripped off, so I buy my eyepieces when I come to the US. When the fall comes, I'll probably buy a 6mm or 12mm Delos and order it from a US dealer. Even with shipping costs, it will be cheaper than the mark ups that UK dealers put on things.


Anyway, further purchases are going to have to wait for the immediate future, my dog needs some expensive veterinary treatment next week (about the same cost as an Delos UK price!), so that is more important.

[Marko]

Thanks for all the thoughts everyone. I suspect picking up an 8mm Delos then perhaps 13mm Ethos later is how I am leaning at this time from an integration of thoughts on this thread.

[Marko]

My 6mm Delos came to the house this week. I am anxious to give it a shot in the field but a few things stand out and I wonder your thoughts on these characteristics.

1) Looking through it into the light of a room I see significant vignetting without careful eye placement. This is troubesome relative to my 7mm Nagler
2) The glass that is exposed relative to the eye is enormous to say the least. I guess that it is almost required to pull out the protective extenstion in practical use to both help center the eye and protect the glass from eyelash.
3) These things are extremely long. So long that I suspect my current eyepiece case will not be deep enough.

Thanks,
Mark

[rmollise]

The Deloses (I find "Deloi" and "Ethoi" a little precious for this old boy's tastes....LOL) are both good eyepieces. The Deloses are fine--I always loved the Panoptics--but they cannot compare to an Ethos. 100-degrees of heaven I call it. If you are a deep sky observer using any type of telescope, you owe it to yourself to at least consider the Ethoses. OR...look at the Explore Scientific 100s. They are damned near as good and much cheaper. I still like the Naglers, but now find it hard to go back to that dadgum soda straw 82-degree field. :D

[Marko]

Field tested my new eyepiece, Delos 6mm, this last wed. Not very good skies and not my main scope but overall I was impressed so far in my 12" with the way it felt once I adjusted the eye relief. Without that eye relief extended it is very easy to get discouraged with loosing the field but with the extention my point of reference was easy to re-obtain so not so much an issue. Full field was easy to view as it's only 72deg or so. The contrast looked very good but this was a really poor site so I look forward to a nice site for the real 'first dark light'. Am on pre-order for the 8mm along with so many other folks. Above 8 I plan on perhaps a 13mm Ethos at some later date. (Maybe a christmas present to myself? Sounds like a plan!).

My biggest issue that has held me off from these guys is they obsolete my age-old eyepiece case for lack of depth. These are so darn long.

[Marko]

After several months I finally got a real deep sky test of my 6 and 8mm Delo's and 13mm Ethos last night for a cold but excellent experience in deep sky observing. Using a spanky clean mirror in my f/3.7 18" StarMaster in NELM 6.6+ skies at 21.5x sqm skies I had some fun and decided that my 7mm Nagler will now be set aside for the 6mm Delos for galaxy cluster and dim galaxy observing.

Pulled 9 galaxies out of the Ngc2684 group in UMa and 11 out of Agc539 in Orion where some had what I had considered the limiting mag for the above mentioned big dob. It was magical contrast and perhaps ideal exit pupil combined with just cleaned mirror and excellent transparency. Seeing was off at perhaps 3.5-4/5 but if you waited for um, the transparency was excellent. I also used the 6mm Delos for galaxy details on large and 3' scale or larger galaxies and it was also proving to be very capable for that perhaps also due to the great contrast.

The exit pupil would be 6/3.7 or 1.6mm so a sweet spot. After a few swaps but more field tests required I felt that for tiny galaxies in clusters and so on that using the paracorr I gave me better contrast and object discovery ability than without the paracorr. With Paracorr I had 1940mm/6mm or mag of 323. I need to do a more careful comparison here as there is a 15% mag increase but the difference seemed noticable.

My prior favorite eyepiece for this work was 7mm Nagler in Paracorr for 278x so they are not apples to apples. Sometimes I would put in the 5mm Nagler for the tiny galaxy work if the skies could support 389x but often the skies would make the 5mm view a bit soft.

The 8mm Delos was nice as well for mid-sized targets with a field of almost 18' for my scope. I did not use it much last night as results with the 6mm were so pleasing.

The 13mm Ethos was a pleasant experience for sharpless or larger targets and I felt it has great contrast as well but to be honest did not do side by side shootout with my 13mm Nagler. I'll save that for another day. The NPB filter yielded a nice nebula examination filter and again I need a shootout as I felt the contrast on the jellyfish SNR in Gem and the NGC2174 (Sh2-252) was good but did not compare it in a shootout. Perhaps next time out or wait for big star parties in summer where I have more free time than a 'one night stand'

[rmollise]

What's an "Ethoi"?.. Sorry I just don't like those plurals...too much for this good old boy, I reckon. :D
Anyhow...I am always surprised when people say they can't see the whole field of the Ethoses. Never had a problem doing so, nor have any of my buddies. The Delos is a fine eyepiece, but I find it hardly ground breaking. It's an improvment on the Panoptic, which is a fine eyepiece given its restrictive field...but I haven't found much to get excited about.

[Jimi Lowrey]

Rod,

Last year during the TSP I did a A-B comparison of the 13 Ethos and the then new prototype 14 Delos in my 48" F/4. Uncle Al was with me at my observatory at the time of the comparison. What I found out and it was confirmed by several other observers was that you could see fainter stars with the 14 Delos than you could see with the 13 Ethos. From my experience the Delos has better light transmission. But there nothing like the 100 degree field of view of the Ethos. I guess there is no perfect eyepiece for every view. Thats why uncle Al has so much of my money ;)

[Ivan Maly]

Indeed I may be mistaken but I'd think that the Japanese plural for "Honda" would be "Honda". Yet we say "Hondas". So I say "Ethoses".

[bearkite]

Folks...

It's been several months since I've replied on this thread and much has changed since then.

I've since bought in to (almost) the entire Delos line and sold off my 9 and 13 T6N's.

I now own the 14, 12, 10, 8, 6, and 3.5mm Deloi (sorry to Rod et al, that's my plural and I'm sticking to it). By the end of this weekend I will have made the trek to Skies to pick up the 4.5 and will then be selling off my 5 Radian. After a 3-day observing run to Pettigrew, NC I decided that the 5 was just to big of a hole in my line-up and decided it was time for it to go.

First of all, the fact that I've made this investment is a good indication of how I feel about these EPs. I love them. Excellent contrast, excellent eye relief, excellent light transmission and neutral color (and I love the twist-up eye cup). Have been very deep with these guys. This includes the 17.1 mag C member of HCG 14.

In the past my normal MO would have been to scout out the star field of whatever it was that I was looking for using a Nagler (let's say a Hickson Group). After confirming the brighter members and that I was in the correct place, I'd start digging for the fainter members using one of the UO Orthos that I own. After expanding my Delos lineup I've used an Ortho exactly once. It's much more comfortable and I just don't feel the need. I don't miss my T6 Naglers at all. I'll hang on to my 22 and 17 T4's. As I said in an earlier post on this thread, I just don't see the need to replace my 17.

As for the Ethos comparison, I think the Ethos is an extraordinary eyepiece. But for me it's a matter of economics and personal preference. I was able to put together a very granular collection of eyepieces for 40% less (and that's for 7 Deloi versus 6 Ethoi). And the 100* FOV has always been lost on me. I'm one of those guys that just can't see the entire FOV without burying my eye in the cup and looking around. I actually LIKE to see the field stop. I know... I'm weird... That field stop has always helped me focus my attention better. With ultrawide FOVs where the edge of the field is beyond what I can see (like the Ethos and T6/4 Naglers) my attention has always tended to wander. I still think that the images I see in an Ethos (especially the 17 and 13) are gorgeous and wonderful. I fully understand the draw. But my scope time is not usually about the Wow Factor but more about detail and resolution. I'll borrow Josh's and Doc's Ethoi when I'm looking for the Wow shot.

And for those of you looking to compare to Pentax XW's... Sorry, never owned one and have looked through very few so am of no help there.

And Uncle Al... If you're out there listening... I already have a spot in my EP case for a 2.5 Delos as soon as you can get them out there!

[Ivan Maly]

Interesting update, Lou. I imagined the Delos line could be an excellent upgrade to orthoscopics the way you used them. (I remember how you and I observed from Cherry Springs in July 2010... time flies. Say hi to "Doc" from me... We observed from Spruce Knob in September 2008, I believe. Wow, time really flies. Coincidentally, he gave me my first look through an Ethos, at that time only the 13 had come out.)