12mm Delos and 12mm Nagler T4

[alan potts]

12mm Nagler or Delos, which is for you.

The review was taken from two months of observations totaling 14.5 scope hours.

Tele-Vue Delos 12mm

When I talk about the 12mm range of eyepieces with a little less than the massive field offered by the Ethos range it was always going to an eyepiece to use as the top end in the LX 12 inch, mainly for planetary work. I know this is not really anywhere near the theoretical limit of this scope but for my liking it was getting near to it, as a magnification of X 254 can be used most of the time where I observe from. Going higher than this even a 1mm increase on a focal length over 3 meters is a fairly large jump, 10mm eyepieces yielding X304.8. With the 72 degree field of view that the Delos range offers I just felt that it was more of a planetary eyepiece for this scope, though it would of course be used in the other scopes as well.

As far as I can see all Delos eyepieces come in the same boxes with different poly-foam liners and there is nothing you can say about this other than it is perfectly adequate without being over the top and like all Tele-Vue eyepieces it comes with caps at no extra cost. The eyepiece looks and feels very well made as you would expect and weighs in at 385 grams as far as I can tell, so not the sort of eyepiece that will give massive balance problems. It is also fitted with the pull twist and lock type of eye-guard which was new on the Delos range and for me was an improvement on the systems offered on the Radian and Nagler T4 ranges. Though the latter was solid enough for me it was the one and only real failing on the Radians, as I have had two focal lengths from the range that almost drop under their own weight.

Delos is offering a slight improvement in the eye-relief stakes over the T4 with 20mm, enough for our friends who have to wear glasses to observe and the eye lens is almost the size of Yorkshire, an exaggeration of course. All in all a very nice eyepiece that ticks all the right boxes with the possible exception of price though it has come down in price since launch date where it was 295 pounds and now they are around 257, so a little less to find but still expensive and sadly not within everyone’s reach.

Tele-Vue Nagler 12mm T4. Wrapped and ready to go.

Now I have had this eyepiece for a couple of years and it has always been a fine performer, so much so I really wonder why I went and bought the 12mm Delos, maybe just because it was there. The eyepiece comes in the older style of packing which is fine but not as protective as the padding afforded to the Delos and Ethos ranges. The box is well made and the eyepiece simply comes wrapped in a thick plastic bag with eye guide ring and silver sticky label telling everyone you use Tele-Vue Power, really must stick one of the on to my scope just to be a posser.

Being something of a scatter brain I forgot a few things with this test as I had promised the eyepiece to a new owner in Cornwall and he was itching to receive it, I had forgot to photograph it out of it’s box and I forgot to weigh it. The latter on the Tele-Vue’s website is given as 1.1 pounds so heavier than the Delos, though not by much. I still would not have thought this would give major balance worries to Dobsonian users unless it was a smaller scope.

The eyepiece has the same very well made look and feel and also gives a larger field of view than the Delos, all Naglers delivering 82 degrees, it is however a little down on eye-relief at 17.1 mm. I do not believe this is a major worry as I know of a site member that has to where glasses and he speaks very highly of this very eyepiece.

Telescopes

I just conducted this test in the two scopes The 190mm, F 5.26  Sky-Watcher Mak/Newtonian and the Meade 12 inch F 10 AFC

The first scope being my fastest was just to see how they faired with edge distortion or pin-cushion on the Moon mainly, though other targets were viewed and the larger scope where I really only view planets, though I did use a few other double stars just to see how they came over.

Targets.

The Moon

Mercury

Mars

Saturn

Sigma Cass

Vega

Meade 12 inch LX.

Mercury

Now first off I can’t even make a comparison here as the 12 mm Delos had not even arrived but I was so thrilled to see Mercury in the twilight that I just had to talk about it. The power was X254 and the conditions were not wonderful. There was plenty of wobbly atmosphere to look though I could clearly see the little less than half phase, it was the first time I had seen it this well in the evening as I have always reserved this as a rising object as opposed to a setting one primarily due to air turbulence. I guess that this is a planet that will never be seen a great deal better than I had just viewed it, it can never be see against a black sky and the air never has a chance to cool at this time of year. Very much a winter morning object but for the best views I would have to do some work with the chainsaw and knock a neighbours barn down.

Mars,

I started this some time ago and Mars was much brighter then than it is now, it was also closer to us and details could be seen well with a scope of this size. I could see something of the polar cap which gives you some idea how long back we are talking about, with both eyepieces the detail shown was as far as I could see the same when viewed on axis, it was only when you moved the disc to the very edge of the Nagler that I could see a slight deterioration in the quality of the image and I do mean slight. I think it is fair to say that there is no real difference no matter where you view the planet through the Delos this is something I have found with all I own, they are remarkable eyepieces.

The surface detail was never that clear and obvious and I would not like to make a guess as to what I was looking at other than to say it was  triangular in shape this was visible on the first of the nights. There was also grey shading that I detect at the side of the eastern disc as well but this was the same in both eyepieces. The observations were over some time  and of course the planet is turning so things cannot be seen the same each night, add to that I have a very poor knowledge of the Mars surface but the detail that could be seen was the same in both eyepieces. I do not know why but Mars never gets me like Saturn even when it is at opposition.

The only thing that was coming to light between the two was it was slightly more difficult to get the eye position right in the Nagler than the Delos, this could well be why the T4 is provided with a special eye placement guide, though I have never tried or really felt the need for one, there is one provided in case.

Saturn.

This is considered about optimum power for the planet by many and I am not going to argue with that statement. The seeing was not wonderful and was variable on all three nights, it has been a very poor year by Bulgarian standards with less than half the clear nights of last year and even then somewhat turbulent. Saturn was more or less in the same part of the sky as Mars on these nights and if anything Saturn was better placed. With the rings being very full placing the disc at the edges of eyepieces and viewing the Cassini division is a very good test, cruel to lesser eyepieces but a good test to fine ones. Again on axis there was nothing to choose between the two, both seemed to display the same image, this was one for bino viewers for sure. The off axis performance was very good as well, I tried to simulate the edge position of Delos in the Nagler to see if there was any degradation of disc, I have to say it was very hard to call. I spent a good deal of time doing this and I have to conclude that there is a very slight advantage which has to go to the Delos, but this is nothing to really worry ones self about. Moving further out where the Delos could not go things did not get and worse, even placing the planet so that only half of it could be seen I could still see the Cassini gap. I could not detect any edge distortion or aberrations with either of the Tele-Vue’s using planets.

Sigma Cassiopeiae.

A reasonably close double at 3.1 arc seconds with the two components at magnitudes 5 and 7.1, not a stiff test of a 12 inch scope but being low down in the North from here and viewed over a forest I was hoping it would make it more difficult. The funny thing about this was when the goto slewed to it the first time it was still below the tree line so I had to wait for it to rise so to speak. When it did it was an easy split in both eyepieces as the conditions were better that they have been though I had cloud to the South which was putting Mars and Saturn off the menu. I was even able to make a split at the very edge of the Nagler just showing what a good eyepiece this was.

Moon.

The Moon was at my favourite position half illuminated and called first quarter, this quarter and half play on words reminded me of the late Dave Allen’s comedy routine of telling the time, with a quarter being fifteen and one being five minutes, I’m sure he told it better though.

When the Moon is at this juncture there is always plenty to see in the way of craters and the terminator gives you the stark contrast of inky black and creamy white that so many of us enjoy and I believe really brings the best out of some scopes. I started out on a crater that I have not written about before, Miller and a few of its alphabetic followers. With Miller being some 45 miles in diameter and Miller ‘A’ some 23 miles in size, it must been a very dangerous place to have been standing all those years ago. I was also taking in the slowly illuminating edge of Nasireddin, it is sometimes nice to sit and watch the Moon move in relation to the Earth and it is fairly obvious over the course of an hour or so, give it a try. Nearer the centre of the Moon I looked at the old favourite of mine the mountain range of Montes Apenninus, where crater Huygen sits and is only a few miles across, but I could not see it at the moment, maybe the following night if it is clear. ( it wasn’t)

Both eyepieces performed as well as one would expect with no real winner, contrast looked the same both were as sharp as a sharp thing and I could not pick up any edge distortion in the Nagler which I can in some of the others I have. The edge performance is something that Tele-Vue’s website talks about in their advertising, claiming the T4 has improvements in this area. I would not say that I could drive a wedge between them at any point, but on the Moon I did just prefer the Delos, I think it was me trying to justify the spending of 309 Euros on it that was doing this as opposed to anything else.

Vega,

This was just a simple star test using one of the brightest stars in the sky to see if I could detect any aberrations at this power, placing the star at the edge and in the centre. Both handled the test very well, X 254 is a lot of power to view a star. The Delos won this with a better over all performance, the 12mm Nagler just showed a tiny bit of lateral colour at the very edge, this of course being an area where we cannot assess on the Delos. 

While I was on Vega I spent time looking for a line of site double that I read about in a thread that one of the members had raised. I could not be sure of seeing this but I was of the opinion I was seeing something close to the main star but without knowing any details with regard to position I will leave this for another day.

Sky Watcher 190mm Mak/ Newtonian.

The Moon

Messier 13

Messier 22

Double double

Porrima

Arcturus

On this scope which I had checked for collimation the two eyepieces gave a power of X83, so low to mid range as I see it. I started out with Porrima.

Porrima,

A tight double in Virgo which is fairly bright at magnitude 2.9, the separation is fairly small and normally requires a bit of coal on the fire to see a split, but why not try and see if X 83 can crack it.

Well, try as I did on two nights, one where the seeing was even something to get excited about, I could not claim a split. I would however say that I could see that it was a double star but just felt that an extra times two of a Powermate would be required to split the pair. Both eyepieces showed the star beautifully on axis and at the edges though as all TeleVue’s are tested to down to F4 I would not really believe that the Mak/Newt would stress the two of them very much at all.

Messier 13.

I can never make up my mind which I prefer this or Messier 22, both are large and wonderful objects in even modest equipment and well worth a look. I normally like to open up a globular cluster with about X150 but Messier 13 is so large that the 12mm eyepieces were providing enough oomph to enjoy them to the full. I popped in the Nagler and used the back of a chair to help hold myself in an upright position, one thing I have against these types of scopes when something is almost overhead you have to stand up, that is opposed to sitting on the concrete when using a refractor.

Doing my usual, try and see a defect at the edge didn’t last long as it was clear that both were firing on all cylinders, the Nagler giving that bit more sky to view and not suffering as a result, these really are as the old Mr Kipling advert told us, exceedingly good eyepieces or was it cakes.

Moon.

As I wanted to see the effect that a full or close to full Moon has on the edge distortion or pin-cushion of the Nagler which by all accounts has been worked on. I had to wait a good long while before I got what I wanted; this was due to adverse weather which made many people homeless in the Northern parts of the country. I managed to get the Moon a day before full and started into the T4. I was not expecting to see any real distortion from the Delos and didn’t. I must say that the edge view in the Nagler was not bad at all, yes there was some distortion but not on the scale that I have witnessed in the 26mm and 31mm T5 Naglers where is can appear in my view fairly horrible. In defense of those two eyepieces viewing the Moon is not something that many people would do but if you had a very long scope, above 4 meters, then it has to be considered.

Messier 22.

I don’t know if this is my favourite globular but it would have to be on a short-list of 5, the only real problem with it is being low down in the sky for much of the UK, it is not that wonderful for me and I am about 11 degrees to the South. This is one of the largest clusters of this type and a wonderful sight in any scope from a dark site, and that is the key word, dark. Again both eyepieces gave a lovely view of this, maybe I was would just comedown on the side of the Delos for no other reason than it framed it better with its smaller field. This area of the sky is rich in wondrous treasures and I don’t know how many times I have longed for the view of this area like from Mexico where it is overhead.

Epsilon Lyra

The double double is probably one of the most looked at in the night sky, well when the clouds let you in any case. I tried this at a lower magnification with the 14mm test where the power was X71, would the extra X12 from the 12mm’s be the straw to break the camels back. I have split this double below X 80 but it was with the 115mm refractor a scope that is in my opinion better at this task. I tried on the first night when seeing was not that good and could not be sure that I was seeing a gap between the star of either set of two. Some weeks late though I had a still and very clear night with excellent transparency and then after viewing for about 45mins I claim a split in the these two doubles, it was not there all the time but a split could be seen for brief periods. Cheating a little and going to the 10mm Ethos confirmed the clear split where it was visible all the time and that was at X100, but it was there for sure at X83. This is of course no record, not even for me but it is the best I have done on this scope, I believe one site member has split this at around X60, that must take; very good conditions, experienced eyes and fine equipment. 

Arcturus.

This being the brightest star in the Northern hemisphere makes it ideal as a light scatter test as Venus is in the morning sky still and I saw it this morning at 6 o’clock but the scopes stayed in where they were. While I was doing this I also checked out the edge aberrations. I think the Delos just had a little more control of everything way off centre, we really are talking in the tiniest words we can find here, minimal, minuscule, minuet and not big. Though the area where I am criticizing the Nagler can not even be shown by the Delos so is it even fair.

Conclusion.

To the best of my knowledge the only other 12mm eyepiece from Tele-vue was the 12mm Radian, this is one I have never seen. There are a few focal lengths where the Company makes multiple same focal length oculars; 10mm for example where we had Radian and now Delos and Ethos or even 8mm where Ethos Delos and Plossl coincide now and there was even a Radian 8mm once, though again I have never layed eyes on one.

This is very much a case of horse for courses and whilst the Nagler and the Delos are not far apart at all, maybe the former appeals more to the Dobsonian owner with its wide field of view and the Delos to planetary astronomers. The one thing I have proved to myself here is that I don’t see Tele-vue making any bad eyepieces, all have there strong points and few weak ones. The weakest one of all is of course the price tag but they cost what they cost for a reason, absolute quality and 100% control over the manufacturing process and they do out gun most other makes, by how much is not the issue, it will always be a personal thing as to whether you want that peace of mind.

I have to come down on the side of the Delos as I bought it and sold the Nagler but I sold a fine eyepiece that in all honesty did not need replacing but I would bet a few of us have done that. I think to close I would say no matter which Tele-vue eyepiece you buy it is going to deliver what you want from an eyepiece, razor sharp to the edge, full contrast, and superb control of all aberrations. Apart from them being free with the morning breakfast cereal what more can you ask for.

Alan.                         

[swamp thing]

Great review.

They sure are close Alan, I've an observing buddy with the Delos and i must admit I cant split them except on AFOV and yes, you guessed right as a dob owner I prefer the Nagler with its bigger field

[avtaram]

A really good detailed report Alan as always.

As I already have a 10mm Delos I'm not sure whether a 12mm would be worth having as well.

Avtar

[YKSE]

Another excellent review Allan,

interesting to know that the differences are so small.

[John]

Very nicely done Alan

[jabeoo1]

Thanks Alan, great write up.  Thanks for taking the time and effort. 

[kirkster501]

The 12mm T4 Nag is one of my favourite EP's.

[Uplooker]

Very good review, very informative. I hope this is not too off topic, but why do people prefer the 12mm T4 Nagler over the 13mm T6 Nagler?

Ian

[astronymonkey]

Very good review, very informative. I hope this is not too off topic, but why do people prefer the 12mm T4 Nagler over the 13mm T6 Nagler?

Ian

The T4 does have nice eye relief, although Im not sure what the other differences would be over the 13mm apart from the slight difference in focal length.

One minor niggle is the need for an extension piece to parfocalise the 12mm with the rest of the T4 range. It would be good if this was included as its only a threaded tube but retails for over 20quid (I think it adds about 1.1inches to the barrell length).

Cheers

[swamp thing]

Very good review, very informative. I hope this is not too off topic, but why do people prefer the 12mm T4 Nagler over the 13mm T6 Nagler?

Ian

For me it's three things. Firstly, I prefer the longer eye relief, I find it a much more comfortable eyepiece to use. Secondly, the bigger eye lens. I find eye placement a doddle on the T4's with no kidney beaning (others mileage on this is different I know), and lastly. I can keep to all 2" fitting eyepieces by using it (no faffing about with adapters).

[Moonshane]

The T4 does have nice eye relief, although Im not sure what the other differences would be over the 13mm apart from the slight difference in focal length.

One minor niggle is the need for an extension piece to parfocalise the 12mm with the rest of the T4 range. It would be good if this was included as its only a threaded tube but retails for over 20quid (I think it adds about 1.1inches to the barrell length).

Cheers

just add a 28mm baader fine tuning ring

[astronymonkey]

Hi Shane,

good idea, I never knew they made one and the only other  one I tried was too long..... so I opted for the TV one in the end.

Its a shame these dont come as standard with the eyepiece though , especially given the price of the EP.

cheers

[alan potts]

I think the main thing with the T4 12mm and the T6 13mm is the eye-relief. I myself did see some kidney beaning or black-out in the 12mm but it really comes down to how much you use it, I think Swamp Thing maybe uses his a lot when compared to me.

The 13mm is a fine eyepiece which I had before I took a fancy to the 13mm Ethos but I really don't think it is for anyone that wears glasses, the extra few millimeters offered by the T4 makes all the difference. On a plus side the 13mm Nagler is a fine gab and go eyepiece, fitting into a pocket without fuss.

Alan

[John]

When TV re-packaged the 13mm Nagler optics they did a remarkable job in shrinking the package and slightly improving the performance too. When I got my 1st 13mm T6 I could not believe that it was an 82 degree eyepiece.

I think the T4 Naglers do offer a subjectively more immersive experience than the T6's because of their large eye lens. That said, had the Ethos 13 not become available I'd have quite happily lived with the 13mm T6 for many years. 

[Uplooker]

Thank you very much for the replies. I certainly understand the advantage of having the 12mm T4 for the two inch barrel, to save switching out a 1.25" adaptor. I have not tried the 12mm but I am very happy with my 13mm T6 ;-)

Ian

[alan potts]

Ian,

You have every right to be happy, it is a very good eyepiece and for the 82 degree FOV top of the heap, I have done a lot of side by side comparisons with the eyepieces I have or have had and there is not very much between any of them. Lets face it when did Tele-Vue start making rubbish, I don't know of a bad one, yes some have been upgraded but even the old T1&2 are still sort after, Moonshane loves his T2 16mm.

Alan.

[Ruud]

Thank you Alan, for a great report. It was a pleasure to read.

After comparing it to the a Nagler T4 12mm, I bought a Delos 12mm. I thought the image quality of the Delos was better (mostly in the areas of contrast and edge performance). Also, the Delos has an easier exit pupil. This, and its near rectangular image geometry, makes the Delos more versatile than the Nagler T4, especially for lunar and daytime observation. 

Both are very fine eyepieces, but the only advantage that the T4 had over the Delos was its wider field of view.

[michael.h.f.wilkinson]

Great report again Alan. The eye relief of the 12T4 is certainly enough for me, but I have heard of people who struggled a bit with a Radian (20mm eye relief) so not all eye sockets are equal, I suppose. Of the T4 series Naglers, the 12T4 is the least immersive, and has the shortest eye relief, but it is still a great little performer.  I am tempted by the Delos 12mm in part because it gives me an excuse to get a 14mm as well, filling the (imaginary, I suppose) "gap" between my 17T4 and 12T4. Going from 119x to 169x is quite a jump, and I felt the 14mm Meade UWA at 145x provided less of a jump (luxury problem, I know). If I just get a 14mm Delos, I get two EPs with almost the same field stop diameter, just with different which might be a bit weird. However, if I get the Delos 12mm, the 14mm makes more sense. Fortunately, when I am thinking in this way, I kick myself in time, and start thinking about other, more productive ways to spend dosh on new kit (Quark, I hear you calling ).