10mm TeleVue Delos, Baader Hyperion zoom and Zeiss Abbe-II orthoscopic

[Andrew*]

The summer days just don't seem to end! We've been blessed with two weeks of sunny, hot weather here in Edinburgh, and today I had a chance for a lovely extended white light solar session with these three eyepieces:

- 10mm TeleVue Delos

- Baader Hyperion Mk III zoom, set midway between the 8mm and 12mm clickstops. Assume this to be very close to 10mm.

- 10mm Zeiss Abbe-II orthoscopic

I used my ED120, giving 90x, with a latest-version Lunt 1.25" Herschel wedge with built-in ND3.0 filter. To cut the light down further I used a single polarising filter on the eypiece barrel, rotating the eyepiece to give the dimmest image available. I felt this gave maximum contrast on solar faculae, so easiest comparison. Seeing was extremely variable, ranging from very steady to totally defocused images, and an intermittent wind interrupted viewing occasionally. Poor transparency resulting in a white haze to the sky also showed in the image.

I won't go into the physical characteristics or specifications of the three eyepieces, but I'll note that the Delos came to focus far further out than the Hyperion, with the Zeiss in the middle. I also had to change over the polarising filter onto the barrels every time I swapped the eyepiece in the focuser. This all meant changeovers were not instantaneous and so I was somewhat relying on memory in these comparisons. Of course I swapped over regularly to double and triple-check and generally I found comparisons consistent.

One of the first things I noticed was the warmer tone in the TeleVue Delos. To be honest, I did not expect this, but against the noticeably cool hue of the Baader zoom, there was a subtle, but unmistakeable difference. The Zeiss was closer to the Baader in this respect, giving a neutral white tone on the sun. I would say this is far from bothersome and I only noticed it through direct comparison.

I spent many swap-overs comparing the on-axis sharpness between the Delos and Hyperion. There was a very handy active region with various sizes of spots and gaps between them, so there was no shortage of targets on which to test the resolution. I kept on thinking I could spot one feature that I hadn't seen in the other, but could always pick it out on swapping back, so that in the end I honestly could not determine one of them as sharper. The only difference came when I inserted the Zeiss and could resolve a more refined outline of an umbra on the limb which was not so defined in the other two. Going round the sun's face, fine details popped out in moments of good seeing slightly easier than they had with the other two eyepieces, but the difference was extremely subtle and was not necessarily more revealing.

Contrast was also not a clear-cut situation: better transparency would make for a better comparison, but overall I felt the Hyperion dropped behind very slightly in picking out faculae further from the limb. Again, there was very little in it as granulation and extensive faculae on both eastern and western limbs were readily visible in good seeing in all three.

It was a bit easier to pick the three apart with regard to brightness, with the Hyperion being a touch dull and the Zeiss taking a slight edge over the Delos. This was especially marked when I removed the polariser and just tried them at full brightness. The intensity in the Hyperion was not so blinding as the other two. Note: viewing with an unfiltered herschel wedge is NOT safe. I was using it with the inbuilt ND 3.0 filter which further reduces the intensity by 1000x, to a safe level. However, the image is still bright and further reduction is recommended.

What I can say for certain though is that of the three, the Delos is most particular about eye placement, which was a little disappointing. It wasn't dreadful, and with some care using the variable eye guard I could reduce kidney-beaning to an acceptable level, however, it was most susceptible to prismatic effects when the eye was not centred on the (enormous) eye lens. This yellow-orange or blue edge was visible in all three eyepieces, but most severe and sensitive in the Delos. I took off my glasses to make sure they weren't to blame. However, I did notice that, when the eye was correctly positioned the Delos delivered true colour to the edge of the field, whereas in the Hyperion, there was a green hue on the limb when viewed off-axis.

Though I didn't do an in-depth off-axis sharpness test, I did notice the Hyperion fell short of the Delos towards the edge of the field.

So that sums up my observations today. In conclusion:

- I'd been wondering for a while whether my Hyperion was falling short on close observation, but am very relieved to say it's holding its own alongside the very best.

- I'm very happy with my new Delos. The eye-guard system is the best I've come across, which is important to me as a spectacle-wearer who can never decide whether to prop them on my head or not. The views are very pleasing too, with only very minor niggles that I will probably get used to.

- the Zeiss continues to show it has the edge over every other eyepiece it comes against. Differences are subtle at most, but always in its favour.

I think a night-time test with steadier conditions might reveal more on how these three great eyepieces compare, because on the sun today, I had to make considerable effort to see any difference at all.

[jetstream]

Awesome report,solar may be an upcoming interest of mine,but I know nothing of it.What is a Herschel wedge?

[Andrew*]

Hi Gerry,

Thanks for your comment.

This is the solar/herschel wedge I use: http://www.365astronomy.com/lunt-125inch-white-light-herschel-wedge-solar-wedge-with-integrated-nd30-filter-p-3045.html

Instead of a high reflectivity mirror on an ordinary diagonal, it has a prism that transmits 95% of the light, reflecting 5% of the light up into the eyepiece. 5% is still way too much to view though, hence the fitted ND 3.0 (10^-3 transmission) filter. Different herschel wedges deal with the excess light and heat coming otu the back in different ways. The worst kind just leave it streaming out unfiltered. This is potentially dangerous, as items or young eyes that get in the way will be quickly burnt. The Lunt has a metal plate and a heatsink. In my ED120, this gets hot to the touch but not burning hot. The best is Baader's CoolCeramic back which somehow manages to stay cool. Even better is the projection of the sun is visible on its surface so it acts as a finder too. Another example of genius design and quality optics by Baader. Expensive, but simply the best.

Andrew

[jetstream]

Excellent explanation Andrew,I'll investigate further.Down the road when I get my DSO setup going and used, my attention will be turned toward soar viewing,I had already looked at some scopes made for it,but once again caution entered the picture.It must be amazing to see the prominences....the scopes looked at were the Coronados,look great not sure of the quality.

[Andrew*]

Hi Gerry, the topic of this thread is white light solar observing. This gives a white view (or yellow if you use a glass filter on the front) of the sun and shows sunspots, faculae and granulation. To observe prominences, filaments, spicules and plages, you need a dedicated hydrogen alpha solar scope such as a Coronado, which gives a deep red/orange view. The etalons that filter out the Hydrogen alpha band are very expensive so it's in a different league from white light equipment.

Andrew

[John]

What an interesting review Andrew

I can't help being curious as to how they would compare at night but, having just returned from a trip to the Highlands, I understand that's in short supply just now !

[Andrew*]

What an interesting review Andrew

I can't help being curious as to how they would compare at night but, having just returned from a trip to the Highlands, I understand that's in short supply just now !

Hi John, welcome back! Yes, as you've discovered it's not very dark here yet. I stayed up late-ish last night and just as I was going to bed I noticed it was perfectly clear and "almost" dark. I'm not going to stay up later than that thanks!

I agree, a night-time view will probably help giving a more thorough assessment.

[alan potts]

A very interesting report on a subject that I have rarely ever looked at. These wegdes sound really good, I used to have a projection box on my old 3 inch refractor back int the 70's. I wish I could get one of these Zeiss eyepieces to how good they are, I think the eyeplacement is only a getting used to the eyepiece thing, I found the same with all mine, now it's easy.

Thanks for sharing you thoughts with us.

Alan.

[John]

The ZAO and the ZAO II's seem to be the benchmark by which all other so called planetary eyepieces are judged. I envy Andrew his set

When I had a Baader 8-24 zoom I found that it was matched or exceeded in performance in nighttime viewing by the fixed focal length Hyperions so I'd expect a ZAO II and a Delos to show somewhat better views of nocturnal astro targets but things don't always work out as one expects and the Baader zoom is one of the best of it's type.

[jetstream]

Hi Gerry, the topic of this thread is white light solar observing. This gives a white view (or yellow if you use a glass filter on the front) of the sun and shows sunspots, faculae and granulation. To observe prominences, filaments, spicules and plages, you need a dedicated hydrogen alpha solar scope such as a Coronado, which gives a deep red/orange view. The etalons that filter out the Hydrogen alpha band are very expensive so it's in a different league from white light equipment.

Andrew

I did not know there were different scope types for different things on the sun,please excuse my ignorance,and your first paragraph stated white light solar session.I had looked on the net at the Coronados,but honestly never knew they can't "do" white light observation.But now I know and I thank you for that Andrew, .

[Andrew*]

The ZAO and the ZAO II's seem to be the benchmark by which all other so called planetary eyepieces are judged. I envy Andrew his set

That is certainly how I see them, and it is why I always use them when assessing an eyepiece. When using an "inferior" eyepiece, I sometimes wonder if I'm getting the best contrast or sharpness possible from the conditions. I ask the question, "using this, am I missing anything?", so pop in a ZAO of equivalent focal length. To be really honest, it's rare that I see any significant difference, and mostly it's down to scatter at high power more than anything else.

What I don't know, is whether my powers of observation are not as refined as other observers, or whether eyepieces have come so far that the range of quality between cheap eyepieces and ultimate eyepieces is just very small! I would expect a bit of both.

Maybe I should send my set to you and you can add them to your comparison of orthoscopics, as you seem to be highly skilled at picking out the differences.

When I had a Baader 8-24 zoom I found that it was matched or exceeded in performance in nighttime viewing by the fixed focal length Hyperions so I'd expect a ZAO II and a Delos to show somewhat better views of nocturnal astro targets but things don't always work out as one expects and the Baader zoom is one of the best of it's type.

In what respects, John? Edge sharpness is where I find the zoom falls short, but in most other respects I find it extremely competent. It could well be that eyepiece quality was simply not a limiting factor in this comparison. None of these three eyepieces are going anywhere any time soon, so I'm sure a night-time version of this comparison will follow

Andrew

[John]

...In what respects, John? Edge sharpness is where I find the zoom falls short, but in most other respects I find it extremely competent. It could well be that eyepiece quality was simply not a limiting factor in this comparison. None of these three eyepieces are going anywhere any time soon, so I'm sure a night-time version of this comparison will follow

Andrew

I was comparing the Hyperions to the Hyperion Zoom during nighttime viewing. The zoom was very good, especially from around 18mm to 8mm but I felt the fixed focal lengths delivered slightly sharper and more contrasty views of the moon and planets - I think Jupiter was the one in question at that time.

I used the Zoom more when I had a PST and found it really good in that capacity.

On the more general point of comparing one excellent eyepiece to another, I've found it's only when the viewing conditions are at their best that the small differences emerge and even then they are subtle and you need to be trying for something thats really pushing the scope / observer to notice them.