Televue

[Don Pensack]

2 hours ago, jetstream said:

I have a few Zeiss optics- all superb- an old Zeiss T coating rangefinder monocular type has better glass and views than a set of Pentax binos I had. The Zeiss T coating zoom 25.1-6.7 also has "zero" (not detectable to me) scatter and is one of my few truly sharp eyepieces, my 2" Zeiss prism is also beyond compare. Then there is the Docter 12.5 UWA (no longer produced).

Question- if there are already glass types, polish levels and coating technologies out there that only a very few use what chance do we have of ever getting the newest latest techno glass out there in astro eyepieces coming up?

I wonder if there are any widefields that go deeper than Delos? any Pentax XW users experience?

The difference in transmission is likely to be on the order of 2%, if that much.  That is ~0.02 magnitudes.  It would take a spectrophotometer to see that difference.

Both Delos and XW are BBAR coated on all surfaces, even the cemented ones.

There is a difference in correction of astigmatism at the edge in faster f/ratios, and in the spectrum of transmission (the XWs were a tad yellower in my color test), and in flatness of the field.

Those differences are unlikely to matter for something on axis in a tracking scope.

If you are looking to see deeper, eyepieces are not the place to look for that.  Larger aperture is.

 

As for the latest technology in lens materials and surface polishes, unless suddenly the eyepiece market is willing to cough up $1000 or more for every eyepiece, we aren't going to see it.

High end camera lenses for professional use are mostly above $10K.  Most of the posts here on SGL are arguing about whether this $100 eyepiece or that one is better.

A Nikon engineer told me they can get 99% transmission through a 20 element lens, but the coating on each lens surface costs about $300.

We will never see that.

 

Still, there are differences in eyepieces that can be measured.

Here are a couple links to peruse:

https://web.archive.org/web/20110622011950/http://cieletespace.fr/files/InstrumentTest/201102_test_oculaires.pdf
https://web.archive.org/web/20130829052725/http://www.cieletespace.fr:80/files/InstrumentTest/201306__6_oculaires_10mm.pdf

 

[John]

9 minutes ago, Don Pensack said:

.....Here are a couple links to peruse:

https://web.archive.org/web/20110622011950/http://cieletespace.fr/files/InstrumentTest/201102_test_oculaires.pdf
https://web.archive.org/web/20130829052725/http://www.cieletespace.fr:80/files/InstrumentTest/201306__6_oculaires_10mm.pdf

 

Really detailed testing - we so rarely see that in astro eyepieces.

 

[Don Pensack]

1 minute ago, John said:

Really detailed testing - we so rarely see that in astro eyepieces.

 

You're right.  It would be great to get some in-depth lab testing, but there isn't enough money in it to pay for the lab equipment.

If such occurs, it is usually an amateur astronomer working for a large optical lab doing government work.

[jetstream]

33 minutes ago, Don Pensack said:

If you are looking to see deeper, eyepieces are not the place to look for that.  Larger aperture is.

Good post Don, those pesky orthos still go a bit deeper than my Delos, which is a deep eyepiece IMHO. Totally agree about aperture- my 24" is much deeper than my 15" etc etc. I would not spend a grand on an eyepiece to go deeper but throw the cash at a bigger scope or ways to get to a darker site.

Speaking of skies and transparency- the thunder yesterday started more fires and the smoke just billowed in an hour ago across the lake. No aperture or eyepiece punches through this.

 

[jetstream]

40 minutes ago, Don Pensack said:

BBAR coated

What does this stand for?

[Littleguy80]

1 hour ago, Space Hopper said:

I'm not actually 100% certain Docter Noblex are no more, but rumours seem to indicate that its true.

I actually had a pair for 2 eyed viewing but decided to sell one of them last year.

I sold it to someone on here, and i often wonder how hes getting on with it ?

My remaining one is a keeper though, and it performs beautifully mono style, with and without a Powermate option.

He’s very happy with it  I’ve had some great views. M51 really stands out in the memory. I also regularly use it with the Baader VIP as a 7mm eyepiece. It’s removed the need for a Pentax XW 7mm. Thank you very much for parting with it  

[globular]

4 minutes ago, jetstream said:

What does this stand for?

BroadBand Anti-Reflective

"Broadband anti-reflective (BBAR) coatings consist of multiple layers, alternating between a high index material and a low index material. The layers are deposited on the substrate via electron-beam deposition. The thickness of the layers is optimized to produce destructive interference between reflected waves and constructive interference between transmitted waves. This results in an optic that has enhanced performance within a specified wavelength band as well as minimal internal reflections (ghosting). "

Edited August 24, 2021 by globular

[jetstream]

Just now, globular said:

BroadBand Anti-Reflective

Thanks I was sure of the "BB". I must say that Televue and Baader have extremely good coatings whatever they are, I think Baaders were Zeiss inspired, another guess. I had a 10mm Ethos that I stupidly sold that had extremely high contrast, super actually. Both the Ethos and Delos coatings/glass are superb as I imagine DeLites are. Naglers/Pans, well some companies have succeeded in getting 90% or so of this level (to me, IMHO).

[jetstream]

8 minutes ago, Littleguy80 said:

It’s removed the need for a Pentax XW 7mm

This is a very high standard. Congrats for this fine acquisition! Maybe Televue can buy the design and start producing them, its a shame they are no more. Mind you the 13E wouldnt like this! LOL!

[Geoff Barnes]

I've often wondered what eyepieces are used in professional observatory telescopes and are they available to mere mortals like us? 

Would they be likely to use Televue ep's?

[jetstream]

3 minutes ago, Geoff Barnes said:

I've often wondered what eyepieces are used in professional observatory telescopes and are they available to mere mortals like us? 

Would they be likely to use Televue ep's?

https://www.siebertoptics.com/SiebertOptics-eyepieces-observatory.html#This 80mm 4 eyepiece

[jetstream]

4 minutes ago, Geoff Barnes said:

Would they be likely to use Televue ep's?

I was conjuring up a widefield 24" set up with a larger secondary (this aperture will support it and not get too big) and a custom focuser. Thankfully I scrapped the idea and saved a wad of cash lol!

[globular]

4 minutes ago, jetstream said:

https://www.siebertoptics.com/SiebertOptics-eyepieces-observatory.html#This 80mm 4 eyepiece

Isn't that just bigger... needed for the size of telescope.... rather than better, per se, as an optical design or construction?

[michael.h.f.wilkinson]

23 minutes ago, Geoff Barnes said:

I've often wondered what eyepieces are used in professional observatory telescopes and are they available to mere mortals like us? 

Would they be likely to use Televue ep's?

As a rule, no EPs are used, only various cameras, spectroscopes, and other gizmos.

 

[jetstream]

14 minutes ago, globular said:

Isn't that just bigger... needed for the size of telescope.... rather than better, per se, as an optical design or construction?

Yes, I have a Siebert, acceptable not exceptional IMHO. But not many make these big EPs I dont think.

Edited August 24, 2021 by jetstream

[Louis D]

27 minutes ago, Geoff Barnes said:

I've often wondered what eyepieces are used in professional observatory telescopes and are they available to mere mortals like us? 

Would they be likely to use Televue ep's?

Back in the day, there was a line of Zeiss professional monocentrics mentioned in a post on CN.  I'll cut and paste the text from CN user vahe here since it bears worth repeating:

As promised I contacted my fried who owns these pro Monocentrics with additional questions, here is his reply:

“Here is some more information about these remarkable oculars.

1) The focal lengths I reported to you for the Professional Monocentrics are correct, and there were no other focal lengths made. None of these eyepieces were available from either standard or limited production. They were only custom made for observatories to use with various large Zeiss telescopes and astrographs. They differ from the amateur monocentric designs in 5 ways: first, the spec level on the design was much more tightly controlled and the level of polish was reported to me to be about twice as fine as the amateur oculars- the highest level Zeiss Jena was capable of; second, they were designed to work down to f/4 whereas most of the f/l's in the amateur monocentrics were designed to work down to f/6; third, they are highly corrected to provide a flat field over a large area to match the large film plates used in the various Zeiss camera systems; fourth, they incorporate some glass types that were not employed otherwise and were proprietary Zeiss melts; finally, they were much more expensive originally than the amateur monocentrics, which is understandable given the custom nature of their production and the extremely fine level of design and finish. I have never seen one advertised for sale anywhere.

2) Both the 35.7mm and 41.4mm were made in two versions. One is the solitary monocentric, and the other adds a field lens to the assembly so that in these longer focal lengths, the field curvature continues to be controlled over very large areas- for the fastest observatory astrographs Zeiss made. I have both versions, and after 15-20 years of careful comparison prefer the one with the field lens as it is more highly corrected and the field lens completely disappears in use. The field lens appears to be more extensively coated than the monocentric assemblies, whatever the case, I simply can't see it in the light path.

3) I would agree with your European friend that the 18.5mm Professional Monocentric is a special ocular, however I have found it to be second to the 24.6mm. This is after comparisons in both fast and slow 8" triplets, the 10" Maksutov, and three Zambuto reflectors from 12.5" to 20" in aperture, as fast as f/4.3 uncorrected for coma.

4) Over a long period of time, I have compared these eyepieces to sets of the original ZAO's, ZAO II's, amateur Zeiss Monocentrics, and three other brands of monocentrics. The Zeiss Professional Monocentrics are notably superior in every focal length. So much so, that I have sold all of the others except for a few outstanding f/l's that seemed to me to be the standouts in the other Zeiss designs- e.g. 25mm original ZAO; the 10mm and 16mm amatuer Zeiss Monocentrics. I did not keep any of the other brands of "monocentrics". In my opinion, there is a bigger difference in low level contrast, sharpness, and detail in the Professional Monocentrics and the ZAO's than between the ZAO's and other high-end orthos or the most highly touted of the other "monocentrics".

5) When used in combination with high quality barlows or Powermates, the Zeiss Professional Monocentrics remain notably superior to comparable effective focal lengths in any of the other eyepeices I have used, including the ZAO's. This is what surprised me the most, originally, but my experience has continued to confirm it over time. This result provided remarkable flexibility early on, before I acquired the complete sets of focal lengths. It allowed me to design two planetary telescopes around a couple of the eyepiece focal lengths, especially the 24.6mm, then vary a full range of planetary powers with various barlows or Powermates.

It is my understanding that only about three dozen of these were ever made. I eventually located and purchased most of them, paying very dearly to complete some of the f/l's. The observatories who had them were in six different countries, and as they switched from film to digital during the 90's and early 2000's I was able to acquire them directly. The most any single observatory had was 2 focal lengths, so its been quite a project and the last one I located was around 2006. There is a number, in the single digits, that seem to have disappeared over time. It sounds like one of your European friends might have a couple of those and is enjoying them very much. I thought it made sense to locate and secure these before they all disappeared as they are both historically significant and in use, pellucid and sublime."

Vahe

[John]

28 minutes ago, Geoff Barnes said:

I've often wondered what eyepieces are used in professional observatory telescopes and are they available to mere mortals like us? 

Would they be likely to use Televue ep's?

Lowell Observatory uses Explore Scientific but that is for outreach rather than research. Research is mostly done with devices other than optical eyepieces.

The Lick Observatory has some Tele Vues for it's 36 inch refractor:

https://mthamilton.ucolick.org/techdocs/telescopes/36inch/telGeneral/

 

 

[jetstream]

@Louis D ok I want one.

[Space Hopper]

3 hours ago, Littleguy80 said:

He’s very happy with it  I’ve had some great views. M51 really stands out in the memory. I also regularly use it with the Baader VIP as a 7mm eyepiece. It’s removed the need for a Pentax XW 7mm. Thank you very much for parting with it  

Haha !  Good to hear its performing ok Neil 😊  Nice to hear from you and i hope you're well.

I've certainly been mono-viewing quite a bit more with it and my BBHS Baader mirror, and its given some memorable views. 

Most memorable was with my 140 with a 2x Powermate on M37, the cluster in Auriga giving 157x

One of my favourite clusters and quite spectacular that night. 

 

[Littleguy80]

10 minutes ago, Space Hopper said:

Haha !  Good to hear its performing ok Neil 😊  Nice to hear from you and i hope you're well.

I've certainly been mono-viewing quite a bit more with it and my BBHS Baader mirror, and its given some memorable views. 

Most memorable was with my 140 with a 2x Powermate on M37, the cluster in Auriga giving 157x

One of my favourite clusters and quite spectacular that night. 

 

Thanks Rob. Doing week thank you  Hope you're also keeping well. 

I have used the Docter/Noblex a few times with my 80mm frac too. The frac really emphasises the sharpness of this eyepiece. Love M37! Looking forward to revisiting it this winter. Here's one of my observing reports where I mention using it. It got a lot of use for surfing galaxies in Virgo.

 

[Space Hopper]

Thanks, and that was a nice session you had back there.

[Don Pensack]

4 hours ago, jetstream said:

Good post Don, those pesky orthos still go a bit deeper than my Delos, which is a deep eyepiece IMHO. Totally agree about aperture- my 24" is much deeper than my 15" etc etc. I would not spend a grand on an eyepiece to go deeper but throw the cash at a bigger scope or ways to get to a darker site.

Speaking of skies and transparency- the thunder yesterday started more fires and the smoke just billowed in an hour ago across the lake. No aperture or eyepiece punches through this.

 

That difference would be invisible in smaller scopes.

[Don Pensack]

4 hours ago, jetstream said:

This is a very high standard. Congrats for this fine acquisition! Maybe Televue can buy the design and start producing them, its a shame they are no more. Mind you the 13E wouldnt like this! LOL!

Not everyone thinks the 12.5mm Noblex was all that great an eyepiece.  It's angular magnification distortion made it unusable for me.

The 12.5mm APM Hi-FW is better in that regard and equally sharp, but has edge of field brightening, another issue I can't live with.

I find the 12.5mm Morpheus better than both of them.  However, I don't use that much, preferring the TeleVue Apollo 11.

[Don Pensack]

4 hours ago, Geoff Barnes said:

I've often wondered what eyepieces are used in professional observatory telescopes and are they available to mere mortals like us? 

Would they be likely to use Televue ep's?

No, most of those big scopes, if ever used visually, use 4" or larger eyepieces of 80mm and longer focal lengths.

In the 60" at Mt. Wilson, a 50mm eyepiece is 488x.

[jetstream]

1 hour ago, Don Pensack said:

Not everyone thinks the 12.5mm Noblex was all that great an eyepiece.  It's angular magnification distortion made it unusable for me.

I figure its a to each your own situation, lots of eyepieces to choose from for sure.