Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Transmission of Zeiss Abbe II

  • Please log in to reply
33 replies to this topic

#1 ThomasM

ThomasM

    Viking 1

  • *****
  • topic starter
  • Posts: 608
  • Joined: 19 Apr 2009

Posted 06 December 2015 - 04:41 AM

Is there anything know about the transmission of the Zeiss Abbe II (ZAO II), are there measurements, a documentation from Zeiss?  For the ZAO I measurements are available.

 

Thomas

 

p.s. I know, one can argue a difference of a few percent is irrelevant, but I am just curios
 


Edited by ThomasM, 06 December 2015 - 04:41 AM.


#2 Greg77

Greg77

    Mariner 2

  • -----
  • Posts: 278
  • Joined: 02 May 2009
  • Loc: Slovenia, EU

Posted 06 December 2015 - 05:15 AM

Here's an interesting list of eyepieces and their transmissions:

 

http://www.amateuras.../tips/tips3.htm

 

CS!

 

Greg



#3 Paul G

Paul G

    Cosmos

  • *****
  • Posts: 8523
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 06 December 2015 - 10:14 AM

Here's an interesting list of eyepieces and their transmissions:

 

http://www.amateuras.../tips/tips3.htm

 

CS!

 

Greg

FWIW, those measurements were made for Markus Ludes by a company that measures optics transmission for a living, with equipment specifically designed for that purpose, equipment that is regularly calibrated and is regularly inspected and certified by the German government, so they are accurate. I suspect the II's are nearly identical to the I's. But even if the II's were made of magic glass and had 100% transmission the difference could not be seen by the human eye.



#4 vahe

vahe

    Surveyor 1

  • -----
  • Posts: 1645
  • Joined: 27 Aug 2005
  • Loc: Houston, Texas

Posted 06 December 2015 - 10:34 AM

"But even if the II's were made of magic glass and had 100% transmission the difference could not be seen by the human eye.'

 

 

And that is the bottom line.

.
Also there are other issues in connection with eyepieces that really sound good on paper but make no difference, specifically the “Newer Coatings” compared to Older coatings, I must confess that I can not see much difference, I have even looked thru some real old Zeiss Orthos that did not seem to have any coatings at all but offered amazing performance.

.
To me one thing that does make a huge difference and is easily visible is the level of polish, the unusually high level of polish stand out instantly, Zeiss has it, Pentax SMC Orthos and Brandons also have it. Any other eyepiece?

.

Vahe



#5 leonard

leonard

    Apollo

  • *****
  • Posts: 1267
  • Joined: 19 Oct 2007
  • Loc: West Virginia

Posted 06 December 2015 - 01:05 PM

     hello ,

 

 

            Read a few articles over the years by the late Bob May where he expounded that very idea, that polish and glass quality was king as far as eyepieces goes , coatings not so much.

 

 

 

Leonard



#6 nevy

nevy

    Apollo

  • *****
  • Posts: 1470
  • Joined: 07 Feb 2012
  • Loc: UK

Posted 06 December 2015 - 01:32 PM

"But even if the II's were made of magic glass and had 100% transmission the difference could not be seen by the human eye.'

 

 

And that is the bottom line.

.
Also there are other issues in connection with eyepieces that really sound good on paper but make no difference, specifically the “Newer Coatings” compared to Older coatings, I must confess that I can not see much difference, I have even looked thru some real old Zeiss Orthos that did not seem to have any coatings at all but offered amazing performance.

.
To me one thing that does make a huge difference and is easily visible is the level of polish, the unusually high level of polish stand out instantly, Zeiss has it, Pentax SMC Orthos and Brandons also have it. Any other eyepiece?

.

Vahe

Mead research grade orthos?



#7 starcam

starcam

    Apollo

  • *****
  • Posts: 1059
  • Joined: 24 Sep 2007
  • Loc: MD

Posted 06 December 2015 - 01:38 PM

The AP SPL's seem to have a nice polish on them.



#8 Paul G

Paul G

    Cosmos

  • *****
  • Posts: 8523
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 06 December 2015 - 02:37 PM

The AP SPL's seem to have a nice polish on them.

The superb polish and ultra clean glass internally are shared by the SPLs and the ZAOs. In fact, Roland's insistence on perfect glass made the SPLs impractical for production.



#9 BillP

BillP

    Hubble

  • *****
  • Posts: 18721
  • Joined: 26 Nov 2006
  • Loc: Spotsylvania, VA

Posted 06 December 2015 - 02:42 PM

 

FWIW, those measurements were made for Markus Ludes by a company that measures optics transmission for a living, with equipment specifically designed for that purpose, equipment that is regularly calibrated and is regularly inspected and certified by the German government, so they are accurate. I suspect the II's are nearly identical to the I's. But even if the II's were made of magic glass and had 100% transmission the difference could not be seen by the human eye.

 

That's interesting.  Do you know the name of the company by chance?

 

And on the not seen by the human eye, FWIW I completely disagree for a few reasons.  One is that every aspect of a system contributes to its performance, and all those aspects work together and build on each other relative to overall performance.  So one cannot look at single factors but must model how single factors will impact all factors as they produce the image (in this case).  Secondly, there is plenty of research (and it is common sense as well), that even the addition of a single photon into the eye can trigger a threshold response between seeing and not seeing.  So when your optical chain can get a percent here and a percent there, it certainly does show visually particularly in threshold response.


  • Sarkikos likes this

#10 BillP

BillP

    Hubble

  • *****
  • Posts: 18721
  • Joined: 26 Nov 2006
  • Loc: Spotsylvania, VA

Posted 06 December 2015 - 02:48 PM

 

The AP SPL's seem to have a nice polish on them.

The superb polish and ultra clean glass internally are shared by the SPLs and the ZAOs. In fact, Roland's insistence on perfect glass made the SPLs impractical for production.

 

 

There were multiple reasons in addition to production difficulties.  I think it was more frustration with the entire process, particularly assembly (as he related to me directly).  The many frustrations come through in his AMart posts (http://www.astromart...=&news_id==).  Working with small things requires a whole different level of patience that is not needed when working with larger things like telescopes.  Not everyone is suited to very small and very detailed work.

 

These eyepieces were discontimued because it was not possible to make them using normal production processes because of the steep internal curvatures. Normally eyepiece are made using multiple spot blocks where as many as 100 small lenses are blocked, ground and polished all at once. The SPL lens elements required grinding and polishing each surface individually, so it was impossible to gain any kind of production advantage. ...

 

It is interesting to me that an ocular is rejected by an amateur for showing a faint ghost from a bright star in the field, yet things like internal cleanliness is hardly ever discussed, and never really appreciated. Since I don't really know what is important in selling these things, I decided some time ago to remove myself from eyepiece manufacturing - it is another world for which I am not really suited.

 

One other thing, the SPL optics were produced in Ukraine by Aries, I merely assembled them into the barrels (a not trivial task, I assure you).

 

Rolando


Edited by BillP, 06 December 2015 - 02:52 PM.


#11 areyoukiddingme

areyoukiddingme

    Skylab

  • *****
  • Posts: 4373
  • Joined: 18 Nov 2012

Posted 06 December 2015 - 03:18 PM

 

 

FWIW, those measurements were made for Markus Ludes by a company that measures optics transmission for a living, with equipment specifically designed for that purpose, equipment that is regularly calibrated and is regularly inspected and certified by the German government, so they are accurate. I suspect the II's are nearly identical to the I's. But even if the II's were made of magic glass and had 100% transmission the difference could not be seen by the human eye.

 

That's interesting.  Do you know the name of the company by chance?

 

And on the not seen by the human eye, FWIW I completely disagree for a few reasons.  One is that every aspect of a system contributes to its performance, and all those aspects work together and build on each other relative to overall performance.  So one cannot look at single factors but must model how single factors will impact all factors as they produce the image (in this case).  Secondly, there is plenty of research (and it is common sense as well), that even the addition of a single photon into the eye can trigger a threshold response between seeing and not seeing.  So when your optical chain can get a percent here and a percent there, it certainly does show visually particularly in threshold response.

 

 

Can you refer to some of this research that shows how a single photon is triggering vision that would have a psychological response? Sounds far from common sense to me. The first study that comes up in google scholar infers that a single photon triggers photo cells, but that's quite different from being able to use that to form an impression.



#12 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42740
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 06 December 2015 - 04:54 PM

FWIW, the theoretical maximum transmission of a 4 element multi-coated eyepiece with 4 air-to-glass surfaces is 98.0%, so treat any measurement above that as "approximate".

 

As to response to a single photon, read:

http://math.ucr.edu/...e_a_photon.html



#13 jackofalltrades

jackofalltrades

    Vanguard

  • -----
  • Posts: 2015
  • Joined: 05 Oct 2014

Posted 06 December 2015 - 05:17 PM

Very interesting chart, I hadn't seen that before.  How do the findings correspond to other reports, where one eyepiece is reported as darker or lacking transparency compared to others?  The TV Plossl readily comes to mind.  It has the highest transmission (efficiency) according to those tests, yet according to many (my own eyes included) it seems just a tad bit darker wrt color rendering and faint star/object visibility.  The T6's, which I've always considered a pretty clean glass, didn't rate as well; and neither did the ZAO's, supposedly one of the holy grails - sts - which rate about equal to the T6's.  Of course if I'm understanding correctly, the ZAO's advantage is glass polish; but wouldn't that affect scatter which would affect transmission throughput?  

 

 

I think it'd be interesting to see where the Brandon would rate in this test, along with some other known performers like the XW's.  Basically, when all is said and done, I'd be inclined to agree with others above that there's a whole lot more to an eyepiece's performance than coatings, amount of glass, type of glass, and transmission (efficiency).



#14 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42740
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 06 December 2015 - 05:51 PM

XWs reach about 96% transmission at 550nm: http://pentaxplus.jp...h/xo-xw/63.html

 

Transmission isn't the only thing that influences what you see.

The spectrum of transmission and its correspondence to the spectral response of your eye and the spectral response of the star being viewed.

 

And an eyepiece with LESS scatter may appear darker because the background sky will appear darker.  

A darker background could indicate lower transmission, but it could also indicate less scatter.

 

I've done stellar magnitude limiting magnitude searches many many times, using the charts in Roger Clark's "Visual Astronomy of the Deep Sky" and found

that variations from eyepiece to eyepiece were on the level of 0.1 magnitude or less (consistent with the measurements) but varied from night to night over 0.2 magnitudes.

 

The ZAOs tested likely were not fully multi-coated.  Many eyepieces of the era had simple MgF2 coatings.

 

Your last statement says it all.  One factor seldom mentioned is how closely the execution of the sample matches the design.  Everything made has +/- tolerances.  That might go a long way toward explaining why 3 samples of the same eyepiece may have minute variations.



#15 areyoukiddingme

areyoukiddingme

    Skylab

  • *****
  • Posts: 4373
  • Joined: 18 Nov 2012

Posted 06 December 2015 - 06:18 PM

FWIW, the theoretical maximum transmission of a 4 element multi-coated eyepiece with 4 air-to-glass surfaces is 98.0%, so treat any measurement above that as "approximate".

 

As to response to a single photon, read:

http://math.ucr.edu/...e_a_photon.html

 

Yep, that's the thing I read. It reports on a study that concludes that the retinal cells do register single photons, but that people don't have perceptual reactions to that. Rather, they have perceptual reactions to bunches of photons, and then only if they arrive with a low latency.

 

Very unclear whether this has much of any consequence for life at the eyepiece.



#16 Starman1

Starman1

    Vendor (EyepiecesEtc.com)

  • *****
  • Vendors
  • Posts: 42740
  • Joined: 23 Jun 2003
  • Loc: Los Angeles

Posted 06 December 2015 - 06:23 PM

I think you can revise your last statement to read:

"It's unlikely this has much of any consequence for life at the eyepiece."


  • Paul G likes this

#17 BillP

BillP

    Hubble

  • *****
  • Posts: 18721
  • Joined: 26 Nov 2006
  • Loc: Spotsylvania, VA

Posted 06 December 2015 - 08:35 PM

 

Yep, that's the thing I read. It reports on a study that concludes that the retinal cells do register single photons, but that people don't have perceptual reactions to that. Rather, they have perceptual reactions to bunches of photons, and then only if they arrive with a low latency.

 

Very unclear whether this has much of any consequence for life at the eyepiece.

 

 

That would be a separate experiment specifically modelling the astronomical observing case, and not some other observing process.  Until those studies are conducted, all one can do is conjecture and forever debate on one side or the other.  Or you can devise your own personal experiment to get you closer to a conclusion.  With the many of hundreds of eyepieces I have had and tested, threshold differences have become very easy to detect.  My experience demonstrates to me that it takes very little difference in a design or execution to make threshold differences, and have seen it in same designs and same manufacturers where the only difference was the coating efficiency, so a very small transmission difference.  Proof enough for me, direct experience, to know it has an impact and that it is observable.  And like all things, depends on how important the small gain is for one to judge it as consequential or inconsequential.  Depending on my observing task at the time it certainly can be consequential.  But if I am just casually observing for enjoyment only, then the small gain is inconsequential.  But we should never judge for others as to whether it is or not, as this is their judgment and decision to make.  But does it make a difference at the eyepiece?  Based on my experiences...yes.  YMMV :grin:



#18 jackofalltrades

jackofalltrades

    Vanguard

  • -----
  • Posts: 2015
  • Joined: 05 Oct 2014

Posted 06 December 2015 - 11:08 PM

XWs reach about 96% transmission at 550nm: http://pentaxplus.jp...h/xo-xw/63.html

 

Transmission isn't the only thing that influences what you see.

The spectrum of transmission and its correspondence to the spectral response of your eye and the spectral response of the star being viewed.

 

And an eyepiece with LESS scatter may appear darker because the background sky will appear darker.  

A darker background could indicate lower transmission, but it could also indicate less scatter.

 

I've done stellar magnitude limiting magnitude searches many many times, using the charts in Roger Clark's "Visual Astronomy of the Deep Sky" and found

that variations from eyepiece to eyepiece were on the level of 0.1 magnitude or less (consistent with the measurements) but varied from night to night over 0.2 magnitudes.

 

The ZAOs tested likely were not fully multi-coated.  Many eyepieces of the era had simple MgF2 coatings.

 

Your last statement says it all.  One factor seldom mentioned is how closely the execution of the sample matches the design.  Everything made has +/- tolerances.  That might go a long way toward explaining why 3 samples of the same eyepiece may have minute variations.

Thanks Don, that makes sense.  I guess though, I should've maybe clarified my comment about being darker though, which I highlighted your reply.  What I was referring to wrt the TV Plossl being darker, even though it shows as being the highest throughput; what I've seen compared to other eyepieces, such as my current Tak Abbes and other minimal glass, is that when comparing side by side on DSO's, the TV gives a bit more trouble with seeing stars at the edge of visibility than the others, and especially color accuracy and rendition.  Even my Hyperions/Stratus have better color accuracy, brilliance and rendition than I find the TV Plossls - sorry, I know saying that here is heresy and you all will likely burn me at the stake for saying it, but it's the truth by my own Mk1 eyeballs.  

 

I doubt the Hyperions/Stratus have anywhere near the rated transmission or lack of scatter the TV Plossls have.  I've experienced the same on planetary nebula.  For one example, just last night, I was outside looking at NGC 7662 (Blue Snowball) nebula.  With the TV Plossls, I often had more difficulty seeing color in it; seeing color was very much seeing dependent in those eyepieces.  Yet through the same scope, with my so-called "junk" 8mm Hyperion :), I can easily see it as bright blue, and can even see the eyeballs of the two offset shells of gas within the nebula, with one side of both shells being brighter, giving it the characteristic appearance of the number 3.  The 8mm TV Plossl never showed that.  That's what I was referring to by darker.  And yes, the TV Plossls were clean and pristine, and wonderful on Jupiter, but a pain on anything else.

 

Anyway, thanks for the info, and sorry if I hijacked or took the thread away from the subject of ZAO.  I'll go back to reading it now.



#19 SandyHouTex

SandyHouTex

    Skylab

  • *****
  • Posts: 4060
  • Joined: 02 Jun 2009
  • Loc: Houston, Texas, USA

Posted 07 December 2015 - 10:13 AM

Here's an interesting list of eyepieces and their transmissions:

 

http://www.amateuras.../tips/tips3.htm

 

CS!

 

Greg

I find it interesting that they ZAOs have no better transmission than the Kasai orthos ($100 apiece) and are beaten by the Pentax O-6.



#20 Paul G

Paul G

    Cosmos

  • *****
  • Posts: 8523
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 07 December 2015 - 12:47 PM

Very interesting chart, I hadn't seen that before.  How do the findings correspond to other reports, where one eyepiece is reported as darker or lacking transparency compared to others?  The TV Plossl readily comes to mind.  It has the highest transmission (efficiency) according to those tests, yet according to many (my own eyes included) it seems just a tad bit darker wrt color rendering and faint star/object visibility.  The T6's, which I've always considered a pretty clean glass, didn't rate as well; and neither did the ZAO's, supposedly one of the holy grails - sts - which rate about equal to the T6's.  Of course if I'm understanding correctly, the ZAO's advantage is glass polish; but wouldn't that affect scatter which would affect transmission throughput? 

 

There's back scatter and forward scatter. Back scatter, which reduces transmission, is affected by the AR coatings. Forward scatter, which doesn't adversely affect transmission but does reduce contrast, is affected by degree of polish and imperfections in the glass like micro bubbles, inclusions, and internal striae.

 

When you compare eyepieces in the chart keep in mind anything above about 90% is indistinguishable from the theoretically perfect eyepiece Don described as far as transmission. Differences seen in "darkness" or "brightness" have to be due to something other than transmission, like contrast, scatter, etc. Of interest is that the 3-6 Nagler did so well, besting the Leica zoom. All TeleVue eyepieces now have tuned AR coatings, optimized for the index of each piece of glass, like the ZAOs. 


Edited by Paul G, 08 December 2015 - 12:53 PM.

  • turtle86 likes this

#21 jackofalltrades

jackofalltrades

    Vanguard

  • -----
  • Posts: 2015
  • Joined: 05 Oct 2014

Posted 07 December 2015 - 01:53 PM

I noticed that too on the Nagler Zoom, and assuming since this is an old(er) test list, the newer coatings on the current models will perform better.  Then again, I don't like to assume.

 

Anyway, I've actually been thinking of getting a TV 3-6 to compare against my Tak and UO Abbes to see which I prefer on planets.  I'm wondering if the TV might not be the better choice as you can really dial it in to match the seeing, not to mention the longer eye relief.  Only thing keeps holding me up is I worry the Nagler Zoom will give up too much to the Abbes wrt sharpness.



#22 Paul G

Paul G

    Cosmos

  • *****
  • Posts: 8523
  • Joined: 08 May 2003
  • Loc: Freedonia

Posted 07 December 2015 - 02:10 PM

I use the TV 3-6 a lot. The ability to dial it in to match the seeing is really helpful.


  • Sarkikos and george tatsis like this

#23 junomike

junomike

    Hubble

  • *****
  • Moderators
  • Posts: 16948
  • Joined: 07 Sep 2009
  • Loc: Ontario

Posted 07 December 2015 - 06:21 PM

I use the TV 3-6 a lot. The ability to dial it in to match the seeing is really helpful.

Matching the perfect magnification can sometimes trump the "simple glass" if the F/L isn't equal.

When equal however I prefer the "simple glass".

TVZ 3 - 6 is a keeper In my case!

 

Mike



#24 RAKing

RAKing

    Cosmos

  • *****
  • Posts: 8562
  • Joined: 28 Dec 2007
  • Loc: West of the D.C. Nebula

Posted 09 December 2015 - 08:49 AM

 

Here's an interesting list of eyepieces and their transmissions:

 

http://www.amateuras.../tips/tips3.htm

 

CS!

 

Greg

I find it interesting that they ZAOs have no better transmission than the Kasai orthos ($100 apiece) and are beaten by the Pentax O-6.

 

 

I find the results of the T6 Naglers (and 16T5) to also be very interesting.

 

Ron



#25 areyoukiddingme

areyoukiddingme

    Skylab

  • *****
  • Posts: 4373
  • Joined: 18 Nov 2012

Posted 09 December 2015 - 06:15 PM

FWIW, the theoretical maximum transmission of a 4 element multi-coated eyepiece with 4 air-to-glass surfaces is 98.0%, so treat any measurement above that as "approximate".

 

As to response to a single photon, read:

http://math.ucr.edu/...e_a_photon.html

 

I agree about the Nagler being interesting. Looks like an outlier if Don's point about light loss is correct.

 

So, another question . . . How solid is the physics behind the claim for 98% transmission for 4 air-to-glass surfaces?

 

It occurs to me that if this theory is very solid indeed, it gives us the ability to estimate measurement error in the table.

 

For example, the Pentax 0-18 is rated at 98.34% max transmission.

 

Using only that eyepiece we have a minimal error of +/- .34%

 

If we rinse and repeat comparing the theoretical transmission with the higher element eyepieces and look for any that have above theoretical transmission, we can consider these as highly conservative errors.

 

If the 98% figure means a .5% loss per lens, then theoretical max for 5 elements is 97.5% (obviously correct me if this is wrong). Nothing in the table exceeds this maximum. So no information there.

 

However, I believe the Type 6 Nagler has 7 elements, meaning a max 96.5% transmission. And yet the measure for the 9mm claims 96.96% transmission, but a theoretical max of 96.5. A +/- .46% error.

 

If my assumptions are correct, then we probably want to consider the errors at the very least .5%.




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics