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Abbe-König versus Schmidt with dielectric coatings (2 Viewers)

Hermann said:
That's interesting. So the dielectric coatings have effectively narrowed the gap between binoculars with Abbe-König and Schmidt-Pechan prisms quite a bit. A 2% difference isn't all that much.



This partly explains why some old binoculars with simple coatings still perform quite well. By the way, I think the current Swarovski Habicht porros, especially the 7x42 with its simple eyepieces, are another example of a highly efficient design with a minimum number of glass to air surfaces.

Of course I realize that measured light transmission is only one factor. The transmitted frequencies and the transmission at different frequencies are at least as important, and perceived brightness may be quite different from measured transmission. The Leica HD range seems to my eyes quite bright, especially in the right kind of light, although the measured transmission values are lower than those of some of Leica's competitors. The Nikon HG range, despite it's Schmidt-Pechan prisms and "oldfashioned" silver coatings on the prisms, isn't really "dim" compared to binoculars with higher transmission values and provide a very pleasing image.

But what these figures show is that in two otherwise identical binoculars Abbe-König prisms (and of course porro prisms) are still superior to Schmidt-Pechan prisms, despite modern dielectric coatings. Whether that superiority makes a visible difference in the field, is another matter. I think it may do, in some situations, but I'm not sure.

However, things may well be different in scopes. With scopes I think the choice of prisms may well be more important than with binoculars.

Hermann
Click to expand...

"But what these figures show is that in two otherwise identical binoculars Abbe-König prisms (and of course porro prisms) are still superior to Schmidt-Pechan prisms, despite modern dielectric coatings. Whether that superiority makes a visible difference in the field, is another matter. I think it may do, in some situations, but I'm not sure."

Did we agree that AK prisms were superior? I thought they were about equal from these tests:

The other recent test from Aug. 2010, is the Europa 42 mm. tests that do
include the new SV and SLC HD.

The results are much the same:

Night 500 nm. Day 550 nm.

Swarovision 8.5x42 89% 90 %
Swarovision 10 x42 84 86
Swaro. SLC HD 8x42 89 92
Zeiss FL 8x42 88% 92%


Note that the comparison is mostly 8x, but it shows how the 10x SV is
4-5% less in transmission than the 8.5x42 SV.

So it follows the SLC HD 8x42 is a bit brighter than the SV 8.5x42.

It appears that Swarovski has pretty much equalled the the Zeiss with the
Abbe Konig design.
 
Hermann said:
Well, this opens another Pandora's box. Are all phase corrections coatings equally efficient? I'm not sure about that myself. And do any such differences in their efficiency - if they do exist - make a visible difference in binoculars? Or in scopes with roof prisms, with their much higher magnification?

Hermann
Click to expand...

I would think phase correction coatings would be similar to AR coatings in that they would vary alot in quality from binocular to binocular.
 
I would think that all coating technologies for lenses and prisms have had a high degree of variability between manufacturers. I would suspect that shortly we will see manufacturers using nanotechnology coating techniques which will allow much thinner and more uniform coatings, and that in the near term, advances in resolution, brightness and contrast will be the direct result of the application of these nano technologies.

Tom
 
[email protected] said:
Did we agree that AK prisms were superior? I thought they were about equal from these tests:

Night 500 nm. Day 550 nm.

Swarovision 8.5x42 89% 90 %
Swarovision 10 x42 84 86
Swaro. SLC HD 8x42 89 92
Zeiss FL 8x42 88% 92%


Note that the comparison is mostly 8x, but it shows how the 10x SV is
4-5% less in transmission than the 8.5x42 SV.

So it follows the SLC HD 8x42 is a bit brighter than the SV 8.5x42.

It appears that Swarovski has pretty much equalled the the Zeiss with the
Abbe Konig design.
Click to expand...

These are tests of complete instruments, not prisms, so nothing can be inferred about the efficiency of the prism designs from these numbers.

It does not "follow" that 8x binoculars have higher light transmission than 10x binoculars. Magnification has no effect on light transmission, so the large discrepancy between the 8.5x and 10x SV results needs some explanation.

In the span of this thread you have quickly changed from not trusting lab measurements to cherry picking one that supports your agenda. If I were inclined to do that I would cherry pick this test, which measured the 8x56 FL at 94.5%, day and 94%, night.

http://www.zeiss.de/C12567A800347580/EmbedTitelIntern/Test_Pirsch_11-06/$File/Test_Pirsch_11_2006.pdf

I'll be accepting that one since it proves that my binocular is brighter than yours. Why do I feel like I'm back on a kindergarden playground?
 
henry link said:
These are tests of complete instruments, not prisms, so nothing can be inferred about the efficiency of the prism designs from these numbers.

It does not "follow" that 8x binoculars have higher light transmission than 10x binoculars. Magnification has no effect on light transmission, so the large discrepancy between the 8.5x and 10x SV results needs some explanation.

In the span of this thread you have quickly changed from not trusting lab measurements to cherry picking one that supports your agenda. If I were inclined to do that I would cherry pick this test, which measured the 8x56 FL at 94.5%, day and 94%, night.

http://www.zeiss.de/C12567A800347580/EmbedTitelIntern/Test_Pirsch_11-06/$File/Test_Pirsch_11_2006.pdf

I'll be accepting that one since it proves that my binocular is brighter than yours. Why do I feel like I'm back on a kindergarden playground?
Click to expand...

"These are tests of complete instruments, not prisms, so nothing can be inferred about the efficiency of the prism designs from these numbers."

I don't really agree with that statement. These are top binoculars with excellent AR coatings so I think if the prism was a real weak spot it would tend to show up in their performance. Also, these figures show that if the SP prism with it's 6 reflecting surfaces is less efficient than the AK prism with it's 4 reflecting surfaces it is easy to compensate with better coatings because obviously the performance is close.

I think these lab tests are close and I don't really think you are going to even notice a percent or two of light transmission. My point is I don't think an AK prism has any big advantage over the SP prism in actual performance anymore even though from a physics standpoint is does. Bettter more efficient coatings are narrowing the gap to the point where it is non-existent.

Do you still have that beast?
 
I believe Henry said in an earlier post that Zeiss acknowledges a 2% difference in transmission between the two prism types. This is probably close to an irreducible minimum and an engineering fact that would have to be compensated for elsewhere in the overall instrument design. So, the strict answer to Hermann's original question is yes, "... the Abbe-König roof prism [is still] superior in transmission and contrast to the Schmidt roof prism..." even though dielectric coatings are used instead of silver coatings.

As a separate issue, one might ask if designers have succeeded in overcoming the A-K transmission advantage, and I guess the answer would also be, yes. Both types of prisms are now used with equal success.

Ed
PS. Henry, I think you're coming around to my side. Understanding child's play is important! ;)
 
Last edited:
henry link said:
These are tests of complete instruments, not prisms, so nothing can be inferred about the efficiency of the prism designs from these numbers.

It does not "follow" that 8x binoculars have higher light transmission than 10x binoculars. Magnification has no effect on light transmission, so the large discrepancy between the 8.5x and 10x SV results needs some explanation.

In the span of this thread you have quickly changed from not trusting lab measurements to cherry picking one that supports your agenda. If I were inclined to do that I would cherry pick this test, which measured the 8x56 FL at 94.5%, day and 94%, night.

http://www.zeiss.de/C12567A800347580/EmbedTitelIntern/Test_Pirsch_11-06/$File/Test_Pirsch_11_2006.pdf

I'll be accepting that one since it proves that my binocular is brighter than yours. Why do I feel like I'm back on a kindergarden playground?
Click to expand...


Let's cherry pick some more and take Allbinos figure for the 10 FL [95.5%], makes the 10 SV look like a Sears brand in comparison.;)
 
elkcub said:
I believe Henry said in an earlier post that Zeiss acknowledges a 2% difference in transmission between the two prism types. This is probably close to an irreducible minimum and an engineering fact that would have to be compensated for elsewhere in the overall instrument design. So, the strict answer to Hermann's original question is yes, "... the Abbe-König roof prism [is still] superior in transmission and contrast to the Schmidt roof prism..." even though dielectric coatings are used instead of silver coatings.

As a separate issue, one might ask if designers have succeeded in overcoming the A-K transmission advantage, and I guess the answer would also be, yes. Both types of prisms are now used with equal success.

Ed
PS. Henry, I think you're coming around to my side. Understanding child's play is important! ;)
Click to expand...

"I believe Henry said in an earlier post that Zeiss acknowledges a 2% difference in transmission between the two prism types. This is probably close to an irreducible minimum and an engineering fact that would have to be compensated for elsewhere in the overall instrument design. So, the strict answer to Hermann's original question is yes, "... the Abbe-König roof prism [is still] superior in transmission and contrast to the Schmidt roof prism..." even though dielectric coatings are used instead of silver coatings."
That's pure baloney! You can't conclude an AK prism has 2% better transmission than an SP prism because somebody at Zeiss SAID they do on THEIR binoculars. You missed the point of the whole thread. The SV with the SP prism is transmitting as much light as the FL with the AK prism. You can't trust what Zeiss says and take it as fact. What makes you think a Zeiss SP prism is exactly the same as a Swarovision SP prism anyway? The Swarovision SP prism could be superior and transmit more light than the Zeiss SP prism. The only way to prove it would be to have an independent lab test the two prisms independently out of the binoculars and see which one transmits more light. Take a Swarovision SP prism and a Zeiss FL AK prism and test them. Henry you could probably do that couldn't you and then we could answer this question once and for all.
 
Last edited:
ronh said:
I just got one of those Docters and verily, fire shoots out the back. It is, at last, the large binocular of my dreams! That's my fanboy rave of the week.


Ron


QUOTE]


The Docter Nobilem 10x50, I presume?
(A respectable porro, for sure ;) )

Best regards,

Ronald
Click to expand...
 
Ronald,
No, the 15x60. I am a stargazer, and especially fond of double stars. My big binocular was a 16x70 Fujinon for several years, but despite some good things about it, I was never satisfied with the slightly blobby star images. I'd stop it down to 60mm, but it still wasn't good enough. The Docter does it for me in this department.
Ron
 
ronh said:
Ronald,
No, the 15x60. I am a stargazer, and especially fond of double stars. My big binocular was a 16x70 Fujinon for several years, but despite some good things about it, I was never satisfied with the slightly blobby star images. I'd stop it down to 60mm, but it still wasn't good enough. The Docter does it for me in this department.
Ron
Click to expand...

>Gasp< A 15x60?!?

Congratulations on finding a REALLY respectable porro, Ron.
Do you use some kind of support, or are you capable of hand holding them?
I had some 15x70's in the early 80's, which, hand held, gave me several images of the same bird running around the entire FOV due to shaking. I sold them to a keen seawatcher. Seawatching hadn't appeared in my birding exploits at the time, and the notion that one can use a tripod to mount bins on, hadn't crossed my mind yet.

Enjoy your Docters!

Best regards,

Ronald
 
Thanks to all those who tried to answer my question, especially to Henry, Ed and Ron for their thoughts and explanations.

Hermann
 
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