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Abbe-Konig Prisms

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Old Wednesday 3rd January 2007, 02:05   #1
308CAL
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Abbe-Konig Prisms

Is Zeiss the only company that uses these type of prisms? Is there a reason why? I compared the 8x42's tonight in zeiss FL and leica ultravid and if there was any difference, my 23 year old eyes couldnt really tell, miniscule at best under the almost full moon.... the leica doesnt use these and thus is much more compact
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Old Wednesday 3rd January 2007, 11:35   #2
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Possibly not the only reasons but both of the gentleman that the prisms are named after worked for Zeiss early in its history and invented that particular prism configuration. There was an interesting link to a site with Zeiss's company history here a few weeks ago. All of the info was on it. Beyond that I do not know.

Quote:
Is there a reason why?
Why they use them? That particular prism design reflects light a low number of times when compared to the standard Schmidt Pechan design. This results in a higher light transmission figure and theoretically a brighter, sharper image.

I have seen the light transmission percentages posted here for both models in question and though your eyes were not able to detect it in the condition you compared them in there is a difference of about 5% favoring the FL.

Last edited by FrankD : Wednesday 3rd January 2007 at 15:33.
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Old Wednesday 3rd January 2007, 13:03   #3
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Abbe-Koenigs have 4 reflections, Schmidt-Pechans have 6, one of which is below the critical angle for total internal reflection, so that one has to be mirror coated. FWIW I don't have any trouble seeing a brighter image through the FL's compared to the Ultravids.

A test of light transmission that appeared in a German firearms journal in 2005 had the following measurements for so called "night" transmission, which I think must mean transmission around 410nm to correspond to maximum sensitivity of the dark adapted eye.

Zeiss 8x42 FL- 90.5%

Leica 10x42 Ultravid- 83.6%
Leica 10x50 Ultravid- 82.3%
Leica 12x50 Ultravid- 82.9%

Not all of this difference would be due to prisms. Zeiss claims only about a 2% difference between the FL's that use AK prisms and the FL's that use SP prisms with their particular dielectric mirror coating.

Last edited by henry link : Wednesday 3rd January 2007 at 14:59.
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Old Wednesday 3rd January 2007, 14:06   #4
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Quote:
Originally Posted by 308CAL
Is Zeiss the only company that uses these type of prisms? Is there a reason why? I compared the 8x42's tonight in zeiss FL and leica ultravid and if there was any difference, my 23 year old eyes couldnt really tell, miniscule at best under the almost full moon.... the leica doesnt use these and thus is much more compact
The Optolyth Royal and ViaNova binoculars use abbe koenig prisms, although I suspect the lack of popularity for this prism configuration is a function of increased size of the binocular, coupled with added manufacturing complexity and resulting higher costs. I also suspect that the inherent advantages of the design have, as you have observed, have been minimized by the use of vastly improved refectivity surfaces for the current crop of Schmidt Pechan prisms. Pre-war Hensoldt binoculars also used abbe koenig prisms and are the actual forerunners of the current Zeiss designs.
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Old Wednesday 3rd January 2007, 20:16   #5
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http://www.zeiss.de/C12567A800347580...ch_11_2006.pdf

well according to this link. the 8x50 trinovid had 81% and the 8x50 ultravid had 89% day and 88% night....

According ot the truth about optics page, "Finally, within the past few years, high end makers have experimented with replacing the mirrored surface of the Schmidt Pechan system with very complex multi-layer coatings of high and low index of refraction minerals. In order to accomplish something approaching total internal reflection, the spectrum of visible light must be broken up into a high number of sub-spectrums, and coating layers developed for each division.

The first efforts used over 30 layers of coatings for a 2-3% increase in efficiency. More recent coating systems employ over 70 layers, in multiple applications, to raise the efficiency of Schmidt Pechan systems to equal or exceed that of the best Abbe-Konig and porro systems." http://www.zbirding.info/zbirders/bl...g/default.aspx

also the graph shows dielectric mirror coatings superior to silver and right @ 100%
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Old Wednesday 3rd January 2007, 20:18   #6
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Quote:
Originally Posted by henry link
Abbe-Koenigs have 4 reflections, Schmidt-Pechans have 6, one of which is below the critical angle for total internal reflection, so that one has to be mirror coated. FWIW I don't have any trouble seeing a brighter image through the FL's compared to the Ultravids.

A test of light transmission that appeared in a German firearms journal in 2005 had the following measurements for so called "night" transmission, which I think must mean transmission around 410nm to correspond to maximum sensitivity of the dark adapted eye.

Zeiss 8x42 FL- 90.5%

Leica 10x42 Ultravid- 83.6%
Leica 10x50 Ultravid- 82.3%
Leica 12x50 Ultravid- 82.9%

Not all of this difference would be due to prisms. Zeiss claims only about a 2% difference between the FL's that use AK prisms and the FL's that use SP prisms with their particular dielectric mirror coating.
what was the 8x42 ultravid?
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Old Wednesday 3rd January 2007, 21:48   #7
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Unfortunately I couldn't make the Zeiss link work, but it wouldn't be the first time I've seen different labs come up with different measurements. For instance, a test in 2000 sent the very same pairs of binoculars to Leica and Swarovski for testing. There were measured differences of as much as 4% for the same binoculars. Besides different lab techniques, it's possible the wavelengths chosen for "night" and "day" transmission are not always the same (optics tend to lose transmission rapidly at wavelengths shorter than green so a graph of the entire visible spectrum is much better) and there is always sample variation which could be as high as 4-5%. A 10x42 Trinovid was included in the 2005 test. It's night transmission was 81.2%. The 8x42 Ultravid was not included, but there's no reason to think it would have measured significantly different from the other Ultravids in that particular test.

I don't see how SP prisms will ever have quite as high transmission as AK or Porro because of the larger number of reflections. If everything else is equal 1.5-2% lower transmission seems about right for an SP with 99.5% dielectric mirror coating compared to AK. A cemented Porro will be a little better than either from having only 2 glass to air surfaces. It's true the differences are small, but they still favor Porro and AK over SP. The statement in the prism article that the light effiiency of Schmidt-Pechan systems has been raised "... to equal or exceed the best Abbe-Konig and porro systems" just doesn't make any sense to me.

Last edited by henry link : Wednesday 3rd January 2007 at 22:50.
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Old Wednesday 3rd January 2007, 22:28   #8
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So will Abbe-Koenig prisms evr make it into a midsized unit. Judging by the difference in size of the Zeiss to cometing SP units it shouldn't have to bee much larger than the EL 32mm already are, although the EL midsize is a rather large midsize. I think the brightness to size ratio would justify it for a few people. Imagine an 8x30 SLC sized binocular with brightness greater than any other midsize, I think it would sell.
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Old Wednesday 3rd January 2007, 23:04   #9
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http://www.zeiss.de/C12567A800347580/EmbedTitelIntern/Test_Pirsch_11-06/$File/Test_Pirsch_11_2006.pdf
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Old Thursday 4th January 2007, 01:48   #10
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update
after looking and comparing at the 8x42's the last 2 days I have some observations:
*)The ultravid had a better image to the edges, the zeiss has something going on around the edges.
1) I much prefer the Leica eyecups, they fit my eyes better, "fit like a glove" comes to mind. The zeiss has larger cups that dont fit as "snug" for me...
2) The lower ring or halo effect I sometimes see in the zeiss annoys me to no end. As a hunter, I need lowlight performance, I am not looking at song birds at noon.. The zeiss is brighter slighlty but this annoying trait surpasses the brightness influence
3) The Leica is much more compact and feels "better" built. Maybe its because it is magnesium and the zeiss is some tupe of fancy fiber reinforced plastic? In reality, they are both very well built, but the Leica has the feel!
4)The Zeiss has a better case. The Leica has better occular covers, they fit snug and are flexible. Both binocs have useful objective covers.
5) The zeiss close focuses noticeable closer and sharper, but I dont need that.
6) both handled flare really well when tested at night with street lights and front porch lights. The zeiss may have been better but it wasnt across the board and neither produced an image that wasnt usuable
7) When comparing each binocular in each eye, the leica looked like it had a browner picture and the zeiss looked bluer. It reminded me of when you turn the brightness up on a TV and it sort of washed out the colors. I wouldnt say the colors were "washed out" though but were less "vivid" to me evber so slightly than the leica
8)The Leica offers a better warranty to the original purchaser but thats where it ends, the zeiss has a transferrable one, the leica doesn't

In the end, the Leica costs more and the eyes tell the story. Mine told me Leica, despite wanting to spend less for the zeiss. I totally was planning on ending up with the Zeiss when I decided to look at these 2, I was just planning on using the ultravid as brand to comare it with but it has the "look" and "feel" that fits "me"...BEST

Last edited by 308CAL : Thursday 4th January 2007 at 02:35.
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Old Thursday 4th January 2007, 11:19   #11
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I am glad to see you made an informed, well thought out decision on which binocular to purchase and use. I think you will be hard pressed to find a binocular that outperforms your Ultravid for many years to come.
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