Abbe-König prisms (1 Viewer)

[ReinierB]

What I wonder as well: what is exactly the advantage of Abbe-König prisms? Is it only the brighness or is it more than that? Swarovski SLC 56 has Abbe-König prisms and achieve 93% transmission (the SLC 42 doesn't have Abbe-König and has "only" 91% transmission).
The Zeiss conquest 56 has Abbe-König (when I'm right), but "only" has 90% transmission and it's the same as the Conquest 42 with schmidt pechan prisms. So that's confusing me.

Is it more than just the transmission/brightness what makes Abbe-König prisms attractive? More pop? More 3D?

 

[Paultricounty]

What I wonder as well: what is exactly the advantage of Abbe-König prisms? Is it only the brighness or is it more than that? Swarovski SLC 56 has Abbe-König prisms and achieve 93% transmission (the SLC 42 doesn't have Abbe-König and has "only" 91% transmission).
The Zeiss conquest 56 has Abbe-König (when I'm right), but "only" has 90% transmission and it's the same as the Conquest 42 with schmidt pechan prisms. So that's confusing me.

Is it more than just the transmission/brightness what makes Abbe-König prisms attractive? More pop? More 3D?

This is a good question, I’m sure this has been covered before in some discussions but without digging through old posts I’ll share my thoughts. I’ve recently learned that it’s not all about light transmission, if we’re talking about brightness. I don’t think people can see the difference between 90% and 92%. In the past I’ve fallen for the allbinos stat machine , in that the higher number is a brighter optic or at the very least that’s what I’ve taken away from the numbers on that website. I’ve learned that there are other factors that go into making a bright pair of binoculars, such as coatings to name one. A perfect example is the Vortex Razor HD and UHD, both tested (taken with a grain of salt) at the same 90%, yet the UHD is clearly and substantially brighter and has now become one of my favorite low light 42mm binos.

The improved 3D impression may have to do with the further separation on the AK prisms. This is something that jumps right out at you when you compare a wide field vintage porro 7x35 to a more modern porro of the same configuration.

Bill Cook went into this in a few discussions, as well as a few other highly regarded optics gurus here on BF.

Paul

 

[William Lewis]

Ak prism have the same separation as sp prisms, they do tend to lead to a larger (longer) binocular than sp prisms though as they are inherently longer. They are still a type of roof prism though so split the light cone on one roof edge as part of the process of turning the view the right way up.

The advantage of them is that they bend the light around through total internal reflection whilst still having a sp like form factor i.e. not a porro. Sp prisms that have surfaces that need to both reflect and transmit light through them which tend to lead to slightly less transmission all other things being equal.

Will

 

[Pinewood]

Hello,

If binoculars with AK prisms are longer than an S-P binocular, there might be some reduction of chromatic aberration but with greater size and weight. My old Dialyt ClassiC 7x42, with its AK prism and moving bridge, rather than internal focussing, suppresses chromatic aberration, quite well.
Yes, an AK binocular may show some stereopsis.

Stay safe,
Arthur

 

[GrampaTom]

This was quite thoroughly discussed back in February. You can read about it here:

A comparison of prism types, and why the Schmidt Pechan seems to have won the premium binoculars

The prism is the heart of a prismatic binocular, the most critical piece of the technology that converts an inverted and inaccessible image, to a natural extension of the eye of the expected orientation and light path. This is achieved through reflections, many reflections, especially if one...

www.birdforum.net

Seemed in retrospect, there were some who thought AK prisms superior theoretically, but then it evolved there was more going on than just prism selection to the performance of the bino "package"

 

[William Lewis]

Hello,

If binoculars with AK prisms are longer than an S-P binocular, there might be some reduction of chromatic aberration but with greater size and weight. My old Dialyt ClassiC 7x42, with its AK prism and moving bridge, rather than internal focussing, suppresses chromatic aberration, quite well.
Yes, an AK binocular may show some stereopsis.

Stay safe,
Arthur

Although the instrument is longer the light path is straighter so the f ratio will be broadly similar - it's more likely the moving eye piece focusing lessening c.a.

 

[Hermann]

The advantage of them is that they bend the light around through total internal reflection whilst still having a sp like form factor i.e. not a porro. Sp prisms that have surfaces that need to both reflect and transmit light through them which tend to lead to slightly less transmission all other things being equal.

That's the point. Higher transmission if all other things are equal. And even if it's only a small difference nowadays, say 2% (it used to be quite a bit higher when aluminium or silver coatings were used) , AK prism are "better" in that respect. BTW, I'm not sure people won't notice that difference myself.

Another point people tend to forget, is that fewer things can go wrong in the production process. Total internal reflection is always "perfect", reflective coatings, even dieeletric coatings, may be faulty, or, shall we say, "less than perfect".

Hermann

 

[Hermann]

I’ve recently learned that it’s not all about light transmission, if we’re talking about brightness.

When it comes to viewing in low light, it's about transmission at differenct wavelengths (ideally the curve should be flat) and contrast. And as all light that is somehow "lost" in the binocular due e.g. to reflections, with the obvious exception of light that is simply absorbed by the glass, remains in the binocular and lowers contrast to some extent, high transmission across the spectrum is always desirable. Porro prisms of whatever type and AK prisms are therefore superior to SP prisms.

There's a reason why Nikon used AK prisms in the WX, optically undoubtedly the best binocular on the market (although pretty useless for normal birding). And why the Habicht is so good optically.

Hermann

 

[tenex]

The Zeiss conquest 56 has Abbe-König (when I'm right), but "only" has 90% transmission and it's the same as the Conquest 42 with schmidt pechan prisms. So that's confusing me.

Abbe-König prisms should have higher transmission than Schmidt-Pechan themselves, due to lossless internal reflection, but the transmission of the entire instrument depends also on the number of elements and quality of coatings. So why did Zeiss not bother to achieve better overall transmission in Conquest 56 (presumably cost) or in that case, why use AK prisms at all? (That might actually be cost too, as AKs should be cheaper to make, requiring fewer coatings.) Similarly, one could ask why SLC 56 achieves "only" 93% when HT 54 has 95%? Presumably Zeiss was working hard to make up for the smaller aperture, but still Swaro could have done a bit better, and why they didn't bother you'd have to ask. Possibly cost and price point, again.

Personally I prefer AK prisms because I don't value compactness as much as I once did, and hate the thought of how all those surfaces and coatings in SPs must mangle the light, though that's surely romantic nonsense in a quantum world.

 

[Paultricounty]

That's the point. Higher transmission if all other things are equal. And even if it's only a small difference nowadays, say 2% (it used to be quite a bit higher when aluminium or silver coatings were used) , AK prism are "better" in that respect. BTW, I'm not sure people won't notice that difference myself.

Another point people tend to forget, is that fewer things can go wrong in the production process. Total internal reflection is always "perfect", reflective coatings, even dieeletric coatings, may be faulty, or, shall we say, "less than perfect".

Hermann

Herman, when you say, if all other things are equal, how would we measure that? How could all things be equal when comparing an AK and a SP? Or are you just talking about equal quality glass, coatings and good application.

My perfect example is the Vortex Razor HD (SP) and Razor UHD (AK) which both measured 86% light transmission on allbinos. With out a doubt and confirmed with multiple observers the UHD by far is brighter. Most likely all things are not equal considering UHD is almost double the price, maybe I answered my own question. Another thing that needs consideration would be how accurate the testing method testing method, how many times the testing method was changed and possibly unit variation, could be the HD was a cherry and the UHD was a dud.

Another example is EDG 88%, Conquest 92% and the SF 93%, none of which have AK prisms, yet the vortex UHD is brighter than the the first two and at least equal to or even brighter than the SF. All of my conclusions of this , is with side by comparisons in different lighting conditions, and I have no bias.


Paul

 

[Maljunulo]

It’s all objective until you add an observer ……. then it goes downhill.

 

[quincy88]

Maybe it's all in my head due to marketing hype, or maybe they are just superior binoculars, but the AKs that I own are exceptionally bright.
My pair of FL 7s is the brightest pair of binoculars that I have ever owned. I'm always a little surprised by the noticeably brighter image when I pick them up after using other pairs for a while. And my SLC 15s are as bright as almost anything else in the Alpha category despite the smaller exit pupil.
Other than brightness, I have not noticed any advantage. Both the FLs and SLCs are very high performers comparable with other very high performers.

 

[Hermann]

Herman, when you say, if all other things are equal, how would we measure that? How could all things be equal when comparing an AK and a SP? Or are you just talking about equal quality glass, coatings and good application.

Equal build quality (glass, coatings and so on). Measurement of the transmission values across the spectrum on high-quality equipment like the stuff Gijs uses. His measurements are probably the most accurate that are publically available. I don't doubt Leica, Zeiss and the like do their own measurements of their competitors bins, but these are not publically available.

My perfect example is the Vortex Razor HD (SP) and Razor UHD (AK) which both measured 86% light transmission on allbinos. With out a doubt and confirmed with multiple observers the UHD by far is brighter. Most likely all things are not equal considering UHD is almost double the price, maybe I answered my own question. Another thing that needs consideration would be how accurate the testing method testing method, how many times the testing method was changed and possibly unit variation, could be the HD was a cherry and the UHD was a dud.

Allbinos ... No comment. I don't take their measurements seriously. Don't forget, at one time they measured one particular porro at 98% transmission. That same porro had 86% transmission in a different test ...

Another example is EDG 88%, Conquest 92% and the SF 93%, none of which have AK prisms, yet the vortex UHD is brighter than the the first two and at least equal to or even brighter than the SF. All of my conclusions of this , is with side by comparisons in different lighting conditions, and I have no bias.

Like I said, I wouldn't trust Allbinos. And maybe, just maybe, the Vortex UHD is really good. That's possible. OTOH, your eyes aren't calibrated, and maybe they are particularly sensitive to some wavelengths the Vortex transmits very well ... It would be interesting to see measurements of that particular binocular done by a professional.

How does the Vortex compare to a Habicht? That would be a nice comparison, because the transmission values across the spectrum for the Habicht are well known.

Hermann

 

[Paultricounty]

Equal build quality (glass, coatings and so on). Measurement of the transmission values across the spectrum on high-quality equipment like the stuff Gijs uses. His measurements are probably the most accurate that are publically available. I don't doubt Leica, Zeiss and the like do their own measurements of their competitors bins, but these are not publically available.

Allbinos ... No comment. I don't take their measurements seriously. Don't forget, at one time they measured one particular porro at 98% transmission. That same porro had 86% transmission in a different test ...

Like I said, I wouldn't trust Allbinos. And maybe, just maybe, the Vortex UHD is really good. That's possible. OTOH, your eyes aren't calibrated, and maybe they are particularly sensitive to some wavelengths the Vortex transmits very well ... It would be interesting to see measurements of that particular binocular done by a professional.

How does the Vortex compare to a Habicht? That would be a nice comparison, because the transmission values across the spectrum for the Habicht are well known.

Hermann

The Habicht 7x42 are my brightest binoculars under any conditions. But the Swaro has a 6mm exit pupal, it’s a Swaro, a porro , less glass and coatings , so they are brighter than anything I’ve ever used. I’d say my Vortex UHD and Noctivids are my brightest roofs, and that’s including my EL’s, SF’s and NL’s.

Say no more about Allbinos 🙏🏼


Paul

 

[[email protected]]

The Habicht 7x42 are my brightest binoculars under any conditions. But the Swaro has a 6mm exit pupal, it’s a Swaro, a porro , less glass and coatings , so they are brighter than anything I’ve ever used. I’d say my Vortex UHD and Noctivids are my brightest roofs, and that’s including my EL’s, SF’s and NL’s.

Say no more about Allbinos 🙏🏼


Paul

I agree. The Swarovski Habicht 7x42 is the brightest binocular I have ever used under any condition. With a 6 mm exit pupil and 96% transmission due to it being a porro with total internal reflection in the prism and less glass with a simple 3 element Kellner eyepiece, it is very hard to beat. For me, it is even brighter than the big roof prism binoculars like the the Swarovski 8x56 SLC or Zeiss HT 8x54 all the time day or low light. But it probably depends on your age. If you are young and less than 30 years old and your pupils are dilating more than 7 mm, the big roofs might be brighter in low light but not in the daytime. For us older codgers, the Habicht 7x42 is the brightest binocular available. That is the single defining characteristic that makes it so unusual. That and it's superb stereoscopic view. It is so dang bright! It is almost like there is a battery inside of it, illuminating the view. It is hard to believe it is just glass and coatings making it so bright.

I love Allbinos.

 

[ReinierB]

The Habicht 7x42 are my brightest binoculars under any conditions. But the Swaro has a 6mm exit pupal, it’s a Swaro, a porro , less glass and coatings , so they are brighter than anything I’ve ever used. I’d say my Vortex UHD and Noctivids are my brightest roofs, and that’s including my EL’s, SF’s and NL’s.

Say no more about Allbinos 🙏🏼


Paul

That is interesting to hear. So you would prefer the Noctovid of the EL. SF en NL when using in dim light? I read different things about the Noctovids. There are fans (Optioca Exotica:

) and not really big fans (Leica 10x42 Noctivid Review).
The transmission is 92% I read? They look rather simple and do no not have a large AFOV and are quite heavy. What is it what makes them "better" than say NL or SF? The contract? The brighness? The colours?

 

[Paultricounty]

That is interesting to hear. So you would prefer the Noctovid of the EL. SF en NL when using in dim light? I read different things about the Noctovids. There are fans (Optioca Exotica:

) and not really big fans (Leica 10x42 Noctivid Review).
The transmission is 92% I read? They look rather simple and do no not have a large AFOV and are quite heavy. What is it what makes them "better" than say NL or SF? The contract? The brighness? The colours?

I’m a huge fan of Ion (Optica exotica) , he’s partly responsible for part of my binocular affliction (really a passion , but I’m humoring Grampatom) and has cost me a lot of money 🤪. Let’s start off by saying that all three the NL, SF and Noctivids we could throw in the EL’s, are all top of the line , best of the best in binoculars. All have have incredible image qualities and all have that wow factor when looking through them. As I’m sure you’ve read on Birdforum , many choose what works best for them and what they like the most from binoculars at this level. Therefore optically one is not better than the other, unless you’re looking for or desire some specific trait, like a a very wide FOV, or a completely flat FOV all the way to the edge , then you could say one has this or that , that is better in one area or another.

As far as build quality and feel, the Noctivids are imo the best of all of them, there I said it, the BEST. The materials, the fit and finish , the elegance and feel is second to none. The Noctivids are about the same weight as the NL’s, SF’s are lighter. The weight does give a very quality feel, but that’s subjective. I have all four and optically I find the image quality in the Noctivids richer , more color pops out at me, so very warm (delicious ) and easier in my eyes over longer observing sessions. All of these binoculars are bright, all have high transmission levels, I think the brightness has more to do with the coatings and the individuals perception from the optics.

If I had to choose one pair of binoculars , it would either be the 8x42 Noctivids or the 10x42NL’s. A real tough choice for multiple reasons.

Paul

 

[Maljunulo]

I would respectfully suggest that your statement should be either “I feel that the Noctivids are the best.” or “The Noctivids are the best for me“

This is a rather subjective area.

 

[Paultricounty]

I would respectfully suggest that your statement should be either “I feel that the Noctivids are the best.” or “The Noctivids are the best for me“

This is a rather subjective area.

Nope, they’re built the best. 🙏🏼✌🏼

 

[Canip]

Nope, they’re built the best.

Thank you for your OPINION 😉