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Nikon EDG 8x42 Schmidt-Pechan prisms (1 Viewer)

M

MBS

Well-known member
Hello,

Contrary to other makers (Zeiss, Swarovski...), the Nikon EDG models are equipped with Schmidt-Pechan prisms, rather than Abbe-König prisms.

Those Schmidt-Pechan prisms (and contrary to Abbe-König prisms) need multi-layer dielectric coating mirror processing to assure the best internal reflections.

Is there already any feedback about the capacity of such surface coatings to endure the test of time (at least for one decade) without any loss of mirroring quality.

In other words is there any possibility that, with time flowing, years after years, the coatings are prone to a deterioration, a peeling, a yellowing, etc.

Problems that can't append with Abbe-König prisms.

Perhaps is it to soon to be able to answer this question?

However, considering the price of such binoculars, to be sure that they are able to stay in good optical condition, years after years, is more than important.

Furthermore the case of a renown terrestrial telescope (used for birding) maker whose some models were prone to lose (through a partial peeling) their objective multi-layer surface treatment, make me a little bit cautious.

By the way, an interesting review of the Nikon EDG 8x42 model :
http://www.scopeviews.co.uk/NikonEDG8x42.htm

By,

MBS
 
Hi,

binoculars with Abbe-Koenig prisms are kinda rare, the vast majority of roof prism binocular models (including those from Zeiss and Swaro) uses Schmidt-Pechan.

Abbe-Koenig has indeed the advantage of not needing a mirrored face and also has no faces used in transmission and reflection at the same time (like SP).

But the optical industry has found that the customer wants the smallest and lightest binoculars possible and thus found ways to cope with those problems of SP prisms fairly well. If you want the optically best prsim system regardless of weight and size, Porro models are still available.

Joachim
 
Hi Joachim,

The problem with Porro prism binoculars is that, if I am not wrong, there isn't any model with these features: really waterproof, fog-proof, with central focusing, ED glasses, and fully multi-coated surfaces (oculars, prisms, objectives), in the 8 x 40 mm format.

Such a binocular being available, I will buy it, having always shown more interest in Porro prism binoculars than in roof prism models.

Because, at an equal level of performances, a Porro prism binocular is cheaper than a roof prism binocular (being less costly to made).

And, I am not specifically eager to own the smaller and lighter binocular available.

I know that roof prism binoculars are sturdier than Porro prism models, as regards decollimation, in case of chocks or vibrations, but high end Porro prism can be equipped with damping systems protecting prism cells against such problems (chocks and vibrations).

Furthermore, to recollimate a Porro prism binocular is probably easier to do than it is for a roof prism model, due to the complexity of internal mechanisms in roof prism binoculars (and complexity deals with repair cost).

As regards the longevity of the multi-layer dielectric coating mirror processing, used for high end roof prism binoculars, I stay a little bit skeptical about the evolution of this kind of manufacturing on the long run.

For the record, the high quality silvering (in fact this is aluminum that is used, protected by an other surface layer) of reflector telescope mirror(s) don't last for ever, either.

MBS
 
Last edited:
MBS said:
Hi Joachim,
The problem with Porro prism binoculars is that, if I am not wrong, there aren't any models with these features: really waterproof, fog-proof, with central focusing, ED glasses, and fully multi-coated surfaces (oculars, prisms, objectives), in the 8 x 40 mm format.
Such a binocular being available, I will buy it, having always being more interested in Porro Prism binocular than in roof prisms models.
Because, at an equal level of performances, a Porro prism binocular is cheaper than a roof prism binocular (being less costly to made).
MBS
Click to expand...
The Swarovski Habicht Porro's are pretty close to what you want and they come in 8x30, 7x42 and 10x40. Their 95% light transmission and high quality glass and EL coatings makes up for a slightly smaller aperture. You don't need ED glass in a porro design.
 
Last edited:
Hi Denco,

The problem with the Swarovski Porro prism models is that they aren't waterproof, but only chock proof (with their rubber armor).

I own a Nikon Action Extreme, in 7x35 mm, that is waterproof, but its optical performances (although on a par with their low price) are not those of Swarovski and sibling models.

If Fujinon had been a maker of 7x35 or 8x40 Porro prism binoculars, with the same technology (FMT-SX) used for their marine 7x50, 15x60 , etc., but this isn't the case.

And, with the Chinese brand offers, it is very difficult to sort between real gems, good models and awful binoculars.

So no solution up to now.

Regards,

MBS
 
Hi,

the Swaro website begs to disagree... all models of the Habicht series are marketed as gas fileld and 4m immersible.

Otherwise Swift Audubon 8.5x44 ED should also tick the boxes.

Joachim, who couldn't care less about waterproofing and enjoys his Nikons (E2 and SE)...
 
jring said:
Hi,

binoculars with Abbe-Koenig prisms are kinda rare, the vast majority of roof prism binocular models (including those from Zeiss and Swaro) uses Schmidt-Pechan.
Click to expand...

The Zeiss HT and Nikon WX are the only somewhat recently introduced binos with A-K prisms that I know of.

MBS said:
The problem with Porro prism binoculars is that, if I am not wrong, there isn't any model with these features: really waterproof, fog-proof, with central focusing, ED glasses, and fully multi-coated surfaces (oculars, prisms, objectives), in the 8 x 40 mm format.
Click to expand...

The Canon 10x42L IS WP comes close, as do the Leica Duovid (Perger porro prisms).
 
Hello MBS,

I must say the Swarovski Habicht serie are fully fogproof and waterproof. And, as I see, with a construction very few binoculars have today. The only thing is there are only three: 8x30, 7x42 and 10x40. And, unfortunately, the 8x30 GA version was discontinued many years ago....

Best Regards

PHA
 
MBS,

Don't forget that the roof prism surfaces of Abbe-König prisms also need a phase coating and that this, like the dielectric reflective coating (in excess of 30 layers) on a Schmidt-Pechan prism, is in a non-reactive Nitrogen environment and is isolated from thermal shocks.

Current anti-reflection coatings have up to 7 layers plus a possible hard coating or hydrophobic coating on the external surfaces of objectives and oculars. Despite their higher vulnerability I am not aware of any problems apart from the example you mentioned, so I think your worries are unfounded.

John
 
Hi,

all kinds of roof prisms need a phase coating to avoid destructive interference between the two half-beams.

Joachim
 
Zeiss was one of the first to install AK in small format roof prisms the BGA (Dialyt) 7X42 and 8X56 and then with the FL series, except the 8 and 10X32. All of these have high transmission, I use the FL 8X42 and 10X42 as my mid size format, low light, dreary winter glass. For the night it is the 8X56/10X56.

It seems like others Maven and Vortex are still using AK prisms in some of their premium glass, so they seem to still be popular, if size does not really matter to the consumer.

And with respect to the EDG, I do not think one will have a problem with the SP prisms.

Andy W.
 
MBS said:
Hi Joachim,

The problem with Porro prism binoculars is that, if I am not wrong, there isn't any model with these features: really waterproof, fog-proof, with central focusing, ED glasses, and fully multi-coated surfaces (oculars, prisms, objectives), in the 8 x 40 mm format.

Such a binocular being available, I will buy it, having always shown more interest in Porro prism binoculars than in roof prism models.

Because, at an equal level of performances, a Porro prism binocular is cheaper than a roof prism binocular (being less costly to made).

And, I am not specifically eager to own the smaller and lighter binocular available.

I know that roof prism binoculars are sturdier than Porro prism models, as regards decollimation, in case of chocks or vibrations, but high end Porro prism can be equipped with damping systems protecting prism cells against such problems (chocks and vibrations).

Furthermore, to recollimate a Porro prism binocular is probably easier to do than it is for a roof prism model, due to the complexity of internal mechanisms in roof prism binoculars (and complexity deals with repair cost).

As regards the longevity of the multi-layer dielectric coating mirror processing, used for high end roof prism binoculars, I stay a little bit skeptical about the evolution of this kind of manufacturing on the long run.

For the record, the high quality silvering (in fact this is aluminum that is used, protected by an other surface layer) of reflector telescope mirror(s) don't last for ever, either.

MBS
Click to expand...

MBS,

I also prefer porros to roofs, not just for the better bang for the buck, but because I prefer the 3-D effect of porros, which I not only find more aesthetically appealing but it also helps me to separate birds from the background. For example, one time when I heard a bird I hadn't before, which had a high pitched whistle, I was looking for it with my Nikon 8x32 LX but couldn't find it. So I switched to my 8x30 E2, and lo and behold it was right where I was looking but it was facing me, so its feathers blended into the grey bark of the trees with the LX, which gives a very compressed spatial view due being a roof with field flatteners. Had the bird been turned away from me, I would have spotted the yellow-tipped tail feathers of a Cedar Waxwing. They visit my backyard in the winter to eat berries.

The problem with making porros waterproof is that sealing the focuser from moisture makes a center focuser very stiff such as the case with the Habichts. Or they can make individual focus EPs for porros such as the Fujis, but they're not very practical for birding unless you have great focus accommodation and can "set and forgot" the EPs. But even then, you have to deal with the long close focus. I use my Fuji 6x30 FMT for nature obseving, and they are great in the winter since I don't have to worry about them fogging up when I take them inside the warm house, but being older now, my eyes don't have the focus accommodation they used to, so I have to turn the EPs to reset the focus for different distances, and the way birds move quickly, I often miss them. For larger, slower moving wildlife, they work well.

I've been floating the idea about having a subforum for discussing porros. What do you think?

Brock, MBA
 
dries1 said:
Zeiss was one of the first to install AK in small format roof prisms the BGA (Dialyt) 7X42 and 8X56 and then with the FL series, except the 8 and 10X32. All of these have high transmission, I use the FL 8X42 and 10X42 as my mid size format, low light, dreary winter glass. For the night it is the 8X56/10X56.

It seems like others Maven and Vortex are still using AK prisms in some of their premium glass, so they seem to still be popular, if size does not really matter to the consumer.

And with respect to the EDG, I do not think one will have a problem with the SP prisms.

Andy W.
Click to expand...
I would call 8x/10x42 roofs full sized and 8x/10x32 mid-sized. Not sure what they call 56mm roofs other than heavy. :)

AK prisms could improve the 8x42 EDG's transmission from 89.8+/-1.5% to 93.9+/- 1.5% (Allbinos transmission numbers for the 8x42 EDG and 8x42 FL, respectively), but perhaps at the expense of compactness.

As to how well the coatings on SP prisms hold up over time, AFIK, as long as the prism coatings are not exposed to air, they should outlast you unless you live to be as old as George Schultz or George Burns, by which time, birders will probably be using digital binoculars except for the purists, who will either hang on to their analog alphas or donate them to Fan Tao's binoculars museum.
 
Hi Brock,

Firstly, good to see you're back posting!

Secondly, to expand on one point in relation to post #12. I’ve not seen any indication that it’s technically more difficult to make a Porro prism binocular waterproof, by using an internal focus mechanism

The obvious example is what I refer to collectively as the MOBL series of Porro prisms; essentially the same units with different RA and markings:
• Minox BD 8x44 and 10x44 (see a review at: https://www.allbinos.com/166-binoculars_review-Minox_BD_8x44_BP.html )

• Opticron HR WP 8x42 and 10x42 (also reviewed at: https://www.allbinos.com/97-binoculars_review-Opticron_HR_WP_10x42.html )

• Bynolt Hawk BCF 8x42 and 10x42 (again reviewed at: https://www.allbinos.com/96-binoculars_review-Bynolyt_Hawk_10x42_BCF.html )

• Leupold Wind River Cascades 8x42 and 10x42 (see the basic details at: https://www.bhphotovideo.com/c/product/419001-USA/Leupold_60992_8x42_Wind_River_Cascades.html )


The lack of other internal focus Porro prism binoculars seems to be the result of economic rather than technical considerations
For the most part, Swarovski and other manufacturers have chosen to produce waterproof Porro's by the expedient of adapting existing designs
As they’ve been able to use existing tooling, they've avoided the need to take on all the costs associated with developing a completely new design


John


p.s. Many will be aware of the Zeiss 7x42 and 8x56 Dialyt roof prism models that used the long lasting Hensoldt external focus design
However, there were also more modern styled external focus roof prism designs such as the Nikon DCF HP WP 8x40 and 10x40 models, see an image from: https://www.raig.co.uk/prismatic-nikon-dcf-hp-wp-8x40-b168/
 

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Last edited:
brocknroller said:
MBS,

I also prefer porros to roofs, not just for the better bang for the buck, but because I prefer the 3-D effect of porros, which I not only find more aesthetically appealing but it also helps me to separate birds from the background. For example, one time when I heard a bird I hadn't before, which had a high pitched whistle, I was looking for it with my Nikon 8x32 LX but couldn't find it. So I switched to my 8x30 E2, and lo and behold it was right where I was looking but it was facing me, so its feathers blended into the grey bark of the trees with the LX, which gives a very compressed spatial view due being a roof with field flatteners. Had the bird been turned away from me, I would have spotted the yellow-tipped tail feathers of a Cedar Waxwing. They visit my backyard in the winter to eat berries.

The problem with making porros waterproof is that sealing the focuser from moisture makes a center focuser very stiff such as the case with the Habichts. Or they can make individual focus EPs for porros such as the Fujis, but they're not very practical for birding unless you have great focus accommodation and can "set and forgot" the EPs. But even then, you have to deal with the long close focus. I use my Fuji 6x30 FMT for nature obseving, and they are great in the winter since I don't have to worry about them fogging up when I take them inside the warm house, but being older now, my eyes don't have the focus accommodation they used to, so I have to turn the EPs to reset the focus for different distances, and the way birds move quickly, I often miss them. For larger, slower moving wildlife, they work well.

I've been floating the idea about having a subforum for discussing porros. What do you think?

Brock, MBA
Click to expand...
Hi brocknroller,

As soon as your subforum for discussing porros will be activated, I'll join immediately.
Signed: a porro binocular enthousiast.
By,
MBS
 
Always happy to see another forum, but a porro specific site seems silly to me.
Either the porro design gets renewed traction in the market thanks to its advantages or it dies.
If the latter, why just porros, we could simply have a nostalgia site, for Galilean and such, or perhaps a miscellaneous optics site, open to scope variants as well.
 

etudiant,​

Porro will never die! That's because binoculars larger than 60mm can only be porro design, for the required interpupillary distance. With roof design, lenses larger than 60mm are so close (touching each other) that we can't have the normal interpupillary distance bigger than 6mm
Conclusion: Roof design for small binoculars / Porro design for large binoculars. But that doesn't mean there can't be some fantastic small binoculars with porro prisms. As the example above, Nikon E2 8x30 is one of porro design binoculars with some fantastic optical qualities like enormous FOV, contrast image, gorgeous Color Profile, and pleasant image. But one qualitie that do not see so prominent in a roof design it is fantastic Stereoscopic image of the porro design, how it was told above. It is a great entertainment and an unparalleled pleasure to look through a good porro binoculars!
 
Last edited:
Hi etudiant, your objection is perfectly incontestable and big binoculars will be Porro ones, for ever, except for some strange other possibilities similar to military trench binoculars for instance.
For sure, Porro binoculars will be more and more a technological niche rather a big market, so the idea that such binoculars deserve their own subforum seems to be justified.
By,
MBS
 
John A Roberts said:
Hi Brock,

Firstly, good to see you're back posting!

Secondly, to expand on one point in relation to post #12. I’ve not seen any indication that it’s technically more difficult to make a Porro prism binocular waterproof, by using an internal focus mechanism

The obvious example is what I refer to collectively as the MOBL series of Porro prisms; essentially the same units with different RA and markings:
• Minox BD 8x44 and 10x44 (see a review at: Minox BD 8x44 BP - binoculars review - AllBinos.com )

• Opticron HR WP 8x42 and 10x42 (also reviewed at: Opticron HR WP 10x42 - binoculars review - AllBinos.com )

• Bynolt Hawk BCF 8x42 and 10x42 (again reviewed at: Bynolyt Hawk 10x42 BCF - binoculars review - AllBinos.com )

• Leupold Wind River Cascades 8x42 and 10x42 (see the basic details at: https://www.bhphotovideo.com/c/product/419001-USA/Leupold_60992_8x42_Wind_River_Cascades.html )


The lack of other internal focus Porro prism binoculars seems to be the result of economic rather than technical considerations
For the most part, Swarovski and other manufacturers have chosen to produce waterproof Porro's by the expedient of adapting existing designs
As they’ve been able to use existing tooling, they've avoided the need to take on all the costs associated with developing a completely new design


John


p.s. Many will be aware of the Zeiss 7x42 and 8x56 Dialyt roof prism models that used the long lasting Hensoldt external focus design
However, there were also more modern styled external focus roof prism designs such as the Nikon DCF HP WP 8x40 and 10x40 models, see an image from: Prismatic Nikon DCF HP WP 8X40
Click to expand...
Hi John,

Sorry I never replied to this, I went sailing in the South Pacific with my Fuji 6x30 FMTR-SX and found that despite globe photos of the Earth from space, I reached the edge of the Flat Earth, and fell off the edge! Fortunately, the Fuji's have a flotation strap, and I was able to catch a ride on a the back of the giant turtle holding up the world. :)

I mentioned these binoculars on another thread recently in regard to Zedster posting what you said, that it's not hard to make WP/FP porros. He was referring to the 8x32 E2, which has.a very wide 8.8* FOV, which he likes but can't use in tropical environments. I wondered if internal focusers limited the FOV, because all the bins you listed have restricted fields of view especially compared to the E2. They are also fairly bulky compared to the tiny E2. So, I wonder if it's just economic or if there are limits on the design?

Brock
 
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