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Porro prism versus Roof prism?

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#26 Erik Bakker  Happy Birthday!

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Posted 20 November 2020 - 08:00 AM

It is fair to say that there are differences between these two designs.

 

Over the last decades, R&D has been focused on improving roof binoculars. Resulting in ever better models. And some surprisingly good affordable models in the US $ 300-400 range. Internal focusing and waterproofing have become the norm in roofs, as have the adjustable eyecups. Generally they focus quite close, in the 2-4m range.

 

Downsides of the design? Limited depth of field, sensitivity to spikes on bright lights and the necessity to apply both phase correction and highly reflective coatings on a roof prism surface. And they are MUCH more sensitive to alignment of their prisms, further increasing the cost to make them well. In exchange you get a sleek form format, generally well suited for eyeglass wearers. As an added bonus, fields of view get sharper to the edge and wider by the decade.

 

Porro’s have there own advantages by design, but are not currently developed any further, in stark contrast to roofs. To their advantage, their designs have wider optical bases, hence much better depth perception in the images at close- and mid range. And no spikes on bright lighthsources, because porro’s don’t introduce them to the image, as roofs easily do where they split the incoming lightbeam. Only the very best have (almost) no visible spikes on bright points of light. Eyepiece designs and instrument designs have come to a hold decades ago. So they tend to represent the design philosofies of decades ago. But some of them are still valid AND outstanding, like Swarovski Habichts, Nikon’s EII, Prostar and Astrolux make clear to their users every day AND night. But they are not easily adaptable to glass-wearers., have fixed or fold-down eyecups and generally have smaller and less wide fields than current roofs. Waterproofing is different too and certainly not as common as with their roof counterparts.

 

The very best roofs have come a long way in narrowing the optical gap with porro’s on-axis, with many additional features to boot.

 

I have owned the best of both designs and found them both to be wonderful, yet different by nature. I still own some of the best of both and could not do without either of them. They are not interchangeable, but excel in different ways. Just choose were the focus of your personal use-cases are. And be prepared to pay double to triple the price for similar on-axis quality.

 

The best example from the same manufacturer making similar magnification and aperture roof and porro binocular models currently being Swarovski. That makes a fair comparison of similar production quality easier. The roof NL 10x42 and porro Habicht 10x40. US $ 3000 vs US $ 1000. For comparable on-axis performance, but vastly different form factors and off-axis performance. Not to mention the night and day difference for eyeglass wearers, field of view and haptics. But the images and user experience for both is outstanding. Just different.


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#27 SandyHouTex

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Posted 20 November 2020 - 10:29 AM

Then why do even $100 porros score about 80-85% light transmission?

Eyepiece and objective coatings.



#28 ihf

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Posted 20 November 2020 - 10:32 AM

Is it fair to say that Porro prisms last longer than Schmidt-Pechan, where the coatings may have durability issues?



#29 SandyHouTex

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Posted 20 November 2020 - 10:35 AM

No.. 

 

Walmart does not sell 42mm or 50mm binoculars for $10.  There is far more to binocular throughput than whether or not the prisms have total internal reflection on one surface, that surface can be coated so there is essentially no loss. 

 

In terms of binocular through-put, the quality of the coatings on the optical surfaces is very important since there are so many elements.  Multiply the number of surfaces by 0.99 versus 0.96.. 

 

A high quality roof will have high quality coatings and much better transmission than inexpensive binoculars.  One issue with inexpensive porro prism binoculars is that they are not operating at full aperture.  I own a pair of 10x50 Simmons. $30 at Walmart is what I paid. Their actual aperture is right at 40mm because the prisms are undersized.  That's loss of brightness of 36%.  

 

My 10x42 Eagle Optics Roof prism operate at full aperture and are brighter than the Simmons Prosports 10x50s.

 

I once bought a pair of Vivitar 7x50's at ACE Hardware for $10 just to see what they were.  You wouldn't bother measuring the through-put, they turned everything green and though the focuser moved the eyepieces, they did not actually focus, just different levels of mushiness. 

 

Jon  

There are many things that affect light through put in a binocular.  This OP asked about the differences between porro and roof prism systems.



#30 asphericalaberration

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Posted 20 November 2020 - 11:02 AM

>Is it fair to say that Porro prisms last longer than Schmidt-Pechan, where the coatings may have durability issues?

 

With reasonable care, modern external coatings are durable. No reason for same-age porros and roofs to differ in the the durability of their external coatings. Aluminized or silvered internal coatings in roofs can oxidize, but I haven't seen it personally. Dialectic coatings should last indefinitely.

 

Porros tend to be much more likely to lose collimation. If they need professional repair as a result, that's an end-of-life issue (with exceptions). So roofs are generally more robust and likely to last longer. Porros are easier to re-collimate, however, and many amateurs can DIY.

 

Porros are harder to seal and waterproof. Most focus by moving their oculars, which pumps air, humidity, and dust into the interior of the bin. They're more likely than roofs to get dirty or wet inside. Most "better" roofs are waterproof now and likely to stay internally clean indefinitely. The internal focusing mechanism standard for roofs avoids migration of dust and water into the bin.

 

For both, retractable eyecups fail first. I've have two pairs of roofs with failed twist-up eyecups and one pair with failed "rubber" eyecups in a unique, irreplaceable design. For both, I've made practical, ugly repairs with electrical tape. I have many vintage porros that need new eyecups.


Edited by asphericalaberration, 20 November 2020 - 11:14 AM.

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#31 Binojunky

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Posted 20 November 2020 - 12:16 PM

I assumed everyone knew that.  A pair of plastic porros at Walmart for $10 will be optically bested by a pair of Vortex Razor roofs that are 100X the cost of the porros.  However the $10 porros will still have better light through put due to complete internal reflection.

Then again I have looked through mid priced ($300) 8x42 porros and found roofs at the same price point outperforming them, in the world of roofs or porros a premium instrument of either design tends to give superior performance to a cheaper pair. As for better light through, thats only part of the equation in a binocular choice, the similar priced roof design may offer ED glass and dielectric coatings which the porro hasn,t, that why its important to try what models you fancy as we all have different tastes, crazyeyes.gif Dave.


Edited by Binojunky, 20 November 2020 - 12:24 PM.

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#32 Mark9473

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Posted 20 November 2020 - 12:16 PM

Then why do even $100 porros score about 80-85% light transmission?

 

Eyepiece and objective coatings.

 

OK, you're playing dense so let's re-word my rhetorical question:

how come porro prism binoculars typically don't have better light transmission than roof prism binoculars?

 

Hint: the answer is that your original statement is wrong.



#33 hallelujah

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Posted 20 November 2020 - 02:21 PM

https://www.cloudyni...s/#entry1473522

 

https://www.cloudyni...ism-binoculars/

 

Stan


Edited by hallelujah, 20 November 2020 - 02:38 PM.


#34 SandyHouTex

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Posted 20 November 2020 - 08:13 PM

OK, you're playing dense so let's re-word my rhetorical question:

how come porro prism binoculars typically don't have better light transmission than roof prism binoculars?

 

Hint: the answer is that your original statement is wrong.

No it isn’t, and if you would just say what you mean we wouldn’t’ have to try and guess.

 

And speaking of dense, the OP asked about the difference of porros (a prism design) versus a roof (another prism design).  Focusing just on the PRISMS, porros will always do better with light through put because of TOTAL internal reflection, versus roofs that need aluminum or silver on their surfaces to improve their reflective characteristics.



#35 SandyHouTex

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Posted 20 November 2020 - 08:19 PM

Good links.  It’s nice to see BillC posting in the first link.  He probably knows more about binos in his little finger than the rest of us will ever know.



#36 SandyHouTex

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Posted 20 November 2020 - 08:22 PM

Good links.  It’s nice to see BillC posting in the first one.  He’s forgot more about binoculars than the rest of us will ever know.  And in the second link, EdZ.  I miss his posts.



#37 Jon Isaacs

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Posted 20 November 2020 - 10:32 PM

There are many things that affect light through put in a binocular.  This OP asked about the differences between porro and roof prism systems.

 

This is what you wrote:

 

"A pair of plastic porros at Walmart for $10 will be optically bested by a pair of Vortex Razor roofs that are 100X the cost of the porros.  However the $10 porros will still have better light through put due to complete internal reflection."

 

The porro prisms themselves are unlikely to have superior transmission because they have  poorer coatings, probably uncoated.

 

But the term "plastic porros" clearly refers the Porro prism binoculars in their entirety.. if the prisms are plastic, there will real problems.

 

Jon


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#38 j.gardavsky

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Posted 21 November 2020 - 07:07 AM

The "plastic Porros" have a polycarbonate (or similar) body, covered with an ugly plastic armor with bad smell.

 

Best,

JG



#39 Erik Bakker  Happy Birthday!

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Posted 21 November 2020 - 08:34 AM

If manufacturers would improve their porro’s as they do with roofs, they would create some very nice instruments indeed. Say e.g. if Swarovski transferred all their improvements in their latest NL design to their Habicht porro’s. That would create stunning performers at half the price of the current NL’s. But that might be a not so good idea for their business model I guess hmm.gif


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#40 Erik Bakker  Happy Birthday!

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Posted 21 November 2020 - 08:38 AM

Personally, I would buy such a new improved and modernized high-end porro from any alpha-producer in a heartbeat. But I think they are gradually shifting towards roof-designs only, at least in the apertures from 10-56mm. 60mm and bigger have remained porro designs, but need a tripod to perform to their full potential anyway. So compactness and waterproofing has been less of an issue than in the 56mm and smaller apertures.


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#41 Erik Bakker  Happy Birthday!

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Posted 21 November 2020 - 08:43 AM

But even today, a well made porro is still a joy to buy new and use. Just make sure it’s strong points match YOUR preferred uses and it’s inherent design differences compared to a roof design don’t get in YOUR way. As always, binoculars are a personal fit. Great for some, not so great for others, like shoes. Personally, I feel privileged we have such a wide choice available to choose our own instruments from. 


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#42 j.gardavsky

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Posted 21 November 2020 - 11:22 AM

In fact, there are quite a lot of the Porros manufactured waterproof, shock proof, etc., and in the aperture sizes from 30mm up to about 110, and used mostly for the law enforcement, or as tactical optics.

 

A good example are the Hensoldt FERO Porros, manufactured in Germany with the apertures 30mm up to 50mm. Not sure, if they will replace them with the roof prism binoculars for any use in the combat situations.

Another example are the BA8 big binoculars from Kunming in China, as nobody would come up with an idea to make the 85mm binoculars with the roof prisms.

 

On the other side,

the roof prism binoculars can be made compact, and some of them can be comfortably held with just one hand.

To make the roof prism binoculars compact, additional lenses are needed, both on the side of the objectives, and on the side of the eyepieces. Otherwise you get the extra long Hensoldt/Zeiss Dialyt (or alternatively the Optolyth Royal), which are looking like, and feeling in the hands like a pair of cucumbers.

 

Best,

JG


Edited by j.gardavsky, 21 November 2020 - 01:40 PM.

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#43 vincenzo maielli

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Posted 05 December 2020 - 02:47 PM

Hi to all. I'm come back to CN, after many time. I'm wrote for CN, in the past, the reviews of Fujiyama 7x50 ZCF, Vixen / Geoma Ultima 8x56 and Fujinon FMTRC-SX2 7x50.

I like very much the Porro prism binoculars, mainly for their best performance in the light transmission. Also, for the most favorable purchase prices. 

A Swarovski EL 10x42 binocular has the same optical performance as my Fujinon FMT-SX2 10x50. While, however, the first costs € 2.200, the second costs € 980.

As for the roof prisms I prefer the Abbe-König ones.
Hello everybody.
Vincenzo Maielli - Bari (Italy)


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#44 garret

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Posted 05 December 2020 - 03:35 PM

 

I like very much the Porro prism binoculars, mainly for their best performance in the light transmission. Also, for the most favorable purchase prices

I just did a quick first side by side comparison between my brandnew 8x56 Steiner porro verses the Swarovski EL 10x50...especial on transmission.

The Steiner should win; it has 30% total more light then the EL (25% by aperture and 5% by more transmission)

But to my surprise the EL seems to be winning in this area,  the dimmer stars of the Pleiades are easier to see in the EL, the open clusters in Auriga are also better viewed in the EL.

I never had a moment that the Steiner had better view because of the higher transmission/ larger aperture.

Could it be that 10x is always better then 8x?

Later tonight Orion is visible, let's see what both make on M42!


Edited by garret, 05 December 2020 - 04:02 PM.

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#45 Grimnir

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Posted 05 December 2020 - 03:53 PM

I just did a quick first side by side comparison between my brandnew 8x56 Steiner porro verses the Swarovski EL 10x50...especial on transmission.

The Steiner should win; it has 30% total more light then the EL (25% by aperture and 5% by more transmission)

But to my surprise the EL seems to be winning in this area,  the dimmer stars of the Pleiades are easier to see in the EL, the open clusters in Auriga are also better viewed in the EL.

I never had a moment that the Steiner has better view because of the higher transmission/ larger aperture.

Could it be that 10x is always better then 8x?

Later tonight Orion is visible, let's see what both make on M42!

 

This is in accordance with the Adler function.

 

Graham


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#46 sonny.barile

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Posted 05 December 2020 - 04:51 PM

I have a simple question about the binocular designs.......for my curiousity.

 

How many here have purchased new Porros and had to send them back because they were not aligned?

 

How many have sent back new roofs because they were not aligned?
 


Edited by sonny.barile, 05 December 2020 - 04:52 PM.


#47 cloudy mind

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Posted 28 December 2020 - 09:33 AM

hi

i'm new to the forum.

i never bought expensive binoculars, during years i have used some mid-priced roof prism (200-400€ nikon, fowa, and others). i bought some cheap ones (25-70€) that were really rubbish. i kept using a very old zenith 7x30 with porro prisms.

 

in recent years the quality of cheap porro prism binoculars made in china has improved dramatically. i bought a pair of visionking 8x30 for 30€, when i looked into them i was "wow! this can't be true". to me was a surprise.

all my chinese roof prism are gone now, i only kept a svbony 10x42 because is light and fogproof and i use it for kayaking, but it's optically quite bad.

 

i later bought a 10x50 porro, more recently a cheap 11x70 with small prisms and quite narrow fov. i was amazed how good the image is and also bright.

now my old 7x30 looks rubbish to my eyes.

 

honestly i think that for cheap binoculars ie <250€ porro prism is a much better choice, at least if you buy online.



#48 Fiske

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Posted 28 December 2020 - 10:30 AM

What has driven the development of roof designs over porro designs is that the ergonomics are far preferred by the majority of binocular purchasers, who are not amateur astronomers. ;-) They are daytime users. They are more compact, lighter, and far more durable. (The roof designs, not the daytime users...)

 

Just added a Nikon 10x42 HG to the portfolio, comparing it side by side with a 10x42 Monarch 5. The contrast, brightness, and sharpness are noticeably better, though the 5 is a darn good glass. The HGs are about $1000 US, while the 5 is about $300 US.

 

An issue with even top porro designs is internal fogging from lubricant outgassing. This has occurred with the Nikon 12x50 SE I own, which now requires repair. Will probably send it to Suddarth Optical for the work. Fold up eyecups are also problematic versus twist-up, which are more durable.

 

What are some top quality porro bins now in production and readily available in the US? In 10x50 sizes, for example?

 

Fiske


Edited by Fiske, 28 December 2020 - 10:31 AM.

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#49 KennyJ

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Posted 28 December 2020 - 11:22 AM

Hi Fiske,

 

Oberwerk 10x50 Ultra are still available, along with several other very similar Individual Focus, Chinese sourced offerings in a variety of guises.

 

They have often been considered just about optically equally to the much celebrated Fujinon FMT-SX model.

 

Kenny



#50 Fiske

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Posted 28 December 2020 - 12:50 PM

Thanks for the recommendation, Kenny. grin.gif

 

Individually focusing eyepieces are an issue for me because I routinely observe both with and without glasses. Doable, but would really prefer central focus. I understand that is an option on the Fujinon, but not sure if it is readily available.

 

Fiske




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