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Roof vs. Porro

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WVHILLBILLYJLM View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WVHILLBILLYJLM Quote  Post ReplyReply Direct Link To This Post Topic: Roof vs. Porro
    Posted: September/02/2008 at 20:39

Can someone explain to me the advantages / disadvantages of these two types of binocs.

Thanks

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lucznik View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lucznik Quote  Post ReplyReply Direct Link To This Post Posted: September/02/2008 at 22:29
Roof:
Smaller
Lighter
More rugged
More Expensive
More "Stylish"
Must have specialized coatings to correct image degradation issues

Porro:
Bigger
Heavier
Somewhat less rugged (though, only under the most trying of circumstances)
Less expensive
Not currently "en vogue"
Better image quality at any given price-point (not prone to the same image problems as roofs)



Edited by lucznik - September/02/2008 at 22:30
What if the hokey pokey really is what it's all about?
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mwyates View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mwyates Quote  Post ReplyReply Direct Link To This Post Posted: September/04/2008 at 09:47
Porros have a more 3-dimensional view.  I really prefer them when I'm sitting ; a really good porro has a view that is unmatched by any roof prism.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: September/04/2008 at 13:44
Spot on, gentlemen.  It is easier to make a good porro and good roof prism binocular.  Also, the fact the the objective lenses are a little further apart allows for a more stereoscopic view and better depth perception in porro binoculars.  For the same reason (widely spaced objectives), minimum focusing distance where you can look at an object with both eyes is longer in a porro (unless we are talking about an inverse porro).  Another shortcoming of porro binoculars is the fact that they are harder to make waterproof while still maintaing center focus.  Still, there are lenty of waterproof porro binoculars out there and several military-spec individual focus porros are incredibly tough and have excellent image (Fujinon Polaris line comes to mind).

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Post Options Post Options   Thanks (0) Thanks(0)   Quote www.technika.nu Quote  Post ReplyReply Direct Link To This Post Posted: September/04/2008 at 14:16
Luzcnik I don't understand why porros should be less rugged than roofs?
Maybe true if you compare various chinese stuff, but not if you compare the quality stuff that is sold from Fujinon, Swarovski or Zeiss.
I do just know of a few roofs in military use, but plenty of porros.....wonder why.....
 
I would say the porros are far stronger than the roofs.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: September/04/2008 at 14:26
Both can be built to be very strong.  Roofs, because everything is contained within a single tube, are, in principle, easier to make tough.

As for most military binoculars being porros, I suspect it has more to do with the fact that you can get a good image for less money.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ed Connelly Quote  Post ReplyReply Direct Link To This Post Posted: September/04/2008 at 14:34
Hey Technika    clean out your mailbox please!!   Bandito
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Post Options Post Options   Thanks (0) Thanks(0)   Quote www.technika.nu Quote  Post ReplyReply Direct Link To This Post Posted: September/04/2008 at 14:43
Its done.........
 
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lucznik View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lucznik Quote  Post ReplyReply Direct Link To This Post Posted: September/04/2008 at 20:20
Originally posted by www.technika.nu www.technika.nu wrote:

Luzcnik I don't understand why porros should be less rugged than roofs?


Because the straight barrels of the roof-prism binoculars allows for the use of a long piano hinge rather than the split hinges of most Porro-prisms. This of course would not be true for today's crop of split-bridge roofs.  Chris has previously confirmed that binoculars with this new design are the most commonly returned for collimation problems.  (Why this new style is so popular is beyond me.)

Also because, as Koshkin already explained, they are more difficult to make waterproof while retaining the central focusing mechanism, a feature that I consider critical in a hunting binocular. (I know you prefer the individual focusing style.)

I too think that the logic that concludes "the military uses porros therefore, porros are more rugged (or better) than roofs" is not sound.   The military contracts out for basic specs and awards those contracts to the lowest bidder.   For example, the US military employs de-badged 60mm Bushnell Elites for many of its sniper teams.  You wouldn't, I think, be inclined to try to argue that this is because this model Elite is the best available spotting scope on the market (in any category). 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote www.technika.nu Quote  Post ReplyReply Direct Link To This Post Posted: September/04/2008 at 23:21
What the US military is using for binoculars is really not interesting, as they have over the years used all kinds of garbage. (WWll M15,M16 and M17 was indeed good binoculars of it's time, but after ww2 have garbage been bought in by big numbers)
This is surprising me very much, but appearantly they do not consider binoculars as important.
 
However if we are looking on many other armies the most common names are Hensoldt, Nedinsco, Zeiss, Swarovski etc and even if those binoculars gets a very tough treatment it's  relative uncommon that they have problems.
Centerfocus is humbug and great for older men with  very poor eyes, therefor is not centerfocus used on military binoculars normally.
With the centerfocus gone the Porroprism is very rugged.
And if we are looking at almost all of the Marine binoculars that is made today for both military or civilian use the most of them are porros....
 
Technika
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: September/05/2008 at 15:35

The reason some porro prism binoculars are less rugged than roofs usually has nothing to do with the split vs straight hinge design used.  This doesn't mean that some split hinge porro binoculars don't have weak hinges, though.  Some porros use a full length hinge along the pivot and STILL aren't as rugged as a well-constructed roof prism binocular.  The reason SOME (not all) porros are less rugged than roofs is simple.  Due to the dogleg shape of the porro prism binocular, there is frequently a lot of unsupported mass in the objective barrels both extended beyond and further away from the center hinge of the binocular.  This creates a long lever arm that causes greater stress exerted on the hinge in the event the binocular is dropped on one of the objective barrels.  In addition, the objective barrel of a porro is usually a separate piece threaded into the prism housing.  A roof prism binocular has straight barrels, with each barrel usually of 1-piece construction, without the objective assembly being a separate piece from the prism section of the binocular.  In addition, the hinge or hinges is usually wider on a roof than a porro of the same length, and a wider hinge resists being knocked out of colimmation better.  This is not always the case, however, with some porro prism binoculars having wider prism housings and little to no objective tubes extending from the prism housing combined with a long hinge.  A good example of this is the Steiner Military/Marine.

As for split vs. straight hinges, it's a mistake to assume one is always more rugged than the other just based on whether it has a split vs. straight hinge.  Some split hinges actually have more bearing surface and are spread further apart along the pivot than some straight hinges.  The strength of the hinge has to do with how well designed the hinge itself and the connection to the main tubes is.  In some cases, 2 hinges spread further apart are actually stronger than a single hinge of the same total width with a narrower span.  It depends on how much unsupported mass extends beyond the span of the hinge or hinges.  I have no doubt that Chris's repair information with regards to split vs. solid hinge binoculars is true.  However, I believe that has more to do with how well-designed the hinge is than whether or not it's split vs. 1-piece.  Imagine a door installed with only 1 hinge, but the hinge is narrow vs. the same door with 2 hinges with greater bearing surface and those 2 hinges are spread further apart than the span of the single hinge.  The latter is a stronger design, because it resists twisting about the pivot point much better.  Some split bridge binoculars I've seen actually have wider total hinge bearing surface than some single hinge binoculars.  Again, it all depends on the design of the individual binocular and the materials and manufacturing tolerances used.  All else being equal, 2 hinges spread further apart with greater surface area than a single hinge will always be stronger.
 
The current popularity of the split bridge design has little do do with strength, though.  It's popular because many people like the ergonomics/feel of split bridge binoculars and to many, it looks cool.  Manufacturers will make what sells.


Edited by RifleDude - September/05/2008 at 15:58
Ted


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: September/05/2008 at 16:19
Here is an example of three hinge designs. The first is a Peregrine 8x42 roof prism, second is a 6x30 Whitetail porro prism and third is a 8x44 Peregrine XP "open hinge" roof prism. The Whitetail appears to have as much hinge length as the Peregrine 8x42 and the XP has close to the total length of the others. I have no plans on beating any of them on rocks, so I'll have to go on arms length campfire postulating from the paid gun-writers.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bird Watcher Quote  Post ReplyReply Direct Link To This Post Posted: September/05/2008 at 19:02
Originally posted by WVHILLBILLYJLM WVHILLBILLYJLM wrote:

Can someone explain to me the advantages / disadvantages of these two types of binocs.


Thanks



Basic Guide For Binoculars

Edited by Bird Watcher - September/05/2008 at 19:03
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