Patrick wrote: Roof prisms are GENERALLY more durable,
I’m not so convinced this is true. Certainly it is the mantra that has been raised for a very long time and I’m sure it is more-than-likely true if you are comparing a very expensive roof prism to a very cheap Porro prism but, if you are comparing optics of similar build quality, I think there is more fantasy and clever marketing than reality in this claim.
For years (even before the advent of common phase correction coatings to help the roof prism’s optical problems) designers of binoculars claimed that added durability and ruggedness was a reason to go with a roof prism binocular. It was explained back then that the roof prism’s long, piano-wire hinge was more stable and less prone to being knocked out of alignment than the relatively flimsy dual arms of the common Porro prism binocular. Then comes the Swarovski EL that has a very Porro-esque dual-arm, split-bridge design and yet they claim it to be the most rugged design ever. It takes only the blink of an eye before just about everyone copies the EL’s racy design (including your favorite, the Nikon EDG) and produces a dual-arm, split-bridge binocular that is “more rugged than anything ever produced yet.” Sounds like mere marketing smoke and mirrors to me.
How are these new split-bridge binoculars supposed to be more rugged? Especially considering there are a few Porros that now even include long piano-wire hinges that were supposed to be the source of the roof prism design’s great strength?
Phil Shoemaker, a popular Alaskan Guide and writer for a few different magazines has been pretty open about his disappointment with the Swaro EL as a “rugged” binocular. He has stated publicly that the EL fails more than any other binocular he sees in his camps.
Patrick wrote: [Roof prisms are GENERALLY] easier to waterproof,
This is partially true. Most Porro prism binoculars use an external focusing mechanism with an integrated O-ring system to supply their waterproofness. This is not as watertight as the fully-internal focusing mechanisms of most roof prism binoculars, though it is still not nearly as weak as many would have you believe and would likely only become an issue if you were to submerge your binocular into fairly deep depths where water pressure could overwhelm the O-rings – and from where you would be unlikely to ever retrieve the binocular anyways. Nevertheless, if the issue is of primary concern to a particular individual, there is actually a selection of Porro prism binoculars that have incorporated fully internal focusing mechanisms and are thus, just as secure and waterproof as any roof prism binocular made.
Patrick wrote: [Roof prisms are GENERALLY] more compact.
This is actually true. With Porro prisms you do, as a general rule, sacrifice some portability for the benefits of the better image quality and lower price.
However, even this is not always as cut and dried as one might hope or expect. It is primarily complicated by the fact that often Porro prism models come with larger objective lenses than do roof prisms; hence you often see Porros of 7×50 and/or 10×50 configurations whereas such are not as common with roof prisms. So too it depends on what exactly we are comparing. It is generally true that Porros are wider than comparable roof prisms (which actually gives them two of their more important optical advantages) but, they are also often shorter making for dimensions that lie somewhat differently on the body but that aren’t really all that different over all. This is certainly true with my 8×42 Porro prism B&L Discoverer and my 8×42 Leupold Golden Ring.
Then there is the issue of weight and here there is even more variability. For example, the Porro prism 8×40 Pentax PCF WP II weighs in at 28.2 ounces. The “comparably priced” Roof prism 8×42 Pentax DCF WP II weighs exactly the same (as does my more expensive B&L). The vastly more expensive 8×43 Nikon EDG actually weighs a touch more at 28.6 ounces and, somewhere right in between the two price extremes, the 8×42 Leupold Golden Ring weighs in at an even heavier 33.2 ounces.
