Porro v Roof

[Stoggler]

Ok, just a nice easy question, although I doubt there's a straightforward answer.

For those amongst us considering buying new bins, one of the considerations is whether to go for porro prisms or a roof prism. I wonder if someone could outline the pros and cons of the two prisms formats used in bins, taking into consideration such things as comparative performance, performance v cost, robustness, and anything else I've missed out.

I'm sure this has been discussed in previous threads, but haven't been able to find any former ones.

Thanks

[ThoLa]

I wonder if someone could outline the pros and cons of the two prisms formats used in bins, taking into consideration such things as comparative performance, performance v cost, robustness, and anything else I've missed out.
Thanks

- It's largely a matter of taste!

- Roof prisms need special treatment to give top level performance. it makes them more expensive.

- a set of roof prisms consists of prisms that have different shapes. a set of Porro prisms conists of two equal prisms, so the Porro concept is again cheaper.

- performance vs. cost should be better for the Porro design.

- absolute performance is equal for both and depends on the quality of the material and the work (independent of which design is chosen)

- robustness depends on the effort of the manufacturer and is independent of the design

- Porros binos have a better spatial resolution because the objectives are farther apart

that's it.
the rest is: personal taste.

Tom

[Stoggler]

Thanks Tom

I've only ever owned porros but that's just a matter of circumstance rather than design, and I've always been open to having roof prisms - for some reason I always thought they were superior to porros. However, with your saying that porro prisms are cheaper when comparing performance, and that the spatial resolution is better, I'd be more inclined to go with roofs.

[ThoLa]

Thanks Tom

I've only ever owned porros but that's just a matter of circumstance rather than design, and I've always been open to having roof prisms - for some reason I always thought they were superior to porros. However, with your saying that porro prisms are cheaper when comparing performance, and that the spatial resolution is better, I'd be more inclined to go with roofs.


- personally I like the ergonomics of the traditional Porros instruments with the open bridge; something that is now increasingly emulated in roof prism binos.

- it is cheaper to cut and grind two identical prisms that to cut and grind two different shapes. Roof prisms commonly need a mirror on at least one side, so additional steps are necessary.

.... and that the spatial resolution is better, I'd be more inclined to go with roofs.

- Spatial resolution is better with a Porro, and poorer with a "Roof".
Some people like it very much; other do not care. It depends on your sensitivity to "depth" (and the circumstances of your observations).

Another aspect is that there are few top level Porros nowadays. The choice of high quality "Roofs" is greater (there's more money to spend;))

Best, Tom

[dustyview]

Tom has hit on all the important stuff. I have roofs I like, but tend to like the image quality of porros more. You should certainly try both for yourself, either at a store that carries good quality binoculars of both designs or by ordering a couple of pairs to compare and then returning the ones you don't want. The one caveat is that with most of the tech and design innovation going into roofs in the last decade or more, you have to look around for top-end porros, which I'm defining as those which manufacturers have built with fully multicoated lenses, perhaps an aspheric element, etc. Porros work well enough as they are that many on the market do not have all of the recent optical improvements. To really make a more "apples to apples" comparison (to the degree that you can with the two different designs) in terms of quality, you will have to search out the good porros. People here like the recently discontinued 8x42 Leupold Cascades, the 6x30 Leupold Yosemites, and the discontinued Nikon SE. I like the Bushnell 7x26 E2 Custom Compact, but I don't know if you're looking for a small or full-sized binocular. There is also the new Raptor/Raven from Vortex/Eagle Optics (search for recent posts). Good luck in your search.

[Tero]

Weight and size is the main drawback to porros for me. There are now decent 30mm porros, look at those.

[Stoggler]

Weight and size is the main drawback to porros for me. There are now decent 30mm porros, look at those.

Is there much of a difference in weight between the two prism types?

[ronh]

I think the optical issues have been covered. There's a couple of mechanical things.

Porros, with very few exceptions focus externally, that is the eyepieces move in and out. That is a difficult arrangement to make watertight. The only Porros that I actually believe to be watertight are individual eyepiece focus marine style binoculars. Virtually all roofers focus internally, and are made watertight.

The Porro is wide and lumpy but easy to hold---a matter of opinion which you like best. There is no good reason for it that I can see, but most Porros have the strap attachments on the bottom of the prism housings, instead of on the sides like a roof bino, so the Porro hangs with the objectives digging into your midsection.
Ron

[ThoLa]

Is there much of a difference in weight between the two prism types?

No.
In fact the size of the prisms is a contributing factor of the overall optical quality.
Some manufacturers use smaller prisms than others, and the result can be shading (vignetting) of the edges of the field of view (dark patches of the exit pupil).

T

[ThoLa]

Weight and size is the main drawback to porros for me. ....

mhh, let's see.
Let's look at one of the few top end Porros:

Swarovski Habicht 8x30: 540 g

For comparison, roof prism models of the same company:
Swarovski SLC 8x30: 590 g
Swarovski EL 8x32: 610 g

And again:

Swarovski Habicht 10x40: 690 g
Swarovski SLC 10x42: 870 g
Swarovski EL 10x42: 800 g


That's what you call a "drawback" ;)
You must be a weight-lifter.

Likes it light,
Tom

[ThoLa]

Porros, with very few exceptions focus externally, that is the eyepieces move in and out. That is a difficult arrangement to make watertight.

but nevertheless possible:

Pentax pcf wp II: tight down to 1 m

Swaro Habicht: tight down to 4 m ! !


More than sufficient for anyone but a submarine captain.
T (terrestrial mammal)

[dustyview]

Yes, the 30-32mm models are pretty light, and of course the compact reverse porros can be very light -- my older Pentax UCFs weigh in at a little over 300g.

Weight and size is the main drawback to porros for me. There are now decent 30mm porros, look at those.

[FrankD]

Is there much of a difference in weight between the two prism types?

My experience is that this depends on the cost/optical parameters. If you consider some of the inexpensive full size porros like the Nikon Action EX, Bushnell Legend, etc... and compare them to roofs either at that price point (Pentax HS, Leupold Acadia, Vortex Diamondback) or higher (Bushnell Legend Ultra roof, Nikon Monarch) then the porros are typically heavier and physically larger. The optical quality though of the inexpensive porros typically betters that of similarly or moderately more expensively priced roofs assuming you stick to center of field performance.

The three internal focus porros currently on the market (Opticron, Leupold Cascade porro and Minox BD BP) are a bit of an exception as they have all the benefits of internally focused roofs along with all of the 3D effect of porros. Their only real negative in my opinion is the fairly narrow field of view (in comparison to some bins).

[denco@comcast.n]

Ok, just a nice easy question, although I doubt there's a straightforward answer.

For those amongst us considering buying new bins, one of the considerations is whether to go for porro prisms or a roof prism. I wonder if someone could outline the pros and cons of the two prisms formats used in bins, taking into consideration such things as comparative performance, performance v cost, robustness, and anything else I've missed out.

I'm sure this has been discussed in previous threads, but haven't been able to find any former ones.

Thanks

Concerning optics I haven't seen any roof prism binoculars that are the equal of the Nikon 8x32 SE including the Zeiss 8x32 FL. For that reason I would say if you want the ultimate view get the Nikon. If you want waterproof and like the roof prisms ergonomics get the Zeiss FL. It is pretty close to the Nikon.

Dennis