Vortex Raptor PORRO bins (2 Viewers)

[John Dracon]

Henry - The worst binocular with overlap issues I have found was the discontinued B&L 10x40. As we all know, the offset of the objectives and oculars in porros is a function of prism construction. And the inherent gain is a significantly shortened instrument. Those clever Germans designed the roof prisms to keep the binoculars reasonably short yet slim. Roofs undoubtedly have an inherent advantage when it comes to very close range. But is it because their objectives are closer together?

But overlap is inherent in all binoculars, porro or roof. Even those so-called reverse porros display as much overlap as the traditional ones, which intuitively shouldn't happen since the objectives are so close together. But I would suggest that other variables come into play when discussing overlap, variables that I don't fully understand.

Certainly power and field can play a role. We all differ in our interpupilary distances and ability to converge. The quality of the optical system off axis may be a huge when it allows us to handle overlap without being overtly conscious of it. Don't know.

When I look through my Zeiss 8x32 Fl at close focus (around six feet) the overlap is pronounced. But it doesn't annoy me. Moved outside on a rock solid mount, the same binoculars show overlap at five miles. I don't know if the Zeiss barrels are parallel or with a slight toe in. But even if we look at what we call infinity in most binoculars, slight overlap is present.

I know we all chuckle at the movies when our hero peers through his binocular and the perfect circle doesn't occur. It doesn't occur with us too We just aren't aware of the overlap since none of us can focus on the entire field at the same time with both eyes.

Just as the Navy found through its experiments that the average person could handle 7 power binoculars better than higher powers, perhaps there is what I would unscientifically call the overlap factor or quotient which causes annoyance with the viewer. It may be inherent in individual binocular models or the individual itself.

I know you are far more analytical than I about optical matters. Is overlap that big a deal? What are the true variables that make overlap so annoying to binocular users? If reverse porros show the same overlap as traditional porros, and they do, what are the optical issues involved.

John

 

[Kevin Purcell]

Roofs undoubtedly have an inherent advantage when it comes to very close range. But is it because their objectives are closer together?

Yes.

But overlap is inherent in all binoculars, porro or roof. Even those so-called reverse porros display as much overlap as the traditional ones, which intuitively shouldn't happen since the objectives are so close together.

Actually the closer objective of reverse porros make them even more easy to use (i.e. have more overlap) at closer distances (though the downside is they have even less ViewMaster 3D effect).

Certainly power and field can play a role. We all differ in our interpupilary distances and ability to converge. The quality of the optical system off axis may be a huge when it allows us to handle overlap without being overtly conscious of it. Don't know.

And that's the problem: convergence.

Bins do not converge. Or rather most bins ... as Pentax Papillo does converge so it can work at very close focus and distance focus too.

When I look through my Zeiss 8x32 Fl at close focus (around six feet) the overlap is pronounced. But it doesn't annoy me. Moved outside on a rock solid mount, the same binoculars show overlap at five miles. I don't know if the Zeiss barrels are parallel or with a slight toe in. But even if we look at what we call infinity in most binoculars, slight overlap is present.

All bins with parallel barrels (i.e. all collimated bins) at infinity show 100% overlap. This is just part of "parallel lines converge at infinity".

You see overlap because the fields of view overlap. You can draw this out yourself if you draw two triangles at the correct scale for the FOV coming from each barrel. As you go further away from the observer the two barrels overlap more and more. The overlap at infinity doesn't depend on the separation of the objectives but at close distances it makes a big difference. The smaller the separation the objectives the more overlap close up.

The overlap at close distance depends upon only two things FOV and objective separation. With a few bins to hand it's easy to verify this.

 

[henry link]

The overlap at close distance depends upon only two things FOV and objective separation. With a few bins to hand it's easy to verify this.

Kevin,

Magnification and horizontal collimation error also affect overlap.

Higher magnification causes greater apparent separation between the same object as seen in the left and right fields and forces the eyes to toe in more than lower magnification.

If you fail to see perfect overlap of the fields at infinity there is probably some horizontal convergent error in the collimation. That may be done intentionally to be certain to avoid divergence. The eye has no problem with convergence but can't handle any divergence. Of course any extra convergence at infinity will be added to the natural convergence at close distance.


John,

I remember the B&L Audubon 10x40. I considered it to be an unacceptable binocular for close viewing because of the poor overlap. The 10x Leupold/Opticron/Minox internal focus Porros should be just as bad or worse.

Henry

 

[FrankD]

I remember the B&L Audubon 10x40. I considered it to be an unacceptable binocular for close viewing because of the poor overlap. The 10x Leupold/Opticron/Minox internal focus Porros should be just as bad or worse.

Henry

Admittedly, yes they are. I do not feel comfortable using them at less than 15 feet or so for that very reason. Even at that distance I almost have to "force my eyes to relax" in order to get a decent image.

 

[henry link]

I'm not surprised, Frank.

One last disadvantage with widely spaced objectives at close distance is that the more the eyes are forced to toe in the more the exit pupils are vignetted.

The optical fix for all of this is to arrange the Porro prisms so that the objectives and eyepieces are in an over/under arrangement rather than side to side. That presents some obvious ergonomic challenges for the designers, but has actually been done a few times, perhaps most notably in the B&L Elite 8x50 Porro. But for the narrow field I would have bought one of those. Of course, moving the objectives closer together eliminates the fun 3-D effect, an exchange I'm already happy to make.

Henry

 

[Kevin Purcell]

The optical fix for all of this is to arrange the Porro prisms so that the objectives and eyepieces are in an over/under arrangement rather than side to side. That presents some obvious ergonomic challenges for the designers, but has actually been done a few times, perhaps most notably in the B&L Elite 8x50 Porro.

Wow, they are an interesting pair of bins

http://www.gunaccessories.com/BauschLomb/Binoculars/elite610850.jpg

and a review here

http://www.birdforum.net/showthread.php?p=793537

And the original porro design though his was for a monocular telescope was over and under

e.g.

http://www.zeiss.com/c12567a100537ab9/Contents-Frame/209b97efa7974715c12569cf00486f72

Is nothing new

 

[ceasar]

Now that is really an interesting binocular! It would have fooled me into thinking it is a roof prism! Could it be described as a semi-reverse porro? With my big paws I could probably handle it.

I remember in the late 1970's, or early 80's, at Hawk Mountain looking through what, I recall, was a rather compact Swift 9 x 36 IF Reverse Porro being used by a gentleman from Boston. I was very impressed by the clarity and sharpness it showed in viewing the ridges over the South Lookout. I don't remember it's FOV, it wasn't important there, but I wished it had a center focus.

Bob

 

[John Dracon]

Thank you for your comments fellows. Very interesting. John

 

[FrankD]

Hmm, I wonder if the Pentax PCF WP II could somewhat fall into this category. After setting the appropriate interpupilary distance the objectives were almost directly under the eyepieces. I don't ever remember finding another binocular quite like it. If the optical quality had been just a bit better I probably would have kept it.

 

[Steve C]

I called Vortex today. One thing I asked them was why would I buy the Raptor instead of a Yosemite. The answer was, the Raptor was more easily repairable, was tripod adaptable, had better glass, better coatings and a better warranty. They said dealer price would likely be around $110-120. Availability in early March.

On another note, the Vulture and Hurricane lines will be no more. The sizes and magnifications of those lines will carry the new coatings of, and live on under the Diamondback label. They said Diamondback availability was not expected until later April. Don't know about waiting that long for the 7x36. On the other hand, they said they do have 32mm Vipers now. Hmmmmmm??? now what?

 

[Kevin Purcell]

Thanks, Steve.

The Raptor porros sound like an interesting little bin. Perhaps they might have better baffling too.

At least they're shrinking their lines (though from sales of the past 6 months neither of those are a surprise). They should be a bit more coherent after the old lines fall out.

The way bins are coming at us fast and think the prudent thing may be to wait until the spring

 

[FrankD]

On the other hand, they said they do have 32mm Vipers now. Hmmmmmm??? now what?

You know darn well what. Get out the charge card and order a set for review.



I am going to wait to give these new porros a go. I like them and the simplicity they represent. If they are anywhere near half decent then my thanks goes out to Vortex for investing in the porro market.

 

[BinoBoy]

The 6.5X are supposedly available now

Here's a place that seems to have them already:

https://www.archerybymail.com/shop/item.asp?itemid=356

Actually, the dropdown list shows they have both 6.5X and 8.5X

 

[Steve C]

No Raptors, or new Diamondbacks for that matter, until April. I tried ordering from a couple of places. Oops sorry the webmaster made a mistake, it should say available for pre order. That includes CameralandNY who is supposed to get the first shipment from Vortex. I even tried getting one from Vortex when I was talking to them abut sending them my Viper. They don't even have any at Vortex. They said they MIGHT get some by the last week in March, but they really think April.

 

[FrankD]

Yep, emailed them yesterday and got an almost instant response. First week in April is the word. I am going to order one of each to see how they perform. Both have me quite intrigued. I like that 8.5x with a 390 foot field of view...and the 6.5x isn't a slouch either.