Call me a sweet old fashioned guy but for 50 years i have owned only porro prism binoculars. My reasons were the price and very importantly the better ( to my eye ) depth of field. Researching the internet has confirmed my beliefs that the porros have a better field of view. However have things changed with all the improvements made to contemporary roof prisms? I am contemplating buying into my first pair of roof prisms but only if the depth of field is at least equal to the porros. The second part of my dilemma is can i buy the kind of equal depth of field quality for $300. plus minus a few dollars ?
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Depth of Field Porro vs Roof prism (1 Viewer)
- Thread starter cappi
- Start date
This subject comes up often but I think that most people have come around to the conclusion that all binoculars of the same power have the same depth of field. Lower power binoculars have deeper fields of view in front of and behind the bird you are looking at than high ones do. Often binoculars which have fast focusing ratios will appear to not have the same depth of field as those with slower focusing ratios because it is easier to "fine tune" your focus with the latter without "overshooting" or "undershooting" the bird you are looking at.
What I think you will notice after switching to roof prism will be that the appearance of the bird you are looking at is larger than it would have appeared in a porro of the same power.
Bob
What I think you will notice after switching to roof prism will be that the appearance of the bird you are looking at is larger than it would have appeared in a porro of the same power.
Bob
looksharp65
Well-known member
cappi,
be sure not to confuse depth of field with 3D-effect.
The depth of field, which by the way depends on the individual user and light conditions, tells how far behind and how far in front of the point of focus the sharpness still is fine.
A monocular has depth of field, but no 3D effect.
But curiously, a spotting scope or monocular can show some kind of odd 3D effect:
I've discovered that when looking at a bird through a scope at decent distance, the far situated background will seem to change its position relative to the bird if the observer moves his head sidewise. Such behaviour can't happen through binoculars because the distance between the oculars and their relative position to the eyes won't allow the freedom of sidewise head movements.
Real 3D effect is achieved through the lateral displacement of the binocular's barrels and the accompanying parallax of the two images. But 3D perception/stereoopsis is something that takes place in the visual cortex of the brain and not in the binoculars optical paths.
The greater parallax of porro (porri?) binoculars gives the user stronger cues to 3D perception, as long as they are not used at too short or too long distances.
//L
http://www.birdforum.net/showthread.php?t=173492&page=2
be sure not to confuse depth of field with 3D-effect.
The depth of field, which by the way depends on the individual user and light conditions, tells how far behind and how far in front of the point of focus the sharpness still is fine.
A monocular has depth of field, but no 3D effect.
But curiously, a spotting scope or monocular can show some kind of odd 3D effect:
I've discovered that when looking at a bird through a scope at decent distance, the far situated background will seem to change its position relative to the bird if the observer moves his head sidewise. Such behaviour can't happen through binoculars because the distance between the oculars and their relative position to the eyes won't allow the freedom of sidewise head movements.
Real 3D effect is achieved through the lateral displacement of the binocular's barrels and the accompanying parallax of the two images. But 3D perception/stereoopsis is something that takes place in the visual cortex of the brain and not in the binoculars optical paths.
The greater parallax of porro (porri?) binoculars gives the user stronger cues to 3D perception, as long as they are not used at too short or too long distances.
//L
http://www.birdforum.net/showthread.php?t=173492&page=2
Last edited:
elkcub
Silicon Valley, California
Cappi,
Unfortunately, the phrase "depth of field" has several meanings. Optically, it is strictly a monocular property, that is, it does not refer to what you see using both eyes. In that domain, as stated in the previous post, it refers to the range of acceptable focus fore and aft of an object at some distance from the observer. Hardly anyone actually means that when evaluating binoculars, because they use both eyes. The term has greatest utility when applied to photography (although not particularly stereo photography).
When both eyes are used with a binocular (as should be the case), the brain fuses slightly different images from each eye, the amount of difference being determined by the separation between the objective lenses. Focused at any working distance, porro and roof binoculars each produce fused images, but the former results in spatial perception having greater depth and smaller apparent images, and the latter in spacial perception having shallower depth and larger apparent images. This is because of the way that depth cues are interpreted by the brain.
In any event, when using both eyes "depth of field" primarily refers to the perception of spatial depth, which is what the observer uses to judge relative distances accurately. In this regard, Porro prism binoculars with more widely separated objectives retain a permanent advantage over roof prism designs.
Ed
Oops, didn't see the other posts. How redundant can I be? :eek!:
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looksharp65
Well-known member
:-O And we're not on Birdforum's payroll...what a shame :-O
Gentlemen, I cant thank you enough for sharing with me the wealth of information you have accumulated thru your years of experience. This info will most likely keep me using the porros for hopefully another 20 years. I often find myself in the dense hardwoods of the northeast and the ability to peer deeper into the rows of trees (out to a max of 80 yards) is of a priority to me. With a budget of $300. I am contemplating buying a pair of Bushnell Legend porros 8x42 or a pair of Pentax 8x40 porro binoculars. Any recommendations of other 8x porros under $300 are definetly welcomed. Again, thank you all so much !!
brocknroller
porromaniac
Cappi,
Okay, I call you a "sweet" old fashioned guy (not that there's anything wrong with that
. A bit tart myself, but old fashioned in that I too prefer porros to roofs for the same reason you do, better 3-D effect, which produces a better perception of depth.
I find that most roofs produce images that look compressed, particularly midsized roofs. Looking at tree lines in the distance, they appear very close together vs. my porros, which give better sense of space between them.
However, at lower powers, roofs can provide a good 3-D effect. The Zen Ray 7x36 ED2 did. At a distance, looking at three people standing together talking, the ZR showed a bit more distance between them than my 8x30 EII porros. The ZR 736 ED2 sells for $375.
http://www.zen-ray.com/shop/zened2-7x36.html
At the $300 level for porros, I'd check out the Swift 8.5x44 820 Audubon (new body style). The older body 820 is still available, same price, but the eyecups are horrible (rings, not even eyecups).
The new style looks like this one on the link below and costs $349.
http://www.eagleoptics.com/binoculars/swift/swift-audubon-8-5-x44-porro-prism-binocular
Brock "Bucky" Barnes
Okay, I call you a "sweet" old fashioned guy (not that there's anything wrong with that
. A bit tart myself, but old fashioned in that I too prefer porros to roofs for the same reason you do, better 3-D effect, which produces a better perception of depth. I find that most roofs produce images that look compressed, particularly midsized roofs. Looking at tree lines in the distance, they appear very close together vs. my porros, which give better sense of space between them.
However, at lower powers, roofs can provide a good 3-D effect. The Zen Ray 7x36 ED2 did. At a distance, looking at three people standing together talking, the ZR showed a bit more distance between them than my 8x30 EII porros. The ZR 736 ED2 sells for $375.
http://www.zen-ray.com/shop/zened2-7x36.html
At the $300 level for porros, I'd check out the Swift 8.5x44 820 Audubon (new body style). The older body 820 is still available, same price, but the eyecups are horrible (rings, not even eyecups).
The new style looks like this one on the link below and costs $349.
http://www.eagleoptics.com/binoculars/swift/swift-audubon-8-5-x44-porro-prism-binocular
Brock "Bucky" Barnes
