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To Prism or Not to Prism?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/05/2015 at 22:15
Hypnogator View Drop Down
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I recently compared a set of Vortex and Nikon 8X42 binoculars at a local sporting goods store.  I wasn't able to detect much difference in the optical quality of the two, but one thing that I did notice was the difference in focus between the non-prism Vortex and the prism Nikon.  When I focused on a street sign about 30 yds away, with the Vortex, I could read the credit card signs on the front door, although they were somewhat fuzzy.  With the Nikon, the signs were completely out of focus and illegible.

It appears to me from this experience that the focus on prism binoculars is more critical, while the non-prism binoculars have a greater depth of field (to borrow a photographic term.)

My question is, for elk and deer hunting in the big woods, would it be better to have the shallower focus of the prism binoculars so that what you are searching for is in sharp focus while objects in the foreground are out of focus, or would it be better to have the greater depth of field of the non-prism binoculars, so that an animal in the periphery of your view would be more recognizable as such?

I appreciate y'alls expertise!

Post Options Post Options   Thanks (1) Thanks(1)     Back to Top Direct Link To This Post Posted: September/06/2015 at 08:59
FrankD View Drop Down
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Not exactly sure what you mean by prism and non prism...... Maybe roof prism and porro prism? Porros are the classic style with objectives out farther than the eyepieces. Roofs have the two in line. Porros are easier to manufacture and have a simpler overall design. This can give greater image quality at any given price point.....up to around $2000. The bad news is that most of them are harder to waterproof and are somewhat bulkier in size.
Post Options Post Options   Thanks (1) Thanks(1)     Back to Top Direct Link To This Post Posted: September/06/2015 at 10:17
Klamath View Drop Down
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All binoculars made by Nikon or Vortex have prisms.  Like Frank says, either porro or roof prisms.  Also telling us you compared a Nikon and a Vortex tells us absolutely nothing.  Might as well have said a Ford and a Chevy.  Lots of Fords, lots of Chevy's, lots of Vortex, lots of Nikon.  Which one of Nikon did you compare to which one of Vortex?  That might get us closer to a point where we can give you some good advice. 


Post Options Post Options   Thanks (1) Thanks(1)     Back to Top Direct Link To This Post Posted: September/06/2015 at 11:32
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Originally posted by Hypnogator Hypnogator wrote:



My question is, for elk and deer hunting in the big woods, would it be better to have the shallower focus of the prism binoculars so that what you are searching for is in sharp focus while objects in the foreground are out of focus, or would it be better to have the greater depth of field of the non-prism binoculars, so that an animal in the periphery of your view would be more recognizable as such?


I notice from your comments and questions that you don't know much about binoculars.That is alright, you came to the right place and we will help as best we can. 
You want more depth of field in a binocular no matter what and where, regardless of where you hunt. 
Depth of field in binoculars depends on magnification or power of binoculars.  Binoculars have numbers on them 7x42, 8x42, 8x32, 10x40, etc. The first number is the power or magnification. The more magnification, the less depth of field and less field of view you get. 
For your deep woods hunting, you want depth of field and field of view and low light performance. Therefore, be sure to get a 8x power binocular. If you get a 10x for big woods, the deer may be gone before you are able to focus and spot them. 
Same goes for your rifle scope. Don't use high power on the scope, 3x or 4x is just fine. If you go in the woods with a 12x scope or binocular, you will waste time searching through your optics because they will have narrow field and shallow field of view.
I hunt deep dark woods and i use 7x binoculars and 3x scope with heavy reticle.  
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/06/2015 at 19:36
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You're right, I don't know a whole lot about binoculars.  My knowledge is pretty much limited to the notion that like rifle scopes, the power is the first number, indicating how many times the image is enlarged, and the second number is the diameter of the lenses in millimeters.  I had figured on a 7x or 8x binocular for the best combination of enlargement and field of view, and on 42 to 50mm for the best combination of light gathering ability with portability (size & weight).

I wasn't really paying a lot of attention to the models other than to compare what I now know (thanks, guys) to be the porro vs the roof prism.  From what I see in the binoculars choices here on SWFA, the two appear to be the Vortex 8x42 Crossfire http://swfa.com/Vortex-8x42-Crossfire-Binocular-P79120.aspx and the Nikon 8x42 Aculon A211 http://swfa.com/Nikon-8x42-Aculon-A211-Binocular-P61650.aspx  I don't really want to get into the Vortex vs. Nikon thing here, 'though I would appreciate any thoughts on that.  What I was asking about is the advantage or disadvantage of a greater depth of field that the roof prism Vortex seemed to give me. 

It would appear to me that the roof prism's greater depth of field would be an advantage in the field.  In perusing the binocs available on SWFA, the Vortex 8x42 Diamondback http://swfa.com/Vortex-8x42-DiamondBack-Binocular-P10849.aspx would be a step up from the Crossfire in quality, while the Vortex 8x56 Vulture HD http://swfa.com/Vortex-8x56-Vulture-HD-Binocular-P44650.aspx would provide the same power with greater low-light capability, albeit at additional size and weight.  Perhaps you guys could make some other suggestions in this class of glass (so to speak).

Thanks for the responses.  I've learned quite a bit already, and look forward to your thoughts on other alternatives.
Post Options Post Options   Thanks (1) Thanks(1)     Back to Top Direct Link To This Post Posted: September/06/2015 at 21:28
Klamath View Drop Down
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Actually anweis is correct in that depth of field is magnification dependent, not prism type dependent.  The porro prism has a 3-D advantage as the objectives are further apart.  Because the objectives are spaced however does not mean you are scanning more area and that the fov will be bigger.  The field is an eye piece design function.

Give us a line on what your budget constraints are if you will.

You are evidently looking for $500 tops it seems, preferably lower.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/06/2015 at 22:42
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Understand that you experts agree that depth of field is magnification-dependent, but how come two 8x binocs had such different degrees of out-of-focus on the door signs when focused on the same street sign further away?  I thought it had to do with the porros vs roof prisms.

Yeah, $400 - $500 is what I would be comfortable spending on a decent pair of binoculars.  Might be willing to go a little higher for a SIGNIFICANTLY better pair.

Again, thanks for the guidance!
Post Options Post Options   Thanks (1) Thanks(1)     Back to Top Direct Link To This Post Posted: September/07/2015 at 09:18
Klamath View Drop Down
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The first thing that actually leaps into focus from your description is this.  The single least useful thing you can do is to look through a binocular without setting it up for your own eyes.  The procedure is as follows.  First, locate the diopter mechanism.  It will be a ring under the right eye piece, or it will be part of the center focus mechanism.  You may need to pull the focus wheel (maybe the whole wheel or sometimes the very back of the knob pulls out) out a bit to unlock it, or it may be movable with a small lever or extension extending upward from the back of the focus wheel.  Now close your right eye (being sure the diopter is locked if on the center focus knob, the center focus won't work with an unlocked diopter) and focus the left eye on a decent reflective object some distance away, with the center focus wheel.  Then close your left eye (the diopter almost always is on the right eye except for Steiner and some Opticron models).  It is a good idea to have the diopter set at zero to start to minimize movement.   With that eye closed, focus the left eye with the center focus.  Close the left eye and manipulate the diopter until the right eye is focused. Lock the diopter mechanism if needed.   Keep away from the center focus here.  You now have the binocular adjusted for each eye.  The center focus can now be used to compensate focus for varying distances.

Having the diopter badly adjusted will cause what you saw.  It is amazing how often this occurs.  As an example, one time at a show I was at the Swarovski booth, I was looking at the stuff and talking to the rep.  A lady walked up with a Swarovski binocular, set it on the table and said..."Young man, how much money do I have to spend to get a decent image?".  The fellow picked up the binocular, looked at it, grinned (the lady damn near thought he was going to be a smart ass here), cranked the diopter to zero and handed her the binocular and said..."here that should help".  The woman was astonished.  She asked what it was he did.  He explained the procedure I outlined above and after trying it a couple of times she left with her properly adjusted binocular.  She had just cranked to diopter ring all the way over so it wouldn't move.

Lots of people will mess with focus to make life rough for the next viewer or just mess things up from sheer ignorance.  The head behind the counter may not be a lot better either.

Until you get a better handle on optics knowledge and a little more background from evaluation your use needs, you don't have to spend a ton of $$.  From Nikon, the Monarch 7 is a very good glass.  The Monarch 5 may suit you too, but the 7 is really worth the extra here.  The Nikon Aculon is a good glass for not a lot of money, one of the better bargains binoculars out there.  Being a porro prism, it is not water proof or dust proof and somewhat bulkier than a roof prism glass.  From Vortex the Diamondback is a very good entry level glass.  The Viper HD and Talon HD represent good steps upward. The Vulture, with its 56 mm objectives is better suited for low light and is bulkier than a smaller size objective.   I'll stay here for now as apparently you have access to a dealer who has both lines.  Being able to see for yourself whether or not a binocular suits you is a lot more important than worrying about small details of one brand vs another.  The more you can see for yourself, the better certainly, but if you find either a readily available Nikon or Vortex glass, just get it and go use and enjoy it.  Be sure to get it set up for your eyes...Smile.


Edited by Klamath - September/07/2015 at 09:27
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: September/10/2015 at 08:42
FrankD View Drop Down
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Ditto on everything Klamath stated.
 
In addition, something interesting I found on a personal level. Depth of field can be misleading. For example, if I focus on a specific object 40 or so feet away I can see the object in sharp focus and then slightly rotate the focus knob one way or the other to get either the foreground or background in focus with the object.
 
If you take two binoculars and focus one to have the main object and the background in focus and then take the second binocular and focus so that the main object and foreground are in focus then it will appear as if one has better depth of field than the other. Hope that makes sense.
 
Also, I have found that focusing tension and focusing speed can play a big role in our perception of depth of field. If a binocular has a fast focus (less number of turns to go from close focus to infinity) or if the focusing tension is particularly "loose", for lack of a better term, then it can appear that the depth of field is fairly shallow. Careful examination of the situation can prove just the opposite.
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