OpticsTalk by SWFA, Inc. Homepage SWFA     SampleList.com
Forum Home Forum Home > Scopes > Rifle Scopes
  New Posts New Posts RSS Feed - John Barsness' .........misunderstandings
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Visit the SWFA.com site to check out our current specials.

John Barsness' .........misunderstandings

 Post Reply Post Reply Page  123>
Author
Message
Rich Coyle View Drop Down
Optics Apprentice
Optics Apprentice
Avatar
Blind as a bat

Joined: October/22/2010
Location: Grants Pass, OR
Status: Offline
Points: 231
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rich Coyle Quote  Post ReplyReply Direct Link To This Post Topic: John Barsness' .........misunderstandings
    Posted: November/18/2010 at 17:52
From another site I porcured the following questions and answers.
 
“If you change the magnification down or up with the scopes when you test them does it change the ability to distinguish line size?”

 

“John, regarding your line test, what is it that you can take away from performing this test. I'm trying to understand if you are testing for resolution, contrast or perhaps brightness of a given scope. If I understand this correctly, you are using an artificial light source to illuminate a chart with various lines in black and white and I'm not seeing how this could evaluate a scope's ability to perform under field conditions with foliage and game colors present where a scope's ability to show color contrast in poor light being important to the end user.”

 

“In my optical tests, done at night on a chart in controlled light conditions, a VX-7 2.5-10x rated right alongside a Swarovski Z6 2-12x and a Schmidt & Bender Summit.

 

My night-time test is done with a chart using black-and white lines, 25 yards from a 100-watt bulb. Scopes are all set on 6x, and rated by the smallest black line that can be seen.”

 
“I'll try to answer the questions about my chart test in one post:
Yes, magnification changes do make a difference in how we see things. Usually higher magnification allows us to see more detail, unless the exit pupil is too small for our eye to use. This is why I set every scope on 6x; this makes it a test of optics rather than magnification.

I chose 6x because very few variable scopes have an objective smaller than 36mm anymore. This results in a 6mm exit pupil at 6x, which is close to the maximum the normal eye can use.

The chart is black-and-white and tests for both sharpness (definition) and brightness. It doesn't test for color because everybody's eyes see color differently, hence any judgment I might make wouldn't necessarily apply to anybody's else's eyes. But definition and brightness do.

So far it's the best repeatable scope optics test I've been able to come up with, short of investing hundreds of thousands of dollars in professional equipment, which I doubt could be recouped by writing optics articles for shooting magazines.”

 

Back to Top
djwarner View Drop Down
Optics GrassHopper
Optics GrassHopper
Avatar

Joined: August/23/2010
Status: Offline
Points: 16
Post Options Post Options   Thanks (0) Thanks(0)   Quote djwarner Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 18:28
I read John Barsness article in the October 2010 issue of GUNS MAGAZINE. It spurred me to test my own scope using a resolution chart I had for evaluating 35mm camera lenses. Black and white line pairs has been a standard method of evaluating lenses for a long time. It is assumed that the high contrast image will indicate the best the lense will do. Obviously, poor light or differing color will adversely affect the image, but the test is to determine how much contrast can be retained as the image passes through imperfect lenses. Other charts include scales of sine wave density rather than a square wave of 100% black or 100% white. The square wave pattern is adequate to evaluate our scopes. When the resolution limit is reached, the lines blur to make a solid grey. 
 
The only complaint I had with John's method is the 25 yards distance used in his tests. Some scopes without adjustable optics may not focus that close. In testing my own scopes, the generic 3-9x40 scope that came with my Marlin 336 was definitely soft at this distance. Re-testing neared to 100 yds still showed it had less resolution that a good pair of Nikon Marine 7x50 binoculars and justified my decision to replace it rathr than to adjust it focus.
 
His comment about resolution improving as you zoom up in power assumes of the three main components of the scope- Objective, zoom group, and eyepiece - that the Objective lens is not the limiting component. His procedure of setting all scopes to 6x does provide a level playing field, but I would think that his readers would also like to know whether Scope A or Scope B maintains any advantage as it zooms up in power.
 
 
 
Non nobis tantum nati
Back to Top
Roy Finn View Drop Down
MODERATOR
MODERATOR
Avatar
Steiner Junkie

Joined: April/05/2004
Location: United States
Status: Offline
Points: 4856
Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 18:43
Rich, you are quoting me in your post in case you didn't know it. What is your point here anyway.
Back to Top
Rich Coyle View Drop Down
Optics Apprentice
Optics Apprentice
Avatar
Blind as a bat

Joined: October/22/2010
Location: Grants Pass, OR
Status: Offline
Points: 231
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rich Coyle Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 19:22
Originally posted by Roy Finn Roy Finn wrote:

Rich, you are quoting me in your post in case you didn't know it. What is your point here anyway.
 
Hello, Roy Finn.
 
My point is that when one turns up the magnification on a scope with good optics one can see more detail even in low light.  Most of the posters here did not realize that, so I used your quote to help them learn.  They are under the impression that increasing magnification increases detail only in good light.
Back to Top
Roy Finn View Drop Down
MODERATOR
MODERATOR
Avatar
Steiner Junkie

Joined: April/05/2004
Location: United States
Status: Offline
Points: 4856
Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 19:29
Here's the short version. Increasing magnification will increase detail in low light so long as the exit pupil of the scope is at least as large as your eye pupil. Same concept as a camera lense aperature.
Back to Top
Roy Finn View Drop Down
MODERATOR
MODERATOR
Avatar
Steiner Junkie

Joined: April/05/2004
Location: United States
Status: Offline
Points: 4856
Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 19:40
Just curious about " John Barnes".....Is that the same guy who invented the X bullet ?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Big Grin
Back to Top
Rich Coyle View Drop Down
Optics Apprentice
Optics Apprentice
Avatar
Blind as a bat

Joined: October/22/2010
Location: Grants Pass, OR
Status: Offline
Points: 231
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rich Coyle Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 19:51
Originally posted by Roy Finn Roy Finn wrote:

Just curious about " John Barnes".....Is that the same guy who invented the X bullet ?
 
 No.  But they are both genius.  By the way, what is the correct spelling of the writer's name?
 
John is the one who inspired my line test with the Swarovski and the Bushnell.  I couldn't find my John chart, so I improvised with the 5/16" lines.  I was trying to make 1/4" lines but I am coputer challenged.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Big Grin
Back to Top
Roy Finn View Drop Down
MODERATOR
MODERATOR
Avatar
Steiner Junkie

Joined: April/05/2004
Location: United States
Status: Offline
Points: 4856
Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 19:54
Barsness
Back to Top
mike650 View Drop Down
Optics God
Optics God
Avatar

Joined: May/14/2006
Location: West of Rockies
Status: Online
Points: 14569
Post Options Post Options   Thanks (0) Thanks(0)   Quote mike650 Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 21:25
Originally posted by Roy Finn Roy Finn wrote:

Barsness


Oh, the pro-Leupold/anti-Swaro guy.  Big Grin
“A hunt based only on trophies taken falls far short of what the ultimate goal should be.” – Fred Bear
Back to Top
Roy Finn View Drop Down
MODERATOR
MODERATOR
Avatar
Steiner Junkie

Joined: April/05/2004
Location: United States
Status: Offline
Points: 4856
Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 21:29
He does seem to be more sensitive to Leupold criticism than any other brand...
Back to Top
RifleDude View Drop Down
MODERATOR
MODERATOR
Avatar
EVIL OPPRESSOR

Joined: October/13/2006
Location: Texas
Status: Offline
Points: 16337
Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 21:55
Originally posted by Rich Coyle Rich Coyle wrote:


Yes, magnification changes do make a difference in how we see things. Usually higher magnification allows us to see more detail, unless the exit pupil is too small for our eye to use.


Note the second half of the sentence you highlighted, though.  This is what various people were trying to explain to you.  Increasing magnification does increase the ability to resolve detail up to a certain point, but light transmission is also reduced as magnification is increased.  Everything is a tradeoff -- to gain one benefit, you always lose another.  There is a point of diminishing returns when magnification starts to exceed the objective lens system's ability to transmit an optimal amount of light to your eye.  Adequate light transmission varies depending on the available light of your surroundings, the intended use of the optic, and the diameter of your eye pupil dilation.  At some point, once you continue to increase magnification, the optic's exit pupil diameter becomes smaller than your eye pupil diameter.  As a result, the view through the scope becomes dim and your ability to resolve detail is reduced.  Increasing magnification also magnifies optical aberrations, so even though theoretical resolution increases, the image becomes softer and contrast is reduced.

In short, the law of diminishing returns applies to magnification as with most things.  More isn't necessarily better.  Increasing magnification doesn't provide an infinitely proportional increase in detail resolution because at some point, light transmission is reduced to the point that image quality suffers.

Ted


Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle.
Back to Top
supertool73 View Drop Down
Optics God
Optics God
Avatar
Superstool

Joined: January/03/2008
Status: Offline
Points: 11814
Post Options Post Options   Thanks (0) Thanks(0)   Quote supertool73 Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 22:15
Originally posted by RifleDude RifleDude wrote:

There is a point of diminishing returns when magnification starts to exceed the objective lens system's ability to transmit an optimal amount of light to your eye.


You mean when using, say, a 42 power scope.  Bucky
Lifetime warranty and excellent customer service don't mean a thing when your gun fails during a zombie attack.

"A Liberal is a person who will give away everything they don't own."
Back to Top
Jon A View Drop Down
Optics Journeyman
Optics Journeyman
Avatar

Joined: March/14/2008
Location: Everett, WA
Status: Offline
Points: 670
Post Options Post Options   Thanks (0) Thanks(0)   Quote Jon A Quote  Post ReplyReply Direct Link To This Post Posted: November/18/2010 at 22:56
Resolution testing on a black and white target does provide much useful information, one just needs to keep in mind it doesn't tell the whole story.  You still need to compare on "camouflaged" objects, simply looking into the woods, looking into the shadows, etc, under various lighting conditions; look toward the sun, looking through mirage, etc to get a more complete picture.  Pure resolution under good conditions is an important chunk of it though.

I use the standard old USAF Resolution chart quite a bit (though I usually print it out on beige target colored paper).  Though I like testing higher powered scopes at higher powers at longer ranges as I feel reveals much better information than testing them at 6X at close range.  Many scopes look pretty good and compare well with other scopes at 6X but show their true colors when you crank up the power.
Back to Top
Rich Coyle View Drop Down
Optics Apprentice
Optics Apprentice
Avatar
Blind as a bat

Joined: October/22/2010
Location: Grants Pass, OR
Status: Offline
Points: 231
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rich Coyle Quote  Post ReplyReply Direct Link To This Post Posted: November/19/2010 at 06:53
Originally posted by RifleDude RifleDude wrote:

Originally posted by Rich Coyle Rich Coyle wrote:


Yes, magnification changes do make a difference in how we see things. Usually higher magnification allows us to see more detail, unless the exit pupil is too small for our eye to use.


Note the second half of the sentence you highlighted, though.  This is what various people were trying to explain to you.  Increasing magnification does increase the ability to resolve detail up to a certain point, but light transmission is also reduced as magnification is increased.  Everything is a tradeoff -- to gain one benefit, you always lose another.  There is a point of diminishing returns when magnification starts to exceed the objective lens system's ability to transmit an optimal amount of light to your eye.  Adequate light transmission varies depending on the available light of your surroundings, the intended use of the optic, and the diameter of your eye pupil dilation.  At some point, once you continue to increase magnification, the optic's exit pupil diameter becomes smaller than your eye pupil diameter.  As a result, the view through the scope becomes dim and your ability to resolve detail is reduced.  Increasing magnification also magnifies optical aberrations, so even though theoretical resolution increases, the image becomes softer and contrast is reduced.

In short, the law of diminishing returns applies to magnification as with most things.  More isn't necessarily better.  Increasing magnification doesn't provide an infinitely proportional increase in detail resolution because at some point, light transmission is reduced to the point that image quality suffers.
 
 
Why do you think I highlighted that?  So guys like you would hopefully realize I saw the whole statement.  I have done enough diminshing light comparisons to know one can extend his viewing time by turning up the power ring.
 
I love theory.  But after awhile one has to test theory and accept the facts of one's repeated tests.  Some time theory works out and sometime it does not.  It could be that there are those who are not so defensive and might give it a try.
Back to Top
Trigger slap View Drop Down
Optics Apprentice
Optics Apprentice
Avatar

Joined: February/25/2010
Location: Kentucky
Status: Offline
Points: 122
Post Options Post Options   Thanks (0) Thanks(0)   Quote Trigger slap Quote  Post ReplyReply Direct Link To This Post Posted: November/19/2010 at 08:20
[QUOTE=Rich Coyle][QUOTE=RifleDude] [QUOTE=Rich Coyle]realize I saw the whole statement.  I have done enough diminshing light comparisons to know one can extend his viewing time by turning up the power ring.
 
 
 Loco Maybe my eyes are different, but I have to reduce magnification in low light!
 
How can we call it unalienable when we allow it to be suspended revoked or restricted?
Back to Top
Rancid Coolaid View Drop Down
MODERATOR
MODERATOR
Avatar

Joined: January/19/2005
Location: United States
Status: Offline
Points: 9318
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rancid Coolaid Quote  Post ReplyReply Direct Link To This Post Posted: November/19/2010 at 09:51
The real beauty of writing for a gun magazine is that if you love a product, somehow that company seems to advertise more in your magazine, it is a heretofore unnoticed phenomenon, I think.

John does love his Leupold.

Maybe they preferentially sell him the ones that don't break so much.


Rich, like few others I have ever known (and like no one outside organized religion I have ever known), you will hold onto your truth long after you should.  Kudos!

I especially like your quoting an OT member from an article, then summarizing that quote by saying the exact opposite of what the quote said, that was so awesome.

I don't use emoticons much, but you've earned it!

Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Thunbs Up
Freedom is something you take.
Respect is something you earn.
Equality is something you whine about not being given.
Back to Top
RifleDude View Drop Down
MODERATOR
MODERATOR
Avatar
EVIL OPPRESSOR

Joined: October/13/2006
Location: Texas
Status: Offline
Points: 16337
Post Options Post Options   Thanks (0) Thanks(0)   Quote RifleDude Quote  Post ReplyReply Direct Link To This Post Posted: November/19/2010 at 09:58
Originally posted by Rich Coyle Rich Coyle wrote:

Why do you think I highlighted that?  So guys like you would hopefully realize I saw the whole statement.  I have done enough diminshing light comparisons to know one can extend his viewing time by turning up the power ring.
 
I love theory.  But after awhile one has to test theory and accept the facts of one's repeated tests.  Some time theory works out and sometime it does not.  It could be that there are those who are not so defensive and might give it a try.
 
Huh?  You only highlighted the first half of the sentence, before the comma.  I'm not expressing theory, I'm explaining the meaning of the second half of the sentence you quoted that you apparently don't understand.  If you did, you would realize that the second half of the very sentence you used to try to make the case that more magnification is always better actually disputes your point. 
 
I'm not defensive; I'm attempting to explain why the benefits of increased magnification have practical limits, based on factual optical principles of light transmission vs. magnification that are inescapable.  I'm attempting to have an intelligent, level-headed discussion with you.  Many of us own the optics you tested, and I assure you, your observations are not typical, even though I don't dispute you observed what you observed.  I own or have used scopes from all of the lines you've mentioned so far for many years.  I have quite a bit of trigger time behind most of the scope brands you can name, I can assure you I'm very familiar with their various qualities, and I have no brand loyalties.
 
Don't misunderstand; increased magnification does indeed increase your ability to resolve detail... but only to a point.  With benefits also comes disadvantages, which is my point.  There isn't an infinitely linear benefit to continually increasing magnification.  At some point, light transmission drops off to a degree that you cannot utilize the additional magnification.  You only extend your viewing time by turning up magnification when the optic's exit pupil size is still large enough to match or exceed the dilated diameter of your eye pupil.  This isn't theory, it is scientific fact that applies to any optic.  If you are seeing an improvement in your ability to see detail in low light as you turn up the power ring to as much magnification as you have available, it is because the exit pupil of the optic you are viewing is still sufficiently large enough to be usable to your eyes at the magnification you selected.  This probably means that your pupils don't dilate as large as the average person so that in low light, your pupils are smaller in diameter than normal.  The exact same principles apply to camera lense apertures.  Just like a high F-number on a camera lens, your eye pupils are the limiting aperture restricting your ability to take in the additional light that you would normally get at lower magnification.
Ted


Money can't buy happiness... but it's much more comfortable to cry in a Porsche than on a bicycle.
Back to Top
Dogger View Drop Down
Optics Jedi Master
Optics Jedi Master
Avatar

Joined: January/02/2007
Location: Ontario, Canada
Status: Offline
Points: 8904
Post Options Post Options   Thanks (0) Thanks(0)   Quote Dogger Quote  Post ReplyReply Direct Link To This Post Posted: November/19/2010 at 10:04
One definition of madness is doing the same thing over and over and over and expecting a different result.
God save the Empire!
Back to Top
mike650 View Drop Down
Optics God
Optics God
Avatar

Joined: May/14/2006
Location: West of Rockies
Status: Online
Points: 14569
Post Options Post Options   Thanks (0) Thanks(0)   Quote mike650 Quote  Post ReplyReply Direct Link To This Post Posted: November/19/2010 at 11:03
Originally posted by Dogger Dogger wrote:

One definition of madness is doing the same thing over and over and over and expecting a different result.





“A hunt based only on trophies taken falls far short of what the ultimate goal should be.” – Fred Bear
Back to Top
Dogger View Drop Down
Optics Jedi Master
Optics Jedi Master
Avatar

Joined: January/02/2007
Location: Ontario, Canada
Status: Offline
Points: 8904
Post Options Post Options   Thanks (0) Thanks(0)   Quote Dogger Quote  Post ReplyReply Direct Link To This Post Posted: November/19/2010 at 11:28
Wow!  Had a flashback for a sec there Mike.  That is disturbing.
God save the Empire!
Back to Top
 Post Reply Post Reply Page  123>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.01
Copyright ©2001-2018 Web Wiz Ltd.

This page was generated in 0.438 seconds.