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Another scope evaluation

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 13:04
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I guess the transitory nature of a scope image and its use primarily as an aiming device explains the lack of scientific testing of scope Vs camera lens where the captured image is studied in minute detail.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 13:11
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the information transmitteed thru the scope is picked by the camera image chip, recorded in a raw file , which would contain, and would be different for all scopes, the color spectrum peculiar to that scope lens system, ist spectral sensitivty at different wavelengths, total light transmission (light meter reading). A color chart card or something similar (umberallas at the beach for 8shots) could be used a test.
lack of scientific interest-- now thats a subject all by itself.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 13:54
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Originally posted by Dale Clifford Dale Clifford wrote:

the information transmitteed thru the scope is picked by the camera image chip, recorded in a raw file , which would contain, and would be different for all scopes, the color spectrum peculiar to that scope lens system, ist spectral sensitivty at different wavelengths, total light transmission (light meter reading). A color chart card or something similar (umberallas at the beach for 8shots) could be used a test.
lack of scientific interest-- now thats a subject all by itself.


We are talking about different things, Dale.  You are talking about measuring MTF, while I am talking about how the result of that measurement correlates to what you see with your eye.

As for the measurement itself, it makes considerable difference on which imaging sensor you use (I make imaging sensors for a living).  Depending on the specifics of the sensor design, your measured MTF can vary considerably.  If you are planning to use a commercial camera, ever RAW files typically have some processing done to them.  The output you are getting is already modified by the image processor.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 13:58
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Originally posted by koshkin koshkin wrote:

How would you use this information as it pertains to scopes, Dale?

ILya


I can't speak for Dale, but I will use this information for evil - just as soon as I figure out what the hell we are talking about!
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 14:00
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Ah!  The real Rancid is here.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 14:02
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Originally posted by Rancid Coolaid Rancid Coolaid wrote:

Originally posted by koshkin koshkin wrote:

How would you use this information as it pertains to scopes, Dale?

ILya


I can't speak for Dale, but I will use this information for evil - just as soon as I figure out what the hell we are talking about!


My question is not idle, RC.  I occasionally take scopes and binoculars to work and run them through some lab tests (stuff roughly along the lines of what Dale is talking about).  While scientifically interesting, it is very difficult to use that to differentiate between two scopes of similar quality and to predict how they perform for different people.

ILya
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 14:16
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Apart from the obvious scope needs of repeatability, water proofness, I'm not sure why it seems so difficult to come to consensus on a group of meaningful measures that would be relevent  and that all scopes could be measured on.
 
Mftg already supply basic physical info, weight, mounting length, eye relief, mag range, obj size etc.   A standardised set of resolution tests, tests for colour, etc  should not be that all difficult to agree on.
 
Agreement is not required from the manufacturers, I was thinking of the user community.
JB has his tests, Gunshow has his - should be able to come up with something standard.


Edited by Dogger - March/25/2009 at 14:51
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 14:57
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Originally posted by Dogger Dogger wrote:

Apart from the obvious scope needs of repeatability, water proofness, I'm not sure why it seems so difficult to come to consensus on a group of meaningful measures that would be relevent  and that all scopes could be measured on.
 
Mftg already supply basic physical info, weight, mounting length, eye relief, mag range, obj size etc.   A standardised set of resolution tests, tests for colour, etc  should not be that all difficult to agree on.
The intangibles of the "human" must be taken into account for any assessment of a rifle scope.  Since no two people are alike, many of the "measures" you would use become unquantifiable across even a small population sample.  I find scopes that others "certify" as UNUSEABLE, quite satisfactory for most applications.  Some claim to see differences in glass quality in some scopes that, as good as my eyes are (20/10 last eye test last year), I just cannot for the life of me find a difference that would make a difference.  ("A difference that makes no difference is no difference" Spock in "The Price of the Phoenix")  Just because something is good, or bad, for you, does not imply it will be for Budperm, BigDaddy or Ed.  Agreement is very difficult.  Any assessment I provide on any scope is mine and I cannot make my eyes "generic" such that my assessment is applicable across the board.  While I think it is a good indicator of potential of the optic and its quality, many will disagree.  Then there are the subconscious influences. Because I have heard all my life that Swarovski is better than Nikon, how much influence does that have in my determination of quality?  Perception, as much as some hate to admit it, IS truth to the perceiver.  There ARE imperfections in glass which can be preceived by most anyone, but some peoples' eye/brain interaction combine those imperfections in a completely different manner than yours or mine might.  What may be bad to us may be acceptable or good to them.  And etc. 
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 15:06
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Price (or "perceived quality") does have an effect. I came across an interesting study made of wine drinkers this past year. In the study the testers put different price labels on bottles of wine, which had nothing to do with the real price. People then drank them and rated the wines.
 
The interesting thing wasn't so much that most people picked the "ecpensive" wines as best, but the tasters had functional MRI tests on their brain functions. It turned out they actually DID experience more "pleasure" when drinking cheap but expensively labeled wine.
 
So aside from the differences in our eyes, our perceptions can be bent by price.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 15:15
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Thanks KB, JB.
 
But don't we already use evaluation experiences of others as a guide? Whether it is telescopes, cameras, cars, TVs etc.  There is usually some standardised equipment testing involved but ultimately we use the reviewers comments as well  and these may be subjective based on reviewer bias.
 
We attempt to mitigate this by looking at product reviews from a number of sources.  Still think we should have something a little more standardised.  Maybe it's not possible but continues to bug the hell out of me.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/25/2009 at 15:17
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Originally posted by John Barsness John Barsness wrote:

...
our perceptions can be bent by price.



Most definitely!



And agree that hard,fast "measures" will be tough for many reasons.  I still meet guys regularly who swear Leupold is the best scope made and "everyone knows that."  And since perception is reality, scopes, as in many things, are deeply personal.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2009 at 02:37
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The scientist in me says that their must be a standard test that can be done along the lines as suggested by Dale. I certainly will not disagree with Koshkin that such a test will not necessarily be the same as the human eye sees or will be the same for each individual. But it will give a result that will be different for each scope. That data can then be intepreted.
It must surely be possible to subject a riflescope to a test for example that will show how much low-light "abilities" each different scope has. Once such a rating is available, the buyer can then assure himself that say scope A with a 0.8 rating is not that much different to him from a scope with a 0.6 rating etc.
Koshkin, for example, can a scope be subjected to a known amount of light (Lux) that enters the scope and can one measure how much light is coming out the other end? Would this result then translate in the so-called low light viewing or abilities of a scope?
 
Camera lenses differ and tests confirm this. When I look at pictures taken with a cheaper canon lens and compare that with one taken using a more expensive canon lens I can see the difference in picture quality. Tests in a lab confirm that the cheaper lens has more abberrations and all kinds of "less of this" etc.
Rifle scopes must be able to be tested similiarly and then graded. The buyer can then decide if he can live with the price he has to pay for the quality he gets.
Again, I had a line-up of 6 scopes. If per John's example, the brand names were switched, how many people would have picked the Zeis as the best? Would some "test" have picked up any real differences and not as the human eye found all the scopes "very similiar" in bright sunny conditions?
Again, with a camera lens, I look at the tests, I can see from the tests that the professional series are streets ahead of the normal lenses. When I look athe price, I manage to convince myself that the normal lens is actually not that bad.


Edited by 8shots - March/26/2009 at 07:01
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2009 at 06:44
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Exactly where I am coming from Wouter.  I don't accept that such testing is not possible or relevent.  To do so just means we have to continue to accept anecdotal evidence for scope performance.
 
I like what JB and Gunshow have done.  We need to define common elements and process that provide data we can use to help narrow our selection.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2009 at 09:49
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the limitations of using MTF are well stated towards the end of the article, apparently a few didn't read them. easiest way to solve that is just use the same sensor in each test, then have the computer subtract the differences if one wanted to go that far. the fact that mtf are used and accepted to test camera lenses is pretty much proof that there is a difference in the difference to put it in Zen terms. Zeiss is known to use them in lens design and one of the reasons there lens work so well in low light. Granted scopes are of a different ilk than camera lines but evaluations based on anything other than first hand use? Shot in the dark at best. Even the differences in quality control for the same model of scope are so far off, it would be difficult to draw a conclusion. Why is this so?? Because scope users won't don't put enough pressure on manufacturers (in terms of product improvement thru competitive pressure) from increased awareness on the part of the consumer. (just use to aim with).

here is another link to someone who incorporated the basic method to use at home.

http://www.normankoren.com/Tutorials/MTF5.html

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2009 at 09:53
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There is a good article on visual acuity on that same web site, and methods of implementing --- if the interest is there.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2009 at 10:11
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Working my way through it Dale.  Interesting info
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: March/26/2009 at 12:53
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Got lost on the math but there are others who can figure that out and interpret results.  Resolution charts were interesting, thanks Dale.
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