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How to test scopes for clarity...

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tjtjwdad View Drop Down
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    Posted: March/03/2009 at 19:13
How is the best way to test and measure the clarity of scopes, especially those with differnt magnification levels as well as objective openings?
 
- Do you adjust them so that the exit pupil is similar?
- How far away is the object thats used as a reference?
 
Just curious,
 
ThX
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 8shots Quote  Post ReplyReply Direct Link To This Post Posted: March/04/2009 at 02:42
No takers??
 
This area of testing has allways been rather objective then subjective. There is no definitve test that seems to be readily available or used by Joe Soap. Most of us look through the different scopes and make up our mind as to what is the best.
 
Most scientific tests calls for eliminating as many variables as possible. So the exit pupils should be the same, the target or picture viewed the same, the distance the same and the light conditions the same.
Then look at the sight picture and make up your own mind which scope gives you the clearest and most true colour sight picture.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dogger Quote  Post ReplyReply Direct Link To This Post Posted: March/04/2009 at 07:58
Check out this thread:
 
 
Both John B and Tom discuss in detail how they test clarity - i.e. resolution.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jetwrnch Quote  Post ReplyReply Direct Link To This Post Posted: March/05/2009 at 19:37
I sometimes use street signs and mailboxes. I look for sharpness of the letters and numbers. powerline wires, etc will also work.  I look for objects with sharp lines and contrasting backgrounds.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: March/05/2009 at 21:10
If shear resolution was the goal I would test scopes during the day when light would not be a factor especially if I were sampling scopes with different sized objective lenses. I would set all scopes at the same magnification for this test. In the thread referenced above, I never did get an answer to the question I posed to Gunshow (Tom) as to how you can test for brightness when the scopes had different sized objective lenses. Instead he chose to answer my question with another question. The point of my inquiry was how to make a level playing ground between scopes with different sized objectives for low light performance. In short, it can't be done fairly. The magnification and exit pupil factors will always be lopsided. I have had conversations with John Barsness about scope comparisons and I think he agrees with me on this topic. As far as what you choose to be your test target, a Snellen cart, USAF resolution chart or even newspaper print should be fine.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: March/05/2009 at 22:06
Gentlemen,

Before we delve into various methods of testing optics, there is a bigger question at hand.  How do you define clarity?

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ed Connelly Quote  Post ReplyReply Direct Link To This Post Posted: March/05/2009 at 22:58
 
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: March/05/2009 at 22:59
Sharp
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: March/05/2009 at 23:02
Originally posted by Roy Finn Roy Finn wrote:

Sharp


Any more detail than that?  That was not an idle question.  When you tell me that a scope looks very clear, what exactly do you mean? resolution, contrast, color, lack of distortion, lack of curvature of field?

There are a lot of factors at play.  What are YOU looking for?

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Roy Finn Quote  Post ReplyReply Direct Link To This Post Posted: March/05/2009 at 23:21
If I asked the question, I would define it as resolution. Contrast and color fidelity would be a seperate topic(s). The presence of distortion from the center field to edge would probably be defined by the quality of the scope and it's design and the level of glass/coatings used at a particular price point. I'm not sure how deep the original poster is looking to go.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billyburl2 Quote  Post ReplyReply Direct Link To This Post Posted: March/06/2009 at 06:37
This is wher the subjectivity and opions start to bump heads. For me in particiular it is not about a level field or fair compairison it is about what scope best suits my needs, at a price that I think is fair or obtainable. As far as testing and compairing scopes, that is something I leave to others, for now.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tjtjwdad Quote  Post ReplyReply Direct Link To This Post Posted: March/07/2009 at 00:47
Originally posted by koshkin koshkin wrote:


There are a lot of factors at play.  What are YOU looking for?

ILya
 
I see your point.  Breaking it down it seems there are many things that come with the "clearest optics/clarity".  I was just curious about how to fairly evaluate a scope for low light resolution.  Should I;
 
- Adjust the scope for the same exit pupil?
- What is a good target/object to gage the results (newspaper, mailbox, commercial, street or traffic sign)?
- In addition to an object, what would be a good background (wooded area, bushes, open field)?
- How do you consider distortion (unless its just plain obvious)?
 
I'm always trying to learn.  With my limited experience I'm under the belief that tube size (1", 30mm etc) is primarly for internal adjustments, although I'd presume it may pass a small amount of extra light, and, the objective opening is for allowing extra light.
 
I also have seen (regarding clarity) that the color spectrum certainly makes a difference.
 
Thanks to everyone who has replied.
 
Jim
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