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Old 22nd July 2016, 11:46 AM
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Default Scopes, accuracy light or heat

Just wondering about the above after Sunday's GP. I have heard some saying the HEAT made their scope read high / low. Others were saying it was the light contrast causing problems.
Myself no exspert in these things think it's light. A little history on this back in the late 80s we used to carry the old type light metre. I bought mine from a jumble sale, the idea was press the button and match scope px to light metre. If the metre went 1/4 way up scale I would allow a yard on px and as it went further up the scale more yards.
So the question is does LIGHT or HEAT effect the PX.
Jeremy
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Old 22nd July 2016, 12:03 PM
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Heat, or rather expansion of different metals will have an effect on both scope and rifle, sometimes measurable, sometimes not.

My old Leupold 20-50 did not seem to budge regardless of hot or cold, where as my EFR becomes totally useless as a rangefinder when hot.

I'm sure light also has an effect and have experienced it sometimes, but as I almost never rangefind on the target face it is not as noticeable as the temperature effect on my scopes.
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Old 22nd July 2016, 12:18 PM
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Heat has an effect on the scope. Light has an effect on how you percieve contrast which detemines focus.
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Old 22nd July 2016, 12:52 PM
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I would say heat expansion was the big issue, I didn't have an issue at ED with my Comp x40
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Old 22nd July 2016, 01:01 PM
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Heat effects scopes, light affects your eyes. Simple really.
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Old 22nd July 2016, 01:06 PM
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Heat effects scopes, light affects your eyes. Simple really.
This ^ plus light also affects the scope lens.
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Old 22nd July 2016, 01:38 PM
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This ^ plus light also affects the scope lens.
How? A lens has no physical propety changes if it's in a light room or a dark room or has light passing through it or not, it's still the same bit of glass, same size shape and density.
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Old 22nd July 2016, 02:02 PM
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How? A lens has no physical propety changes if it's in a light room or a dark room or has light passing through it or not, it's still the same bit of glass, same size shape and density.
Diffraction
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Old 22nd July 2016, 02:12 PM
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Diffraction
And?

Diffraction doesn't do anything to the lens. It's a propery of it. It's just light passing through it in a scattered manner, and at the wavelength end of things it's allowing the light waves to seperate based upon their wavelength, forming a prism. It still doesn't alter the lens's physical character, it's still the same size, shape and density, which is what controls how light behaves through a lens.

Unlike heat which does change it's size, shape, and density and thus alters how light passes through it. But more likely the expansion of items in the scope's construction just moves the parallax lens assembly a fraction of a mm and it focuses to a slightly different point.
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Old 22nd July 2016, 02:30 PM
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And?

Diffraction doesn't do anything to the lens. It's a propery of it. It's just light passing through it in a scattered manner, and at the wavelength end of things it's allowing the light waves to seperate based upon their wavelength. It still doesn't alter the lens's physical character, it's still the same size, shape and density, which is what controls how light behaves through a lens.

Unlike heat which does change it's size, shape, and density and thus alters how light passes through it. But more likely the expansion of items in the scope's construction just moves the parallax lens assembly a fraction of a mm and it focuses to a slightly different point.
OK I'll bite.

The question was does light effect it, I'm saying yes it does because there's a soft machine and another lens behind it. I'm not saying the lens changes. Diffraction changes the quality of the image, targets in dark often appear softer and targets on the horizon with the sun low will white out. Are they not examples of light effecting it?

You're a camera guy, you must have stopped down a lens to get a better image surely?
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