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Are low powers optically better?

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DAVE44 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DAVE44 Quote  Post ReplyReply Direct Link To This Post Topic: Are low powers optically better?
    Posted: March/29/2008 at 07:46
I have heard and read several times that low powered variables have better LIGHT MANAGEMENT than larger powered larger objective lens models? Is this true? What is meant by better LIGHT MANAGEMENT? Do low powered small objective lens models have better brightness and resoloution than a larger objecive lens models even when the exit pupil figures out to be the same?    I thought that as long as the exit pupil was the same the image would be of equal brightness and resoloution. Will someone tell me what is meant by BETTER LIGHT MANAGEMENT.
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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/29/2008 at 08:04
Not sure about "light management" although I would guess that longer scopes present more of a challenge in that area. In general, though, the more you magnify an image, the more the image can suffer from distortion. Image quality is more important than the much over emphasized term "brightness".  As far as equal exit pupil sizes are concerned, scopes with different sized objective lenses could not be set to equal magnification settings and still maintain the same exit pupil diameters. Exit pipil is determined by the objective size and magnification.

Edited by Roy Finn - March/29/2008 at 21:15
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Post Options Post Options   Thanks (0) Thanks(0)   Quote doctor duck Quote  Post ReplyReply Direct Link To This Post Posted: March/29/2008 at 19:01
 A larger objective will allow you to get the same exit pupil as a smaller objective but you could be at a higher magnification. Exit pupil is objective lens diameter divided by magnification. A 50 mm lens at 5x would yield an exit pupil of 10.  A 30mm lens at 3x would also yield an exit pupil of 10. The larger objective will allow you to use a higher magnification in the last minutes of light. I prefer the larger objective for this reason in a hunting scope.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: March/29/2008 at 19:25
I am not entirely sure what is meant by the term "light management".

One difference between a lower powered variable and a higher powered variable is that with a high powered scope, you often have to have some additional lenses to keep the image aberration free.  Those extra lenses can have some effect on image quality.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: March/29/2008 at 21:40

better light management is a marketing term used by leo and some others in reference to their perception of adjusting transmission specific to certain wavelengths. usually zeiss and swaro have better transmission in shorter wavelengths giving them an advantage in low light and "bluer" conditions.

there are only a few companies with product depth enough to begin answering this question, as an example if one assumed the entire line of v3 scopes were made the same way, some conclusion could be made, but as construction methods differ accross brands comparisons would be iffy.

in larger objectives the light coming in on opposite sides of the lens must be bent more than a smaller lenses then re-focused. in this case it would be obvious that the larger lenses would cause more problems. however with this known, the manufac. can correct the problem and pass the cost along to the consumer.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote DAVE44 Quote  Post ReplyReply Direct Link To This Post Posted: March/30/2008 at 07:22
Hmmm, if larger lenses cause the light coming in to be bent more then that must explain why Bushnell Elite 4200s with 50mm objectives are so long compared to their smaller 40mm and 36mm objective lens models... to help decrease the angle of the light being bent and thus fixing the image problems. I guess that makes sense, so what do the other scope brands such as nikon do to fix this image problem if they dont increase the length of their scopes like Bushnell?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: March/30/2008 at 09:06
yes that is correct, the longer the scope the better the image, (all things being equal). it increases the cost of product if the scope is shorter to get the same or better image quality, one reason leos cost more, also the reason why low range variables are shorter obviously.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RONK Quote  Post ReplyReply Direct Link To This Post Posted: March/30/2008 at 09:24

 

 I seem to recall a thread  in which some posters reported a relatively poor image in thier Burris Short Mag series, and Bushnell's long scopes are well-respected for excellent optical qualities.
Might be something to the length being the deciding factor, at least within a given price range...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Dale Clifford Quote  Post ReplyReply Direct Link To This Post Posted: March/30/2008 at 13:20
a really good example are IOR notice how the front part have such a long taper and the saddle is set so far back some of them are hard to mount. (on a gun of course).
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Post Options Post Options   Thanks (0) Thanks(0)   Quote koshkin Quote  Post ReplyReply Direct Link To This Post Posted: March/30/2008 at 18:46
Length of a scope has a certain effect on the image.  However, it is not the length per se, but the speed (referred to as the F/#) of the objective lens system that makes a difference.  For a scope where the limiting aperture is the objective lens, the F/#= D/F where D is the diameter of the objective lens and F is the focal length of the lens system.  A lower F/# indicates a faster lens system.  For example, F/4 is a faster lens system than F/12. 

Hence, with a smaller objective lens, you do not need a particularly long scope.  With a larger objective lens you either have to make a longer scope, or deal with aberrations that accumulate near the edges of the image.  In order to deal with the aberrations you often have to add a lens or two.

ILya
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Post Options Post Options   Thanks (0) Thanks(0)   Quote DAVE44 Quote  Post ReplyReply Direct Link To This Post Posted: April/08/2008 at 18:11
Curious, if low powered variables with smaller objectives can be shorter in length and have a good image why in the world did Zeiss come out with low powered variables that were longer and heavier than the 3-9x40 Conquest?

Edited by DAVE44 - April/08/2008 at 18:12
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lucznik Quote  Post ReplyReply Direct Link To This Post Posted: April/08/2008 at 18:38
Maybe because a "good image" isn't good enough for some.

Perhaps to offer something in a lower price category (due to the extra weight.)

Or maybe to offer it in a higher price category - due to having a "superior" image or the ability to withstand greater abuse.




What if the hokey pokey really is what it's all about?
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