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brightness diff 8X32 vz 10X42

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thinkingman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thinkingman Quote  Post ReplyReply Direct Link To This Post Topic: brightness diff 8X32 vz 10X42
    Posted: October/19/2006 at 12:15

I am considering trading my Kahles 8X32 for Kahles 10X42.

How much, if any, difference in brightness can I expect?

What would you do?

Purpose is hunting in Pacific NW, pretty dark and cloudy alot of the time.

Thanks,

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lucznik View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lucznik Quote  Post ReplyReply Direct Link To This Post Posted: October/19/2006 at 12:49

The 10x42 Kahles has (essentially) the same exit pupil as the 8x32; 4.2mm for the 10x and 4mm for the 8x  That 0.2 mm difference is real but, not likely very significant.  Their coatings are the same so, no help there. The extra magnification of the 10x will likely make things appear a bit brighter in the same way that getting closer to an object in a dark room always allows you to see that thing better.

 

Within the same lineup and magnification specifications, the 42mm glass will always be brighter than a 32mm glass.  In other words, an 8x42 Leica Ultravid is brighter than an 8x32 Ultravid (exit pupils of 5.25 for the 8x and 4.2 for the 10x.)  Similarly a 10x42 Zeiss FL will be brighter than an 10x32 FL and so on and so forth. When you cross lines however, the same is not always true.  Thus (for example,) an 8x32 Zeiss FL could very well be as bright or brighter than say an 8x42 Bushnell Legend. The difference here is going to be in lens coatings (both quantity and quality.)

 

If increased brightness is what you are really after, then you should be increasing the objective lens size while keeping the magnification the same. In other words, get an 8x42 Kahles. 

What if the hokey pokey really is what it's all about?
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thinkingman View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thinkingman Quote  Post ReplyReply Direct Link To This Post Posted: October/19/2006 at 12:55

Thanks,

I know the exit pupil is essentially the same, the advantage I hope to gain is more magnification.

Any more info or ideas appreciated.

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lucznik View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote lucznik Quote  Post ReplyReply Direct Link To This Post Posted: October/19/2006 at 13:00

Beyond the "getting closer" phenomenon described previously, the 10x42 binocular is not going to be brighter than the 8x32.  To get both greater magnification and increased brightness you would need to increase the objective lens size to the 50+mm class of binocular.  I don't know if Kahles makes a 10x50+ but, Bushnell, Nikon, Minox, and numerous others do and are within the same basic price range.)

What if the hokey pokey really is what it's all about?
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anweis View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote anweis Quote  Post ReplyReply Direct Link To This Post Posted: October/20/2006 at 10:22

In dim light, you loose detail because of the handshake associated with the 10x binoculars.

For really dim light, you want low power and big lenses. I am not sure that a 8x42 or a 7x42 will make your hunt more succesful than a 8x32, but they will look brighter.

But the quality of the binoculars is more important. Your Kahles 8x32 is better than some $60 8x42.

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