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what can I do with 8x42 binoculars?



 
 
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  #13  
Old August 16th 08, 12:53 PM posted to sci.astro.amateur,sci.astro,alt.astronomy,uk.sci.astronomy,alt.astronomy.solar
Painius Painius is offline
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Default what can I do with 8x42 binoculars?

"A.Lee" wrote in message
...
John C. Polasek wrote:

On Mon, 4 Aug 2008 06:11:56 -0700 (PDT), wrote:


I have recently bought a pair of Nikon ATB Monarch 8x42 binoculars
mainly for outdoor use and wildlife observation.....
Is 8x42 really useless for night sky observation on can I see
some planets besides the Moon? ....


You may be interested to know that your eye, in night accommodation,
opens to 7 mm. The exit pupil or "light spot" from an 8x42 = 42/8 =
5mm. The exit pupilfrom a 10x70 is 70/10 = 7 mm. Any exit pupil
larger than 7 mm will be of no value.
The intensities are as 7^2/5^2 = 49/25 = 2:1.


For the mathematically challenged amongst us, was that a yes or no to
the query?
Are you saying a pair of 10x80's will be no good, and a pair of 7x30
will be better?
Thanks
Alan.


I'm no expert, Alan, but the way i read it, John is saying
that because the human eye dilates to no more than 7 mm,
it might cost more for a larger than 7 mm "light spot" or
"exit pupil", and it would be no better than one with the
7 mm exit pupil. And yet the 7 mm would be larger than
the one you mention, 30/7 = 4.3, so the 7 mm would be
better than that, yes.

So if you have to pay a little more for the 7 mm, it would
be better than the 4.3 mm. But if you had to pay more
for an 8 mm, you're better off with a less costly 7 mm.

HTH

happy days and...
starry starry nights!

--
Indelibly yours,
Paine Ellsworth

P.S.: Thank *YOU* for reading!

P.P.S.:
http://painellsworth.net


  #14  
Old August 16th 08, 01:58 PM posted to sci.astro.amateur,sci.astro,alt.astronomy,uk.sci.astronomy,alt.astronomy.solar
Dennis Woos
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Default what can I do with 8x42 binoculars?

I think that there is a lot of confusion over exit pupil size, with both
binoculars and telescopes. For a good general discussion of the issues, see:

http://www.skyandtelescope.com/equip...tml?page=4&c=y

With binos, there are the added factors of size/weight, and the benefits of
an oversized exit pupil for ease of eye positioning. I think the bottom line
is that there are no hard rules here, and that obsessing over exit pupil
size is pointless. Every aperture/magnification/exit
pupil/optical-mechanical package has advantages and disadvantages. Your 8x42
binos will capture some number of objects as well as or better than every
other instrument! Enjoy them.

Dennis


  #15  
Old August 16th 08, 06:53 PM posted to sci.astro.amateur,sci.astro,alt.astronomy,uk.sci.astronomy,alt.astronomy.solar
[email protected]
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Default what can I do with 8x42 binoculars?

On Aug 4, 4:11 pm, wrote:


@ Saul: I expect that you Celestron 8x56 can get a *lot* more light
than my Nikon ATB Monarch in 8x42. I did consider the Nikon ATB
Monarch in 8.5x56 but I just could not afford them (I got my 8x42 at
200 bucks, so I can hardly complain about the price). I suppose that
42 vs. 56 is a huge difference, but I hope to be able to afford some
decent x56 or even x70 one day :-)


Your binoculars should be fine to use for astronomy. Rather than
getting some larger 70-80 mm binos, think more in terms of a simple
150 mm or larger Newtonian telescope for a similar price.
  #16  
Old August 30th 08, 10:14 PM posted to sci.astro.amateur,sci.astro,alt.astronomy,uk.sci.astronomy,alt.astronomy.solar
Dead Paul
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Default what can I do with 8x42 binoculars?

On Thu, 14 Aug 2008 22:23:32 -0400, John C. Polasek wrote:

On Mon, 4 Aug 2008 06:11:56 -0700 (PDT), wrote:

Hi,

I have recently bought a pair of Nikon ATB Monarch 8x42 binoculars
mainly for outdoor use and wildlife observation (I live in East Central
Florida) and I realize that these are less than ideal for observing stars
or planets and that something like a 10x70 (or more) would be better.
Still, since I have three kids which I am homeschooling, a green laser
and a decent astronomy program on my computers (Kstars) I was wondering
what I could do with the binoculars I have. Is 8x42 really useless for
night sky observation on can I see some planets besides the Moon? What
else, if anything, can one observe with such low power bins?

Many thanks for any pointers!

M.

PS: Any chance of seeing the Space Station?

You may be interested to know that your eye, in night accommodation, opens
to 7 mm. The exit pupil or "light spot" from an 8x42 = 42/8 = 5mm. The
exit pupilfrom a 10x70 is 70/10 = 7 mm. Any exit pupil larger than 7 mm
will be of no value. The intensities are as 7^2/5^2 = 49/25 = 2:1. John
Polasek


Exit pupil value depends on the observers age. A youngster may be able to
accommodate a 7mm exit pupil when fully dilated but a 40 or 50 year old?
Not a chance. Think approx 4mm exit pupil being more useful.

--
___ _______ ___ ___ ___ __ ____
/ _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / /
/ // / _// __ |/ // / / ___/ __ / /_/ / /__
/____/___/_/ |_/____/ /_/ /_/ |_\____/____/

  #17  
Old August 31st 08, 06:12 AM posted to sci.astro.amateur,sci.astro,alt.astronomy,uk.sci.astronomy,alt.astronomy.solar
Painius Painius is offline
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Default what can I do with 8x42 binoculars?

"Dead Paul" wrote...
in message ...

. . .
--
___ _______ ___ ___ ___ __ ____
/ _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / /
/ // / _// __ |/ // / / ___/ __ / /_/ / /__
/____/___/_/ |_/____/ /_/ /_/ |_\____/____/

___ ______ ___ ___ ___ _ ___
/ _ \/ __/ _ | / _ \ / _ \/ _ |/ / / / /
/ // / _/ / __ |/ // / / ___/ __ / /_/ / /__
/___ /___/_/ |_/___ / /_/ /_/ |_\____/____/

Better?

hth

happy days and...
starry starry nights!

--
Indelibly yours,
Paine Ellsworth

P.S.: Thank *YOU* for reading!

P.P.S.: http://yummycake.secretsgolden.com


 




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