7x50 binocular recommendation

(...)

Thanks for the info. I agree with Jon that the best way
to evaluate binoculars is hands on. However this is somewhat
problematic with 7x50's as I'd have to do so during the day.
Anyway, both my pupils still open to over 7mm so I'm not too
worried about wasting much apeture.

I'll definitely try to check out the celestrons - I've got
a friend who has a pair and I always thought they were
excellent.

Main reason I like the 7x50's - easy to hold steady (I won't
be mounting them) and a wider field of view. Speaking of
which, anyone know of any 7x50's with a large field of view?

-Eric

Tony Flanders wrote:

Paul Lawler wrote in message

MOST people's eyes do not open to 7mm even in the darkest locations.

I wouldn't go *that* far! It's true that 7x50 binoculars have been
downrated since their glory days a couple of decades ago, when they
were considered the only binoculars worthy of serious consideration
for astronomy. And it's also true that if your pupils only open to
5mm, then 7x50 binoculars won't show any more than 7x35. However,
they also won't show any less than 7x35. The only disadvantages
of 7x50 as opposed to 7x35 are slightly greater weight and bulk
and (possibly) higher price. Set against that is the fact that
7x50 binoculars are more forgiving about interocular spacing and
where you place your eyes. If your eyes open to 5mm and your
binocular's exit pupils are 5mm, then you have to space the
eyepieces *exactly* the right distance and center your eyes
*exactly* behind them to take full advantage of the aperture.
That's why 7x50 is recommended for use on the deck of a ship.

As for 7x50 versus 10x50, the 10x50 will without a doubt show
fainter objects, and more detail in all objects. However, the
7x50 have a much wider true field of view (all other things
being equal) and are arguably easier to hand-hold.

All in all, most astronomers prefer 10x50, 8x40 or some such
specifications to 7x50, but 7x50 *certainly* fill an important
niche, and will always be the favorite size for some people.

- Tony Flanders

Why did 7x become associated with 50-mm binoculars? Was the Navy behind
it? Did it have something to do with exit pupils, field of view and a
moving ship?


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Why did 7x become associated with 50-mm binoculars? Was the Navy behind
it? Did it have something to do with exit pupils, field of view and a
moving ship?

I think it had something to do with the cart and chariot wheel spacing that was
behind the design of the Roman road system. ;-)

Why did 7x become associated with 50-mm binoculars? Was the Navy behind
it? Did it have something to do with exit pupils, field of view and a
moving ship?

Actually, I know that the "bino expert" in our club has explained this to
me, as well as why the Japanese came up with a different standard,.
However, it probably was in the wee hours of the morning, and I am unable to
recall very much. I will get an update in the near future, and will post
what I find out.

Dennis

Thanks for the info. I agree with Jon that the best way
to evaluate binoculars is hands on. However this is somewhat
problematic with 7x50's as I'd have to do so during the day.
Anyway, both my pupils still open to over 7mm so I'm not too
worried about wasting much apeture.

I'll definitely try to check out the celestrons - I've got
a friend who has a pair and I always thought they were
excellent.

Main reason I like the 7x50's - easy to hold steady (I won't
be mounting them) and a wider field of view. Speaking of
which, anyone know of any 7x50's with a large field of view?

-Eric

The Fujinon FMT SX 7x50 has a 7°30' Tfov. They are waterproof,
however, they cost $419.95. the quality of the FMY SX Polaris series
is known very well.

The Fujinon 7x50 WP-XL Marine waterproof has a 7° Tfov and only costs
$139.95. I don't know the quality of this binoc.

edz

On 10 Sep 2004 12:18:03 -0700, (edz) wrote:


Thanks for the info. I agree with Jon that the best way
to evaluate binoculars is hands on. However this is somewhat
problematic with 7x50's as I'd have to do so during the day.
Anyway, both my pupils still open to over 7mm so I'm not too
worried about wasting much apeture.

I'll definitely try to check out the celestrons - I've got
a friend who has a pair and I always thought they were
excellent.

Main reason I like the 7x50's - easy to hold steady (I won't
be mounting them) and a wider field of view. Speaking of
which, anyone know of any 7x50's with a large field of view?

-Eric

My 7x42 zeiss are really great..... and more.... 8.6° Absolutly
FANTASTIC.........

but Fujinon must be also very good , My 10x70 Fujinon are also great
with 5.3°

have a good day

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(Jon Isaacs) wrote in message ...
Not to quibble, but to balance this statement, it must be said that 10x
is somewhat harder to hand hold than 7x -- at least for me. And
generally you get a somewhat smaller FOV with 10x, as well.

Phil

I find 10x binos harder to hand hold, but I still see more in them. Birders
seem to prefer either 8x or 10x, I think again the same issue, see more in 10x
but a bit shaky. Personally I find Roof Prism binoculars easier to hand hold.
Roof Prism binoculars also have the advantage that they are most often water
proof and nitrogen purged so that they don't fog up internally.

FOV is something of an issue, though it is pretty rare to find 7x50s with
widefield eyepieces. I have often wondered if this had something to do with
prism sizing and the larger exit pupil.
----

A 50mm objective tends to have a longer focal length than a 35mm. To
get the same low mag with the 50mm, you would need a longer focal
length eyepiece that might not have an increased barrel diameter (and
field stop) to match.

Why did 7x become associated with 50-mm binoculars? Was the Navy behind
it? Did it have something to do with exit pupils, field of view and a
moving ship?

Many people in their 20s and 30s have a dark-adapted pupil size of
approximately 7mm. Thus to take full advantage of one's night vision, a
binocular used at night would have an exit pupil of 7mm. Thus a 7x bino
would have an objective lens size of 49mm, or 50mm in popular production
sizes.

Likewise a 10X night bino would be 10x70, and many 11X's are 11x80.

In actually practice, for most people, a 7x42 will work just as well. Many
people's pupils do not expand all the way to 7mm, especially if you are over
40 (there are exceptions), a lot of night observing is not done under
perfectly dark conditions - so if there are some lights around then your
eyes might not go to 7mm, and a 7x42 is lighter and easier to hold still.
And a decent quality 7x35 is certainly a usable instrument.

Likewise for many people a 10x50 may serve them better than a 10x70. While
it will be a bit less bright, the weight and size will make using it for
extended viewing much easier.

There are many other factors to consider for binoculars. Eye relief (if you
wear glasses), field of vision (typically binos with very wide fields of
vision will not be as sharp), lens coatings, prism quality, etc., etc., .

I own a Celestron Ultima 7x42 and it is very nice night and day binocular.
Good coatings, relatively light, reasonable field of view, sharp images,
good eye relief.

Alan