Binoculars ---> Telescope

[snip]

I wasn't sure which one this was, NGC 6231, but my mind went to a
fascinating one near the tail of Scorpio. Lo and behold, that's the one.
Yes, I had a chance to browse it for the first time with the Apogee
20x100, 3 weeks ago from Athens and it does look quite 3D.

The view does not compare with my Tasco 60x700, though.

One of the most beautiful, imo.

--
I. N. Galidakis
#

Eventually, _everything_ is understandable

I think it has to do with the way the eye and mind processes data, one
sometimes falsely inteprets differences in brightness as differences in
distance. There are a lot more cues than paralax that gives something its
three dimensional appearance.

One of my favorite clusters is NGC 6231, the "Northern Jewel Box." Never more
than 15 degrees above the horizon, this multi-colored cluster often appears 3
dimensional even in the single eyepiece of a telescope.

jon

The parallax data that the computers use is based on separation of
two Astronomical Units whereas binoculars have a separation of less
than 1.3 ?? 10^-12 Astronomical Units. Binoculars are not capable of
stereopsis at stellar distances.

Ref:

[snip]

Well, the distance to the objects can be taken "for all practical
purposes" to be infinity, so the object's parallax for the two images
between the two eyes (even slightly enhanced by the bino distance) would
be very close to 0, so I agree on this.

I am still wondering why do I get the distinct 3D sensation and what
causes it. Perhaps sphericity of field in low quality achromats?
[snip]

--
I. N. Galidakis
#

Eventually, _everything_ is understandable

[snip]

The images on your links below seem to have been generated by a
computer, so I'd agree the 3D sensation is illusionary. I am not so sure
about big binos though. Anybody knows of any refs?

Cool. My impression is that something is fishy with an object left and
down of Aldebaran in the following:

> #

This object seems to have a displacement far greater than any star-like
object between the pictures. Looks like it's floating in mid space, for
those of us who can cross-eye and see in stereo at will. Maybe the
pictures took into account planets as well?
--
I. N. Galidakis
#

Eventually, _everything_ is understandable

I am not disputing that, I notice the "3D" effect myself.

I was just pointing out that the separation of the objectives makes no
difference in that "3D" effect at astronomical distances. It does make a
difference however when viewing at some terrestial distances.

For close focusing another problem arises and that is that each eye may have a
completely different image.

For example, a normal pair of Porro Prism binoculars have the objectives
separated by about 5 inches. At a close focus of 7 feet (roof prism territory
for most binos) the edges of the FOVs would just touch each other with a 7
degree FOV.

jon

I'm sure the 3D is illusionary--actually you can test this, as there
are 3D images of the Pleiades that you can compare to what you see.

#
Stereo Charts For R.A. 3.75 Dec. 24 Mag 10

#
#

I'll say! Observing all the clusters in that book is a prospect
that would make even the most fearless observer blanch. Compared
with that, observing the entire NGC would be a romp in the park.

- Tony Flanders

[snip]

In big binos there's a distinct sense of "depth" when looking at rich
regions. When I see the Pleiades through the 20x100, I clearly see
something which resembles a 3D jewel box. That is, some stars "appear"
closer than others.

It may well be illusionary. Long time ago I experimented with artificial
3D imagery and found that the brain has a tendency to "generate" a 3D
feeling, when merging two 2D pictures slightly displaced, even when the
displacement was not actually caused by normal parallax. This may
partially explain the 3D sensation with big binos.

> jon
--
I. N. Galidakis
#

Eventually, _everything_ is understandable

Doesn't seem to me that this is going to be of any advantage for astronomical
viewing.
jon

The two most impressive things about the Fuji Polaris 7x50's
performance to me were:

1. The depth of field when at infinity focus. Everything from as
close as 30 feet or so out to infinity is in focus! This can give the
illusion of a clearer view than other binos that are in the same
class.

2. Tremendous depth perception due to the wide spacing of the
objectives. Undeniable advantage. I think you'll be hard pressed to
find a bino that gives a more accurate sense of depth at moderate to
large distances than the Fuji 7x50. It has a marine heritage, so
perhaps they designed it to spot distant battleships and carriers on
the horizon and to tell which one was closer. ;-)

I did end up getting tired of the weight and individual eyepiece
focus, so I looked around and found a bino that is lighter, optically
as sharp, has a wider field of view, and seems about as bright despite
having smaller aperture: the Zeiss Classic 7x42. And for astronomy,
I've found the Nikon Superior E 10x42 to easily outperform both of
those due to a combination of higher magnification and superb optics.

But I haven't yet found a bino to match the Fuji's depth of field...

Cheers,
Ritesh

...

I find that this comes and goes.

Most (read "virtually all") of my observing is done in the backyard under
mag 5.5 zenith with mag 4 on the south horizon. I have 3", 5", 8" and 12.5"
scopes. The 5" is an F12 Mak, and the 8" an F10 SCT. The 8" I use primarily
for imaging, and the 5" for "planet" or "moon only" sessions. The 12.5" is
an F4.8 Dob and comes out for DSO's and more serious planet (GRS, moon
transits, Saturn's Rings) and lunar observing (Plato's craterlets).

Interestingly I have found that using the 12.5" seems to come with an
inherent need to "get the most out of the sky". The smaller scopes are more
specialized by their aperture limitations, and don't carry this self-imposed
burden. The 3" scope (an 80mm F5 achromat) is fun to use, because the
expectations I have for it's performance are more narrow, thus I impose a
limit of looking at wide field objects and brighter DSO's in the M catalog.
It takes a lot less planning since I know where most of the more isolated
(as in, not the Virgo cluster) Messiers are, and that allows for far more
serendipity in a casual observing manner.

Last night on my way from Albireo to M27 in the ST80, I stumbled onto Stock
1. This is not an object that I would normally stumble on because it isn't
obvious in a narrow field, at first glance. However, all by its lonesome in
a 2+ degree field of view, it's an interesting subject.

As a follow on to that, I am really enjoying the Herald-Bobroff atlas. It is
super easy to use as a desktop reference. Along with _Star Clusters_ by
Willman-Bell Publishing, my cup is full. Great stuff for open cluster
lovers.

Anyway, generally what brings my wide field observing days to an ebb, is sky
glow. After a while at the long focal length large aperture telescopes, the
sky glow in wide-fields doesn't seem so bothersome, at first. Once the wide
field sky glow has taken its toll on my will, I will no doubt go back to big
aperture and high power.

For the bug season, and on super cold nights, the little RFT pays big
dividends as a quick look scope.

-Steve Paul

My most fun equipment is

o Oberwerk 15x70 binos on UniMount (Univeral Astronomics)

o StellarVue AT-1010 on MicroStar (ditto)

I have the D&S Compact tripod for air travel and a heavier Bogen --
which will let me mount my C5+ on the MicroStar.

The Oberwerks are newer ones and are very good for their price (and
Fujinon 16x70 have eye relief too short for me). I use the binos for
really wide views at 15x and the AT-1010 from 20x upward.

Also have a 10" Dob and an NS8GPS; but those are not exactly "grab and go".

I seem to be getting addicted to the wide-field approach to astronomy

Phil

I have 8x40, 15x70, and 20x80 binoculars. The 8x40's are WWII era and have
excellent optics, and I've yet to try another binocular that is as light
weight. Still, I experience some shake. The 15x70's are by far my most used
binocular, even though they are far more affected by shake. The 20x80's are
pretty much impossible to hand hold, not because of their weight, but
because the increasing magnifications seem to have an almost linear response
to the shakes. I've concluded that the shakes are not a result of the weight
of the binocular at all (that just has an impact on one's endurance), but
the ability to hold one's arms steady; magnification just making the problem
more obvious.

I solved the problem of wide-field

Individual preference, how much shake are you willing to put up with and for
how long..

I think the M6-M7 region is a nice one for binoculars, both clusters are
observable with 7X binoculars from a moderately light polluted sky. With 10X
there are more stars visable in the clusters but things less pleasing.

However putting the 10X binoculars on a tripod makes a big difference, there
are fainter stars and the steadiness make the view much more pleasant IMHO.

For me, I find a good test is Albireo, it is separated from its companion by 33
arc seconds, hard to see hand held but with a tripod I can see the pair at 7x
or 10x.

I like binoculars for the freedom they provide. The binoculars you currently
own are should do a nice job, since you have decided to get a telescope, I
suggest going ahead with that and enjoying that experience for a while. For a
while you will probably want to spend money on accessories, eyepieces and the
like.

Later is the time to come back and choose some different binos.

jon

I guess that explains why everytime I go out to observe with
friends/relatives,
they always pick Fuji leaving me with Ultima ;-) My only complaint about
Fujinons is weight, but I guess it's the price of tank-like construction ;-)
On the other hand, they are wery nicely balanced.

--
Dimitri

On Sat, 26 Jun 2004 22:29:14 -0400, "Dimitri I. Rakitine"

Your question is a good one that is not easily answered. Historically
the standard reply on s.a.a. has placed the hand held magnification
limit around 10x.

My own experience is fairly limited in binocular magnifications (a
drawback to living in the middle of nowhere), yet reasonably
experienced in binocular use -- at least in the use of those I own.

As a result of your question I just completed a comparison test
amongst the binoculars I own. I compared three different binoculars,
all of reasonably good optical quality. Each was used hand held as
well as firmly mounted.

Before getting to the test results, I'll mention some previous
experience: I've usually used my 7x50s and 8x42s hand held, and I've
usually used my 20x80s firmly mounted. The two smaller binoculars are
easily hand held and have been enjoyable to use in that manner. Yet
for checking out lunar detail or double stars even those relatively
small binoculars have benefitted from a solid mount.

On the reverse side of the coin, I've found that I can use my 20x80s
hand held for quick looks, such as checking off Messier objects (For
resolving details a firm mount is essential for the 20x80s).

Today's experiment:

I live on a hill in a rural setting. Down below, across a meadow is a
neighbor. One of the items I focused my attention on was lettering on
a horse trailer. The words could not be made out with hand held 7x50
or 8x42 binoculars. The words were not easy with the hand held
20x80s, but I was able to make them out after several seconds of study
-- a guess at first, but with more time the guess became a certainty.

When the binoculars were firmly mounted the words could be correctly
guessed (with much difficulty) with the 7x50s. The words were
slightly better with the mounted 8x42s. Not all letters were
distinct, but when put together to form words it was possible to fill
in the gaps to correctly guess the words. The unmounted 20x80s proved
to be superior to the mounted smaller binoculars, but only after
sufficient time was spent fishing out details from the jiggling image.

The mounted 20x80s provided *far* more detail than when they were used
hand held and far more detail than the mounted smaller binoculars. The
individual letters were sharp, crisp, and very easily read with
nothing more than a brief glance. Panning around with the mounted
20x80s revealed a wealth of detail that was not noticed with any other
arrangement tested.

So what does all this mean? It means that when used hand held the
8x42s were better than the 7x50s, and the 20x80s were better than the
8x42s. It also means that even 7x50s benefit from a firm mount, but
larger more powerful binoculars benefit even more from a solid mount.

My guess would be that for binoculars from 9 to 11x some people would
prefer mounted use and others would feel that hand held use doesn't
unduly compromise performance. I'm personally content to leave 8x as
the maximum magnification for binoculars used primarily for hand held
use. Of course, some people can hold binoculars steadier or less
steadily than others

It's worth keeping in mind: Not all binoculars are created equal.
Some have stopped down objectives via internal stops and/or undersized
prisms. Glass types differ, coatings differ (sometimes they're even
absent from some surfaces). Furthermore it was assumed that the
original poster was *not* asking about image stabilized binoculars.

Sketcher
To sketch is to see.

For me this borderline is about 10x. A good test of this is to look
at Jupiter's moons. If you can resolve the moons in your bino without
the image dancing around too much, the bino will be pretty
hand-holdable for you.

Regarding your bino comparison, the Fuji Polaris units are optically
in an entirely different class than the Celestron Ultima series. You
would need to go to Zeiss, Nikon, Canon, and their ilk to get similar
quality.

Cheers,
Ritesh

Sorry, I'm not sure I understand -- or you may be missing something important.
I seen many different models in the Celestron Ultima line, and they're all
conventional center-focus binoculars. That means that there is an
individual adjustment for the right eyepiece only. First you focus the
left eye with the center focus, then you adjust the right eye by twisting
the eyepiece. Works fine for me with or without glasses.

Look, if you want magnification, by all means get a telescope -- regular
binoculars can't compete. I can see *far* fainter objects and *far*
more detail in a 50mm telescope at 30X than in my 10x50 binoculars.
Not even close, not worth discussing. But of course, I don't get
that lovely wide field and convenient hand-holdability with the scope.

As for magnification and hand holding, it all depends what you want.
I can't get a genuinely crisp image even at 7X when I'm hand-holding
binoculars -- but I do find the image quite acceptable. At 10X, I
find the image annoyingly shaky if I'm just standing up, but when
I'm reclining in a deck chair or lying on the ground, it's just fine.
Frankly, I wouldn't do *any* serious binocular astronomy standing up;
not only are the images lousy, but it's a pain in the neck.

Then there's image-stabilized binoculars -- a whole new experience!
You can't have your cake and eat it too, but IS binoculars come
mighty close.

- Tony Flanders

Hi Dimitri,

I sugest you the Celestron C65, it's realy small, lightweight, a
Makusov design, and very not expensive, it's like a monocular, but you have
a zoom eyepiece on it, so you can magnify at 30x 60x and 90x. If you wan't
stay in binocular, look for Konus... the 10x50 is not bad, but a zoom Bino
is also available, 10-30x60, 32oz... (the 10-30x50, 29oz). Over that, need a
mount...

"Dimitri I. Rakitine" <> a ??crit dans le message de
...

---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (#).
Version: 6.0.712 / Virus Database: 455 - Release Date: 2004-06-02

Even with 7x50 you will have more comfort and see more if you have a
parallelogram mount like the UniMount from Universal Astronomics. Then
you can move up to 15-16x70 or 20x80 ay time you want.

Phil

...

I'm not an optics expert, but my point was that 9x magnification binocs were
not easy to hold steady, and images
they provided were not as pleasant as 7x50 Fuji's provided. Maybe I need
more practice in using 9x63s - I can definitely
see a difference in light gathering capability, but image quality suffers a
lot.

--
Dimitri

Probably just what you've switched. When I used to use 7x50s, I never
needed a tripod, but when going with 20x60s, I always used a tripod. Too
bad your Celestrons aren't working out. The larger light grasp can make a
difference as I found out with my 20x60s.

Carl