# Why can't I see Jupiters moons ?

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I am able to see jupiters moon with my x7 binoculars, but why
can't I see them when I take a picture of Jupiter with my
Olympus 2020 zoom. I used the full zoom (x3) plus the digital
zoom (2.5), but nothing, i.e. only jupiter ???

Anonymous

<olivia> wrote:

> I am able to see jupiters moon with my x7 binoculars, but why
> can't I see them when I take a picture of Jupiter with my
> Olympus 2020 zoom. I used the full zoom (x3) plus the digital
> zoom (2.5), but nothing, i.e. only jupiter ???

Camera lens zoom is determined differently than binocular
and telescope power. The 'X' in 10X binoculars is totally
different than the 'X' in a 10X zoom lens.

Zoom describes the range of focal length that a *variable*
lens has.

Your Oly has a variable focal length lens. (Using 35mm camera
equivalents), your 2020 has a minimum focal length of 35mm The
maximum focal length is 105mm

To determine zoom of a lens, you divide the maximum focal length
by the minimum focal length.

In your case, 105mm divided by 35mm = a zoom of 3

This DOESN'T mean your lens can magnify like a 3X telescope,
it only means the minimum and maximum focal lengths are
3X apart.

To determine the magnifying power of a lens, the loose rule
of thumb is to divide the focal length by 50. It's not
absolutely precise, but it's close enough.

A 50mm lens has a magnifying power of 1X
A 100mm lens has a magnifying power of 2X
A 200mm lens has a magnifying power of 4X

And so on.

Lets look at your lens.. 105mm plus the digital zoom of 2.5
gives you a maximum effective focal length of 105mm x 2.5 = 262.5mm

The maximum magnifying power of your camera with digital zoom
turned on is 262.5mm divided by 50 = 5.25X

That's less than your 7X binoculars..

One more thing.. The moons of Jupiter are not very bright. You can't
just aim and snap.. To photograph them, you NEED to put the camera on a
tripod and take a long exposure of around 5 seconds at ISO 400.
Anonymous

On Sun, 22 May 2005 00:53:19 +0100, <olivia> wrote:

> I am able to see jupiters moon with my x7 binoculars, but why
> can't I see them when I take a picture of Jupiter with my
> Olympus 2020 zoom. I used the full zoom (x3) plus the digital
> zoom (2.5), but nothing, i.e. only jupiter ???

Two reasons I can think of, but they're only guesses. First, is
Jupiter brighter than its moons? If you're not sure, maybe there
are some astronomical albedo tables that you could search for. You
might try increasing the exposure time, unless you're already using
the max. allowed by your camera. I hope you're using a really solid
tripod.

Second, even at full zoom (and I doubt that the digital zoom would
help) jupiter itself is probably a pretty small part of the image.
If you greatly magnify the image on your computer you could probably
count how many pixels wide it is. Divide the number of pixels by
the ratio of Jupiter's diameter to its moon's diameter. This will
tell you how wide the moon should be, in pixels. If the result
isn't at least 2, you're unlikely to notice any moons in the
picture. If it's in the range of 2 to 4, any motion at all, such as
vibration transferred through the ground is likely to contribute
enough blur to make the moons difficult to see.
Related resources
Anonymous

Jim Townsend wrote:

> <olivia> wrote:
>
>>I am able to see jupiters moon with my x7 binoculars, but why
>>can't I see them when I take a picture of Jupiter with my
>>Olympus 2020 zoom. I used the full zoom (x3) plus the digital
>>zoom (2.5), but nothing, i.e. only jupiter ???

> Lets look at your lens.. 105mm plus the digital zoom of 2.5
> gives you a maximum effective focal length of 105mm x 2.5 = 262.5mm

The digital zoom adds nothing. Jupiter's moons are effectively
point sources (like stars) so the only factor is aperture of the
lens, ISO and exposure time. If the lens is 105mm and f/5.6,
then its aperture is 105/5.6 = 18.7 mm. This picture of Jupiter
and its moons:
http://www.clarkvision.com/galleries/gallery.astrophoto...

required a 2 second exposure at 700mm, f/8 at iso 200. The aperture
was 87 mm, so an 18.7 mm lens has an area factor of 87/18.7 squared
= 22 times more light gathering power. You would need a 22 * 2 seconds
= 44 second exposure to get the moons. But the earth will rotate in
that time, so the moons would be short streaks and not in one pixel.
It would be borderline to record Jupiter's moons with your camera
unless it was on a tracking mount. Try 10, 15, and 20 second
exposures at your highest ISO, then boost the image
brightness in your image editor and see if you can pick them out.
Good luck.

Roger
Anonymous

Jim Townsend wrote:

> <olivia> wrote:
>
>
>>I am able to see jupiters moon with my x7 binoculars, but why
>>can't I see them when I take a picture of Jupiter with my
>>Olympus 2020 zoom. I used the full zoom (x3) plus the digital
>>zoom (2.5), but nothing, i.e. only jupiter ???
>
>
>
> Camera lens zoom is determined differently than binocular
> and telescope power. The 'X' in 10X binoculars is totally
> different than the 'X' in a 10X zoom lens.
>
> Zoom describes the range of focal length that a *variable*
> lens has.
>
> Your Oly has a variable focal length lens. (Using 35mm camera
> equivalents), your 2020 has a minimum focal length of 35mm The
> maximum focal length is 105mm
>
> To determine zoom of a lens, you divide the maximum focal length
> by the minimum focal length.
>
> In your case, 105mm divided by 35mm = a zoom of 3
>
> This DOESN'T mean your lens can magnify like a 3X telescope,
> it only means the minimum and maximum focal lengths are
> 3X apart.
>
> To determine the magnifying power of a lens, the loose rule
> of thumb is to divide the focal length by 50. It's not
> absolutely precise, but it's close enough.
>
> A 50mm lens has a magnifying power of 1X
> A 100mm lens has a magnifying power of 2X
> A 200mm lens has a magnifying power of 4X

That's true only for 35mm film and/or digitals with the same size sensor.

A more accurate rule of thumb would be 1X magnification is focal length
divided by diagonal size of film frame or sensor. A 35mm film frame is
about 63mm diagonally, but 50 will give you a close enough approximation
to remember easily. f=126mm would give you about 2X magnification,
f=189mm would be 3X, and so on.

With a smaller sensor, the corresponding focal length needed gets smaller.

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Anonymous

olivia wrote:
: I am able to see jupiters moon with my x7 binoculars, but why
: can't I see them when I take a picture of Jupiter with my
: Olympus 2020 zoom. I used the full zoom (x3) plus the digital
: zoom (2.5), but nothing, i.e. only jupiter ???

You have already received info on the difference in how binocs and cameras
use the term X. And you got info on exposure based on the moon instead of
Jupiter itself. But one other thing to consider. In your calculations, use
only the Optical zoom number. Digital zoom will not help in this case. A
digital zoom just takes the data from a small part of the largest optical
image and multiplies it to fill the image. So this does not increase the
details available, just makes the details already available larger (and
fuzzier). I know that this description is very inacurate and there will be
others who may give long math rich explainations of the process of Digital
Zoom, but for the newcomer to the concept it will get the idea across.

So between your 105mm max optical zoom (roughly equal to 2x binocs), and
the blurring of the digital zoom you will not come anywhere close to the
resolution of your 7x binocs. At best you are getting 2x.

To match your 7x binocs you would need a 350mm lens (aprox) and you would
have to meter the exposure to the brightness of the moons. If the metering
is done on Jupiter itself, the moons would be so under exposed as to be
nearly (or completely) invisible. The best way to get a photo of
astronomical objects may be to use a regular astronomical telescope and a
camera adapter to replace the eyepiece of the telescope.

Randy

==========
Randy Berbaum
Champaign, IL

"Randy Berbaum" <rberbaum@bluestem.prairienet.org> wrote in message
news 6ovmv\$opj\$1@wildfire.prairienet.org...
> olivia wrote:
> : I am able to see jupiters moon with my x7 binoculars, but why
> : can't I see them when I take a picture of Jupiter with my
> : Olympus 2020 zoom. I used the full zoom (x3) plus the digital
> : zoom (2.5), but nothing, i.e. only jupiter ???
>
> You have already received info on the difference in how binocs and cameras
> use the term X. And you got info on exposure based on the moon instead of
> Jupiter itself. But one other thing to consider. In your calculations, use
> only the Optical zoom number. Digital zoom will not help in this case. A
> digital zoom just takes the data from a small part of the largest optical
> image and multiplies it to fill the image. So this does not increase the
> details available, just makes the details already available larger (and
> fuzzier). I know that this description is very inacurate and there will be
> others who may give long math rich explainations of the process of Digital
> Zoom, but for the newcomer to the concept it will get the idea across.
>
> So between your 105mm max optical zoom (roughly equal to 2x binocs), and
> the blurring of the digital zoom you will not come anywhere close to the
> resolution of your 7x binocs. At best you are getting 2x.
>
> To match your 7x binocs you would need a 350mm lens (aprox) and you would
> have to meter the exposure to the brightness of the moons. If the metering
> is done on Jupiter itself, the moons would be so under exposed as to be
> nearly (or completely) invisible. The best way to get a photo of
> astronomical objects may be to use a regular astronomical telescope and a
> camera adapter to replace the eyepiece of the telescope.
>
> Randy
>
I have really good 7x50 binoculars but I am not convinced they have enough
power to see Jupiter, let alone it's moons.
Anonymous

Darrell wrote:
> "Randy Berbaum" <rberbaum@bluestem.prairienet.org> wrote in message
> news 6ovmv\$opj\$1@wildfire.prairienet.org...
>
>>olivia wrote:
>>: I am able to see jupiters moon with my x7 binoculars, but why
>>: can't I see them when I take a picture of Jupiter with my
>>: Olympus 2020 zoom. I used the full zoom (x3) plus the digital
>>: zoom (2.5), but nothing, i.e. only jupiter ???
>>
>>You have already received info on the difference in how binocs and cameras
>>use the term X. And you got info on exposure based on the moon instead of
>>Jupiter itself. But one other thing to consider. In your calculations, use
>>only the Optical zoom number. Digital zoom will not help in this case. A
>>digital zoom just takes the data from a small part of the largest optical
>>image and multiplies it to fill the image. So this does not increase the
>>details available, just makes the details already available larger (and
>>fuzzier). I know that this description is very inacurate and there will be
>>others who may give long math rich explainations of the process of Digital
>>Zoom, but for the newcomer to the concept it will get the idea across.
>>
>>So between your 105mm max optical zoom (roughly equal to 2x binocs), and
>>the blurring of the digital zoom you will not come anywhere close to the
>>resolution of your 7x binocs. At best you are getting 2x.
>>
>>To match your 7x binocs you would need a 350mm lens (aprox) and you would
>>have to meter the exposure to the brightness of the moons. If the metering
>>is done on Jupiter itself, the moons would be so under exposed as to be
>>nearly (or completely) invisible. The best way to get a photo of
>>astronomical objects may be to use a regular astronomical telescope and a
>>camera adapter to replace the eyepiece of the telescope.
>>
>>Randy
>>
>
> I have really good 7x50 binoculars but I am not convinced they have enough
> power to see Jupiter, let alone it's moons.
>
>
Probably not. My brother used to have a pair of 16x50 that did a good
job on both Jupiter, and Saturn. I could clearly see the 4 major moons.
Of course, his 6" reflector did even better!

--
Ron Hunter rphunter@charter.net
Anonymous

"Matt Ion" <soundy@moltenimage.com> wrote in message
news:r2Sje.1432956\$6l.1421020@pd7tw2no...
> Jim Townsend wrote:
>
>> <olivia> wrote:
>>
<SNIP>
> A more accurate rule of thumb would be 1X magnification is focal length
> divided by diagonal size of film frame or sensor. A 35mm film frame is
> about 63mm diagonally, but 50 will give you a close enough approximation

A more accurate diagonal length of a 35mm frame (36mm * 24mm) would be
more like 43mm. (Pythagorus)

Deep
Anonymous

"Jim Townsend" <not@real.address> wrote in message
news:118vmotb1cm4ra0@news.supernews.com...
> <olivia> wrote:
>
>> I am able to see jupiters moon with my x7 binoculars, but why
>> can't I see them when I take a picture of Jupiter with my
>> Olympus 2020 zoom. I used the full zoom (x3) plus the digital
>> zoom (2.5), but nothing, i.e. only jupiter ???
>
>
> Camera lens zoom is determined differently than binocular
> and telescope power. The 'X' in 10X binoculars is totally
> different than the 'X' in a 10X zoom lens.

That's true.

>
> Zoom describes the range of focal length that a *variable*
> lens has.
>
> Your Oly has a variable focal length lens. (Using 35mm camera
> equivalents), your 2020 has a minimum focal length of 35mm The
> maximum focal length is 105mm
>
> To determine zoom of a lens, you divide the maximum focal length
> by the minimum focal length.
>
> In your case, 105mm divided by 35mm = a zoom of 3
>
> This DOESN'T mean your lens can magnify like a 3X telescope,
> it only means the minimum and maximum focal lengths are
> 3X apart.

So far, so good.

>
> To determine the magnifying power of a lens, the loose rule
> of thumb is to divide the focal length by 50. It's not
> absolutely precise, but it's close enough.
>
> A 50mm lens has a magnifying power of 1X
> A 100mm lens has a magnifying power of 2X
> A 200mm lens has a magnifying power of 4X

No.

You can easily prove to yourself that this is wrong. Take a 50mm lens which
can be removed from the camera with the diaphragm wide open. (Screw-mount
SLR lenses generally are this way, while many others, eg. Minolta AF bayonet
mount, stop down all the way when removed from the body unless the
activating pin is held in the full open position.)

Now hold that lens over a page of typescript and vary the distance until
it's in focus. You will see that the typescript is *considerably* magnified,
which of course would not be the case if it had "a magnifying power of 1x,"
which would be no magnification at all. The 50mm lens will in fact magnify

The magnifying power of a lens is traditionally taken to be 250 divided by
the focal length of the lens in mm. In other words, it is exactly the
*reverse* of your idea; magnifying power *decreases* with longer focal
length, it does not increase.

This too you can easily prove to yourself. Take a strong magnifier or loupe,
say 10x or more, and see how short its focal length is by projecting the
image of a distant subject onto some suitable surface, such as a piece of
paper. Compare this with a relatively weak magnifying glass of 2x or 3x,
which you will find has a much longer focal length.

Similarly, anyone who uses a microscope would (or should) be able to tell
you that higher power eyepieces have shorter focal lengths than lower power
ones do. (The eyepiece lens magnifies the virtual image formed by the
microscope's objective lens.) The same thing is true of binoculars and other
telescopes, for that matter; shorter f.l. eyepieces give proportionally
greater magnification, though in the case of binoculars you generally don't
know what the eyepiece f.l. is.

The problem here is that "magnification" has effectively different meanings
in different applications. Yes, 7x binoculars magnify the image 7 times
compared to the unaided eye, and a 20x spotting scope magnifies the image 20
times compared to the unaided eye. And yes, a 200mm lens magnifies an image
4x IN THE CAMERA, COMPARED TO a 50mm lens. But outside of that specific
comparison it is meaningless to say that a 200mm lens has a magnification of
4x. That has no relationship whatever to the magnification of a telescope or
binoculars, just as neither has any direct relationship to the power of a
magnifying glass or loupe.

N.

"Deep Reset" <DeepReset@hotmail.com> wrote in message
news 6q1h8\$o9b\$1@nwrdmz02.dmz.ncs.ea.ibs-infra.bt.com...
> "Matt Ion" <soundy@moltenimage.com> wrote in message
> news:r2Sje.1432956\$6l.1421020@pd7tw2no...
> > Jim Townsend wrote:
> >
> >> <olivia> wrote:
> >>
> <SNIP>
> > A more accurate rule of thumb would be 1X magnification is focal length
> > divided by diagonal size of film frame or sensor. A 35mm film frame is
> > about 63mm diagonally, but 50 will give you a close enough approximation
>
> A more accurate diagonal length of a 35mm frame (36mm * 24mm) would be
> more like 43mm. (Pythagorus)
>
> Deep
>
>
Well some might say that 63mm is about 43mm. It is after all only 20mm
longer.)
More seriously, the normal focal length for 35mm film should be about 43mm;
however, the use of 50mm as the normal lens is so deeply ingrained that it
will never be replaced.
Jim
Anonymous

"Darrell" <spam@this.eh> wrote:

> I have really good 7x50 binoculars but I am not convinced they have
> enough power to see Jupiter, let alone it's moons.
>
>

Jupiter is one of the brightest objects in the sky. I knew a 10 year old
kid once who couldd see all four of Jupiter's moons naked-eye. Amazing what
you can see before the lens of the eyes starts to become fibrous with age.

I have seen the planet Uranus without any optical aid at all.

> > : I am able to see jupiters moon with my x7 binoculars, but why
> > : can't I see them when I take a picture of Jupiter with my
> > : Olympus 2020 zoom. I used the full zoom (x3) plus the digital
> > : zoom (2.5), but nothing, i.e. only jupiter ???
> >
> > You have already received info on the difference in how binocs and
cameras
> > use the term X. And you got info on exposure based on the moon instead
of
> > Jupiter itself. But one other thing to consider. In your calculations,
use
> > only the Optical zoom number. Digital zoom will not help in this case. A
> > digital zoom just takes the data from a small part of the largest
optical
> > image and multiplies it to fill the image. So this does not increase
the
> > details available, just makes the details already available larger (and
> > fuzzier). I know that this description is very inacurate and there will
be
> > others who may give long math rich explainations of the process of
Digital
> > Zoom, but for the newcomer to the concept it will get the idea across.
> >
> > So between your 105mm max optical zoom (roughly equal to 2x binocs), and
> > the blurring of the digital zoom you will not come anywhere close to the
> > resolution of your 7x binocs. At best you are getting 2x.
> >
> > To match your 7x binocs you would need a 350mm lens (aprox) and you
would
> > have to meter the exposure to the brightness of the moons. If the
metering
> > is done on Jupiter itself, the moons would be so under exposed as to be
> > nearly (or completely) invisible. The best way to get a photo of
> > astronomical objects may be to use a regular astronomical telescope and
a
> > camera adapter to replace the eyepiece of the telescope.
> >
> > Randy
> >
> I have really good 7x50 binoculars but I am not convinced they have enough
> power to see Jupiter, let alone it's moons.

You can see Jupiter just with your eyes, after the moon it is the 2nd
brightest object in the night sky. 4 moon are barely visible with x7.
I can almost guarantee you won't see any moons with x16 because
of the shake, unless you have some form of tripod arrangement.
Anonymous

olivia wrote:
>>>: I am able to see jupiters moon with my x7 binoculars, but why
>>>: can't I see them when I take a picture of Jupiter with my
>>>: Olympus 2020 zoom. I used the full zoom (x3) plus the digital
>>>: zoom (2.5), but nothing, i.e. only jupiter ???
>>>
>>>You have already received info on the difference in how binocs and
>
> cameras
>
>>>use the term X. And you got info on exposure based on the moon instead
>
> of
>
>>>Jupiter itself. But one other thing to consider. In your calculations,
>
> use
>
>>>only the Optical zoom number. Digital zoom will not help in this case. A
>>>digital zoom just takes the data from a small part of the largest
>
> optical
>
>>>image and multiplies it to fill the image. So this does not increase
>
> the
>
>>>details available, just makes the details already available larger (and
>>>fuzzier). I know that this description is very inacurate and there will
>
> be
>
>>>others who may give long math rich explainations of the process of
>
> Digital
>
>>>Zoom, but for the newcomer to the concept it will get the idea across.
>>>
>>>So between your 105mm max optical zoom (roughly equal to 2x binocs), and
>>>the blurring of the digital zoom you will not come anywhere close to the
>>>resolution of your 7x binocs. At best you are getting 2x.
>>>
>>>To match your 7x binocs you would need a 350mm lens (aprox) and you
>
> would
>
>>>have to meter the exposure to the brightness of the moons. If the
>
> metering
>
>>>is done on Jupiter itself, the moons would be so under exposed as to be
>>>nearly (or completely) invisible. The best way to get a photo of
>>>astronomical objects may be to use a regular astronomical telescope and
>
> a
>
>>>camera adapter to replace the eyepiece of the telescope.
>>>
>>>Randy
>>>
>>
>>I have really good 7x50 binoculars but I am not convinced they have enough
>>power to see Jupiter, let alone it's moons.
>
>
> You can see Jupiter just with your eyes, after the moon it is the 2nd
> brightest object in the night sky. 4 moon are barely visible with x7.
> I can almost guarantee you won't see any moons with x16 because
> of the shake, unless you have some form of tripod arrangement.
>
>
Elbows braced on the roof of a car works...

--
Ron Hunter rphunter@charter.net
Anonymous

On Sun, 22 May 2005 11:22:56 -0400, "Darrell" <spam@this.eh> wrote:

>I have really good 7x50 binoculars but I am not convinced they have enough
>power to see Jupiter, let alone it's moons.
>

I got a long way down the path toward a career in astronomy because,
as a kid, I aimed 7x50 binocs at Jupiter one night and saw Jupiter's
disk (obviously not a star), and 4 bright stars nearby, all more or
less in a line. I didn't know what it was, so I recorded the positions
of the stars. They were quite bright and quite a distance from
Jupiter.

The binocs were top quality USNavy issue. It helped to steady the
heavy binocs against something.

The next night I looked at it again, and the nearby "stars" had moved!
But they were still more or less in a line. I recorded the positions
every clear night for a month or so. Of course many times I could see
less than 4. I finally made it to a library (this was in the early
60's), and compared my charts with with diagrams in Sky & Telescope,
learned I had been looking at Jupiter, and figured out which moon was
which. I was hooked.

I still use the binocs for looking at the (luckily) dark night sky.

Duncan
Anonymous

On Sun, 22 May 2005 11:22:56 -0400, in rec.photo.digital , "Darrell"
<spam@this.eh> in <hNednWVOktxDPg3fRVn-uw@rogers.com> wrote:

[snip]

>I have really good 7x50 binoculars but I am not convinced they have enough
>power to see Jupiter, let alone it's moons.

I have seen Jupiter, unaided, in New York City. It is pretty bright.

--
Matt Silberstein

All in all, if I could be any animal, I would want to be
a duck or a goose. They can fly, walk, and swim. Plus,
there there is a certain satisfaction knowing that at the
end of your life you will taste good with an orange sauce
or, in the case of a goose, a chestnut stuffing.

"Matt Silberstein" <RemoveThisPrefixmatts2nospam@ix.netcom.com> wrote in
message news:mhk2919j1pek6985283ma7shnke0b6b2s3@4ax.com...
> On Sun, 22 May 2005 11:22:56 -0400, in rec.photo.digital , "Darrell"
> <spam@this.eh> in <hNednWVOktxDPg3fRVn-uw@rogers.com> wrote:
>
> [snip]
>
>>I have really good 7x50 binoculars but I am not convinced they have enough
>>power to see Jupiter, let alone it's moons.
>
> I have seen Jupiter, unaided, in New York City. It is pretty bright.
>
I can see the bright object, I know it's Jupiter. But with my 7x50 I still
see a star like object, and I don't see it's satellites. On Friday Jupiter
was in the sky near the moon. I will correct my earlier statement I doubt I
can see it's moons through my 7x50's I am skeptical people can resolve
enough detail to see the moons un-aided.
Anonymous

"Darrell" <spam@this.eh> wrote:

>
> "Matt Silberstein" <RemoveThisPrefixmatts2nospam@ix.netcom.com> wrote
> in message news:mhk2919j1pek6985283ma7shnke0b6b2s3@4ax.com...
>> On Sun, 22 May 2005 11:22:56 -0400, in rec.photo.digital , "Darrell"
>> <spam@this.eh> in <hNednWVOktxDPg3fRVn-uw@rogers.com> wrote:
>>
>> [snip]
>>
>>>I have really good 7x50 binoculars but I am not convinced they have
>>>enough power to see Jupiter, let alone it's moons.
>>
>> I have seen Jupiter, unaided, in New York City. It is pretty bright.
>>
> I can see the bright object, I know it's Jupiter. But with my 7x50 I
> still see a star like object, and I don't see it's satellites. On
> Friday Jupiter was in the sky near the moon. I will correct my earlier
> statement I doubt I can see it's moons through my 7x50's I am
> skeptical people can resolve enough detail to see the moons un-aided.
>

Most people can't but I saw a kid do it once. He was able to describe the
positions of all of the moons. It takes young, perfect eyes and a

If you can't see a small disk with your 7X50's either something is wrong
with them or something is wrong with your eyes. Try focusing better. The
moons should be readily visible as well, even in a trashed out city sky.
Anonymous

On Mon, 23 May 2005 05:21:05 -0000, Bubbabob wrote:

> Most people can't but I saw a kid do it once. He was able to describe
> the positions of all of the moons. It takes young, perfect eyes and a

And not all people's vision is limited to 20/20. Whenever I had
my vision tested in school, reading succesive lines of progressively
smaller letters on the eye chart, they always had me stop reading
letters when I could have gone several lines beyond. And I guess
were fairly young (about 30, and possessing good vision themselves),
I could always read highway road signs long before the car got close
enough for them to make out what was on the signs. Now that I think
of it, they didn't exactly encourage my assistance.
Anonymous

Nostrobino wrote:

> The problem here is that "magnification" has effectively different meanings
> in different applications. Yes, 7x binoculars magnify the image 7 times
> compared to the unaided eye, and a 20x spotting scope magnifies the image 20
> times compared to the unaided eye. And yes, a 200mm lens magnifies an image
> 4x IN THE CAMERA, COMPARED TO a 50mm lens. But outside of that specific
> comparison it is meaningless to say that a 200mm lens has a magnification of
> 4x. That has no relationship whatever to the magnification of a telescope or
> binoculars, just as neither has any direct relationship to the power of a
> magnifying glass or loupe.
>

Yes, you're right.. Magnification is the wrong term to use.
There is *so* much more to it technically.

Just in my defense ;-) context does have a lot to do with it. If
the discussion was about macro lenses, then yes, magnification
is a completely different ball of wax.

I guess from now on, I'll use the term "approximate telescope equivalent"
rather than magnification when saying a 100mm lens for a 35mm format
camera is 2X :-)
Anonymous

Ron Hunter wrote:

> Darrell wrote:
>
>> I have really good 7x50 binoculars but I am not convinced they have enough
>> power to see Jupiter, let alone it's moons.
>>
>>
> Probably not. My brother used to have a pair of 16x50 that did a good
> job on both Jupiter, and Saturn. I could clearly see the 4 major moons.
> Of course, his 6" reflector did even better!

I can see the moons with 7x50 binoculars although it is
easier with 10X binoculars.

This discussion got me digging through old photos and I
finally found a shot I took back in January 2002 with my
2 megapixel Canon Pro90IS.

The focal length in 35mm terms was 380mm I used the
camera's 2X digital zoom in this one.

The image is a straight 500x350 crop from the original.
No processing was done.

http://www.mts.net/~jwt/jupmoon.jpg

1.3 seconds
f/3.5
ISO 50

(Yes, the Pro90 was pretty prone to purple fringing as can
be seen in the slightly blown out Jupiter :-)
Anonymous

"Jim Townsend" <not@real.address> wrote in message
> Nostrobino wrote:
>
>
>> The problem here is that "magnification" has effectively different
>> meanings
>> in different applications. Yes, 7x binoculars magnify the image 7 times
>> compared to the unaided eye, and a 20x spotting scope magnifies the image
>> 20
>> times compared to the unaided eye. And yes, a 200mm lens magnifies an
>> image
>> 4x IN THE CAMERA, COMPARED TO a 50mm lens. But outside of that specific
>> comparison it is meaningless to say that a 200mm lens has a magnification
>> of
>> 4x. That has no relationship whatever to the magnification of a telescope
>> or
>> binoculars, just as neither has any direct relationship to the power of a
>> magnifying glass or loupe.
>>
>
> Yes, you're right.. Magnification is the wrong term to use.
> There is *so* much more to it technically.
>
> Just in my defense ;-) context does have a lot to do with it. If
> the discussion was about macro lenses, then yes, magnification
> is a completely different ball of wax.

True.

>
> I guess from now on, I'll use the term "approximate telescope equivalent"
> rather than magnification when saying a 100mm lens for a 35mm format
> camera is 2X :-)

You may be just exchanging that ball of wax for a can of worms. ;-)

N.
Anonymous

<olivia> wrote in message news:428fca13\$1_2@mk-nntp-2.news.uk.tiscali.com...
> I am able to see jupiters moon with my x7 binoculars, but why
> can't I see them when I take a picture of Jupiter with my
> Olympus 2020 zoom. I used the full zoom (x3) plus the digital
> zoom (2.5), but nothing, i.e. only jupiter ???

You might trying increasing your exposure time. The human eye is much more
sensitive than a CCD imager, the eye being able to perceive a lit candle at
a distance of 30 miles or so.

If you can't photograph the Galilean satellites, though, you can bend over
with your camera and shoot Uranus. (Sorry, one of my grade-school neural
nets just fired off a volley.)
Anonymous

On Mon, 23 May 2005 05:21:05 -0000, Bubbabob
<rnorton@_remove_this_thuntek.net> wrote:

[snip]

>If you can't see a small disk with your 7X50's either something is wrong
>with them or something is wrong with your eyes. Try focusing better. The
>moons should be readily visible as well, even in a trashed out city sky.

Right. But remember that the moons move from night to night. Often all
four won't be visible. Occasionally none will be visible because they
will be either in front of Jupiter, behind it, or in its shadow.

Duncan

"Jim Townsend" <not@real.address> wrote in message
> Nostrobino wrote:
>
>
> Yes, you're right.. Magnification is the wrong term to use.
> There is *so* much more to it technically.
>
> Just in my defense ;-) context does have a lot to do with it. If
> the discussion was about macro lenses, then yes, magnification
> is a completely different ball of wax.
>
> I guess from now on, I'll use the term "approximate telescope equivalent"
> rather than magnification when saying a 100mm lens for a 35mm format
> camera is 2X :-)
>
I have seen camera store clerks describe a 10X (10:1 zoom ratio) as being
more powerful than 7X binoculars, and he tried to correct the customer who
said, "I think that's wrong"
Anonymous

"Darrell" <spam@this.eh> wrote in message
news:Ma6dnX-8-cGnmw_fRVn-qg@rogers.com...
>
> "Jim Townsend" <not@real.address> wrote in message
>> Nostrobino wrote:
>>
>>
>> Yes, you're right.. Magnification is the wrong term to use.
>> There is *so* much more to it technically.
>>
>> Just in my defense ;-) context does have a lot to do with it. If
>> the discussion was about macro lenses, then yes, magnification
>> is a completely different ball of wax.
>>
>> I guess from now on, I'll use the term "approximate telescope equivalent"
>> rather than magnification when saying a 100mm lens for a 35mm format
>> camera is 2X :-)
>>
> I have seen camera store clerks describe a 10X (10:1 zoom ratio) as being
> more powerful than 7X binoculars, and he tried to correct the customer who
> said, "I think that's wrong"

GUFFAW!

Now there's a clerk who's in the wrong line of work.

N.

"Paul H." <xxpaulhtck@zzcomcast.yycom> wrote in message
>
> <olivia> wrote in message
> news:428fca13\$1_2@mk-nntp-2.news.uk.tiscali.com...
>> I am able to see jupiters moon with my x7 binoculars, but why
>> can't I see them when I take a picture of Jupiter with my
>> Olympus 2020 zoom. I used the full zoom (x3) plus the digital
>> zoom (2.5), but nothing, i.e. only jupiter ???
>
> You might trying increasing your exposure time. The human eye is much
> more
> sensitive than a CCD imager, the eye being able to perceive a lit candle
> at
> a distance of 30 miles or so.
>
> If you can't photograph the Galilean satellites, though, you can bend over
> with your camera and shoot Uranus. (Sorry, one of my grade-school neural
> nets just fired off a volley.)
>
What and see Klingons?
Anonymous

On Mon, 23 May 2005 14:54:52 -0400, Darrell wrote:

> What and see Klingons?

Good grief. Who'd want to see any remnants of that offal empire?

Not enough light.
I would suggest a few very large strobes set about 2000 miles form the
surface of each moon.
If you can't afford that, get a camera with a faster lens.

--
http://www.chapelhillnoir.com
home of The Camera-ist's Manifesto
The Improved Links Pages are at
A sample chapter from "Haight-Ashbury" is at
http://www.chapelhillnoir.com/writ/hait/hatitl.html

<olivia> wrote in message news:428fca13\$1_2@mk-nntp-2.news.uk.tiscali.com...
> I am able to see jupiters moon with my x7 binoculars, but why
> can't I see them when I take a picture of Jupiter with my
> Olympus 2020 zoom. I used the full zoom (x3) plus the digital
> zoom (2.5), but nothing, i.e. only jupiter ???
>
>
Anonymous

On Mon, 23 May 2005 23:45:17 GMT, "Tony" <tspadaro@nc.rr.com> wrote:

>Not enough light.
> I would suggest a few very large strobes set about 2000 miles form the
>surface of each moon.

I tried that the other day, but by the time the wireless remote trigger
signal reached them, the camera had already taken the photo and so they
were of no use. Does anyone make FTL-activated remote strobes?

Regards,
Graham Holden (g-holden AT dircon DOT co DOT uk)
--
There are 10 types of people in the world;
those that understand binary and those that don't.

It helps to move the camera closer too.

--
http://www.chapelhillnoir.com
home of The Camera-ist's Manifesto
The Improved Links Pages are at
A sample chapter from "Haight-Ashbury" is at
http://www.chapelhillnoir.com/writ/hait/hatitl.html

"Graham Holden" <look@bottom.of.post> wrote in message
news:55r591925rae9m74o6il4vumq0v19q5vjd@4ax.com...
> On Mon, 23 May 2005 23:45:17 GMT, "Tony" <tspadaro@nc.rr.com> wrote:
>
> >Not enough light.
> > I would suggest a few very large strobes set about 2000 miles form
the
> >surface of each moon.
>
> I tried that the other day, but by the time the wireless remote trigger
> signal reached them, the camera had already taken the photo and so they
> were of no use. Does anyone make FTL-activated remote strobes?
>
>
> Regards,
> Graham Holden (g-holden AT dircon DOT co DOT uk)
> --
> There are 10 types of people in the world;
> those that understand binary and those that don't.

>
> I can see the moons with 7x50 binoculars although it is
> easier with 10X binoculars.
>
> This discussion got me digging through old photos and I
> finally found a shot I took back in January 2002 with my
> 2 megapixel Canon Pro90IS.
>
> The focal length in 35mm terms was 380mm I used the
> camera's 2X digital zoom in this one.
>
> The image is a straight 500x350 crop from the original.
> No processing was done.
>
> http://www.mts.net/~jwt/jupmoon.jpg
>
> 1.3 seconds
> f/3.5
> ISO 50
>
> (Yes, the Pro90 was pretty prone to purple fringing as can
> be seen in the slightly blown out Jupiter :-)
>

This is great, well done!! I think it's your X7.5 optical zoom which made
the difference. Are the moon always in one stright line, if it's a
coincidence
that would be remarkable.
Anonymous

<olivia> wrote:

>> The image is a straight 500x350 crop from the original.
>> No processing was done.
>>
>> http://www.mts.net/~jwt/jupmoon.jpg
>>
>> 1.3 seconds
>> f/3.5
>> ISO 50
>>
>> (Yes, the Pro90 was pretty prone to purple fringing as can
>> be seen in the slightly blown out Jupiter :-)
>>
>
> This is great, well done!! I think it's your X7.5 optical zoom which made
> the difference. Are the moon always in one stright line, if it's a
> coincidence
> that would be remarkable.

No, they aren't like that all the time. The moons move pretty
fast and appear in different locations each night.

It was this phenomena that led Leonardo da Vinci to realize that
the earth revolves around the sun :-)

> I can see the bright object, I know it's Jupiter. But with my 7x50 I
still
> see a star like object, and I don't see it's satellites. On Friday Jupiter
> was in the sky near the moon. I will correct my earlier statement I doubt
I
> can see it's moons through my 7x50's I am skeptical people can resolve
> enough detail to see the moons un-aided.

It's tricky, try not to focus you sight, look slightly away, they are very
very
dim, but you can just about see them (tiny speckles). Jupiter can almost be
seen as a round ball raher than a fuzzy star, but x7 is really not
sufficient to see
jupiter as a ball,
the problem is that for > x7 you need a tripod. With a small telescope you
will clearly
see jupiter/mars/staurn as little balls, you will see the 4 jupiter moons
and the
2 saturn rings.
Anonymous