Re: Anyone shoot the eclipse?
mscot...@aol.com
> Pudentame wrote:
> > Anyone shoot the eclipse?
>
> Yes.
>
> Rita
At 2am there was nothing to see, and just a bit of cloud about
At 3am, it was thick cloud
Michael (in UK)
Paul Furman
>
> At 3am, it was thick cloud
>
> Michael (in UK)
This is all I got (not much):
http://uk.youtube.com/watch?v=xZJH0_T2agI
3-second time lapse, wide angle
Rob MacTurk
news:kYkvj.12626$R84....@newssvr25.news.prodigy.net...
http://robertmacturk.smugmug.com/gallery/4380032_HGg9g#257192537
Other than some light sharpening in Lightroom, as shot.
Rob
Rockville, MD
Cynicor
Your middle image has a visible box around it.
Rob MacTurk
"Cynicor" <j...tru.p..in@sp.eake.a.sy.net> wrote in message
news:69Cdna3PLbbPhCPa...@speakeasy.net...
Your eyes are better than mine - I don't see a box. Anyway, that's why the
caption says amaturish. haha
Nervous Nick
> "Paul Furman" <pa...@-edgehill.net> wrote in message
>
> news:kYkvj.12626$R84....@newssvr25.news.prodigy.net...
>
> > mscotgr...@aol.com wrote:
> >>> Pudentame wrote:
> >>>> Anyone shoot the eclipse?
>
> >> At 2am there was nothing to see, and just a bit of cloud about
>
> >> At 3am, it was thick cloud
>
> >> Michael (in UK)
>
> > This is all I got (not much):
> >http://uk.youtube.com/watch?v=xZJH0_T2agI
> > 3-second time lapse, wide angle
>
> http://robertmacturk.smugmug.com/gallery/4380032_HGg9g#257192537
>
> Other than some light sharpening in Lightroom, as shot.
Nice job!
I myself wasn't able to do photograhic justice to this event. All I
had available was a little handheld P/S camera with a tele-extender.
I was surprised at what I actually got, once I forced the camera to
focus correctly. FWIW:
http://santafe.kriho.com/sightings/eclipse2008.htm
--
YOP...
anir...@gmail.com
Check at the following link
http://spaceweather.com/eclipses/gallery_20feb08.htm
Steve
through a Sigma 70-300 APO DG Macro zoom at 300mm.
http://www.flickr.com/photos/sss_random_shots/sets/72157603957730222/show/
I have like 100 more that I'll eventually put into some sort of show,
mosaic, or something. Or maybe not.
Steve
Paul Furman
> Check at the following link
> http://spaceweather.com/eclipses/gallery_20feb08.htm
Nice! http://spaceweather.com/eclipses/20feb08/Mohammad-Taher-Pilevar1.jpg
Paul Furman
You can merge those bracketed exposures in PS quickly with a soft eraser
about the size of the moon.
Mardon
Here's mine; first 4 images in the top row of thumbnails:
http://www.JustPhotos.ca/galleries/sky/
EXIF is embedded if anyone wants the times.
Steve
wrote:
I was thinking about combining them. I have Paint Shop Pro 9, but the
idea is the same. I'll get to it eventually.
Steve
Rob MacTurk
news:nospam.m-m-A93F1...@cpe-76-190-186-198.neo.res.rr.com...
> FWIW, here's my eclipse shot showing some stars around the moon:
>
> http://www.mhmyers.com/d80/DSC_10266.jpg
>
Very nice - how did you get the stars?
Rob
Cynicor
They come free with the sky.
Actually, the bright object to the left of the moon may be Saturn.
Paul Furman
> Paul Furman wrote:
>
>> You can merge those bracketed exposures in PS quickly with a soft eraser
>> about the size of the moon.
>
> Please explain more details about that.
Here's an example from last year:
http://edgehill.net/Misc/misc-photos/8-27-07-eclipse/pg1pc3
Steve has 2 exposures for a few of those and those could be merged
easily by erasing out the blown bright spots with the darker exposure on
a lower layer. Or with HDR software I suppose.
> FWIW, here's my eclipse shot showing some stars around the moon:
>
> http://www.mhmyers.com/d80/DSC_10266.jpg
Nice! I like the stars. There are a couple stars in mine from last year
(at totality) showing as dashed lines with the 2-second exposure. I
probably should have boosted the ISO to avoid that.
Ockham's Razor
Paul Furman <paul-@-edgehill.net> wrote:
Only one is a star. The one at Seven O"Clock is Regulus. The one at 12
O"Clock is Saturn.
--
With or without religion, you would have good people doing
good things and evil people doing evil things. But for good
people to do evil things, that takes religion.
Steven Weinberg
Ockham's Razor
<nospam.m-m-855F8...@cpe-76-190-186-198.neo.res.rr.com>,
M-M <nospa...@ny.more> wrote:
> In article <GNSdncx5AaCtbyPa...@speakeasy.net>,
> You're right. That is Saturn to the left and Regulus above.
I heard the opposite, but am probably wrong.
Steve
>In article <8Puvj.2440$pl4....@newssvr22.news.prodigy.net>,
> Paul Furman <paul-@-edgehill.net> wrote:
>
>> You can merge those bracketed exposures in PS quickly with a soft eraser
>> about the size of the moon.
>
>
>Please explain more details about that.
>
>FWIW, here's my eclipse shot showing some stars around the moon:
>
>http://www.mhmyers.com/d80/DSC_10266.jpg
Here's a pair of mine (reduced for flickr) that show some
stars/planets around the moon.
http://www.flickr.com/photos/sss_random_shots/2284678706/sizes/o/
http://www.flickr.com/photos/sss_random_shots/2283890165/sizes/o/
What's amazing to me is, when you look at the full size images, how
much motion blur is visible even at a 2 second exposure.
Steve
Rob.
http://www.justphotos.ca/galleries/aircraft/patio.htm
would this become annoying after a while?
Paul Furman
The one I linked above is also 2 seconds and ISO 100, and streaked.
That's too long, the ISO should be turned up (& aperture opened?).
Another route is to align & stack several short consecutive photos, the
rotation of the moon will blur at some point too.
Steve
wrote:
>Steve wrote:
The rotation of the moon will not cause blur because it rotates at the
same rate as it orbits. That's why there's always the same dark side
of the moon, and light side.
Steve
Jeff R.
"Steve" <st...@example.com> wrote in message
news:edd0s39mh9sblcobo...@4ax.com...
> The rotation of the moon will not cause blur because it rotates at the
> same rate as it orbits. That's why there's always the same dark side
> of the moon, and light side.
>
> Steve
"Far" side, and "near" side.
A "Dark" side there is not...
Steve
wrote:
True. It was a poor reference to Pink Floyd.
Steve
Mardon
> http://www.justphotos.ca/galleries/aircraft/patio.htm
>
> would this become annoying after a while?
Nice to see you were poking around my photo site. :)
No. My wife and I both enjoy the planes. If the airport were busier, that
might become a different story. I'd guess that a couple of dozen aircraft
landing on this runway would be a busy day.
Roger N. Clark (change username to rnclark)
The moon rotates in the sky with the rotation of the earth.
From our point of view on the earth, the moon rotates as it moves
across the sky with respect to our local horizon.
For example, when the moon is rising, the north
pole of the moon would point approximately to the left
in an image, but would point to the right when it is setting
(from the northern hemisphere).
Roger
Steve
to rnclark)" <user...@qwest.net> wrote:
>The moon rotates in the sky with the rotation of the earth.
> From our point of view on the earth, the moon rotates as it moves
>across the sky with respect to our local horizon.
>For example, when the moon is rising, the north
>pole of the moon would point approximately to the left
>in an image, but would point to the right when it is setting
>(from the northern hemisphere).
If you put your camera on a motor driven equatorial mount and point it
at the moon, you don't have to worry about the moon rotation causing
blur because it rotates at the same rate as it orbits. If the north
pole of the moon is on the left of your image frame as the moon rises,
it will still be on the left of your image frame as the moon sets.
However, if you want to get technical, the moon does have variations
in it's presentation to an observer on earth so that it's not
*exactly* in the same orientation all the time. The part of the moon
we see varies over the course of a month and even over the course of
an evening. It's called lunar libration. But that's a long term
effect and certainly doesn't effect short time exposures, on the order
of seconds or even minutes. It's nothing like the motion blur you get
if the camera is stationary and your exposure is a couple of seconds.
See http://en.wikipedia.org/wiki/Libration
Steve
Roger N. Clark (change username to rnclark)
> On Sat, 23 Feb 2008 16:39:44 -0700, "Roger N. Clark (change username
> to rnclark)" <user...@qwest.net> wrote:
>> The moon rotates in the sky with the rotation of the earth.
>> From our point of view on the earth, the moon rotates as it moves
>> across the sky with respect to our local horizon.
>> For example, when the moon is rising, the north
>> pole of the moon would point approximately to the left
>> in an image, but would point to the right when it is setting
>> (from the northern hemisphere).
>
> If you put your camera on a motor driven equatorial mount and point it
> at the moon, you don't have to worry about the moon rotation causing
> blur because it rotates at the same rate as it orbits. If the north
> pole of the moon is on the left of your image frame as the moon rises,
> it will still be on the left of your image frame as the moon sets.
Well, there are multiple issues with what you say:
1) The original discussion was not talking about using an
equatorial mount.
2) It depends on the equatorial mount. For example, with
a German equatorial mount, you have to do a flip of
orientation at the meridian, so what I said regarding
the rising and setting moon is correct.
3) If you use an equatorial mount that does not require
the flip. what you say is technically correct, but
not the result people would view. Here is what happens:
On the rising moon, the moon's north pole is to the left
in the frame (northern hemisphere photographers), and remains
toward the left through moon set. But in the setting moon
image, without reorienting the camera on the equatorial
mount, the camera is upside down so the horizon is at
the top of the frame. Thus, any photographer displaying
the picture would flip the image so the horizon
is at the bottom. Then the lunar north pole points to
the right, a 180 degree rotation.
> However, if you want to get technical, the moon does have variations
> in it's presentation to an observer on earth so that it's not
> *exactly* in the same orientation all the time. The part of the moon
> we see varies over the course of a month and even over the course of
> an evening. It's called lunar libration. But that's a long term
> effect and certainly doesn't effect short time exposures, on the order
> of seconds or even minutes. It's nothing like the motion blur you get
> if the camera is stationary and your exposure is a couple of seconds.
> See http://en.wikipedia.org/wiki/Libration
Yes.
Here is a 4-second 2003 lunar eclipse image done with a Losmandy
G11 equatorial mount (I had clouds for the recent eclipse):
http://www.clarkvision.com/galleries/gallery.astrophoto-1/web/eclipse_c11.09.2003_IMG_0992-0133-utc.c-0.67x-872.html
Roger
Paul Furman
> Paul Furman wrote:
>> Steve wrote:
>>> M-M wrote:
>>>
>>>> FWIW, here's my eclipse shot showing some stars around the moon:
>>>>
>>>> http://www.mhmyers.com/d80/DSC_10266.jpg
>>> Here's a pair of mine (reduced for flickr) that show some
>>> stars/planets around the moon.
>>>
>>> http://www.flickr.com/photos/sss_random_shots/2284678706/sizes/o/
>>> http://www.flickr.com/photos/sss_random_shots/2283890165/sizes/o/
>>>
>>> What's amazing to me is, when you look at the full size images, how
>>> much motion blur is visible even at a 2 second exposure.
>> The one I linked above is also 2 seconds and ISO 100, and streaked.
>> That's too long, the ISO should be turned up (& aperture opened?).
>> Another route is to align & stack several short consecutive photos, the
>> rotation of the moon will blur at some point too.
>
> The rotation of the moon will not cause blur because it rotates at the
> same rate as it orbits. That's why there's always the same dark side
> of the moon, and light side.
Here's a time lapse someone did of the recent eclipse which shows a
small amount of rotation of the surface of the moon:
http://www.maniacworld.com/Feb-20th-Lunar-Eclipse-Timelapse.html
It's spinning clockwise like a frisbee although not enough to matter for
a 2 second exposure probably.
salmobytes
<usern...@qwest.net> wrote:
...anyone shoot the eclipse
I put a 400mm vibration damped Nikor lense on a D70,
on a tripod and experimented with manual exposures.
I got amazingly blurry and useless images, even though
firmly mounted on a tripod.
I found myself wondering if the vr lense didn't get confused
somehow.....perhaps it never found a reference point and jiggled
itself
silly trying to get it right. That lense has been very useful in
other contexts, like shooting rain forest birds in Trinidad.
salmobytes
> You used the self timer or IR remote, right?
Yes, I used the IR remote. Was that an ignorant mistake?
Steve
to rnclark)" <user...@qwest.net> wrote:
>Steve wrote:
>> On Sat, 23 Feb 2008 16:39:44 -0700, "Roger N. Clark (change username
>> to rnclark)" <user...@qwest.net> wrote:
>>> The moon rotates in the sky with the rotation of the earth.
>>> From our point of view on the earth, the moon rotates as it moves
>>> across the sky with respect to our local horizon.
>>> For example, when the moon is rising, the north
>>> pole of the moon would point approximately to the left
>>> in an image, but would point to the right when it is setting
>>> (from the northern hemisphere).
>>
>> If you put your camera on a motor driven equatorial mount and point it
>> at the moon, you don't have to worry about the moon rotation causing
>> blur because it rotates at the same rate as it orbits. If the north
>> pole of the moon is on the left of your image frame as the moon rises,
>> it will still be on the left of your image frame as the moon sets.
>
>Well, there are multiple issues with what you say:
>
>1) The original discussion was not talking about using an
> equatorial mount.
The original discussion was talking about the blur while using a fixed
tripod with exposures as low as 2-4 seconds. And that has nothing to
do with rotation of the moon. Only rotation of the earth.
Steve
salmobytes
What shutter speeds did you use? How sturdy is the tripod setup?
What
> specific lens and what version VR? Does the lens have a normal/active VR
> setting switch? Is VR recommended for tripod use in the lens manual? Nikon
> has had 3-4 flavors of VR implementations and some might not be useful on a
> tripod.
I used n 80-400mm vr Nikor zoom.
I used F5.6 and shot 1 second -- 10 seconds.
They all came out quite blurry.
The camera is set to asa 200 and I seldom remember to try
bumping up the speed, for some reason.
The ten second exposures were a lot worse than the 1 second
exposures, but they were all surprisingly bad. I'm not sure
what I did wrong. I'm a beginning hacker, not anything approaching
a professional, so I'm not trying to attain any kind of authority
or hotrod stature by posting this (I'm an asker here, not an
answerer).....
Roger N. Clark (change username to rnclark)
>
> I used n 80-400mm vr Nikor zoom.
> I used F5.6 and shot 1 second -- 10 seconds.
> They all came out quite blurry.
> The camera is set to asa 200 and I seldom remember to try
> bumping up the speed, for some reason.
>
> The ten second exposures were a lot worse than the 1 second
> exposures, but they were all surprisingly bad. I'm not sure
> what I did wrong. I'm a beginning hacker, not anything approaching
> a professional, so I'm not trying to attain any kind of authority
> or hotrod stature by posting this (I'm an asker here, not an
> answerer).....
You did nothing wrong except expose too long. The blur you
experienced is caused by the Earth's rotation.
The apparent movement of the moon, sun, stars and planets in the
sky is up to about 15 angular arc-seconds per time second.
A D70 has pixel spacing 0f 7.9 microns (0.0079 mm).
The angular size of one D70 pixel with a 400 mm lens is:
angular size = 206265 * 0.0079/400 = 3.9 arc-seconds.
So the Earth's rotation moved the moon in your camera,
about 15/3.9 or 4 pixels per second. With a 400 mm lens
even 1/4 second exposure would be slightly blurry. About 1/8
second or less would be needed for a sharp picture.
(The 206265 factor is the number of arc-seconds in one radian.)
Roger
Roger N. Clark (change username to rnclark)
Steve,
Please look back at the posts: the first line of mine above
you quoted, and then Paul's post that started this. He said
do multiple short exposures and stack them. The exposures
of 2 to 4 seconds would be blurred due to rotation of the
earth (see my response to Sandy). With a D70, and 400 mm lens
one needed exposures of 1/8 second or faster to stop the effects
of Earth's rotation. Now if you need 4 seconds of exposure,
you need 32 exposures 1/8 second each. If you do mirror
lock-up and wait a few seconds for vibrations to settle,
that sequence could take 2 to 3 minutes.
From our point of view relative to our local horizon, the
moon appears to rotate in our sky (depends on latitude)
on average 15 degrees per hour (of course 0 at the poles) so
in 3 minutes the rotation could be 45 arc-minutes (it's actually
more complex than this; one needs specific lat, long),
(note for the moon passing through the zenith, rates go much higher.)
On a D70 with a 400 mm lens, that would be (assuming 15 degrees/hour)
(1 pixel = 3.9 arc-seconds, moon diameter ~1800/3.9 ~461 pixels)
a rotation at the edge of the moon of about 2.9 pixels.
Stacking the 32 images would result in blurry edges.
Of course, some stacking software can do rotations too.
The link to the video Paul posted illustrates this effect quite well.
Roger
David J. Littleboy
"Roger N. Clark (change username to rnclark)" <user...@qwest.net> wrote:
>
> So the Earth's rotation moved the moon in your camera,
> about 15/3.9 or 4 pixels per second. With a 400 mm lens
> even 1/4 second exposure would be slightly blurry. About 1/8
> second or less would be needed for a sharp picture.
Speaking of 400mm lenses and the moon, on another list someone mutterred
about making sure you got the active AF point on the moon.
Dumb question: Why wouldn't one simply manually set the focus to infinity?
David J. Littleboy
Tokyo, Japan
David J Taylor
[]
> Speaking of 400mm lenses and the moon, on another list someone
> mutterred about making sure you got the active AF point on the moon.
>
> Dumb question: Why wouldn't one simply manually set the focus to
> infinity?
> David J. Littleboy
> Tokyo, Japan
1 - the lens may not have a focus scale.
2 - there may not be a mechanical stop at infinity.
3 - the infinity point may not be precisely accurate, especially over a
temperature range.
David
Dudley Hanks
"Roger N. Clark (change username to rnclark)" <user...@qwest.net> wrote in
message news:47C24CD9...@qwest.net...
I've got a small reflex telescope I've been dying to try out on the moon for
quite some time, and I had been hoping to get a crack at the eclipse but had
to miss it this time. And, after reading these posts, it's probably a good
thing because I think I'd have ended up with a worse image than most.
This discussion has me wondering because I had been planning to use a Canon
Powershot A720 point and shoot to capture the image.
Would the sensor (presumably smaller) increase the blur factor at a given
shutter speed? I'm thinking that if the pixels are closer together, then
more pixels would be exposed per time factor which would exaggerate the
problem.
According to the Windows picture viewer, my A720 shoots at a resolution of
180 dpi while the Rebel XT resolution is only 70 dpi. I'm assuming the
lower resolution indicates larger pixels.
Thanks in advance for considering this question.
Dudley
David J Taylor
[]
> I've got a small reflex telescope I've been dying to try out on the
> moon for quite some time, and I had been hoping to get a crack at the
> eclipse but had to miss it this time. And, after reading these
> posts, it's probably a good thing because I think I'd have ended up
> with a worse image than most.
> This discussion has me wondering because I had been planning to use a
> Canon Powershot A720 point and shoot to capture the image.
How were you planning to attach the camera to the telescope?
> Would the sensor (presumably smaller) increase the blur factor at a
> given shutter speed? I'm thinking that if the pixels are closer
> together, then more pixels would be exposed per time factor which
> would exaggerate the problem.
Does the telescope have a drive? For a given angle of view, the blur as a
percentage of the image width will be the same (when you have no drive).
More pixels would simply provide a better image of the blur.
> According to the Windows picture viewer, my A720 shoots at a
> resolution of 180 dpi while the Rebel XT resolution is only 70 dpi. I'm
> assuming the lower resolution indicates larger pixels.
>
> Thanks in advance for considering this question.
> Dudley
The "dpi" figure is a meaningless number filling a field in the file
header. For the actual pixel size, see, for example, Roger's site or DP
Review.
XT
http://www.dpreview.com/reviews/canoneos350d/page2.asp
3456 x 2304 pixels
22.2 x 14.8mm sensor
6.4um pixel spacing.
A720
http://www.dpreview.com/reviews/canona720IS/
3264 x 2448 pixels
"1/2.5-inch" 5.76 x 4.29mm sensor
1.76um pixel spacing
David
Chris Malcolm
> The original discussion was talking about the blur while using a fixed
> tripod with exposures as low as 2-4 seconds. And that has nothing to
> do with rotation of the moon. Only rotation of the earth.
A fixed universal reference frame disappeared from astronomy when
Newton's model was overtaken by Einstein's. The rotations are relative.
--
Chris Malcolm c...@infirmatics.ed.ac.uk DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]
Steve
to rnclark)" <user...@qwest.net> wrote:
But the original post that started this discussion was when I said:
>What's amazing to me is, when you look at the full size images, how
>much motion blur is visible even at a 2 second exposure.
And at those 2 second exposures, any rotation doesn't come into play.
Only the shift across the sky.
I guess what started this confusion is a mis-communication. When Paul
said:
>Another route is to align & stack several short consecutive photos, the
>rotation of the moon will blur at some point too.
I thought he actually meant the rotation of the moon will blur. That's
not correct. The rotation of the moon does not cause any blur because
the moon's rotation is at the same rate as it's orbit. If the moon's
rotation were significantly different than it's orbit (as it was many
many moons ago) you could not get a blur free full image of the moon
no matter what you did.
What he meant to say (and what I now see is what you understood him to
say) is that the rotation of the earth causes the apparent orientation
of the moon from earth to rotate. That, as you said, can be easily
fixed by aligning the rotation of the images when stacking.
Steve
Roger N. Clark (change username to rnclark)
> I guess what started this confusion is a mis-communication. When Paul
> said:
>
>> Another route is to align & stack several short consecutive photos, the
>> rotation of the moon will blur at some point too.
Paul is correct.
> I thought he actually meant the rotation of the moon will blur. That's
> not correct. The rotation of the moon does not cause any blur because
> the moon's rotation is at the same rate as it's orbit. If the moon's
> rotation were significantly different than it's orbit (as it was many
> many moons ago) you could not get a blur free full image of the moon
> no matter what you did.
Didn't you read my last post (the one your are replying to)?
I calculated the rotation of the moon over a 3 minute period
RELATIVE TO THE LOCAL HORIZON, which is also also with respect
to camera tripod axes.
The Chris' post tried to clarify further saying it is relative.
Imaging and stacking many frames of the planets, especially Jupiter
(with its approximately 10-hour rotation period) must be done quickly,
within a few minutes or rotation does cause blur. Amateur astronomers
take video clips of planets at high magnification and stack the frames
producing stunning images with small telescopes, better than could be
done by large professional observatories a few years ago.
> What he meant to say (and what I now see is what you understood him to
> say) is that the rotation of the earth causes the apparent orientation
> of the moon from earth to rotate. That, as you said, can be easily
> fixed by aligning the rotation of the images when stacking.
That's what I said and understood Paul to say from the start, and his
posted video clip illustrated that very clearly:
Roger N. Clark (change username to rnclark) wrote Feb 24:
> The moon rotates in the sky with the rotation of the earth.
> From our point of view on the earth, the moon rotates as it moves
> across the sky with respect to our local horizon.
Paul Furman wrote:
> Here's a time lapse someone did of the recent eclipse which shows a
> small amount of rotation of the surface of the moon:
> http://www.maniacworld.com/Feb-20th-Lunar-Eclipse-Timelapse.html
Roger N. Clark (change username to rnclark)
> I've got a small reflex telescope I've been dying to try out on the moon for
> quite some time, and I had been hoping to get a crack at the eclipse but had
> to miss it this time. And, after reading these posts, it's probably a good
> thing because I think I'd have ended up with a worse image than most.
>
> This discussion has me wondering because I had been planning to use a Canon
> Powershot A720 point and shoot to capture the image.
>
> Would the sensor (presumably smaller) increase the blur factor at a given
> shutter speed? I'm thinking that if the pixels are closer together, then
> more pixels would be exposed per time factor which would exaggerate the
> problem.
>
> According to the Windows picture viewer, my A720 shoots at a resolution of
> 180 dpi while the Rebel XT resolution is only 70 dpi. I'm assuming the
> lower resolution indicates larger pixels.
>
> Thanks in advance for considering this question.
> Dudley
Dudley,
What you describe can work pretty well. It is called digi-scoping.
Simply put the camera up to the eyepiece of the telescope and take
a picture. How long you can expose depends on the magnification
you get, or how many big the moon is across in pixels.
The moon moves one lunar diameter approximately every 2 minutes.
So, if the moon is 1000 pixels across in your camera, it will move
about 1000 pixels / 120 seconds = 8.3 pixels per second.
A sharp image will have movement no more than 1/2 pixel, so
1/16 second. The moon (not eclipsed) is plenty bright for
such exposures.
The challenge with digi-scoping is getting the camera square
with the telescope. Here is one I did with an old P$S camera
in 2001 with Saturn going behind the moon:
http://www.clarkvision.com/galleries/gallery.astrophoto-1/web/moon_saturn-track_600.html
I had the camera on a tripod. It was a real pain as I had to
move both the camera and tripod every minute and realign the two
because of the moon's movement. You can buy adapters that
allow you to attach a small camera to the telescope, and that's the
way to go if you are going to do much of this. I think I've
seen them for about $40.
Roger
acl
> Steve <st...@example.com> wrote:
> > The original discussion was talking about the blur while using a fixed
> > tripod with exposures as low as 2-4 seconds. And that has nothing to
> > do with rotation of the moon. Only rotation of the earth.
>
> A fixed universal reference frame disappeared from astronomy when
> Newton's model was overtaken by Einstein's. The rotations are relative.
>
Rotation isn't really relative, though, because a rotating frame isn't
inertial. If I am inside a rapidly rotating drum, looking out, I can
easily work out that it's me rotating and not you, standing outside,
by measuring apparent forces. Of course if the rotation is slow this
doesn't matter, to a good approximation.
Unless we're discussing general relativity and equivalence between
acceleration and force etc., but that's a different story.
Paul Furman
> Steve wrote:
>
>> I guess what started this confusion is a mis-communication. When Paul
>> said:
>>
>>> Another route is to align & stack several short consecutive photos,
>>> the rotation of the moon will blur at some point too.
>
> Paul is correct.
Well it seems I was mistaken about "the rotation of the moon will blur
at some point too." the video clip shows this rotation (moon spinning
like a frisbee) but it's only a few degrees over several hours so not
really relevant for this discussion. Also worth noting is that a
non-eclipsed moon reflects enough light that none of this is an issue,
it's only when the moon is dark that you need exposures so long that the
earth's rotation blurs the shot, or maybe if shooting at f/32.
Dudley Hanks
Yes, I've got an adapter for the Digital Rebel, but the view through the
pentaprism is too dark for me to make out anything. I thought that I'd try
the A720 first because I should be able to see what's going on via the LCD,
especially since it gains up in low light.
I'm pretty sure I can get an adapter for the A720 as well, but don't want to
do that until I actually get a shot that works.
Thanks for the info, Roger. I never thought about using a tripod on the
camera as well as the telescope. Like you say, arranging the to will be
tricky, but it would allow for longer exposures.
Now, if I can just talk my boys into giving me a hand, it should be fun. My
younger son is picking up an A570 today, so he might be more inclined to
snapping some lunar picks.
Take Care,
Dudley
Steve
to rnclark)" <user...@qwest.net> wrote:
>Steve wrote:
>
>> I guess what started this confusion is a mis-communication. When Paul
>> said:
>>
>>> Another route is to align & stack several short consecutive photos, the
>>> rotation of the moon will blur at some point too.
>
>Paul is correct.
>
>> I thought he actually meant the rotation of the moon will blur. That's
>> not correct. The rotation of the moon does not cause any blur because
>> the moon's rotation is at the same rate as it's orbit. If the moon's
>> rotation were significantly different than it's orbit (as it was many
>> many moons ago) you could not get a blur free full image of the moon
>> no matter what you did.
>
>Didn't you read my last post (the one your are replying to)?
>I calculated the rotation of the moon over a 3 minute period
>RELATIVE TO THE LOCAL HORIZON, which is also also with respect
>to camera tripod axes.
Yes, which is how I figured out that you were not referring to the
rotation of the moon. When Paul said "the rotation of the moon will
blur at some point", I mistakenly thought he was referring to the
rotation of the moon.
>> What he meant to say (and what I now see is what you understood him to
>> say) is that the rotation of the earth causes the apparent orientation
>> of the moon from earth to rotate. That, as you said, can be easily
>> fixed by aligning the rotation of the images when stacking.
>
>That's what I said and understood Paul to say from the start, and his
>posted video clip illustrated that very clearly:
But the first post I responded to did not include a video clip. That
post only said "the rotation of the moon", which I took to mean the
rotation of the moon. My mistake.
Steve