M13 in Hercules

A shot taken the other night with a Canon 10D on a Mirage 8 Mak-Cas.
I'm still finding my feet with the scope and my imaging gear. However
most of my efforts seem to be going into dealing with my camera/CCD &
processing - the scope just sits there and does what it's supposed to
do. Very nice and surprisingly stable on top of a GP-DX mount. Image
was collected unguided.

http://www.digitalsky.org.uk/dso/m13-2005-05-10.html

--
Pete
http://www.digitalsky.org.uk

In article , Pete Lawrence wrote:
A shot taken the other night with a Canon 10D on a Mirage 8 Mak-Cas.
I'm still finding my feet with the scope and my imaging gear. However
most of my efforts seem to be going into dealing with my camera/CCD &
processing - the scope just sits there and does what it's supposed to
do. Very nice and surprisingly stable on top of a GP-DX mount. Image
was collected unguided.

http://www.digitalsky.org.uk/dso/m13-2005-05-10.html


Nice one.

For the benefit of the thickies here (me), I've seen people say 'guided'
and 'unguided'. What does these terms refer to? I assume it's something to
do with tracking?

Jim
--
Find me at http://www.ursaMinorBeta.co.uk
"Brace yourself, this might make your eyes water."

"Jim" wrote in message
...
In article , Pete Lawrence
wrote:
A shot taken the other night with a Canon 10D on a Mirage 8 Mak-Cas.
I'm still finding my feet with the scope and my imaging gear. However
most of my efforts seem to be going into dealing with my camera/CCD &
processing - the scope just sits there and does what it's supposed to
do. Very nice and surprisingly stable on top of a GP-DX mount. Image
was collected unguided.

http://www.digitalsky.org.uk/dso/m13-2005-05-10.html


Nice one.

For the benefit of the thickies here (me), I've seen people say 'guided'
and 'unguided'. What does these terms refer to? I assume it's something
to
do with tracking?
Exactly.
There are a series of 'levels':
1) Untracked. Here the camera is stationary, and exposures will show start
trailing after a little while. This is sometimes used for 'star trail'
pictures, and can also be used for short exposures, with software then
combining multiple images, and correcting for the rotation/shift of the
image.
2) Alt/Az tracking. Here there are two motors working together to keep the
star central in the FOV. This corrects for image shift, but leaves
rotation (this can be corrected using a camera rotator). Downsides are
that it required multiple motors to all work together to get good
tracking, and guiding is harder to organise, than with systems where the
camera/view are not rotating. Again short exposures can be used, and
software to now just correct for rotation, without shift.
3) Tracking. Here there is a motor, trying to move the camera 'in sync'
with the sky. The image will show trailing eventually, from any error in
the alignment of the tracking axis, and the polar axis, and from any
irregularities in the gears involved.
4) Manual guided. Here the photographer has a seperate scope attached to
the same mount, or an 'off axis guider', that takes a small part of the
light from the main scope, and he/she, manually adjusts the drive, to keep
a star centred.
5) Camera guided. Here there is the same system as above to feed light to
a second camera, with software which automatically 'guides' the scope.
Historically, '4' was the method by which all long exposure astro images
were taken, till relatively recently, when the CCD camera and computer
allowed automated guiding to appear. Now it is possible to build a very
competent guide system, using a webcam, laptop, and quite cheap software.
The commonest two systems in amateur use now, are '3', and '5', with '3',
generally being limited to wider field, or shorter exposures (limiting the
amount of blur being shown).

Best Wishes

On Thu, 12 May 2005 10:50:34 +0100, Jim
wrote:

In article , Pete Lawrence wrote:
A shot taken the other night with a Canon 10D on a Mirage 8 Mak-Cas.
I'm still finding my feet with the scope and my imaging gear. However
most of my efforts seem to be going into dealing with my camera/CCD &
processing - the scope just sits there and does what it's supposed to
do. Very nice and surprisingly stable on top of a GP-DX mount. Image
was collected unguided.

http://www.digitalsky.org.uk/dso/m13-2005-05-10.html


Nice one.

For the benefit of the thickies here (me), I've seen people say 'guided'
and 'unguided'. What does these terms refer to? I assume it's something to
do with tracking?

Not thick at all and it took me a while, when I was starting out, to
realise what the term meant.

When a scope is just tracking at the sidereal rate (i.e. there's no
connection between the object and the drive) that's unguided.

When a device such as an autoguider is used to 'connect' the drive to
the object (or guide star) then that's guided. The connection is done
by indicating to the autoguider which star is to be used for guiding.
Minor tracking errors in the telescope are then corrected by the by
commands issued from the autoguider to the main telescope drive.

--
Pete
http://www.digitalsky.org.uk

On Thu, 12 May 2005 10:16:03 GMT, "Roger Hamlett"
wrote:


Exactly.
There are a series of 'levels':
snip

A much more comprehensive answer than mine - thanks Roger :-)

--
Pete
http://www.digitalsky.org.uk

In article , Roger Hamlett wrote:

"Jim" wrote in message
...
In article , Pete Lawrence
wrote:
A shot taken the other night with a Canon 10D on a Mirage 8 Mak-Cas.
I'm still finding my feet with the scope and my imaging gear. However
most of my efforts seem to be going into dealing with my camera/CCD &
processing - the scope just sits there and does what it's supposed to
do. Very nice and surprisingly stable on top of a GP-DX mount. Image
was collected unguided.

http://www.digitalsky.org.uk/dso/m13-2005-05-10.html


Nice one.

For the benefit of the thickies here (me), I've seen people say 'guided'
and 'unguided'. What does these terms refer to? I assume it's something
to
do with tracking?
Exactly.
There are a series of 'levels':
1) Untracked. Here the camera is stationary, and exposures will show start
trailing after a little while. This is sometimes used for 'star trail'
pictures, and can also be used for short exposures, with software then
combining multiple images, and correcting for the rotation/shift of the
image.
2) Alt/Az tracking. Here there are two motors working together to keep the
star central in the FOV. This corrects for image shift, but leaves
rotation (this can be corrected using a camera rotator). Downsides are
that it required multiple motors to all work together to get good
tracking, and guiding is harder to organise, than with systems where the
camera/view are not rotating. Again short exposures can be used, and
software to now just correct for rotation, without shift.
3) Tracking. Here there is a motor, trying to move the camera 'in sync'
with the sky. The image will show trailing eventually, from any error in
the alignment of the tracking axis, and the polar axis, and from any
irregularities in the gears involved.
4) Manual guided. Here the photographer has a seperate scope attached to
the same mount, or an 'off axis guider', that takes a small part of the
light from the main scope, and he/she, manually adjusts the drive, to keep
a star centred.
5) Camera guided. Here there is the same system as above to feed light to
a second camera, with software which automatically 'guides' the scope.
Historically, '4' was the method by which all long exposure astro images
were taken, till relatively recently, when the CCD camera and computer
allowed automated guiding to appear. Now it is possible to build a very
competent guide system, using a webcam, laptop, and quite cheap software.
The commonest two systems in amateur use now, are '3', and '5', with '3',
generally being limited to wider field, or shorter exposures (limiting the
amount of blur being shown).


Wow. Thanks for that, that's a lovely explanation.

Thanks. Again.

Jim
--
Find me at http://www.ursaMinorBeta.co.uk
"Brace yourself, this might make your eyes water."

In article , Pete Lawrence wrote:
On Thu, 12 May 2005 10:16:03 GMT, "Roger Hamlett"
wrote:


Exactly.
There are a series of 'levels':
snip

A much more comprehensive answer than mine - thanks Roger :-)


Yours was good as well though :-)

Thanks.

Jim
--
Find me at http://www.ursaMinorBeta.co.uk
"Brace yourself, this might make your eyes water."

http://www.digitalsky.org.uk/dso/m13-2005-05-10.html

--
Pete
http://www.digitalsky.org.uk

Great image Pete.

The 'propellor' feature is quite obvious!

This field with the orange star and nby galxy is beautiful through a large
'scope.

Regards
Paul

"Roger Hamlett" wrote in message
news
5) Camera guided. Here there is the same system as above to feed light to
a second camera, with software which automatically 'guides' the scope.
Historically, '4' was the method by which all long exposure astro images
were taken, till relatively recently, when the CCD camera and computer
allowed automated guiding to appear. Now it is possible to build a very
competent guide system, using a webcam, laptop, and quite cheap software.
The commonest two systems in amateur use now, are '3', and '5', with '3',
generally being limited to wider field, or shorter exposures (limiting the
amount of blur being shown).

I'm looking to get into this at the low end of the cost scale to start with,
and as I'm off on a trip to the US fairly soon, I was thinking about picking
up the new Meade DSI Pro camera and either a Meade LPI or DSI to use as a
guide camera.

Presumably for this to work, I need to use an off axis guider (as I don't
have a separate guide scope) of some type to feed the guide star image to
the DSI or LPI - Meade's literature says that their software now supports
any number of DSIs and one LPI and that any imager can be selected for
guiding.

Anyway - my scope is not wedge mounted, but I seem to see in the Meade
literature that their new software will perform automatic field derotation.
Does anyone have any experience of this type of thing ?

I see on a lot of photos that many people use a 0.63 focal length reducer
for much of their astrophotography with f10 SCTs - is the main benefit of
this purely to make the setup "faster" at the cost of some focal length, or
are there additional benefits as well ?

Cheers,

Alasdair

(off out to try for some photos of the moon with a Nikon D70 at prime focus
tonight.....)

Jim wrote:

A much more comprehensive answer than mine - thanks Roger :-)


Yours was good as well though :-)

Thanks.

Jim

When's the wedding?

Cheers

Martin

--
Martin Frey
http://www.hadastro.org.uk
N 51 02 E 0 47