What do I need for astro photography?

Gareth Slee wrote:

Jim wrote:

Any advice gratefully received.

Jim


Hey guys! How about keeping this on topic?

...Oops sorry... thought I was on ucsm :-)

This _is_ rather turning into the uk.comp.sys.mac Outdoor Activities
Club :-)

Jim
--
Find me at : http://www.ursaminorbeta.co.uk
Please help to bring old whisky literature back into print - visit
www.ClassicExpressions.co.uk

Gareth Slee wrote:

Jim wrote:

Any advice gratefully received.

Jim


Hey guys! How about keeping this on topic?

...Oops sorry... thought I was on ucsm :-)

Huh?

--
Andy Hewitt
http://web.mac.com/andrewhewitt1/

On Mon, 5 Mar 2007 08:50:30 +0000, Jim wrote:

I have an older Orion Optics Europa 250 'scope with 1.25" eyepieces. I also have
a Canon EOS350D camera. I'd like to start some simple astro photography, but I'm
completely clueless as to what I need to mate the two together - just how does
the camera get attached to the 'scope?

Any advice gratefully received.

Hi Jim,

An EOS to t-thread adapter to attach onto the front of your camera.
Mine cost me £10 from my local camera shop who had a box of them under
the counter strangely.

You then need a 1.25" nosepiece with a T-thread that screws into the
adapter.

You'll also need to get hold of a remote switch to fire the camera's
shutter as pressing it attached to the scope will cause you lots of
wobble. Alternatively, set the timed shutter delay on the camera so
you can press the shutter and then move back for hands free firing.

A 1.25" fitting is almost certainly going to cause vignetting in your
images. A 2" adapter (2" nose piece and a T-thread at the back to
screw into the EOS adapter) will lessen this greatly. However, to use
this you'd need to upgrade your 1.25" eyepiece holder/focuser.

Welcome to the money pit ;-)
--
Pete
http://www.digitalsky.org.uk

In article , Pete Lawrence wrote:
On Mon, 5 Mar 2007 08:50:30 +0000, Jim wrote:

I have an older Orion Optics Europa 250 'scope with 1.25" eyepieces. I also have
a Canon EOS350D camera. I'd like to start some simple astro photography, but I'm
completely clueless as to what I need to mate the two together - just how does
the camera get attached to the 'scope?

Any advice gratefully received.

Hi Jim,

An EOS to t-thread adapter to attach onto the front of your camera.
Mine cost me £10 from my local camera shop who had a box of them under
the counter strangely.

Right-o.

You then need a 1.25" nosepiece with a T-thread that screws into the
adapter.

Right-o. I assume that you remove the lens from the camera (told you I was new
at all this) but you are still able to use an e/p with the 'scope?


You'll also need to get hold of a remote switch to fire the camera's
shutter as pressing it attached to the scope will cause you lots of
wobble. Alternatively, set the timed shutter delay on the camera so
you can press the shutter and then move back for hands free firing.

Already got that last year when I was trying to photograph lightning, so check
on that.

A 1.25" fitting is almost certainly going to cause vignetting in your
images. A 2" adapter (2" nose piece and a T-thread at the back to
screw into the EOS adapter) will lessen this greatly. However, to use
this you'd need to upgrade your 1.25" eyepiece holder/focuser.

[eyes starting to glaze]

Welcome to the money pit ;-)

You're not exactly selling this to me! :-)

Jim
--
Find me at http://www.ursaMinorBeta.co.uk

Please help to bring two classic works of whisky literature back into print
by visiting http://www.ClassicExpressions.co.uk Thank you.

On Tue, 6 Mar 2007 12:19:58 +0000, Jim wrote:

In article , Pete Lawrence wrote:
On Mon, 5 Mar 2007 08:50:30 +0000, Jim wrote:

I have an older Orion Optics Europa 250 'scope with 1.25" eyepieces. I also have
a Canon EOS350D camera. I'd like to start some simple astro photography, but I'm
completely clueless as to what I need to mate the two together - just how does
the camera get attached to the 'scope?

Any advice gratefully received.

Hi Jim,

An EOS to t-thread adapter to attach onto the front of your camera.
Mine cost me £10 from my local camera shop who had a box of them under
the counter strangely.

Right-o.

You then need a 1.25" nosepiece with a T-thread that screws into the
adapter.

Right-o. I assume that you remove the lens from the camera (told you I was new
at all this) but you are still able to use an e/p with the 'scope?

There are three main ways to couple a camera to a telescope. The first
is basically holding the camera (including it's lens) up to the
eyepiece. That's called afocal coupling. This is normally only done if
you can't remove your camera's lens - which you can. So here you have
an eyepiece and a camera lens.

The second method is eyepiece projection and this doesn't tend to be
used that widely. Here you have an adapter which holds an eyepiece and
allows you to vary the distance between the eyelens (the lens that
would be closest to your eye) and the camera's chip. This is for
cameras which can have their lenses removed (including webcams). So
here you have an eyepiece and no camera lens.

The third method, which is most common with DSLR cameras, is prime
focus coupling. Here you lose both the eyepiece and the camera's lens.
The path to the camera's chip is as pure as it gets - i.e. there's no
glass between it and the telescope's primary mirror. This is the route
you want to follow Jim.

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

In article , Pete Lawrence wrote:

The third method, which is most common with DSLR cameras, is prime
focus coupling. Here you lose both the eyepiece and the camera's lens.
The path to the camera's chip is as pure as it gets - i.e. there's no
glass between it and the telescope's primary mirror. This is the route
you want to follow Jim.


How do you go about getting greater magnification in that situation?

Jim
--
Find me at http://www.ursaMinorBeta.co.uk

Please help to bring two classic works of whisky literature back into print
by visiting http://www.ClassicExpressions.co.uk Thank you.

On Tue, 6 Mar 2007 12:44:25 +0000, in uk.sci.astronomy , Jim
wrote:

In article , Pete Lawrence wrote:

The third method, which is most common with DSLR cameras, is prime
focus coupling. Here you lose both the eyepiece and the camera's lens.
The path to the camera's chip is as pure as it gets - i.e. there's no
glass between it and the telescope's primary mirror. This is the route
you want to follow Jim.


How do you go about getting greater magnification in that situation?

You use a high-density CCD and enlarge the image photographically. You
can also use a Barlow.

Remember that the eyepiece spreads out the photons more, ideally for
photography you want to avoid that...
--
Mark McIntyre

On or about 2007-03-06,
Jim illuminated us with:
In article , Pete Lawrence wrote:

The third method, which is most common with DSLR cameras, is prime
focus coupling. Here you lose both the eyepiece and the camera's lens.
The path to the camera's chip is as pure as it gets - i.e. there's no
glass between it and the telescope's primary mirror. This is the route
you want to follow Jim.


How do you go about getting greater magnification in that situation?

Depending on what you're trying to do, you usually want less not more
magnification. In my very limited experience, you get a much smaller
field of view (approximately the same as more magnification, but of
course there can be other effects going on) with a camera than you do
through the most powerful useful eyepeice. For anything other than the
moon, you'll probably be operating at the limits of the light
gathering capacity of the telescope and much more importantly, your
ability to focus the image. Then you'll be ready to start learning
about image-processing :-)

--
Mark
Real email address | Time is money, money is the root of all evil,
is mark at | and knowledge is power.
ayliffe dot org | Therefore, procrastination is the key to world peace.

The third method, which is most common with DSLR cameras, is prime
focus coupling. Here you lose both the eyepiece and the camera's lens.
The path to the camera's chip is as pure as it gets - i.e. there's no
glass between it and the telescope's primary mirror. This is the route
you want to follow Jim.


But isn't the image at prime focus really tiny ?

--
Boo

On Tue, 06 Mar 2007 16:38:11 +0000, Boo
wrote:

The third method, which is most common with DSLR cameras, is prime
focus coupling. Here you lose both the eyepiece and the camera's lens.
The path to the camera's chip is as pure as it gets - i.e. there's no
glass between it and the telescope's primary mirror. This is the route
you want to follow Jim.


But isn't the image at prime focus really tiny ?

Depends on the instrument that delivering the image. My C-14 @ f/11
delivers a very respectable image scale whereas my ED80 @ f/7.5
doesn't.

The focal length is what determines the image scale you'll get. Prime
focus is pure but adjustable via optical amplifiers (which make it
less pure). If the image is too small, then you'd use a Barlow or
PowerMate to increase the effective focal length but the power of the
amplifier. Conversely, if the image scale is too large for your tastes
you'd use a focal reducer.

There are practical limits to how far you can push a telescope and
whether the image scale it's delivering is optimal for the chip
capturing the light.
--
Pete
http://www.digitalsky.org.uk