first PST H-alpha images

I'm enjoying the view thro my new PST despite the low winter sun at
52oN and have posted my first imaging attempts at

http://home.freeuk.com/m.gavin/pstmg.htm

I've a lot to learng.

(Maurice Gavin) wrote:

I'm enjoying the view thro my new PST despite the low winter sun at
52oN and have posted my first imaging attempts at

http://home.freeuk.com/m.gavin/pstmg.htm

I've a lot to learng.

Bravo - before you learn more, teach me how to achieve this!

Cheers

Martin

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

Hi Maurice

It certainly is a nice scope and fantastic value. There is a very useful
article on H alpha solar imaging in July 2004 Sky & Telescope (page 137). It
may also be worth your while joining the [Coronado_PST] Yahoo group. The
resident expert Paul Hyndman has just today explained how to get good
images. Do note however the image linked to in his letter was not taken with
a PST.

I have a few images on my website http://www.graviton.demon.co.uk attempting
to follow the S & T article's advice.
--
Dave Smith


"Maurice Gavin" wrote in message
...
I'm enjoying the view thro my new PST despite the low winter sun at
52oN and have posted my first imaging attempts at

http://home.freeuk.com/m.gavin/pstmg.htm

I've a lot to learng.

On Thu, 27 Jan 2005 16:39:22 -0000, "Dave Smith"
wrote:

Hi Maurice

It worth your while joining the [Coronado_PST] Yahoo group. The
resident expert Paul Hyndman has just today explained how to get good
images. Do note however the image linked to in his letter was not taken with
a PST.

Already joined the Group but didn't appreciate Hyndmans images not
from the PST.

I have a few images on my website http://www.graviton.demon.co.uk attempting
to follow the S & T article's advice.

Very nice images - I've yet to capture surface features - do I need
flat fielding and how? the image seems unevenly illuminated and any
contast stretch make it much worse.

Dave Smith

On Thu, 27 Jan 2005 10:56:25 +0000, Martin Frey
wrote:


Bravo - before you learn more, teach me how to achieve this!

Martin


I thought a Barlow to project direct onto Canon 300D sensor should be
best but currently just holding the camera [with its lens] in afocal
mode behind eyepiece seems just a good but I'm not satisfied with
results!

Maurice

Possibly irrrelevant, but I *always* get similar patchy shading if I
use spot focussing with my Sony P71 on the Sun. So I always set focus
to infinity on astro objects. I believe my camera is confused by the
intervening optics. Your posh camera may not be.

Your afocal hand-held method is quite practical if the telescope is
firmly held. But camera shake must be almost inevitable where the
slightest vibration is possible. Could you hang your PST on a bigger
scope for stability and some vibration-damping inertia? You'd get a
proper drive into the bargain. :-)

But you knew all this anyway. I'm just sharing my humble experiences in
case anybody else is tempted to try replicating your methods.
*
Chris.B
Pedant by appointment.

Some of Paul Hyndmans images are with the PST -see
http://www.astro-nut.com/sun-pst.html
but most of his images are taken with a solarmax90 I believe. They are all
very impressive.

--
Dave Smith
http://www.graviton.demon.co.uk


"Maurice Gavin" wrote in message
...
On Thu, 27 Jan 2005 16:39:22 -0000, "Dave Smith"
wrote:

Hi Maurice

It worth your while joining the [Coronado_PST] Yahoo group. The
resident expert Paul Hyndman has just today explained how to get good
images. Do note however the image linked to in his letter was not taken
with
a PST.

Already joined the Group but didn't appreciate Hyndmans images not
from the PST.

I have a few images on my website http://www.graviton.demon.co.uk
attempting
to follow the S & T article's advice.

Very nice images - I've yet to capture surface features - do I need
flat fielding and how? the image seems unevenly illuminated and any
contast stretch make it much worse.

Dave Smith

On 28 Jan 2005 00:13:30 -0800, wrote:

Maurice

Possibly irrrelevant, but I *always* get similar patchy shading if I
use spot focussing with my Sony P71 on the Sun. So I always set focus
to infinity on astro objects. I believe my camera is confused by the
intervening optics. Your posh camera may not be.

Your afocal hand-held method is quite practical if the telescope is
firmly held. But camera shake must be almost inevitable where the
slightest vibration is possible. Could you hang your PST on a bigger
scope for stability and some vibration-damping inertia? You'd get a
proper drive into the bargain. :-)

But you knew all this anyway. I'm just sharing my humble experiences in
case anybody else is tempted to try replicating your methods.
*
Chris.B
Pedant by appointment.

A valid point Chris. It seems as long as you don't touch the scope
even if by hand the camera seems very unsteady the captured image seem
sharp with auto exposures of ~1/100s @ 1600ISO.

Yes the camera is prefocused at infinity before holding up to the
eyepiece. This assume the eyepeice is focused at infinity too!
Strangely my eyes prefer to 'view' thro the scope as if it were at
~60cm /2ft range [a bit like reading a book] so I adjust things
accordingly.

Maurice

Daft question: If your camera is pre-focussed at infinity, then can't
you use the camera focussing screen to focus your telescope accurately?

I use a 12V 5" TV with a video cord sometimes to get a larger image of
what the camera is seeing. There are even small LCD TV screens now in
the same size range for around =A3100 which would be even nicer than a
mini-CRT. The larger image greatly aids in centring and squareness of
the camera to the eyepiece.

In your covered observatory you could use a suitably large coloured
computer monitor in the shade. Assuming you have a video-out socket on
your camera of course. I found the mini-TV particularly useful on the
Venus transit in rapidly changing cloud cover. Though I am fortunate in
that my mount and telescope are rigid enough to allow me to place my
camera lens into the eyepiece rubber-eyecup without vibration.
I would urge you to try placing your PST (if only temporarily) on a
larger and more rigid telescope and mount to gain maximum benefit of
its potential resolution for imaging. Tracking would surely be an
advantage.
*
Regards
Chris.B