DSI Pro question

I'm looking at the adds for the DSI Pro. I have also looked at the adds
for the original DSI (colour). The maximum exposure time for either
camera is supposed to be 1 hour. Has anybody ever tried this ? I ask
because the sample images are all stacked up 30s exposures. I haven't
seen any individual exposure longer than 30s. Also, anybody know what
the well depth and read noise are ?

Thanks.

Eric.

Eric wrote:
I'm looking at the adds for the DSI Pro. I have also looked at the adds
for the original DSI (colour). The maximum exposure time for either
camera is supposed to be 1 hour. Has anybody ever tried this ? I ask
because the sample images are all stacked up 30s exposures. I haven't
seen any individual exposure longer than 30s. Also, anybody know what
the well depth and read noise are ?

Thanks.

Eric.

One reason for the short times is simple. "tracking error"
At 30s you can get by with just about anything with a motor.
At 1 hour you need a very very expensive mount and drive and
guider CCD and guide scope.. All of which will come to about $10,000.
That seems like a lot of up-front expense for a $300 camera.
You may as well pitch in another $6000-8000 and get a better/bigger CCD
camera and another $1500 for the software to process the images.
Oh, I forgot about the $5000-15000 for the telescope.

Well, you can get by with a lot less, but not for 1 hour exposures.

Steve

One reason for the short times is simple. "tracking error"
At 30s you can get by with just about anything with a motor.
At 1 hour you need a very very expensive mount and drive and
guider CCD and guide scope.. All of which will come to about $10,000.
That seems like a lot of up-front expense for a $300 camera.
You may as well pitch in another $6000-8000 and get a better/bigger CCD
camera and another $1500 for the software to process the images.
Oh, I forgot about the $5000-15000 for the telescope.

Well, you can get by with a lot less, but not for 1 hour exposures.

Steve

So it does do 1 hour exposures ?

"Eric" wrote in message
news:Gdk7e.27489$vt1.3740@edtnps90...
One reason for the short times is simple. "tracking error"
At 30s you can get by with just about anything with a motor.
At 1 hour you need a very very expensive mount and drive and
guider CCD and guide scope.. All of which will come to about $10,000.
That seems like a lot of up-front expense for a $300 camera.
You may as well pitch in another $6000-8000 and get a better/bigger CCD
camera and another $1500 for the software to process the images.
Oh, I forgot about the $5000-15000 for the telescope.

Well, you can get by with a lot less, but not for 1 hour exposures.

Steve

So it does do 1 hour exposures ?

I guess we will have to wait and see once the camera gets into the hands of
experienced independent users but I too noticed that all the images shown
were 30sec max. This is not really making use of the available 16bits.
There are plenty of people able to take images significantly longer than
this (though perhaps not as long as an hour) with modest equipment using for
example inexpensive webcam based autoguiders. IMO you are quite right to
be sceptical about the capability of a non Peltier cooled camera to be able
to take 1hr exposures. These Ex view Had chips are not renowned for their
low noise a ambient temperatures.

Robin

I guess we will have to wait and see once the camera gets into the hands of
experienced independent users but I too noticed that all the images shown
were 30sec max. This is not really making use of the available 16bits.
There are plenty of people able to take images significantly longer than
this (though perhaps not as long as an hour) with modest equipment using for
example inexpensive webcam based autoguiders. IMO you are quite right to
be sceptical about the capability of a non Peltier cooled camera to be able
to take 1hr exposures. These Ex view Had chips are not renowned for their
low noise a ambient temperatures.

Robin



I'm just trying to see if it will make a reasonably inexpensive
'science' camera.

If the dark current limits the long exposure, I can slap a peltier chip
on the back. If the software is what limits the long exposure, that's
just dumb.

I know this isn't supposed to be a professional camera, but I'd like to
know what it is before I buy it.

Eric.

"Eric" wrote in message
newsJF7e.26043$VF5.9346@edtnps89...
I guess we will have to wait and see once the camera gets into the hands
of
experienced independent users but I too noticed that all the images
shown
were 30sec max. This is not really making use of the available 16bits.
There are plenty of people able to take images significantly longer
than
this (though perhaps not as long as an hour) with modest equipment using
for
example inexpensive webcam based autoguiders. IMO you are quite right
to
be sceptical about the capability of a non Peltier cooled camera to be
able
to take 1hr exposures. These Ex view Had chips are not renowned for
their
low noise a ambient temperatures.

Robin



I'm just trying to see if it will make a reasonably inexpensive
'science' camera.



Hi Eric

This is my interest in it too. Let us know how you get on if you decide to
go for it. BTW have you asked around the DSI Yahoo groups? I find
http://groups.yahoo.com/group/DeepSp...ger-uncensored quite good. More
technical content and less newbie noise ;-)

Robin
----------------------------------------------------------------------------
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Robin Leadbeater
54.75N 3.24W
http://www.leadbeaterhome.fsnet.co.uk/astro.htm
----------------------------------------------------------------------------
-

I'm just trying to see if it will make a reasonably inexpensive
'science' camera.

Hi Eric

This is my interest in it too. Let us know how you get on if you decide to
go for it. BTW have you asked around the DSI Yahoo groups? I find
http://groups.yahoo.com/group/DeepSp...ger-uncensored quite good. More
technical content and less newbie noise ;-)

Robin

Just joined. Thanks.

Eric.

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Hash: SHA1

"rl" == Robin Leadbeater writes:

[...]
rl These Ex view Had chips are not renowned for their low noise a
rl ambient temperatures.

Hmmm, while a webcam based imager is unlikely to be anywhere close to
optimal, I would have sworn that I heard Ron Wodaski say that the Ex
View HAD chips where designed to almost not need dark frames during
Saturdays' NEAF conference on CCD imaging. I'm wondering if while
scribbling notes I missed some context....

roland
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Roland B. Roberts, PhD RL Enterprises
6818 Madeline Court
Brooklyn, NY 11220
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On Mon, 18 Apr 2005 15:32:21 -0400, Roland Roberts
wrote:

Hmmm, while a webcam based imager is unlikely to be anywhere close to
optimal, I would have sworn that I heard Ron Wodaski say that the Ex
View HAD chips where designed to almost not need dark frames during
Saturdays' NEAF conference on CCD imaging. I'm wondering if while
scribbling notes I missed some context....

Their dark current is very low, but plenty high enough to require dark
frames for exposures longer than a few seconds at ambient temperatures.
But they can be cooled without regulation and not normally require
darks.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

"Roland Roberts" wrote in message
...
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

"rl" == Robin Leadbeater writes:

[...]
rl These Ex view Had chips are not renowned for their low noise a
rl ambient temperatures.

Hmmm, while a webcam based imager is unlikely to be anywhere close to
optimal, I would have sworn that I heard Ron Wodaski say that the Ex
View HAD chips where designed to almost not need dark frames during
Saturdays' NEAF conference on CCD imaging. I'm wondering if while
scribbling notes I missed some context....

roland
- --

Hi Roland,

I think the temperature is the key. AFAIK, except for the DSI, all ExView
chipped long exposure cameras are cooled, even the low end 8bit models like
the video camera based SAC8. Even the uncooled integrating video cameras
like the Ex View based Mintron etc start to struggle against noise beyond a
few seconds exposures.

There are some CCDs which give reasonable performance at ambient eg the
ICX424AL (HAD based but not ExView) as used in the webcam based 8 bit ATIK
2HS, but not in an hour exposure.

BTW I do not know offhand of any webcam based cameras using Ex View
technology. I think all the ExView chips currently manufactured are designed
for Video rather than webcam applications.

Robin