Step up from Toucam ?

"Dr John Stockton" wrote in message
...

You've read all you can about how various types of ADCs and DVMs work, I
trust? Schemes intended for getting slower conversions at sub-ppm
resolution may be adaptable for different speed/accuracy regimes.


Just to go back to Dylan's original question for a moment, can anyone
recommend something that WOULD be a good step up from a Toucam for Planetary
imaging ?

I would like to be able to get higher resolution on the planets, given all
other things being equal.

"adm" wrote in message
...

"Dr John Stockton" wrote in message
...

You've read all you can about how various types of ADCs and DVMs work,
I
trust? Schemes intended for getting slower conversions at sub-ppm
resolution may be adaptable for different speed/accuracy regimes.


Just to go back to Dylan's original question for a moment, can anyone
recommend something that WOULD be a good step up from a Toucam for
Planetary imaging ?

I would like to be able to get higher resolution on the planets, given
all other things being equal.
Unfortunately, as I tried to say at the beginning, I don't think there is
much 'step up', for planetary work.
To get more resolution, increase the magnification....
Webcams, have represented a 'breakthrough' in planetary imaging, allowing
people from the most unlikely sites, to get very good planetary images,
that better in many cases, images taken with scopes/cameras costing dozens
of times more.

Best Wishes

"Dr John Stockton" wrote in message
...
JRS: In article , dated
Tue, 14 Feb 2006 15:52:28 remote, seen in news:uk.sci.astronomy, Roger
Hamlett posted :

Difference is between quantisation noise, and quantisation _error_.
Quantisation 'noise', would be a random process, and as such ammenable
to
multiple images finding the real data underneath. Unfortunately,
quantisation error, is a non random process (it is _influenced_, by the
randomness of the data underneath). You get ADC's, that over particular
ranges, will tend to 'stick' on a particular value. If you generate
psuedo
random noise, on a small scale signal, and feed it through most ADC's,
and
then try to regenerate the signal by stacking, you find this fixed
pattern
being seen, rather than the small scale data. I was involved some time
ago, with a number of tests, trying to perform stacking like this on
small
scale audio signals, and in practice, these effects destroyed the
ability
to reconstitute the data, beyond perhaps about 5 bits extra, (using in
excess of 1024 samples).

How about adding a larger-scale analogue signal, such as a slow sine
wave or sawtooth, in such a manner that it averages out in the final
digital result? That way each portion of the result would result from
measurements using many portions of the core converter.

The analogue might be added electrically, or maybe as illumination on
the sensor.
That ought to work. Given that CCD cameras have a bias voltage applied, it
suggests an interesting experiment.
There are a number of seperate 'terms' involved, and some have quite a lot
of stuff about it on the web. Differential non linearity (covers the
'jump' behaviour at some points). However one I have never seen much
about, is the tendency of CCD's in particular, to not completely 'empty'
their wells after a flush. On some cameras, this can result in a ghost
reading for muliple frames.
In audio, there is the term 'SINAD', which is used for how well the ADC
really performs in reproducing frequencies, versus it's theoretical
performance. I have never seen anything similar, for CCD maging though.

You've read all you can about how various types of ADCs and DVMs work, I
trust? Schemes intended for getting slower conversions at sub-ppm
resolution may be adaptable for different speed/accuracy regimes.

Best Wishes

"adm" wrote in message
...


Just to go back to Dylan's original question for a moment, can anyone
recommend something that WOULD be a good step up from a Toucam for
Planetary
imaging ?

I would like to be able to get higher resolution on the planets, given all
other things being equal.



The Lumenera LU075 as Pete mentioned near the top of the thread allows
faster frame rates (What Damian Peach is using these days)

There have been some tests published on QCUIAG which suggest that the USB2.0
1.3Mpixel Logitech Fusion webcam can match and possibly improve on the
performance of the Toucam Pro despite being CMOS technology

Also Steve Chambers/Jon Grove are curently working on a dedicated planetary
camera to complement the Artemis. Keep a look out on QCUIAG too for the
latest news on that one.

Robin

Robin Leadbeater wrote:
"adm" wrote in message
...


Just to go back to Dylan's original question for a moment, can anyone
recommend something that WOULD be a good step up from a Toucam for
Planetary
imaging ?

I would like to be able to get higher resolution on the planets, given all
other things being equal.



The Lumenera LU075 as Pete mentioned near the top of the thread allows
faster frame rates (What Damian Peach is using these days)


It is not because it allows higher frame rate but because it does that
*and* it yields a much better raw frame (far less noisy) as well as
showing a higher sensitivity w.r.t. other similar devices.

Andrea T.

"Roger Hamlett" wrote in message
...

"adm" wrote in message
...

"Dr John Stockton" wrote in message
...

You've read all you can about how various types of ADCs and DVMs work, I
trust? Schemes intended for getting slower conversions at sub-ppm
resolution may be adaptable for different speed/accuracy regimes.


Just to go back to Dylan's original question for a moment, can anyone
recommend something that WOULD be a good step up from a Toucam for
Planetary imaging ?

I would like to be able to get higher resolution on the planets, given
all other things being equal.
Unfortunately, as I tried to say at the beginning, I don't think there is
much 'step up', for planetary work.
To get more resolution, increase the magnification....

Fair enough. In which case I need a higher power Barlow.

Webcams, have represented a 'breakthrough' in planetary imaging, allowing
people from the most unlikely sites, to get very good planetary images,
that better in many cases, images taken with scopes/cameras costing dozens
of times more.

Absolutely - I'm still blown away with what can be done with a £50 camera
and am nowhere near reaching the limits of it. I was just interested in
whether or not there was anything out there with higher resolution. Of
course, more pixels for the same image size means smaller pixels which in
turn means less photons per pixel, which means more noise....

"Robin Leadbeater" wrote in message
...

"adm" wrote in message
...


Just to go back to Dylan's original question for a moment, can anyone
recommend something that WOULD be a good step up from a Toucam for
Planetary
imaging ?

I would like to be able to get higher resolution on the planets, given
all
other things being equal.



The Lumenera LU075 as Pete mentioned near the top of the thread allows
faster frame rates (What Damian Peach is using these days)

Interesting - but £750. And still only 640 x 480 pixels

There have been some tests published on QCUIAG which suggest that the
USB2.0
1.3Mpixel Logitech Fusion webcam can match and possibly improve on the
performance of the Toucam Pro despite being CMOS technology

Very interesting - and at £50, probably worth a try. 1280 x 960

Also Steve Chambers/Jon Grove are curently working on a dedicated
planetary
camera to complement the Artemis. Keep a look out on QCUIAG too for the
latest news on that one.

Robin

Thanks Robin.

"adm" wrote in message
...

"Robin Leadbeater" wrote in message
...

"adm" wrote in message
...


Just to go back to Dylan's original question for a moment, can anyone
recommend something that WOULD be a good step up from a Toucam for
Planetary
imaging ?

I would like to be able to get higher resolution on the planets, given
all
other things being equal.



The Lumenera LU075 as Pete mentioned near the top of the thread allows
faster frame rates (What Damian Peach is using these days)

Interesting - but £750. And still only 640 x 480 pixels

Number of pixels does not matter much for panets. Even at 0.1arcsc/pixel
(higher resolution than you are ever going to get from the ground) planets
are are going to be less than 480 pixels diameter.

To get higher resolution, use optimum magnifiction (say around
0.25arcsec/pixel, but open to debate) get a bigger aperture so you can take
more, shorter exposures, and a camera that can support them, move to the top
of a mountain ;-)


There have been some tests published on QCUIAG which suggest that the
USB2.0
1.3Mpixel Logitech Fusion webcam can match and possibly improve on the
performance of the Toucam Pro despite being CMOS technology

Very interesting - and at £50, probably worth a try. 1280 x 960

Probably best to look at Steve Chambers report first
http://www.pmdo.com/fusion.htm


Robin