any plans for "cooled camera detectors?"

Hi Everyone,

Astrophotgraphers typically use "cooled detectors" to take long exposures
with CCD's, because the dark-current of the detector is massively reduced
along with the temperature of the detector. One can themo-electrically cool
a CCD, but I believe this requires a lot of current, and the kind of battery
typically stored onboard a handheld camera wouldn't do the job. But what
about a larger battery pack worn on the belt, then wired to the camera?
Could the detector itself be thermally isolated from the rest of the camera
(via thermally non-conductive struts) so that the detector (and not the
entire CAMERA) be cooled enough to greatly reduce thermal noise and allow
one to take very long exposures (half hour long, hour long) without the
concern of detector noise? Are there new solid state detectors out there
with lower thermal noise? Let's say you didn't want to take hour long
exposures, but just two or three minutes long -- one wouldn't have to cool
the detector as much. I'm just thinking that reducing the detector noise
could dramatically improve photographic results, since I read a lot of
complaints about detector noise on digital cameras. Perhaps the concept of
a "cooled camera" is only practical for BIG cameras, or those that don't
have to be moved around much (like something mounted on a large movie
camera, or on the back of a big telescope). But with new miniaturization
technologies, I wonder if cooled CCD's are a possibility, at least in a
larger DSLR? This is a speculative sort of "what if?" question that I'm
raising, and nothing else...

-Scott Speck

You mean the peltier cooler?These were used for extreme overclocking with
pentium 3s...when the cpu speed was still measured in MHz.They need huge
power supplies, something like 120 W(extra)120 W in 12 V is 10 amperes,quite
a large current.Extra batttery packs wouldn't do, mains power is
needed.That's another reason why even a 1000 euro laptop is never as
powerful as my 700 euro celeron, complete with cd r/w drive, 17"crt and
printer.See www.checkmate.gr, it's in english anyway.
--
Tzortzakakis Dimitriïs
major in electrical engineering, freelance electrician
FH von Iraklion-Kreta, freiberuflicher Elektriker
dimtzort AT otenet DOT gr
Ï "Scott Speck" Ýãñáøå óôï ìÞíõìá
...
Hi Everyone,

Astrophotgraphers typically use "cooled detectors" to take long exposures
with CCD's, because the dark-current of the detector is massively reduced
along with the temperature of the detector. One can themo-electrically
cool
a CCD, but I believe this requires a lot of current, and the kind of
battery
typically stored onboard a handheld camera wouldn't do the job. But what
about a larger battery pack worn on the belt, then wired to the camera?
Could the detector itself be thermally isolated from the rest of the
camera
(via thermally non-conductive struts) so that the detector (and not the
entire CAMERA) be cooled enough to greatly reduce thermal noise and allow
one to take very long exposures (half hour long, hour long) without the
concern of detector noise? Are there new solid state detectors out there
with lower thermal noise? Let's say you didn't want to take hour long
exposures, but just two or three minutes long -- one wouldn't have to cool
the detector as much. I'm just thinking that reducing the detector noise
could dramatically improve photographic results, since I read a lot of
complaints about detector noise on digital cameras. Perhaps the concept
of
a "cooled camera" is only practical for BIG cameras, or those that don't
have to be moved around much (like something mounted on a large movie
camera, or on the back of a big telescope). But with new miniaturization
technologies, I wonder if cooled CCD's are a possibility, at least in a
larger DSLR? This is a speculative sort of "what if?" question that I'm
raising, and nothing else...

-Scott Speck

Scott Speck wrote:
Hi Everyone,

Astrophotgraphers typically use "cooled detectors" to take long
exposures
with CCD's, because the dark-current of the detector is massively
reduced
along with the temperature of the detector. One can
themo-electrically cool
a CCD, but I believe this requires a lot of current, and the kind of
battery
typically stored onboard a handheld camera wouldn't do the job. But
what
about a larger battery pack worn on the belt, then wired to the
camera?
Could the detector itself be thermally isolated from the rest of the
camera
(via thermally non-conductive struts) so that the detector (and not
the
entire CAMERA) be cooled enough to greatly reduce thermal noise and
allow
one to take very long exposures (half hour long, hour long) without
the
concern of detector noise? Are there new solid state detectors out
there
with lower thermal noise? Let's say you didn't want to take hour
long
exposures, but just two or three minutes long -- one wouldn't have to
cool
the detector as much. I'm just thinking that reducing the detector
noise
could dramatically improve photographic results, since I read a lot
of
complaints about detector noise on digital cameras. Perhaps the
concept of
a "cooled camera" is only practical for BIG cameras, or those that
don't
have to be moved around much (like something mounted on a large movie

camera, or on the back of a big telescope). But with new
miniaturization
technologies, I wonder if cooled CCD's are a possibility, at least in
a
larger DSLR? This is a speculative sort of "what if?" question that
I'm
raising, and nothing else...

-Scott Speck



There are several interesting threads on this subject on the
sci.astro.amateur newsgroup; they usually degenerate into "film
resolution vs. digital resolution" discussions, but they still have a
lot of good info.

The CMOS sensors used in eg. Canon's dSLR's are supposed to have less
noise, but I'm not the one to really answer that question (and I'm not
going to get involved in a Canon vs. Nikon flame war).

AFAIK, the problem with CCD's is that they have a phenomenon known as
"dark current" from heating of the chip when it is on for long periods
- the upshot of it is that the longer the CCD is on, the more noise
occurs. Cooling the CCD (with stuff like dry ice, Peltier
thermoelectric coolers, liqid nitrogen, etc) significantly reduces
this, so you can get useful hour-long (or more) exposures.

An interesting way around this is to combine several (or many - tens of
thousands even) short exposures into one good long exposure. A freeware
program called Registax does this - I've tried it for some afocal pics
I took through a 150mm reflector of Saturn and Jupiter; it works OK,
especially to reduce noise and increase resolution. It also apparently
works (with the proper equipment) for some deep space objects; they
have to be the brighter ones, though, because the darker ones simply
don't put enough photons out to significantly change a (for example) 15
second exposure.

A cooled CCD camera for astrophotography is expensive, but they're
available. You can get a used older one for US$800-1000 according to a
recent thread I read. I've seen them new for a few thousand dollars -
not out of reach if you're really commited to the hobby, and probably a
bit less than you'd spend for a decent refractor or Mak, to take the
pics through.... I also read something recently about making your own
CCD astrophotography camera, that could be cooled with dry ice - in the
$500-600 range for all the parts.

Good Luck!
ECM

Hi ECM,

Thanks for the info. I suppose I'm wondering, though, if "cooled detector"
technology might ever make it into a name-brand SLR-type handheld digital
camera. Perhaps, for any shutter speed that one would find useful or
typical for DSLR's, the dark current really isn't a factor, so there's no
NEED to cool the camera. And, if one is using the camera for
astrophotography, one could then use a specialized cooled-detector camera,
as you described.

Thanks,
Scott

"ECM" wrote in message
ups.com...
Scott Speck wrote:
Hi Everyone,

Astrophotgraphers typically use "cooled detectors" to take long
exposures
with CCD's, because the dark-current of the detector is massively
reduced
along with the temperature of the detector. One can
themo-electrically cool
a CCD, but I believe this requires a lot of current, and the kind of
battery
typically stored onboard a handheld camera wouldn't do the job. But
what
about a larger battery pack worn on the belt, then wired to the
camera?
Could the detector itself be thermally isolated from the rest of the
camera
(via thermally non-conductive struts) so that the detector (and not
the
entire CAMERA) be cooled enough to greatly reduce thermal noise and
allow
one to take very long exposures (half hour long, hour long) without
the
concern of detector noise? Are there new solid state detectors out
there
with lower thermal noise? Let's say you didn't want to take hour
long
exposures, but just two or three minutes long -- one wouldn't have to
cool
the detector as much. I'm just thinking that reducing the detector
noise
could dramatically improve photographic results, since I read a lot
of
complaints about detector noise on digital cameras. Perhaps the
concept of
a "cooled camera" is only practical for BIG cameras, or those that
don't
have to be moved around much (like something mounted on a large movie

camera, or on the back of a big telescope). But with new
miniaturization
technologies, I wonder if cooled CCD's are a possibility, at least in
a
larger DSLR? This is a speculative sort of "what if?" question that
I'm
raising, and nothing else...

-Scott Speck



There are several interesting threads on this subject on the
sci.astro.amateur newsgroup; they usually degenerate into "film
resolution vs. digital resolution" discussions, but they still have a
lot of good info.

The CMOS sensors used in eg. Canon's dSLR's are supposed to have less
noise, but I'm not the one to really answer that question (and I'm not
going to get involved in a Canon vs. Nikon flame war).

AFAIK, the problem with CCD's is that they have a phenomenon known as
"dark current" from heating of the chip when it is on for long periods
- the upshot of it is that the longer the CCD is on, the more noise
occurs. Cooling the CCD (with stuff like dry ice, Peltier
thermoelectric coolers, liqid nitrogen, etc) significantly reduces
this, so you can get useful hour-long (or more) exposures.

An interesting way around this is to combine several (or many - tens of
thousands even) short exposures into one good long exposure. A freeware
program called Registax does this - I've tried it for some afocal pics
I took through a 150mm reflector of Saturn and Jupiter; it works OK,
especially to reduce noise and increase resolution. It also apparently
works (with the proper equipment) for some deep space objects; they
have to be the brighter ones, though, because the darker ones simply
don't put enough photons out to significantly change a (for example) 15
second exposure.

A cooled CCD camera for astrophotography is expensive, but they're
available. You can get a used older one for US$800-1000 according to a
recent thread I read. I've seen them new for a few thousand dollars -
not out of reach if you're really commited to the hobby, and probably a
bit less than you'd spend for a decent refractor or Mak, to take the
pics through.... I also read something recently about making your own
CCD astrophotography camera, that could be cooled with dry ice - in the
$500-600 range for all the parts.

Good Luck!
ECM

On Sat, 12 Mar 2005 09:57:01 -0500, "Scott Speck"
wrote:

Hi Everyone,

Astrophotgraphers typically use "cooled detectors" to take long exposures
with CCD's, because the dark-current of the detector is massively reduced
along with the temperature of the detector. One can themo-electrically cool
a CCD, but I believe this requires a lot of current, and the kind of battery
typically stored onboard a handheld camera wouldn't do the job. But what
about a larger battery pack worn on the belt, then wired to the camera?
Could the detector itself be thermally isolated from the rest of the camera
(via thermally non-conductive struts) so that the detector (and not the
entire CAMERA) be cooled enough to greatly reduce thermal noise and allow
one to take very long exposures (half hour long, hour long) without the
concern of detector noise? Are there new solid state detectors out there
with lower thermal noise? Let's say you didn't want to take hour long
exposures, but just two or three minutes long -- one wouldn't have to cool
the detector as much. I'm just thinking that reducing the detector noise
could dramatically improve photographic results, since I read a lot of
complaints about detector noise on digital cameras. Perhaps the concept of
a "cooled camera" is only practical for BIG cameras, or those that don't
have to be moved around much (like something mounted on a large movie
camera, or on the back of a big telescope). But with new miniaturization
technologies, I wonder if cooled CCD's are a possibility, at least in a
larger DSLR? This is a speculative sort of "what if?" question that I'm
raising, and nothing else...


Cooled detectors have a few issues in practice.

First, Peltier coolers require a good deal of
power. Don't forget, they *move* heat, they
don't actually remove it. The moved heat still
needs to be dissipated.

Secondly, there's the issue of condensation on
the sensor itself. I'm not sure how that's
dealt with.. maybe by blowing a stream of dry
nitrogen over the sensor.

But as you can see, there are practical issues
to be dealt with.


rafe b.
http://www.terrapinphoto.com

How about a heat pipe from the sensor to a small ice bucket on the top of
the camera? Perhaps the size of a 35mm film canister with a snap on lid.
Put some ice in there, and your sensor will cool down.

Yes, condensation on the sensor could be an issue. I forget how much you'd
have to cool the sensor to have a useful reduction in noise. But I'm sure
it doesn't have to go to absolute zero.

Problem is, you'd have to add a bag of party ice to your photo kit.

Pete

As for condensation on the sensor, what if the CCD itself was in a small
vacuum-sealed chamber, thereby eliminating the condensation problem?
Vacuum-sealed display/detection devices have been around for a long time
(CRT's in TV's), so that technology is proven. I like the idea of the ice
bucket... Too bad you couldn't stick a couple'a beers in there, too. :-)
-Scott

"Pete" wrote in message
...

How about a heat pipe from the sensor to a small ice bucket on the top of
the camera? Perhaps the size of a 35mm film canister with a snap on lid.
Put some ice in there, and your sensor will cool down.

Yes, condensation on the sensor could be an issue. I forget how much you'd
have to cool the sensor to have a useful reduction in noise. But I'm sure
it doesn't have to go to absolute zero.

Problem is, you'd have to add a bag of party ice to your photo kit.

Pete

Scott Speck wrote:

Hi ECM,

Thanks for the info. I suppose I'm wondering, though, if "cooled detector"
technology might ever make it into a name-brand SLR-type handheld digital
camera. Perhaps, for any shutter speed that one would find useful or
typical for DSLR's, the dark current really isn't a factor, so there's no
NEED to cool the camera. And, if one is using the camera for
astrophotography, one could then use a specialized cooled-detector camera,
as you described.

Thanks,
Scott

The modern DSLRs are doing multiple things to reduce dark current.
For example, the Canon DSLR, like the 20D, 1D Mark II, turn
off electronics during a long exposure to reduce heating of
the sensor. You can do exposures of ten to 20 minutes at
high ISO and get images with less noise than equivalent
speed film with these cameras. Then combining multiple
exposures reduces noise further, making the dark current
effectively a non issue.



The CMOS sensors used in eg. Canon's dSLR's are supposed to have less
noise, but I'm not the one to really answer that question (and I'm not
going to get involved in a Canon vs. Nikon flame war).

AFAIK, the problem with CCD's is that they have a phenomenon known as
"dark current" from heating of the chip when it is on for long periods
- the upshot of it is that the longer the CCD is on, the more noise
occurs. Cooling the CCD (with stuff like dry ice, Peltier
thermoelectric coolers, liqid nitrogen, etc) significantly reduces
this, so you can get useful hour-long (or more) exposures.

An interesting way around this is to combine several (or many - tens of
thousands even) short exposures into one good long exposure. A freeware
program called Registax does this - I've tried it for some afocal pics
I took through a 150mm reflector of Saturn and Jupiter; it works OK,
especially to reduce noise and increase resolution. It also apparently
works (with the proper equipment) for some deep space objects; they
have to be the brighter ones, though, because the darker ones simply
don't put enough photons out to significantly change a (for example) 15
second exposure.

No, amateurs are doing this quite effectively and getting
results within a factor of 2 to 4 of state of the art
cooled systems. The main cause of this factor is the
limited bandwidth and transmission of the filters over the DSLR
sensors, and not the performance.

Roger

Scott Speck wrote:
Hi Everyone,

Astrophotgraphers typically use "cooled detectors" to take long exposures
with CCD's, because the dark-current of the detector is massively reduced
along with the temperature of the detector. One can themo-electrically cool
a CCD, but I believe this requires a lot of current, and the kind of battery
typically stored onboard a handheld camera wouldn't do the job. But what
about a larger battery pack worn on the belt, then wired to the camera?
Could the detector itself be thermally isolated from the rest of the camera
(via thermally non-conductive struts) so that the detector (and not the
entire CAMERA) be cooled enough to greatly reduce thermal noise and allow
one to take very long exposures (half hour long, hour long) without the
concern of detector noise? Are there new solid state detectors out there
with lower thermal noise? Let's say you didn't want to take hour long
exposures, but just two or three minutes long -- one wouldn't have to cool
the detector as much. I'm just thinking that reducing the detector noise
could dramatically improve photographic results, since I read a lot of
complaints about detector noise on digital cameras. Perhaps the concept of
a "cooled camera" is only practical for BIG cameras, or those that don't
have to be moved around much (like something mounted on a large movie
camera, or on the back of a big telescope). But with new miniaturization
technologies, I wonder if cooled CCD's are a possibility, at least in a
larger DSLR? This is a speculative sort of "what if?" question that I'm
raising, and nothing else...

-Scott Speck



I did see a couple of example pictures from a camera that was allowed to
sit outside in cool weather one night for a while. The pictures taken
when the camera had cooled about 30 degrees were SIGNIFICANTLY less
noisy. I was rather impressed, but haven't seen anything to quantify
this effect for any particular camera.


--
Ron Hunter

Ron Hunter wrote:

I did see a couple of example pictures from a camera that was allowed to
sit outside in cool weather one night for a while. The pictures taken
when the camera had cooled about 30 degrees were SIGNIFICANTLY less
noisy. I was rather impressed, but haven't seen anything to quantify
this effect for any particular camera.

EOS DIGITAL Astrophotography Guide:
http://web.canon.jp/Imaging/astro/index-e.html

M31 Andromeda Galaxy
EOS 20D @ ISO 800 12x5min
4" Skywatcher Newton f4,5:
http://www.schweifstern.de/images-pa...31_20D_450.htm

Canon vs Nikon DLSRs for Astrophotography:
http://www.astropix.com/HTML/M_DAP/M150/M150.HTM

Canon 1D Mark II Second Light
http://www.astropix.com/HTML/M_DAP/M10/M10.HTM

Digital Astrophotography
http://www.astropix.com/HTML/M_DAP/TOC_DAP.HTM

Dark frames analisys
http://usuarios.lycos.es/rbarbera/noise/astrod70.html

Canon 10D Digital SLR Camera for Deep Sky Imaging
http://www.hostultra.com/~ghonis/051803D10.html

ClarkVision Photography: Astrophoto 1 Gallery
http://www.clarkvision.com/galleries...y.astrophoto-1

Astrophotography Signal-to-Noise with a Canon 10D Camera
http://clarkvision.com/astro/canon-10d-signal-to-noise


web search will find hundreds. thousands of other sites.

Roger