Cooling of CCD cameras, what temp do you use and why?

[Alchemy]

Long title, but pretty much what I'm interested in.

I've got myself a qhy9 which has quite a range for cooling, I started at -20 as I figured it could be used all year round, and then a set of calibration files would last longer. ( extra question how often do you replace calibration files), there is still some noise when it's stretched, more than my qhy8 but it's also more sensitive so I guess that evens it out.

So..... Is there any benefit in going lower, and I mean real benefit as opposed to theoretical. And where do most of you prefer to set your cooling?
If there is a noticeable benefit I would be tempted to go there, the other option might be longer subs so signal overrides noise..although there has been some comment regarding bloated stars on this chip (I went from 20 min to 10 min so I can go back that long for dimmer targets)

Thanks for your input

Clive

[Terry B]

On my ST10XME I use -25 deg as I can achieve that all year round. I do need to use water cooling though in summer to assist it.
I have tried -15 and it has more hot pixels as espected. At -30 it is cleaner but I can't maintain that temp in summer.
I use the same darks, offsets for a long time and update flats as needed so like to keep to the same temperature.

[peter_4059]

I use -10 on the qhy8pro as it can achieve this temp all year round so same calibration files can be used. I started off comparing stretched darks at -10,-15 and -20 and couldn't notice any difference so decided -10 would do. I think it is going to depend on the type of CCD the camera has as to how much benefit you are going to get by going colder. The QHY8 has the Sony ICX453 CCD whereas the QHY9 has the KAF8300.

[mill]

I have a QHY9m and have it set to -20 all year round.
Even in summer it goes to -20 and runs at 60% power.
I am running it at 13.8Volt so i set it to not go higher than 75% power.

[ptc]

key reasons to cool
1) management of dark shot noise
2) management of cosmetic defects/Dark FPN
3) management of RBI

There's a relationship between the level of cooling used and the maximum time you can expose and still have the dark shot noise less than the read noise of the camera. That time point is usually regarded as the maximum practical exposure time (see pages 6-9 of the linked pdf below)

http://www.narrowbandimaging.com/incoming/cooling_crisp.pdf

Cosmetic defects can and do accumulate with time; usually they are pixels that have higher dark signal than surrounding pixels. The bad effects of such leaky pixels can be minimized by deep cooling (page 10)

RBI is a problem to varying degree with KAF series sensors. The KAF09000 is particularly bad. The best known method for managing such RBI is to flood the sensor with NIR light, flush it and then expose. This fills the traps prior to the exposure, placing the sensor into a known state. During exposure some of the charge leaks from the traps into the image. The charge leakage will leave patterns observable in the image that are a form of Dark Fixed Pattern Noise and these are removed completely by proper dark subtraction. However the average signal level leaking from the traps does contribute to the dark shot noise (typically dominates versus thermal dark signal) so this needs to be considered along with the thermally generated dark signal when selecting a cooling target operating point.

Surprisingly, the KAF series require substantial cooling in order to support longish exposures and low read noise target limits (pages 11-19)

Hope that was helpful.

[strongmanmike]

Another concise analysis Richardo

So two key things I saw there were

1) Dark shot noise is NOT removed by dark subtraction
Only cooling can reduce dark shot noise for a given sensor

and

2) Lower read noise in a camera is certainly desirable but you need good cooling available to exploit the improvement.

The example you included of managing cosmetic defects with cooling was pretty telling too

Great explanation mate :thumbsup:

So in the end is it basically the colder the better really..? :cold:

To answer your question Cliveus, I use -30C year round so I can be lazy with the same set of darks but given Richards explanation I should probably exploit the low read noise of my ProLine better and go lower temps in the winter months :question:

Rich, I understand dark libraries should be re-shot periodically, how often does one need to redo dark libraries to keep exploiting low read noise and cooling?

Mike

[ptc]

you really need to measure it to know how much difference the extra cooling will make. In that data I posted is some measured data from Tim Khan's ML8300 running at -25C with and without light flood (Page 17)

He has very low read noise so his cooling at -25C and no light flood is sufficient for a 400 second exposure

of course none of this matters with bright objects shot in bright skies with broadband filters. The background signal levels are way larger than the noise contribution from dark signal components.

as far as libraries go: I have seen that the ambient temperature can affect the bias level a tad. Since you should NOT use dark scaling when using the light flood, you might want to take darks at extremes of ambient temperatures encountered during a year of imaging. There's really no reason to toss them unless you are picking up more costmetic defects or you have a long term bias drift issue which I doubt.

[strongmanmike]

Ok, so:

1) Colder the better is valid but most useful under dark skies where it is advantageous and noticeable.

2) A library of darks is usable for quite a while (even years?)

So perhaps I should keep the set of -30C darks for spring/summer and do a new set of -40C darks for use in winter?

Mike

[ptc]

if -30C is sufficient to meet the exposure criteria then -40C will offer no additional advantage

my comment about darks taken in extremes of ambients expected was directed more to one operating temperature (say -25C) but at extremes of environmental ambient temperatures (like summer and winter ambients)

the change in ambient temperatures can make a few DN difference in the average bias level so that is where it might be a good idea to have a couple sets of darks. One for winter and one for summer temperatures

[strongmanmike]

This relates to Clives original question in a way ie what real difference is there in going colder. Going significantly colder is good but only if the camera has lower native read noise in the first place - correct? If your camera has higher native read noise going colder won't help that much?



Hmm, this is new to me....so because my camera is low read noise in the first place and once I have determined the lowest all year achievable chip temperature it is then the ambient temperature at which the darks are taken (rather than the chip temperature) that needs to vary ie I should take a set of -30C darks when the ambient is say +20C (simulates a typical summer night) and another set of -30C darks when the ambient is say +5C (simulates a typical winter night)..?

Or am I out of my mind...? :nerd:

Mike

[Alchemy]

A few things I'm not used to,

Dark shot noise ? Is this the bias frame ?

Light flood.... Never done that, or even heard of anyone here doing it, however given the 8300 chip had a 400 sec for -25 , I might have to lower my temp somewhat.

Mine runs to -50 of ambient , fortunately nights here generally aren't over 20 too often. So -30 is doable on most nights.

Lots to consider there, thanks for the replies from all.

[cventer]

Page 17 says the data is from KAF 16803 chip not 8300 ? did I miss something ?

Also interested in this light flood you speak of. How does one do this ?

[frolinmod]

The camera does it. Your camera either has this feature or it doesn't. If your camera had this feature, you'd know about it. :D

[marki]

Keep my QHY9 at -20 C all year round without any problems. Exposures are usually around 600 sec and calibration removes anything left over. Have run it as low as -35 C on a cold winters night but gained little from doing so so will leave it where it is.

Mark

[jase]

Cool thread, no pun intended. Thanks for all the info.

It does make me think I should be running cooler with the Apogee U16M with D9 cooling package. During winter running at a -30c set point, TEC power is only at 20%, so I wouldn't have any challenge in getting the camera down to -40c or -50c. A few months ago I had the camera serviced by Apogee. They tested the camera at -62c below ambient according to the test report, no doubt this is in a controlled environment. During summer, I don't like running the TEC power higher the 80%. If I run at a set point of -30c all year round, TEC never reaches this. I refresh the calibration library every three months with a quick script that I run on a night where the weather is bad.

[Paul Haese]

QSI583, during winter it holds -20C easily. Spring the same. Summer most nights -15C, rarely -20C. Darks done every 3-4 months. The images start to show black squares and this tells me it is time for new darks.

Clive if you can do -20 or -25C all year around then do that.

[ptc]

yes, I mistyped. it was a ML16803 not ML8300

[ptc]

I regularly run my cameras near 95%. so long as it has enough headroom to maintain a constant temperature there's no risk at higher power numbers.

what is your reason to avoiding running higher power numbers than 80%? You are only needlesslty limiting yourself by erecting artificial barriers.

[ptc]

well obviously if you haven't heard of it there are things that are commonly done that you need to learn how to do.. or at least understand what they do and decide if it is appropriate for your usage.

The Cassini and Galileo probes both had light flood to manage RBI. it is implemented in FLI ML and PL cameras too.

Except for FLI and to a lesser extent Apogee, no one else that I am aware of implements light flood. These camera companies are in denial as to the issues associated with RBI and it is a very real phenomenon observed in ALL KAF series sensors: with some significantly worse than others.

Dark shot noise is completely unrelated to bias frames. It is the noise you get by virtue of a non-zero signal level (average) in dark frames. It is numerically equal to the square root of the number of electrons in the frame.

So 100 electrons per pixel of average dark signal level means you have 10 electrons of dark shot noise. This is random noise like read noise. so you manage it by averaging many frames together. For dark signal you can do one better and that is by cooling... so you can make it smaller in a per frame basis by cooling or you can average many frames together to 'beat it down' (like read noise).

When you take 4x the frames then you get to reduce the noise by a factor of two....

sounds like some of you guys could benefit from my basic lecture series of the basics of electronic imaging... noise sources, management thereof and how to get high SNR images and how to tell when good enough is good enough!


Keep in mind that if you are imaging something faint where read noise is a consideration, then dark shot noise will also be a consideration and if you cannot run as cold as you would like to keep the dark shot noise less than the read noise, you may be better off to reduce your exposure time and take more exposures....

this stuff isn't terribly complicated but there are a few basics that I cover in my lecture series that I think anyone that is serious about imaging ought to know... sort of like the basics of how an internal combustion engine works and the importance of lubrication, gearing and tires by way of analogy....

[jase]

Voltage

When you are running the camera near 95%, what is the voltage draw? If I hit 95%, I get a low voltage warning as the TEC consumes considerable power. Running at constant 98% or more, the camera becomes unstable. I've ensured the camera has ample power, I've even connected it to a regulated 12vdc 10amp source, same result.

[jase]

Also Richard....

What is your opinion of cooling and longevity of the CCD chamber seal? I'm aware many (telescope rental companies and education institutes) don't warm up the cameras during the day light hours as by doing so it apparently prolongs the longevity of the CCD chamber seal.

Fact or Fiction?

[gregbradley]

It is an interesting thread. I run my ML8300 either at -35C or -40C. There are a few hot nights in summer where it may struggle to achieve -40C but it always will reach -35C in less than 5 minutes.

The Proline I also run at -35C and it achieves that again almost all year round except for the odd really hot summer night which is not that common for me. I have run the Proline at -40C in winter but as mentioned there is no discernible difference and -40C isn't
achieveable all year round.

I noticed originally when I had an STL11 how much cleaner the image was when on those rare cold winter nights I could get it to go to -35C.
It certainly was the sweet spot for that particular camera.

Dark noise is never an issue with my images from these FLI cameras.
They are close to noise free but there is still some slight improvement from darks.

Jase I would be going for lower temps with your D09. It has powerful cooling.
The only thing that may get in your road is the firmware. It is designed to work out its
own setpoint. So you could tell it to go to -40C and it should but the firmware may kick in
if the % power is beyond its programmed setting (80%?? - ask Apogee what they set it to).

My U16M would do that occassionally which can upset an imaging run if you are not expecting it.
I suppose though it will happen in the first 35 minutes. That's when I asked it to achieve too high
a cooling number but my one was the standard cooling package not the D09. I never saw a voltage
warning either. But then the D09 no doubt draws a lot more power. Perhaps it is a firmware issue
rather than an actual voltage issue.

I had a vertical line which is common with 16803 chips develop about 2 months ago where there were none.
I have a particularly clean chip which was hand picked. Fresh darks got rid of it. Also these lines as Richard
pointed out fade with heavier cooling and are less of an issue. They used to drive me crazy with my STL11
as they sometimes would not dark subtract out with that camera for some odd reason. Perhaps I did something
wrong with the dark subtract.

Greg.

[Alchemy]

It would appear my camera doesn't have some of the features discussed.... Meh .... Can't have everything

.

That would seem to be the general consensus from those who've replied, I did a stretch on my darks and couldn't see anything out of the ordinary, so summer will be 20 and I might drop it when it cools, and do the dark library like jase every 3 months or so.

Whilst the uber tuning of things is possible, I'm not running a formula 1 machine so I won't get too upset by minor imperfections.

[ptc]

The dark lines are usually caused by a partially blocked column that results in a 'skim' or more properly, a deferred charge.

You did nothing wrong: unfortunately they will neither dark-subtract or flat field out. They usually are small so the best bet is combining deep cooling with a dithering of aiming between shots and a combining algorithm such as median or some other method that rejects "flyers"

the cooling will minimize the badness associated with these traps and the dithering and combine method will eliminate them from the final processed image.

[ptc]

I don't think there's a single answer that is true for all designs.

It really depends on how the camera and seal are made

I can say that leaving the sensor biased up 24/7 will increase the liklihood of random radiation damage.

The sensors are bombarded constantly by radiation. ]Under the right circumstances some of it can cause hole-electron pair generation in the gate oxide. This is very undesirable, but the damage can be self-repairing (annealing) under the right conditions.

when an energetic particle passes through the gate oxide and collides with atoms in it, it loses energy and that can create hole-electron pairs within the gate oxide. If these oppositely charged "particles" remain physically close to each other, there's a statistical probability that they will recombine, and if they do there's no lasting damage.

However the hole has very low mobility compared to the electron and what often happens is that the electron is swept away by an electric field (like if the sensor is under bias) and that leaves a hole trapped in the gate oxide. That causes a shift in the flatband voltage if enough of them are so trapped and that can cause the sensor's dark current to increase significantly in pixels so damaged.

Leaving the sensor under bias simply increases the probability that the recombination does not happen. So if you have two identical sensors sitting next to each other, one powered up and one not, the one that is powered up will age faster than the other one....

It is certainly possible to design a camera that can be cooled separately from powering up the electronics, so in theory it should be possible to leave one cooled down but not under bias, so as to minimize the risk, but none of the amateur Astrocams I have seen work that way.

the FLI ML and PL cameras have very good seals. Thermally cycling them seems to have no effect on the integrity of the seals.

I've heard that the reason Apogee takes a half hour to cool down is out of concern of the integrity of their seals. I haven't personally compared the design of the seals of the two brands to see how they differ. I suspect that the Apogee seal design is reasonably robust and using a half hour to cool down is being unnecessarily conservative from the perspective of chamber seal integrity.

Perhaps there's another reason for the long cool down like thermal runaway?
That's poked its ugly head up occasionally in certain camera designs in the past. One thing is certain; the fans aren't arranged in such a way to efficiently shed heat from the heatsink in the Uxxx designs: the fans' airflow stagnates at the bottom of the heatsink in the one I examined.

From a marketing perspective, it seems easier to swallow telling someone to accept slow thermal slews to keep the chamber seal good than to prevent thermal runaway....

claiming the former will tend to cast doubt on the operational integrity of your competitor versus the latter which reveals a design deficiency in your own product: two different ways to spin the same issue....

[ptc]

[QUOTE=Alchemy;773214]
That would seem to be the general consensus from those who've replied, I did a stretch on my darks and couldn't see anything out of the ordinary, so summer will be 20 and I might drop it when it cools, and do the dark library like jase every 3 months or so.
QUOTE]

keep in mind that groupthink is often wrongthink: witness "The earth is flat" belief from yesteryear.

the only way to know for sure is to measure the dark signal under the planned exposure conditions (exposure time and temperature) and compare to the read noise and background signal levels.... that of course is neglecting RBI

[ptc]

sounds like you have a problem with the design of the camera or power supply.

there's no good reason that a properly designed camera and or power supply cannot run at full load and behave properly.

what are you using Jase?

[jase]

You're right Greg, I should be pushing the camera harder. A set point of -40c all year round is certainly achievable with the D9F cooling, undoubtedly lower in winter. The voltage problem isn't firmware related. Apogee would have advised if it were given the camera came back from a routine service a few months ago. I suspect it is power related. The power supply I have is not Apogee certified, but a third party of similar output. The original fried a while ago. I think I'll place an order for another original to see if this alters the situation.

===

Richard,
Thanks a lot for your comprehensive input and opinion on the CCD chamber seals. Not doubted your knowledge as I know you work with these CCD's all day long, but there are a lot of hypothetical and probabilities as one could expect. Its so darn hard to get a clear statement from any manufacture on the topic...and I guess...who cares when they offer lifetime warranty on the chamber seal anyway. I think you nailed it in your opening two sentences, though I'm still intrigued to the logic and reasoning of others. I agree with your statement regarding a camera powered up will age faster. Though you can apply the same logic to owning a car. A car you leave in the garage will last longer than the one your drive around. I've had to replace a few fans, no different to tires on a car.



What is the reasoning manufacturers haven't done this? Manufacturers make the assumption that ALL users cool and turn off their camera each session?



Yes, I can understand that. You are obviously referring to the non-D9F configuration of the Uxxx designs. At least I hope you are, as you would also be implying the FLI PL isn't efficient. The Apogee D9F configuration is near identical as the FLI PL with the three fans blowing air through the heat sink. The only difference being the Apogee D9 has a larger heat sink than the FLI PL in both depth and width, but the heat sink/air flow design is fundamentally the same.



Power supply. See note above to Greg's response. I'll order an "official" replacement power supply from Apogee. What I've got works, but there is no way I could operate at 95% cooling power with the current supply. I pushed the camera last night and achieved 48C below ambient but MaximDL was reporting 10.9V UNDERVOLTAGE. I've got a lab report for the camera that indicates it was tested out as 62C below ambient so I'm assured its not the camera...time to get ordering.

[ptc]

yes the non-D9 Version... the D9 has adopted a non-stagnating configuration for the fan/heatsink as was a feature of the PL and ML from FLI from the get-go

As for your power supply issue: it is disappointing to spend a fortune on a camera to later discover they have a power supply that doesn't measure up to the task for which it was assigned. It may be that the better cooling offered by the D09 option uses more current than the original configuration and that they failed to account for that by shipping with the same old power supply.

It could be a simple oversight but it is nonetheless disappointing to spend that much money and get less than what you paid for.

For the record the FLI cameras have no such anomalies even at 100% power. They have no cooling headroom at 100% of course but they at least supply sufficient current and work correctly there.

Again I regularly operate mine at 95-97% power with no bad effects. For my 39Mpixel with its two output amplifiers, any sort of error in cooling will reveal the seam from the two sides... it is that sensitive to dark signal/dark cal frame mismatches.

[jase]

Thanks Richard.

Are you going to answer my previous questions or simply fly the FLI flag?

You sure are quick to make assumptions. Suggest you read the facts in future. The current power supply in use didn't even come from Apogee. You are welcome to still hold them erroneously accountable but whatever you do don't get disappointed, I'm certainly not! In fact I find it remarkable how resilient the camera is being able to drop 48C below on a bad power source (only 14C off lab benchmark of 62C below).

[Alchemy]

..

[originaltrilogy]

What is RBI?

[jase]

http://www.ptbmagazine.com/features/2009/feat1_0409.html

Courtesy of Richard himself.

[strongmanmike]

He he Richard is one of a kind :innocent:

Delta 62C huh? that's not bad :thumbsup:, my PL11002 could do that but not my PL16803 (bigger chip) - from a quick test on a summer afternoon last year it could only go 58C delta.

Mike

[avandonk]

I reckon I could use the frankenfridge to supply -15C liquid coolant to my PL16803. Lets see delta 58C plus -15C is -73C!
Bert

[DavidTrap]

Not sure if chilled liquid coolant is a good idea Bert. The manual for my camera repeatedly says not to use water cooled below below the dew point when using liquid cooling as the heat exchanger mounted on the camera will potentially drop below the dew point. This will lead to condensation on the camera which might fry the electronics.

DT

[ptc]

I'll second that.. chilled water must be used with great caution: otherwise the condensation resulting from it will indeed put the electronics at risk!

[ptc]

well glory be! I didn't know that was online!

here's a more recent publication, this time done through SPIE (Society of Photo Optical Engineers)

http://www.narrowbandimaging.com/incoming/033006_1_1314293318_1.pdf

the article was written in 2008 and for some reason the SPIE wizards lost it for three years. Better late than never I suppose....

Hey, sorry about missing your comment about the power supply. I had arrived in Korea yesterday after traveling about 22 hours from the US connecting through Taiwan. Sometimes I amaze myself as to what I fail to see when I am so jet-lagged!

anyway, point taken that you are using a different power supply versus what Apogee supplies with the camera.

[ptc]

I can only speculate... First of all I haven't seen any evidence that thermal cycling damages seals: I've heard claims made by Brown of Apogee, but that could be an excuse to avoid fixing a thermal runaway problem while at the same time casting doubt on the integrity of the designs of his competitors as I mentioned yesterday. Clearly the air cooled Uxxx series has an airflow stagnation problem as we discussed. That obviously makes heat removal from the heatsinks less efficient than the way the Proline does it and the way the D09 does it (that appears to have adopted the same method used by the Proline which did it that way several years before the D09 was introduced). One thing is certain, it is a lot easier to make up a cock and bull story than it is to:
1) redesign the fans/heatsinks, test and deploy (cost $$$$)
2) deal with angry customers that want the 'fixed' version for free (and rightly so....)

it is much easier to claim you are the only one doing it right and the other guys are not... so long as no one can prove you are lying, of course....

So this entire 'thermal cycling causes seal damage' theory may be a case of chasing phantoms. But true or not, it should not be a big deal to change the control circuitry/microcontroller firmware to let the cooler run without turning on the clocks and power to the sensor.

Knowing the way the FLI guys operate, if anyone would be willing to do a customization, they would. I suspect all would do it if they thought it would bring in more business... But I rather strongly suspect this entire thesis about seals is a red herring. I'll go on record saying that I don't buy it and I have used lots of fancy cameras with big sensors over the years, and simply flip the switch off when I am finished: no damage...

I am currently overseas on biz but I have some reference material about the issue with ionizing radation/recombination for biased versus non-biased sensor storage that I should be able to make available. That is most definitely NOT a red herring.... however it will be about two weeks before I am home again and have access to my library :P

It would be a shame to see these observatory fellows damaging their sensors from radiation damage (leaving powered up) in order to avoid a suspected chamber seal hermeticity problem that really is a non-existent problem and was simply spin put forth by a cynical vendor that wants to avoid being held accountable for fixing what clearly is a demonstrable weakness in the cooling system mechanical design.

you can say what you want but Apogee's cooling behavior is singular in the industry and since I haven't seen a pile of trashed cameras sporting damaged seals or cracked sensors (their earlier party line position that they have since abandoned) from thermal cycling, I dare say there's more evidence piling up against the Apogee party line being true than evidence in support of it....

:lol:

[jase]

Thanks Richard. No apologies needed, in fact since you're in the region if you make it to Singapore over the next couple of days I'll buy you a beer or two, or more.

I would like to clarify that the CCD chamber seal discussion on cycled cooling was not only applicable to Apogee cameras as you indirectly imply, but ALL camera manufacturers. Your response was precisely what I wanted to hear regarding the CCD chamber seals. Thanks. No need for a warm up period either - great. I would be most interested in reading your supporting materials on random radiation damage be it permanent or temporary, along with the likelihood. Feel free to post the link here or private message me offline once you've got access to your library. Appreciate your input.

[avandonk]

I was just joking folks. Why mess with something built by experts.

It seems to be that a good guiding principle is to go a low as practicable.

I have been following this thread with interest as I have yet to use a cooled CCD astro camera.

My frankenfridge for the Canon 5DH never had a problem with condensation as the camera and sensor were the hottest objects in the fridge.

Bert

[ptc]

Hey I am happy to help if I can but I also have pretty strong positions I take, mainly because I've either been there and done that or I just happen to know the material from my many years as a semiconductor design engineer (35 years in the biz). But I will always give reasons why I say what I do rather than just say "because I say so" or "I heard that blah blah is true". My world is a world of truth and facts and not much grey (except patents, and that is an entirely different topic)...

On chamber seals: the reason I singled out Apogee is because Wayne Brown, the owner, has gone on the record stating that :
1) they take a half hour to cool down to prevent damaging the sensor, claiming that the 5-7 minute slew everyone else does constitutes a military "destructive test" which is just utter nonsense. Mil Standard 883C clearly states the temperature slews for thermal shock (destructive testing) take less than 10 seconds to go from -40C to +125C. Of course most people that read that poppycock from him would have no knowledge of Mil Standard 883C, but I do.
2) backed off on the damaged sensor claim when confronted with the facts that there is not a pile of damaged sensors accumulating from all vendors but Apogee and that certainly creates a mountain of evidence to refute his statement. So the position morphed into a chamber seal issue. Of course there's still no mountain of failed camera chamber seals piling up so that statement seems unsupportable by fact.

So the third possibility is the thermal runaway issue, which is where I'd lay my money were I a betting man. Seeing how the air cooled one has stagnating airflow in the heatsink and with four puny little fans, it looks to me like they can add heat to the sink faster than they can shed it.... that translates to thermal runaway in that situation.

The simple workaround is to limit the power going to the TEC to prevent that situation from arising. The U8300 I tested never showed the power level higher than 37% during the cool down when I tested it and if that percentage is honest, then that sure looks to me that they have intentionally limited the power being applied to the TEC.

The early STL11Ks had a propensity to have that thermal runaway problem under some conditions so it isn't like this is unprecendented. To SBIG's credit they fixed them including the ones that had been sold before they figured out that they had a problem.

In my opinion Apogee if my suspicion is true, is taking both a lazy and sleazy way out by making up a cock and bull story designed to deflect criticsm from the believers and at the same time cast a rock at their competitor by creating FUD that there's a long term reliability problem lurking in the bushes in all cameras that aren't made by Apogee.

Well it ain't so on the reliability problem as evidenced by tens of thousands of user-hours and no failed seals.... so where are they Wayne? Furthermore why is the same damn seal suddenly reliable when you pay $2000 extra for the D09 cooling option? I smell a rat, how about you?

It really chaps my tail end to see people on the supply side exploiting the trust and ignorance of their customers who largely not technical and simply believe what they are told. Unfortunately unless people speak up when they smell the wet, warm and brown being cast about, it will never stop. I do speak up and encourage others to as well. We all win when we are dealing with honest brokers rather than someone ready to pull a fast one on you. When people call them on the carpet when they are lying and it happens again and again, it will stop or they will lose their customers trust and eventually the customers too.

Regarding S'pore: I seldom get down there but there's a technical conference that is held there annually for which I may submit a paper next year. I missed the Call for Papers this year so I am not on the agenda.

However when I head that way I will certainly rattle your cage ahead of time as I would really enjoy meeting you and all the rest of the participants on this forum face to face sometime... I've met Gordon Haynes (UK) and Antonio Rosalino (PT) in my travels and nearly got to meet Kitajima-san (JP) this past spring but the Fukushima Daiichi disaster stopped me from going to Nara to present an accepted paper at the International Conference on Electronic Packaging held in April of this year. I just had to abort the trip out of big concerns for food/water safety.

Just to show you folks that I'm not feeding you a line about what I do I call your attention to this recent news release (this is why I am in Korea)

http://finance.yahoo.com/news/Invensas-Corporation-to-bw-2844195365.html?x=0&.v=1

[Bassnut]

At risk perhaps,but I have often liquid cooled my st10xme with iced water till it was dripping weT in hi humidity without a problem at all.

[ptc]

That is asking for trouble and here's why. When the PCB gets wet the solder on all those surface mount chips can get wet and if it does, it can and will cause dendrite growth. Those are little "whiskers" that grow like spikes from the solder. Eventually they end up shorting solder balls or traces together.....

http://www.narrowbandimaging.com/incoming/creep-corrosion.jpg


The failure can happen rapidly in the presence of ionic contaminants or it can take some time but eventually that's the failure mode. so your camera may work OK now but eventually it will fail. I have seen three ST10XMEs that first had the -X guider output fail due to this dendrite growth. One was mine and it happened because I too had been using chilled water and my camera got soaking wet twice. Mine failed about 6 months later. Another happened to a fellow that lives on the Florida Gulf Coast and is in a very humid environment and dew condensed on the camera (he lives near salt water in a humid environment but he was not using water). He was advised by SBIG to open it up occasionally and use a toothbrush to scrub the PCB

Another failed for a fellow in Tennessee that was in a very humid scenario using chilled water

One thing that can be done is for the manufacturers to use conformal coatings on the PCBs once they are assembled. That is how marine electronics such as VHF radios and Radar systems are made robust.

I've been complaining that none of the makers do that. For the money we spend on this stuff, they could afford a few bucks to conformally coat the PCBs but no one does....

the Proline cameras have the electronics protected from the elements. That's a good thing. The Microline does not have environmentally protected electronics.

Obviously the ST10 does not either. Not sure about other brands

The use of fine pitch surface mount components and ball grid arrays only aggravates the problem. Unfortunately my industry has switched nearly exclusively to such packaging technology. People want tiny Iphones and notebook PCs so miniaturized components is the way it is done.

The area array BGAs (ball grid arrays) are particularly bad because all of the solder connections are below the chip's package and cannot be visually inspected.... you can use underfill to prevent moisture from getting in but that makes rework difficult

here's a nice reference that speaks to many other failure modes including what I just described

http://www.narrowbandimaging.com/incoming/about_AMI__Read-Only__01.pdf

look at page 7 for the moisture induced dendrites. Simply getting the PCB wet can cause growth but do so with power applied and you have it accelerated

At the end of the day you are better off buying a camera that is designed to cool well. SBIGs and QSIs do not have that property.

[Bassnut]

Yes, I understand and agree with what you say. I am asking for trouble in the long term. Seems daft to me sbig don't conformal coat, it's not hard or expensive. I might even do it myself (after a scrubbing)

[alpal]

What was the result of this thread?

I have a QHY9 camera & I have run it quite a few times at -31 & once at -34 degrees.
I have been told that there is a risk of eventually cracking the KAF 8300 sensor.
Apparently the lowest you should go is -20 degrees & you should
go to that temperature slowly & also allow the chip
to warm up at the end of the imaging session - slowly.

Has anyone ever cracked their sensor chip by running it all the time at the coldest temperatures?

[allan gould]

Exactly my experience with the same camera. 90 percent of the time I run at -20C and in summer -15C usually with 5 or 10 min subs.

[alpal]

Hi Allan,
Does this mean that you're scared to take it colder?

[nobbygon]

My qhy9 ccd chip cracked the 4-5th time I used it. Catch you later $400. It was being cooled to -25C. I had maxim using the warm up feature but that still didn't help. I was told later that the kaf8300 chip should not be cooled below -10 as it dramatically increases the chance of cracking.

I don't understand how people get to -62 and don't have their chips explode.

[alpal]

Thanks for the heads up.
I won't cool mine to the maximum anymore.

[troypiggo]

Did you just put your hand up to present one at next year's AAIC? :)

Bolts? Omaroo? Reading this? :)