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Old 21-10-2019, 07:13 PM
RyanJones
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What Have I Done ????

Hi All,

I thought I'd start up a new thread rather than dragging out my old thread on my cooling project because I've created a monster problem and I need some advice.

I have been waiting for a better heatsink and a thermostat to arrive for my DSLR Peltier cooling project and they did last week so the weekend was time to finish construction and do some testing. The Cold finger worked better than I ever thought it would being able to maintain a stable temp of 0 Degrees in a 20 Degree ambient room. After a bit of fiddling I set it to 3 Degrees and started taking darks to look at the noise. This is where the problems began......

The plan was to take 10 darks @ 3 Degrees then 10 @ ambient and compare them. 8 subs in and the camera froze. I don't mean icy, it became unresponsive, not even to the on/off switch ( and it was on ! ) so I removed the power and let it warm up for a few minutes. It fired back up and started working again so I left it for 1/2hr or so to get to true ambient. Figuring I'd just gone too cold with the finger, I set about taking my ambient darks. 10 subs in and no problems......but....... I then went to take a normal image and I got Err 99 on the camera. I'll save you the investigation but essentially at some point my shutter has jammed/become unresponsive. More fiddling etc. etc. I figure I've killed the camera. Upsetting to say the least but I have another Identical camera so I just have to spectrum modify it and ill be back in business. But then I looked at the darks.......

Below are 2 x 100% crops of my darks. First is with the cooler on, 2nd with it off ! What the hell ????? A screen full of Blue hot pixels ? Clearly I've caused this with the finger but how ? The second ambient sub shows my fairly normal noise pattern although there is a significant pattern of blue hot pixels in the full image ( not pictured ) coming from the bottom of the sensor that diminished the more ambient subs I took. This one being the best of the set.

As I said, I'm not happy that I've killed a camera but I do have a solution but I don't want to pull the new camera apart twice so I need to know what the likely cause of this issue is so I can either rectify it and fit the cooler or not fit it at all.

Any help is greatly appreciated.

Cheers

Ryan
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Old 21-10-2019, 07:31 PM
RyanJones
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So it seems when I converted it to JPEG it clears the blue hot pixels so I took a screen shot to show what it looks like.
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Old 21-10-2019, 09:39 PM
glend (Glen)
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ERR99 is a general fault code. Likely you had internal condensation causing a problem. In the past I have managed to clear Err99 by powering down, removing battery, and restarting but it doesn't always work.as far as your jammed shutter is concerned, it might clear after power down but have a look into the camera to see if it is held open.. There is a way to cycle the shutter, but you need to trip the shutter actuator and for that you have to disassemble to get to the actuator arm and spring. The shutter maybe ok if you can release it.

I used to keep a spare 450D shutter on hand, they can be bought online, sometimes from Canon parts shops in the US, about $80, or you can get salvaged ones from China sold by camera strippers on Aliexpress for about $40.
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Old 22-10-2019, 12:00 PM
RyanJones
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Thank you for your suggestions Glenn. I did power down several times but to no avail. I was thinking the likely cause was going to be inadequate moisture control so that is something to consider. As I said though, my concern is more about the Blue hot pixels it produced when it cooled. Are we thinking this is a moisture issue too and if so, why only blue pixels ?
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Old 22-10-2019, 11:31 PM
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You definitely went too cold. At 20C and 50% humidity the dew point is about 9C (see this calculator for example). If you cool below the dew point you get condensation. Basically you ended up with water inside your camera.

1. Let the camera dry thoroughly. Put it in a non-dusty place with the lens off (and no lens-cap) so it can dry faster. Without battery. Use desiccant (or rice) next to it to absorb moisture faster.

2. Never cool below the dew point or you will get condensation.

3. All commercial cameras are sealed and filled with argon or some other gas. When we were playing with the cold-finger cooled 450Ds the best idea for the deep cooling was to seal the camera in a plastic bag with desiccant and to fill the bag with argon gas (you can get the gas from Bunnings, the regulator came from eBay). Seal the bag as well as you can. I remember having -5C at the back of the sensor without issues. The main thing was keeping the camera dry. There were always leaks but usually I could get 2 nights before needing to refill the argon.

Hope this helps.
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Old 23-10-2019, 07:26 AM
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Thank you Luka for that detailed run down. I really appreciate it. From your signature and what youve written you sound like youre the man to talk to about this.

Re: The gas filled bag. I can get argon from work because its what we use as a shielding gas for welding so if I decided to go to that extreme I could.

That solves the probable cause for the camera shut down. Do you think that it was moisture on the circuits/sensor that caused the blue hot pixel mess too ? If so that brings me quite a bit of comfort knowing that I just need to address the moisture issue. Yes Im aware its not as simple as I just made it sound lol.

Thank you again for your advice.

Ryan
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Old 23-10-2019, 10:44 AM
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Firstly to give credit where it is due, the argon-filled bag was actually Glen's idea. A while ago few of us modified 450D to use cold finger straight on the back of the sensor (450D was best suitable for that). Glen was one of the pioneers.

Do not think that the argon filled bag is easy. They are impossible to seal properly and always need refilling.

Regarding the blue pixel mess, I can think of two things:
1. The condensation on the circuit board can cause shorts and can cause electronics damage or camera crashing. This is my guess what happened.
2. Thermal contraction/expansion - don't let the camera cool down/warm up too fast.
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Old 23-10-2019, 12:28 PM
RyanJones
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Quote:
Originally Posted by luka View Post
Firstly to give credit where it is due, the argon-filled bag was actually Glen's idea. A while ago few of us modified 450D to use cold finger straight on the back of the sensor (450D was best suitable for that). Glen was one of the pioneers.

Do not think that the argon filled bag is easy. They are impossible to seal properly and always need refilling.

Regarding the blue pixel mess, I can think of two things:
1. The condensation on the circuit board can cause shorts and can cause electronics damage or camera crashing. This is my guess what happened.
2. Thermal contraction/expansion - don't let the camera cool down/warm up too fast.
Thank you to both glen and yourself for your insights. As much as I can see how the argon filling would work and how impressed I am of the lengths that you guys went to in your experimentation, I dont think its an avenue I will attempt as I can understand how hard it would be to achieve.

What I think I will do though is attempt to reduce moisture as much as possible starting first with setting my cold finger above the dew point referencing from the link you sent me.

Thank you both again for your help. I really appreciate it.

Ryan
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Old 23-10-2019, 04:12 PM
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So is the camera still alive Ryan?
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Old 23-10-2019, 06:33 PM
RyanJones
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Originally Posted by ChrisV View Post
So is the camera still alive Ryan?
Sadly I think I’ve killed this one so no. At least to the point where starting fresh on my other 350d would be a better way to spend my time. I think part of my pain in killing this one is because I was practically gifted it by Glen Burgess ( IIS member ) and his help getting me into the modified camera scene was instrumental in the step I took and I’ve gone and killed his camera
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Old 23-10-2019, 07:08 PM
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Ryan I am sad to here about your set back...
For your next one would it help to house the camera in a box, balsa would be good, and put some desiccant in there?
Alex
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Old 23-10-2019, 08:18 PM
RyanJones
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Originally Posted by xelasnave View Post
Ryan I am sad to here about your set back...
For your next one would it help to house the camera in a box, balsa would be good, and put some desiccant in there?
Alex
Hi Alex,

Before deciding to go down the cold finger avenue I did contemplate the cool box solution but I decided not to for several reasons including its bulkiness. In light of what happened it may have been a safer direction. Id like to try and get my cold finger working in its current guise. Now I know where Ive gone wrong and the issues I need to address Id like to persevere with it. This still may turn out to be beyond my limited talents but Id like to try. A significant part of what I enjoy about this hobby is solving the challenges it presents us.

Cheers

Ryan
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