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Old 13-10-2014, 12:06 PM
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Ongoing issue with Atik 11000

Dear all,

further to my previous call for help, all is not well in the state of Denmark.

It would seem, for whatever reason, my beloved Atik 11000 is doing something funny.

It appears to be collecting and storing photons even when it is not taking an image...

To explain...

If I remove the sensor cover and expose the sensor to light, and then cover the sensor and take a "dark" frame, the shot comes out completely saturated. The next "dark" comes out fine.

I have done a lot of experimentation with this and am confident that this is what is going on. The thing is, it does it on 2 separate computers. So I am thinking that it is not a software problem. Or is it? Will uninstalling and then re-installing the software make a difference?

Bintel is doing a sterling job in their discussions with Atik, but I am an impatient bugger. Has anyone heard of this type of issue before and if so what is the fix?

Cheers,

DJ Scotty
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Old 13-10-2014, 12:12 PM
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These do not have RBI flood?

The FLI's have an RBI function to remove residual "burn in" between subs - I enable it all the time,and it only adds a few seconds to the exposure while it deals with it.

You can read about it here: http://gxccd.com/art?id=418&lang=409

I thought the high-end AtiK's had the RBI flood feature? Have a look through the extended menu - enable it on install to access additional featureslike the window heater etc.
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Old 13-10-2014, 12:25 PM
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Shiraz (Ray)
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From what I read, the 11002 is an interline chip and does not suffer from Residual Bulk Image, so RBI flooding is not needed. I guess that, if the chip is vastly overexposed, there could possibly be trapped carriers that need to be cleared by a read. If the camera works OK on following frames, do a quick read before exposing frames that you want.
ref: http://gxccd.com/art?id=418&lang=409

Last edited by Shiraz; 13-10-2014 at 01:33 PM.
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Old 13-10-2014, 12:33 PM
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Ok.

The trouble is, it has only started doing it last week. I have had it for a couple of months now.

And the resulting images look nothing like the RBI in the links provided, but more like those attached. Very severe bleed...

It seems to coincide with the attempted removal of the user-replacable desiccant chamber
Attached Thumbnails
Click for full-size image (Sensor shot1.jpg)
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Old 13-10-2014, 01:41 PM
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Shiraz (Ray)
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Originally Posted by DJScotty View Post
Ok.

The trouble is, it has only started doing it last week. I have had it for a couple of months now.

And the resulting images look nothing like the RBI in the links provided, but more like those attached. Very severe bleed...

It seems to coincide with the attempted removal of the user-replacable desiccant chamber
then I would guess that you have light leakage from the vicinity of the dessicant chamber. The manual says nothing about the dessicant - what did you have to do to replace it? Have you tried doing some testing in a darkened room to see if the effect changes with ambient light levels? Just to be clear, if you get an image like that attached on the first read, you get good images thereafter?

Another remote possibility is that the contact between the chip and the cooler has been disturbed, resulting in one side of the chip being warm.

Last edited by Shiraz; 13-10-2014 at 03:17 PM.
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Old 13-10-2014, 03:07 PM
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Hmmmmm, where do I start with this...

On Saturday , I did my experimentation.

I have taken darks in full light and at night in very dark conditions and of varying lengths, ie 2 sec, 5 minutes, 15 minutes and 30 minutes. All consistently saturated if exposed to light before taking the dark, but the second or third dark was fine.

The duration and intensity of the light source affected the overall saturation of the image. For example, with no filter and a Compact Fluorescent Lamp (CFL) turned on (ie very bright conditions) it was fully saturated across the whole sensor. With my Oxygen filter in and a very brief flash of the CFL, it was about 30000 ADU. I also partially exposed the sensor to bright light and got a roundish pattern with dark bits at the bottom corners which corresponded to the round sensor cover.

That photo attached before was a 30 minute exposure of the eagle through an Oxygen filter. There is an old fluro in the kitchen about 5m from the scope that caused that bleeding. (I looked up the spectograph thingy of old fluros and they seem to emit very strongly in Red wavelengths) Originally, I thought it was the Oxygen filter because over the past couple of weeks, I have used the Ha filter with no such effect. However, last night I used the Ha filter again and got a similar pattern. However, later on in the night, I took a 30 minute sub of the Horsehead with no issue whatsoever... And that was pointing towards the waning gibbous moon and a streetlight across the road. However, the fluro in the kitchen was off... So I am certain that the fluro is causing that issue.

There doesn't seem to be any light leakage.

The problem is that the sensor is registering light when the electronic shutter is supposed to be closed. It's almost as if the pixels are never turned off. And this is consistent across both my laptop, which I use in the field (and in the backyard) and my main tower which I use to take darks on.

Now, I know very little about the internal workings of this camera. When it says "electronic shutter", does that mean a physical thing or is it a "digital" thing that stops the pixels detecting photons...

And yes, the funny pattern only hangs around for the first image.

In regards to the desiccant chamber, I tried to remove it to bake it in the oven as I was getting fogging on the glass of the camera when imaging at -15 degrees. It has been very humid up here in Brisbane recently. I used a flat screwdriver . It came partially out and then stuck. The screwdriver then proceeded to take great gouges out of the slot. So I screwed it back in and left it.

So,

Cheers,

DJ Scotty
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Old 13-10-2014, 05:16 PM
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Bassnut (Fred)
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Quote:
Originally Posted by DJScotty View Post

If I remove the sensor cover and expose the sensor to light,
Cheers,

DJ Scotty
Carefull when your in panic mode. Exposing in a lit room with any astro cam produces this kind of image, did for me, just sayin .
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Old 13-10-2014, 06:00 PM
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He He

Quoting someone out of context to make them look like they said something dumb! Do you work for a reality TV show Fred

Nice work!
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Old 13-10-2014, 06:53 PM
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I'm not sure about this camera but I did notice that several other brands of camera using this CCD include a mechanical shutter. Perhaps the shutter is not closing properly on the first command. This would expose the CCD to light during a dark. The second command might complete the closure and all looks good. I had a bit of the same problem a while back with my Moravian G2-8300. The shutter was binding on a wire that came unglued. I saw the issue in lights. Sometimes it worked OK, sometimes not.

Peter
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Old 13-10-2014, 07:10 PM
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Thanks for the reply Peter. From what understand this camera does not have a mechanical shutter

hhers
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Old 13-10-2014, 09:48 PM
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Ok... Problem solved

I think Fred you were on to something... If you shine a bright enough light into a sensor for long enough, it is bound to be affected in some way. What I was doing, shining a CFL into the sensor for 5 seconds is an extreme thing to do in regards to light exposure. Is it any wonder the sensor was collecting light when it wasn't supposed to be

Under normal circumstances, you won't experience these sorts of conditions.

I left the camera in a semi dark spot with the sensor exposed for 5 minutes. Then covered the sensor, took a 2 second dark, no problems.

Even a 2 minute light sub right next to the computer monitor I am using right now didn't really show up that much.

So the bottom line here is, I have to be really careful that the fluro in the kitchen remains off when imaging, and, I worry too much...

Cheers everyone.

DJ Scotty
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Old 15-10-2014, 08:11 PM
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Hi everyone...

I was wrong.

I am going to throw my theory out to everyone to see what you think.

Last night, I imaged at 1 degree C and the problems returned.

Tonight, I dropped the sensor temp back down to my standard -15 degrees C. The problems disappeared.

So, from this, my conclusion is that the temperature of the sensor is causing the issue.

Does that sound right?

Thanks for your help.

DJ Scotty
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Old 23-10-2014, 05:22 PM
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You may want to see if there's any moisture build up or discoloration around the CCD's sensors pins. This sometimes occurs, and needs to be cleaned properly. Which may explain why at high cooling temps, the problems gone, but at lower, it occurs.
Just use a old toothbrush, and some isopropanol to clean the pins around the CCD. Be careful there's no temp sensor, or other delicate wires around the sensor.
Use a hair dryer, or portable heater to dry out the chamber before sealing it again.

Theo.
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