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strutsinaction

QSI690 - white lines in darks

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Hi

I took delivery of a QSI690 WSG-8 last week and have just started playing with it (inside, I might add). The drivers that came with the camera installed fine and SGPro can connect and capture images (albeit on my desk with the cover in place).

So, I've taken a few darks just to get used to SGPro and the camera but on close inspection of the images (images viewed at 100%) I see a white line that runs vertically from (650,1729) to (650,2690). I can see this line in SGPro (with autostretch on) and also in FITS Liberator.

Here's a crop showing the line: 

QSI690 Dark 120s

So, I'm guessing that this is not normal and the camera need to be returned to IKI. What do you think?
Regards
John

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Looks like a column defect that should be sorted by a bet of bias.

Edited by swag72

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Some "defects" are deemed acceptable by manufacturers.

BTW, IKI is on holiday till next Thursday.

Dave

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I had a column defect on brand new QHY5-II. I queried it but was told that the manufacturer viewed it as acceptable/normal.

I wasn't particularly bothered as it was a £130 camera, the defect is removed with a dark frame and it's only used for guiding.

But a 3 grand imaging camera is a different matter....

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Hi John

I have a similar column defect on my Atik 460ex and has Sara has rightly pointed out it can be processed out using bias frame calibration.

Steve

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Thanks for the comments/advice, folks!

I had a look on the technical support knowledge base on the QSI website and saw the following which agrees with you:

Q: I see bright or dark columns in my uncalibrated images. Is that normal?

A: Columns with average values brighter or darker than the background are common on CCDs and completely normal.  While the effect is very visible on stretched bias or dark frames, the columns are typically only a few hundred ADUs above the background values and will calibrate out completely with standard calibration techniques. The bright columns typically start at a "trap," a bright pixel with some charge that gets "trapped."  A small amount of that trapped charge gets transferred into adjacent pixels as the image is shifted out of the CCD producing the bright column.  The magnitude of the charge that gets redistributed down the bright column is entirely predictable at any given temperature and exposure length.  This is why the effect is removed by standard calibration techniques.
I'll contact IKI next week for his thoughts too but I no longer think this is a defect.
Regards
John

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As you lower your cooling, it should go away. My 314+l does the same thing until it gets to about 5c. Then it goes away.

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Hi SkyGibbon

My darks and the bias frames were taken at -5C and -10C. I guess I could go lower and see what happens.

Regards

John

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I'd rather not have them on my CCD sensors but they are a fact of life and completely resolvable as already mentioned. I gave myself a horrendous shock when I first took delivery of my QSI 683 (total coincidence that this was also a QSI I can re-assure you!) when I tested it in my lounge soon after delivery - hot pixels, apparently bad columns, I nearly cried but my later laughter at my own foolishness made the rest of the day sooo sweet ........... as I have a KAF 8300 sensor in mine, I find it helps to remember to put the cooler on ......Doh!

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Steve

Just goes to prove that even the experts get it wrong sometimes  :smiley:

I contacted QSI for their view. Like you and others have said, just 'a fact of life' but they have asked me to send a bias frame taken at -20C just to check.

I did ask them about Class 1 and Class 2 sensors since I had read on their website that Class 2 should not suffer from any column defects. They said this only applied to Kodak sensors not Sony. Everyday's a school day!

Regards

John

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QSI's response after examining my bias frame:

That effect is not a column defect. It is the result of a single pixel with slightly higher dark current that leaves a trail as the column is read out. It is not uncommon with Sony sensors and CCDs in general. This behavior is completely within Sony's specifications.

I can live with that.

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My QSI583 has exactly the same thing :) I was concerned too but it is removed with calibration frames.

Enjoy the new camera

Phil

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I have a bright column on one camera but I just dial it's number in to the column repair in Astro Art when I stack - and it vanishes.

Olly

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