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Old 28-09-2009, 10:04 PM
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40D Banding Issue

Ive found that my modified 40D has a banding effect in processed images, and reviewing a bias frame at ISO800 banding is present and I have no idea why nor how to rid this from my images.

Has anyone suffered from this and been able to remove it ?

Heres a bias frame at ISO800 at 1/8000, cropped and levels adjusted to show the banding effect.
Taken with Nebulosity
Second with Canon EOS Utility; both slightly processed, cropped in PS to show the banding effect
Attached Thumbnails
Click for full-size image (banding.jpg)
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Click for full-size image (banding2.jpg)
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Last edited by leinad; 28-09-2009 at 10:15 PM.
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Old 29-09-2009, 05:33 AM
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I'm finding similar with my 30D and 40D. Haven't had time to get to the bottom of it yet, but will be soon testing to find the source. My list of likely culprits includes using mains power supply and AC adapter instead of the camera battery, and pulse width modulated dew controller leads causing some sort of interference.
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Old 29-09-2009, 11:17 AM
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Quote:
Originally Posted by troypiggo View Post
I'm finding similar with my 30D and 40D. Haven't had time to get to the bottom of it yet, but will be soon testing to find the source. My list of likely culprits includes using mains power supply and AC adapter instead of the camera battery, and pulse width modulated dew controller leads causing some sort of interference.
Hi Troy,

These were taken using mini-usb to usb cable straight to laptop.
Banding is present using camera battery and DC-AC adaptor.

Banding is less obvious when taking an image through EOS utility.

My understanding is this banding is present through a wide range of Canon cameras; but how to get rid of it in the 'lights' ?

help!..
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Old 29-09-2009, 12:39 PM
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Any others conquered this banding problem?
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Old 29-09-2009, 01:00 PM
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Take a series of of bias frames and if they are relatively the same it is normal sensor bias. If there is a major difference it is EM interference.

How you get rid of bias etc.

Take flats and darks at the same exposure and temperature as your flats

Take darks at the same temperature as your lights.

Take bias frames as well if you need to remove noise from your lights with darks at a different temperatures.

Here is a single exposure at 1min at f/5 at 300mm with 1600 ISO corrected for darks and flats and stretched. 1.3MB

http://d1355990.i49.quadrahosting.co...T_IMG_0056.jpg





Here is a good start

http://www.saratogaskies.com/article...ook/index.html


Bert

Last edited by avandonk; 29-09-2009 at 01:51 PM.
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Old 29-09-2009, 01:59 PM
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Quote:
Originally Posted by avandonk View Post
Take a series of of bias frames and if they are relatively the same it is normal sensor bias. If there is a major difference it is EM interference.

How you get rid of bias etc.
Take flats and darks at the same exposure and temperature as your flats
Take darks at the same temperature as your lights.
Take bias frames as well if you need to remove noise from your lights with darks at a different temperatures.
Here is a single exposure at 1min at f/5 at 300mm with 1600 ISO corrected for darks and flats and stretched. 1.3MB

http://d1355990.i49.quadrahosting.co...T_IMG_0056.jpg

Here is a good start
http://www.saratogaskies.com/article...ook/index.html

Bert

Thanks Bert.

I took a series of Bias frames and they all have the same noise pattern effect. I have the camera away from any power leads, plugged directly to laptop with usb cable.

I did process the lights with x2 darks and offsets but the pattern noise is still present when overprocessing.

Thanks for the article link, I'll have a read later this evening. http://www.iceinspace.com.au/forum/....s/thumbsup.gif

Do you have another sample of that images without flats and stretched that shows pattern noise ?
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Old 29-09-2009, 04:12 PM
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Quote:
I have the camera away from any power leads, plugged directly to laptop with usb cable.
Try taking your bias frames without the camera connected to the laptop.

Might also be worth checking Canon's site to see if there are any firmware updates, banding has been an issue addressed in firmware for some EOS DSLR's.
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Old 29-09-2009, 04:22 PM
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Quote:
Originally Posted by acropolite View Post
Try taking your bias frames without the camera connected to the laptop.

Might also be worth checking Canon's site to see if there are any firmware updates, banding has been an issue addressed in firmware for some EOS DSLR's.
I updated the firmware last night to v1.1.10
No change of banding noticeable.

I'll try taking an image tonight directly to CF Card.
Can you take remote images however using Nebulosity and save the images on the CF Card instead of the laptop ?
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Old 29-09-2009, 07:54 PM
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Attached is a bias at 1/8000 @ ISO800 from camera standalone to CFcard then downloaded and curves/levels, crop adjusted.

Noise pattern is still present.
Attached Thumbnails
Click for full-size image (banding2-cfcard.jpg)
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Old 29-09-2009, 10:37 PM
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Waxing_Gibbous (Peter)
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Its an annoying trait of some Nikons too. May have something to do with the sensors (both co's use Sony)
This artifact, when it occurs, is particularly noticable at high ISO numbers and dark backgrounds. All sorts of theories abound. Try over on www.fredmiranda.com. earch for "banding" & "EOS 40D".
If its still under warranty send it back to Canon for a tune-up.
Good luck.
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Old 29-09-2009, 11:00 PM
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Daniel,

There is an option in Nebulosity 2, in the preferences, somewhere, which allows you to save in the native CR2 format on the card, as well as slurp the FITS files to the PC.

Peter, are you sure about Canon using Sony sensors? I was under the impression that they either made their own, or used an un-named supplier for their sensors. At least that's my understanding from reading DP Review.

Regards,
Humayun
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Old 29-09-2009, 11:23 PM
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Researching some more tonight, the annoying line noise occurs at ISO800 or higher even with High ISO NR, etc On.
At ISO400 I don't notice it. Whether it be 1/8000 or 1sec exposure.
With the higher gain of ~x4 of the 40D over the 400D/350D, Ive read that a 40D shot at ISO100 is equivalent to the latter at ISO400 at same exp times.

I'm going to try ISO400 10min next time, instead of ISO800 5mins.

Need to make a lightbox this week so I can apply a proper processing routine. Just need to decide how to build the box for my needs.
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Old 29-09-2009, 11:52 PM
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I'll continue to argue my case for ISO-400.

Regards,
Humayun
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Old 30-09-2009, 06:42 PM
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Octane,
I believe Sony are still supplying both Nikon and Canon and who knows who else. Thay are the largest manufacturer of CCD/CMOS sensors.
They may be built to a spec. but it was my impression that the main diff. was in the processing algorythms propriatory to each company.
Commercial relationships of this sort are notoriously well camoflaged but... who knows?
Anyway, 2nd your ISO 400. Much easier to remove noise.
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Old 30-09-2009, 06:58 PM
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My 2 cents.. :

Banding has nothing to do with sensor and/or firmware.
It is a low frequency noise, generated in camera circuits, and it is more or less random.
The only remedy is stacking (which averages noise , LF or HF).
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Old 30-09-2009, 07:48 PM
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Just been over to dpreview and fredmiranda. The upshot is: nobody knows!!!!
Bojan: your theory is sound except that in many, but not all, cases banding shows up in the same spots every time. Roughly in order of acceptance by those on these forums:
Theory A) "Something" to do with the way the firmware scans/processes the image.
TheoryB) Masked pixels being read onto the image.
TheoryC) RF interference
Theory D) Quality control. These are mass produced cameras and as such thre's bound to be some variance.
Thery E) Some combination of the above
In any case the banding in your shots is quite exceptional. If it's still under warranty, send it back alon wit prints and full EXIF details to Canon.
Good luck!
Peter
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Old 30-09-2009, 08:42 PM
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Banding in the same places is also consistent with my theory.
If a noise is generated by processor (and gets somehow into analogue circuitry), it has to be in sync with line/frame reading.
It is possible to get rid of it by careful design, but then those cameras would have been much more expensive (and astro cameras actually are..)
Remember, all those DSLR's are NOT astro cameras. In normal, everyday photography, in most cases banding is not obvious, and when it becomes obvious, then it is caused by faulty component (power supply filtering for example or something similar).
So, yes, I agree with Peter, this camera is most probably faulty and needs repair.
My 400D also shows banding, but on individual shots only, and only when images are stretched to the extreme. Stacking removes the problem completely.
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Old 30-09-2009, 09:59 PM
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Damn laptop! dont you hate it when you write a lengthy post and the browser crashes

I don't think it's a fault issue tha can be corrected. Chances of a another camera with/without the issue is a game of dice according to posts on the web.

Without a light box as yet I can't stack correctly to attempt removing this banding.

Thanks everyone for your feedback, I'll post more on my tests later.
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