20D: HORRIBLE BANDING CAUSED BY FLASH

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Archive 2004 · 20D: HORRIBLE BANDING CAUSED BY FLASH

Softechie
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p.2 #1 · 20D: HORRIBLE BANDING CAUSED BY FLASH

Sam, Is that you the one who posted the 20D banding problem on DPR?
If that's you then I've read your banding problem and found it's very interesting. I've read your conclusion but haven't seen any resolution on the problem. Have you got one? BTW, great job there!

Sam Bennett wrote:
jdee wrote:
Sam,

If you send me your email I can send over the pictures to after I get home from work tonight. I don't have a website to post them on.

Thanks!

Send them to photos@swiftbennett.com , thanks.

Nov 16, 2004 at 03:42 PM

Rune
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p.2 #2 · 20D: HORRIBLE BANDING CAUSED BY FLASH

jdee wrote:
1) Does this happen with all 20d's? Maybe a few people want to try this out. My camera was set to iso 200 with 30seconds @f14 in manual with second curtain flash. Try it on a dark night exposure where most of the histogram is pushed to the left...or underexpose by a stop or two. Even if you don't underexpose by this much, the banding is still really bad, but this will really bring it out.

I have taken quite some ISO 3200 pics with my 20D, and I have enjoyed exploring the new possibility to take B&W photos (with and without flash) together with ISO 3200.

I find the pictures amusing, interesting and artistic. I do not, however, experience any banding nowhere near what your pictures show, something must be wrong with your camera.

Nov 16, 2004 at 04:28 PM

Sam Bennett
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p.2 #3 · 20D: HORRIBLE BANDING CAUSED BY FLASH

Softechie wrote:
Sam, Is that you the one who posted the 20D banding problem on DPR?
If that's you then I've read your banding problem and found it's very interesting. I've read your conclusion but haven't seen any resolution on the problem. Have you got one? BTW, great job there!

Yes, it appears I'm the DPR user everyone seems to be referring to. No, there's no resolution that I know of. I've basically shrugged it off for the time being since it really appears to be a Canon hardware issue. I will simply avoid using the 50MM in situations where AI Servo is needed - luckily I have this luxury in the sport I'm shooting.

It should be noted that the problem I'm seeing DOES NOT appear to be a problem specific to the 20D - other users reported similar issues with both the 10D and D60 with a variety of lenses. Additionally, the problem I'm seeing is NOT limited to high-ISOs, although it is certainly more noticeable there.

In my case, only one of 5 lenses causes the problem - the 50MM f/1.4. I suspect this is because of its tendency to hunt a bit on low-contrast subjects. It may occur in the other lenses in the right situations, but I haven't seen it in my testing.

Regarding the other poster's theory about voltage: it would be interesting to test this problem with a power adapter instead of a battery, since theoretically it should provide more consistent voltage. Unfortunately I don't have one.

Nov 16, 2004 at 04:57 PM

Sam Bennett
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p.2 #4 · 20D: HORRIBLE BANDING CAUSED BY FLASH

Just to reiterate: I do not know at this time if jdee is seeing the same problem I see. The 20D (and every other Canon dSLR) displays various levels of banding at every ISO - this is a fact of life with all dSLRs right now. However, the banding I'm talking about is very abnormal - it is an extremely distinct type of banding. Here are two photos, taken seconds apart with identical settings which shows the particular problem I'm referring to:

"Normal" level of banding:

This image is copyrighted by the owner

Abnormal banding:

This image is copyrighted by the owner

So lets be careful to not confuse jdee's problem with mine. Until I receive the original images, it will be impossible to determine if the issues are related.

Nov 16, 2004 at 05:05 PM

craig360
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p.2 #5 · 20D: HORRIBLE BANDING CAUSED BY FLASH

I have noticed banding myself with my 20D and even called Canon, emailed them an image, and they said "we didn't see any banding in the sample". They must have been blind because it is very similar to that of Sam's banding. I will post an example later, but I clearly have banding with some regularity at ISO 800 and above.

Nov 16, 2004 at 05:54 PM

RDKirk
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p.2 #6 · 20D: HORRIBLE BANDING CAUSED BY FLASH

How does it compare to pushing color negative film to 3200?

Nov 17, 2004 at 02:39 AM

jdee
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p.2 #7 · 20D: HORRIBLE BANDING CAUSED BY FLASH

Craig,

Have you spoke to Canon about this? I haven't talked to them yet, but the more testing I do, the more obvious it is that there is a problem.

What I still can't figure out is if everyone has this problem and just don't notice it, or if this is a problem with a few cameras and something Canon can fix.

Like I mentioned before, I never saw this probel with my rebel, even though the noise was fairly pronounced sometimes at 1600.

Nov 17, 2004 at 03:01 AM

Sam Bennett
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p.2 #8 · 20D: HORRIBLE BANDING CAUSED BY FLASH

RDKirk wrote:
How does it compare to pushing color negative film to 3200?

What's your point, exactly? Color negatives don't suffer banding issues and do not warrant any mention in this discussion. Color negatives may indeed have more "grain", but that's an entirely different discussion.

What we have in some cases with banding is a sensor that will show different bandings characteristics shot to shot with identical camera settings. You'll be hard pressed to convince me it isn't an issue Canon should try to address.

Nov 17, 2004 at 03:39 AM

jdee
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p.2 #9 · 20D: HORRIBLE BANDING CAUSED BY FLASH

Sam,

I sent you two full sized pictures to check out. The second one I pushed about half a stop to show the banding a little better. Let me know what you think.

Nov 17, 2004 at 03:55 AM

vachss
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p.2 #10 · 20D: HORRIBLE BANDING CAUSED BY FLASH

When you see banding are the bands always the same width? I wonder if this is an integer number of pixels whether a relatively simple chunk of code (or possibly even a PS action) could be written to address this. Artifacts with well defined periodicity are sometimes the easiest to remove.

Granted Canon ought to fix this, but if we can do it ourselves then I wouldn't get too bent out of shape over it.

Nov 17, 2004 at 04:14 AM

ChrisMoon
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p.2 #11 · 20D: HORRIBLE BANDING CAUSED BY FLASH

I just got my 20D in the mail, pumped it up to 3200 iso, exposed at 30 seconds and 20f with a 2nd curtian flash (on camera), put it in the bathroom, shut the door, and had banding all over the place! Im using a 50mm 1.4 on manual. On top of that, the grip for the 20D is a bad design... do any of you feel the same?

Nov 17, 2004 at 06:52 AM

ChrisMoon
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p.2 #12 · 20D: HORRIBLE BANDING CAUSED BY FLASH

ok, so I did a whole bunch of tests. Here is my conclusion. The banding occers only when you use the on-board flash. The lower the iso the less the banding. An external flash produces no banding, and using no flash at all also produces no banding. The is fine for those who will only use external flases, but when I travel with friends, I want to be able to use the on-board flash! I have not tried to do this with the noise reduction on. Mabe tomarrow, canon will be getting a call... let me know if any of you find the same results.

Nov 17, 2004 at 07:25 AM

forrest5000
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p.2 #13 · 20D: HORRIBLE BANDING CAUSED BY FLASH

For what its worth,
I got the exact same problem with my 10D shooting indoors at 3200ASA (at a wedding) Canon replaced the sensor under warranty. While it was in for repair the shop gave me a loan of both a D60 and then a 10D and both cameras exhibited this effect under these types of conditions.
I’m sure someone in Canon could explain it but I suspect it is a function of how the senor and software intrepid the incoming info under these circumstances.

I've never seen banding at any other ASA setting on any canon.

Nov 17, 2004 at 10:29 AM

stevei
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p.2 #14 · 20D: HORRIBLE BANDING CAUSED BY FLASH

There's someone on dpreview who is having this exact problem with his shiny new 1Ds Mark II:
http://forums.dpreview.com/forums/read.asp?forum=1032&message=11095080

One respondent has suggested a faulty oscillator, it certainly seems like there is some sort of electrical fault causing the problems.

Steve

Nov 17, 2004 at 12:31 PM

jaapv
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p.2 #15 · 20D: HORRIBLE BANDING CAUSED BY FLASH

This would invalidate Chris Moon's test result. I doubt that anybody would use flash for astronomical shots . By the way, the DPreview photograph looks horribly overexposed (or underexposed and overcorrected).

Nov 17, 2004 at 12:40 PM

stevei
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p.2 #16 · 20D: HORRIBLE BANDING CAUSED BY FLASH

I meant that the type of banding seen in the image is exactly the same, not necessarily the precise cause.

The common thread between all the examples appears to be some sort of electrical factor. Onboard flash has done it in some cases, in others the autofocus motor of a specific lens, in the case of the person on dpreview it seems to be afflicting every shot.

So, the most likely explanation, to me, seems to be that there is an electrical fault that can be present with varying degrees of severity. Some cameras never have any banding, some have it all the time, some are in between and need an additional contributing electrical factor to cause it. High ISO is always going to be more revealing of such problems.

Steve

Nov 17, 2004 at 01:08 PM

jaapv
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p.2 #17 · 20D: HORRIBLE BANDING CAUSED BY FLASH

I agree. So it seems it is time now for the electronics experts to step in!

Nov 17, 2004 at 01:13 PM

Sam Bennett
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p.2 #18 · 20D: HORRIBLE BANDING CAUSED BY FLASH

jdee's problem definitely seems similar to mine, but much much more pronounced. The frequency and width of the bands also varies across the image, which is quite odd. The shot settings are as follows - ISO 200, 30 seconds, f/7.1, Second-Curtain Internal Flash:

This image is copyrighted by the owner

Crop, showing transition from high frequency to low frequency banding:

This image is copyrighted by the owner

It certainly appears Canon has some work to do in minimizing electrical interference in their sensors between this and the similar banding I see with AI Servo and some lenses.

Remember, while this is a long-exposure shot, it is also an ISO 200 shot, it is NOT a high-ISO issue.

Nov 17, 2004 at 01:50 PM

stevei
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p.2 #19 · 20D: HORRIBLE BANDING CAUSED BY FLASH

Yep, long exposures are another thing that will reveal any electrical problems, as well as high ISO.

My advice, for what it's worth, is that anyone who has this problem should assume, until it's proven otherwise, that the fault only affects a small number of individual 20D copies, and hence they should ask for a replacement for their defective camera. If you find the same problem on the second and third cameras you try, a rethink will be needed.

Steve

Nov 17, 2004 at 02:43 PM

dave miner
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p.2 #20 · 20D: HORRIBLE BANDING CAUSED BY FLASH

Send it back, needs to be repaired by Canon. Sorry Dave

Nov 17, 2004 at 03:06 PM

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