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03-23-2008, 01:42 PM   #1
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K20D some images are striped

Playing around with the K20d of the friend of mine, I've noticed that some of the images made in different situations have same striped pattern. This pattern clearly visible and quite unpleasant thing to have on the shot. Reasons causing it to appear seems to be irrelevant to anything, because you can make several shots with the same parameters but not all of them will have such pattern. Changing output file type also not changes nothing, stripes may appear as well in jpeg and any RAW files.
Did anybody had such problem, and what kind of solution ( except of servicing or changing camera) can be used if any.

thnks

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PENTAX K20D  Photo 
03-23-2008, 02:22 PM   #2
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Can you elaborate and tell us what the settings, shooting conditions, iso etc are.

Dave
03-23-2008, 02:26 PM   #3
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Please post the original shot, uncropped. Thanks.
03-23-2008, 02:27 PM   #4
Ash
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Settings might be relevant here.
? High ISO noise

I've had a few shots from my K100D/K10D feature colour noise banding of this sort (hard to tell on yours - you may need to attach a larger image to see it more clearly), but it mainly happened at high ISO and underexposed areas of the photo, especially at night or low light areas. K20D should be less prone to this.

If you're saying several shots taken with the same settings under the same conditions give you different results, then something else may be going on - keep testing it and let us know.

03-23-2008, 02:28 PM   #5
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EXIF data is present in the crop above( originally image shot in DNG)
Make - PENTAX Corporation
Model - PENTAX K20D
XResolution - 240
YResolution - 240
ResolutionUnit - Inch
Software - K20D Ver 1.00
DateTime - 2008:03:23 21:20:01
Artist - Vlad
ExifOffset - 210
ExposureTime - 1/15 seconds
FNumber - 4.50
ExposureProgram - Aperture priority
ISOSpeedRatings - 800
ExifVersion - 0221
DateTimeOriginal - 2008:03:23 00:00:00
DateTimeDigitized - 2008:03:23 00:00:00
ShutterSpeedValue - 1/15 seconds
ApertureValue - F 4.50
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Flash not fired, compulsory flash mode
FocalLength - 37.50 mm
SensingMethod - One-chip color area sensor
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
FocalLengthIn35mmFilm - 57 mm
SceneCaptureType - Standard
Contrast - Hard
Saturation - Normal
Sharpness - Hard
SubjectDistanceRange - Close view

Other shots where I've noticed the same issue were shot in JPEG with "four star" quality, EXIF data is below:
Make - PENTAX Corporation
Model - PENTAX K20D
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
Software - K20D Ver 1.00
DateTime - 2008:03:22 10:46:11
YCbCrPositioning - Co-Sited
ExifOffset - 692
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
FocalLengthIn35mmFilm - 27 mm
SceneCaptureType - Standard
Contrast - Hard
Saturation - Normal
Sharpness - Hard
SubjectDistanceRange - Distant view
ExposureTime - 1/180 seconds
FNumber - 5.60
ExposureProgram - Aperture priority
ISOSpeedRatings - 200
ExifVersion - 0221
DateTimeOriginal - 2008:03:22 10:46:11
DateTimeDigitized - 2008:03:22 10:46:11
ComponentsConfiguration - YCbCr
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Flash not fired, compulsory flash mode
FocalLength - 18.00 mm
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 3104
ExifImageHeight - 4672
SensingMethod - One-chip color area sensor
FileSource - DSC - Digital still camera
SceneType - A directly photographed image

Maker Note (Vendor): -

Thumbnail: -
Compression - 6 (JPG)
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
JpegIFOffset - 54352
JpegIFByteCount - 7418

and

Make - PENTAX Corporation
Model - PENTAX K20D
Orientation - Top left
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
Software - K20D Ver 1.00
DateTime - 2008:03:22 10:29:50
YCbCrPositioning - Co-Sited
ExifOffset - 598
ExposureTime - 1/500 seconds
FNumber - 5.60
ExposureProgram - Aperture priority
ISOSpeedRatings - 200
ExifVersion - 0221
DateTimeOriginal - 2008:03:22 10:29:50
DateTimeDigitized - 2008:03:22 10:29:50
ComponentsConfiguration - YCbCr
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Flash not fired, compulsory flash mode
FocalLength - 47.50 mm
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 4672
ExifImageHeight - 3104
InteroperabilityOffset - 54284
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Auto
White Balance - Auto
FocalLengthIn35mmFilm - 72 mm
SceneCaptureType - Standard
Contrast - Hard
Saturation - Normal
Sharpness - Hard
SubjectDistanceRange - Distant view

Maker Note (Vendor): -
Mode - Auto
Quality - Best
ISO - 200
White Balance - Auto

Thumbnail: -
Compression - 6 (JPG)
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
JpegIFOffset - 54408
JpegIFByteCount - 6313
03-23-2008, 02:33 PM   #6
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QuoteOriginally posted by Ash Quote
Settings might be relevant here.
? High ISO noise

I've had a few shots from my K100D/K10D feature colour noise banding of this sort (hard to tell on yours - you may need to attach a larger image to see it more clearly), but it mainly happened at high ISO and underexposed areas of the photo, especially at night or low light areas. K20D should be less prone to this.

If you're saying several shots taken with the same settings under the same conditions give you different results, then something else may be going on - keep testing it and let us know.
Not necessary high ISO noise, as you can see from data above two shots were done at ISO 200 which is not too high, and there were no underexposure.

I'll try to test more, but as I said, camera is not mine i just tried to take up my mind on possible switch from Ds to K20 and used my friend's camera just to play with, so throurough test maybe not so easy to do.
03-23-2008, 02:45 PM   #7
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QuoteOriginally posted by GWP Quote
Please post the original shot, uncropped. Thanks.
Not this one, just because of that file which was cropped not mine, and person on it maybe not so happy about posting it here but the other one plain cityscape can be found here
03-23-2008, 02:47 PM   #8
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The shot above was at ISO 800 Tv 1/15 with lots of underexposed areas, but probably not enough to bring out noise, even without NR.

If you're considering buying a K20D, don't use this as a reason not to.
Try posting a couple of larger sized images of the same thing with the same settings, one with this mysterious banding and one without.

03-23-2008, 04:40 PM   #9
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QuoteOriginally posted by spe Quote
Playing around with the K20d of the friend of mine, I've noticed that some of the images made in different situations have same striped pattern. This pattern clearly visible and quite unpleasant thing to have on the shot. Reasons causing it to appear seems to be irrelevant to anything, because you can make several shots with the same parameters but not all of them will have such pattern. Changing output file type also not changes nothing, stripes may appear as well in jpeg and any RAW files.
Did anybody had such problem, and what kind of solution ( except of servicing or changing camera) can be used if any.

thnks
Looks like a typical RF interference pattern more obvious in high ISO shots in shadow areas. This can be created by passing cars (with failing plug leads), mobile phones, etc. In some cases (Nikon D200 I seem to remember) it was caused by the lens motor in AFC mode. Nothing much you can do, but thats why it does not appear in every shot. All cameras are somewhat susceptible.

There was one concert I shot where every shot showed the same pattern. Camera was a Minolta Dimage 7i. I never saw it again, so I assume there was some strong RF source at the gig - possibly radio mikes.
03-24-2008, 03:57 AM   #10
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QuoteOriginally posted by *isteve Quote
Looks like a typical RF interference pattern more obvious in high ISO shots in shadow areas. This can be created by passing cars (with failing plug leads), mobile phones, etc. In some cases (Nikon D200 I seem to remember) it was caused by the lens motor in AFC mode. Nothing much you can do, but thats why it does not appear in every shot. All cameras are somewhat susceptible.

There was one concert I shot where every shot showed the same pattern. Camera was a Minolta Dimage 7i. I never saw it again, so I assume there was some strong RF source at the gig - possibly radio mikes.
Maybe, but the pattern appears in different places, for example that walkaway shot was done in place were no cars passing by at least in 100-200 m radius, not so sure about mobile phone base stations but in town you can hardly find a place without them , and I don't think that mobile phone was too close to the camera anyway ( no BT devices like headphone were used). The main problem is that my Ds never showed such pattern under any situation, even when I was taken shot near to the port and military radar stations.
04-05-2008, 10:50 AM   #11
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Hi there,

i had not seen this post before starting a new thread :
https://www.pentaxforums.com/forums/pentax-dslr-discussion/24253-k20d-dithering-problem.html

i also get the problem, as i say in my last post on the other thread. that happens only for the first image after turning on the camera.

i was shooting far from any RF noise source, in the adirondacks

in my opinion it is an initialisation problem, and it happens on the processing of the image, perhaps during the bayer matrix conversion as it is clearly a vertical sinus cardinal appearing over all the image

i wish a pentax engineer would have a look at that

for the moment, i keep the camera on, and always shoot a first image to make sure i don't get the problem
04-05-2008, 11:24 AM   #12
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I noticed this on one of my shots. I have to go back into Aperture and make sure it is from the K20d and check the exif data but given the f stop I'm pretty sure it is the K20d with 77ltd.

04-05-2008, 11:32 AM   #13
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cmos uses less power more supceptable to interfearance but isn't the cmaera metal ? screening it from RF ?
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