Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-23-2009, 05:51 PM   #1
Forum Member




Join Date: Jan 2009
Location: Berlin, Germany
Posts: 62
K20D, Yellow tint in middle of frame

Hi guys,

just arrived here and would like to ask for your comment. I purchased a K20d and took a row of frames particulaly at higher ISO as 1600, 3200, 6400, as I like in principle the behaviour of the camera at these settings. The noise looks very much like analog film grain and I saw impressive prints in A4 (about letter format) and half of that from a unit that I unfortunately do not own myself. The one I got produced a strange noise in different situations, especially visible when pointing it at a white wall. While upper and lower portion looke blueish or purpleish, the center of a frame showed a yellow tint. This was visible down to even 100 ASA when looking closely enough in pictureds other than what I enclosed here for reference. It most likely appeared at White Balance set to tungsten, but also under other settings. High ISO noise reduction as well as any other setting, such as contrast, sharpering, did not contribute. May I ask you whether you had any experience like this yourself. Could you make a shot as mentioned and see what happens at your end? I got the camera replaced once and will return it another time as I have seen the model behave far better. How likely is it to get a "good" sample? Pentax doesn't seem to be aware of the phenomenom yet, but promised to look into it.

Thanks for comments and best regards,

Kai from Berlin, Germany

Attached Images
 
01-23-2009, 09:50 PM   #2
Veteran Member




Join Date: Nov 2006
Location: Hong Kong
Posts: 1,934
What light source did you use?

What light source did you use?
01-24-2009, 05:02 AM   #3
Forum Member




Join Date: Jan 2009
Location: Berlin, Germany
Posts: 62
Original Poster
that was an energy saving lamp. thought the cast of light onto the wall might be causing that, so made a shot of the same area holding the camera upright, but that didn't make a difference. to me it looks like the sensitivity of the sensor itself is less than in the center. shots of dark surroundings show blue dotted noise there while the center still is almost black with less noise.

k.
01-24-2009, 08:18 AM   #4
Veteran Member




Join Date: Nov 2006
Location: Hong Kong
Posts: 1,934
QuoteOriginally posted by kasv Quote
that was an energy saving lamp. thought the cast of light onto the wall might be causing that, so made a shot of the same area holding the camera upright, but that didn't make a difference. to me it looks like the sensitivity of the sensor itself is less than in the center. shots of dark surroundings show blue dotted noise there while the center still is almost black with less noise.

k.
Did you shoot at a shutter speed higher than 1/60th second then? Or even much higher?

01-24-2009, 09:53 AM   #5
mer
Senior Member




Join Date: Nov 2007
Location: Greece
Posts: 237
It is the lamp that's causing it .
01-24-2009, 12:51 PM   #6
Forum Member




Join Date: Jan 2009
Location: Berlin, Germany
Posts: 62
Original Poster
QuoteOriginally posted by RiceHigh Quote
Did you shoot at a shutter speed higher than 1/60th second then? Or even much higher?
1/60th. here the complete EXIF:

Make - PENTAX Corporation
Model - PENTAX K20D
Orientation - Top left
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
Software - K20D Ver 1.00
DateTime - 2009:01:17 20:09:54
YCbCrPositioning - Co-Sited
ExifOffset - 598
ExposureTime - 1/60 seconds
FNumber - 4.50
ExposureProgram - Manual control
ISOSpeedRatings - 6400
ExifVersion - 0221
DateTimeOriginal - 2009:01:17 20:09:54
DateTimeDigitized - 2009:01:17 20:09:54
ComponentsConfiguration - YCbCr
ExposureBiasValue - 0.00
MeteringMode - Multi-segment
Flash - Not fired, compulsory flash mode
FocalLength - 0.00 mm
FlashPixVersion - 0100
ColorSpace - sRGB
ExifImageWidth - 1200
ExifImageHeight - 797
InteroperabilityOffset - 54284
SensingMethod - One-chip color area sensor
FileSource - Other
SceneType - Other
CustomRendered - Normal process
ExposureMode - Manual
White Balance - Manual
FocalLengthIn35mmFilm - 0 mm
SceneCaptureType - Standard
Contrast - Hard
Saturation - Normal
Sharpness - Hard
SubjectDistanceRange - Distant view

Maker Note (Vendor): -
Mode - Auto
Quality - 5
ISO - 24
White Balance - Tungsten

Thumbnail: -
Compression - 6 (JPG)
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
JpegIFOffset - 54408
JpegIFByteCount - 5615

k.
01-24-2009, 06:03 PM   #7
Veteran Member




Join Date: Nov 2006
Location: Hong Kong
Posts: 1,934
QuoteOriginally posted by mer Quote
It is the lamp that's causing it .
Possibly..
01-24-2009, 06:06 PM   #8
Veteran Member




Join Date: Nov 2006
Location: Hong Kong
Posts: 1,934
QuoteOriginally posted by kasv Quote
1/60th. here the complete EXIF:

Make - PENTAX Corporation
Model - PENTAX K20D
Orientation - Top left
XResolution - 72
YResolution - 72
ResolutionUnit - Inch
Software - K20D Ver 1.00
DateTime - 2009:01:17 20:09:54
YCbCrPositioning - Co-Sited
ExifOffset - 598
ExposureTime - 1/60 seconds
FNumber - 4.50
ExposureProgram - Manual control
ISOSpeedRatings - 6400
In order to confirm your source of problem, try increasing the shutter speed and to see if the vertical width of the yellow band would decrease. Try one (far) below 1/180s and one (far) above 1/180s if possible.

Please post back these pics when done. I guess I could isolate the problem this time and tell you something if so.

01-24-2009, 10:27 PM   #9
Loyal Site Supporter
Canada_Rockies's Avatar

Join Date: Nov 2007
Location: Sparwood, BC, Canada
Photos: Gallery | Albums
Posts: 9,554
QuoteOriginally posted by kasv Quote
that was an energy saving lamp. thought the cast of light onto the wall might be causing that, so made a shot of the same area holding the camera upright, but that didn't make a difference. to me it looks like the sensitivity of the sensor itself is less than in the center. shots of dark surroundings show blue dotted noise there while the center still is almost black with less noise.

k.
By an energy saving lamp, I am assuming you are talking about fluorescent lighting. Although our eyes think the light is continuous, it is not, it flickers at the frequency of the source electrical feed - 60 Hz in North America mostly, 50 Hz in Europe. A good general rule for snapping under these conditions is to use a shutter speed that is longer than two cycles of the lamp. This also applies to television screens - in which case it is double the scan rate that you want to use. Rice High got the speed problem backwards. You want to go slower, not faster.
01-25-2009, 03:07 AM   #10
Forum Member




Join Date: Jan 2009
Location: Berlin, Germany
Posts: 62
Original Poster
QuoteOriginally posted by mer Quote
It is the lamp that's causing it .
well, considered that as well. yet, shot the same area with k100d super at 3200 iso and the result was even; color tint depending on the wb of course, yet the whole area was covered and i found no blueish or other differntly colored stripe on top or bottom or elsewhere. never came across that or similar behaviour durign some 10000 shots with k100ds od ist dl in the past. so there really must be sth special to k20d. tried 4 units now plus one samsung g20 and all showed the same yellowish center tint.

if you had a k20d pls. try and compare and let me see you results.

k.
01-25-2009, 06:09 AM   #11
Inactive Account




Join Date: Jan 2007
Location: Finland
Posts: 125
I think it is not the yellow, but the blue tint. I have that appearing at high isos and this looks very similar. Read more about that from here:
https://www.pentaxforums.com/forums/pentax-dslr-discussion/47584-strange-k20d...-patterns.html
01-25-2009, 04:36 PM   #12
Forum Member




Join Date: Jan 2009
Location: Berlin, Germany
Posts: 62
Original Poster
first of all thanks for all your contributions. addressing what mer, ricehigh and can. rockies said, took the same "measurement" at different shutterspeeds.
the unit is in fact a different one thanks to my friendly dealer who replaced it another time. this seems to be less prone to the issue, thus making it harder to illustrate. but see yourself.
first a shot in the shade of daylight, i.e. no lamp on other than the sun. this 0002. 0015 is a shot of the bottom of a black frying pant osee how black black is reproduced at that ISO. Looks quite even to me compared to what I saw before. now the wall shots. surprisingly, all shutterspeeds looked about the same as 0049, which appears quite even to me. at most a little trace of what i observed with the other models.
chose a different object that was more likely to cause the issue. see the results enclosed with this and following msg.

cheers, kai
Attached Images
         
01-25-2009, 04:40 PM   #13
Forum Member




Join Date: Jan 2009
Location: Berlin, Germany
Posts: 62
Original Poster
to me all this looks less bad than before. however, see the rest here.
Attached Images
       
01-25-2009, 04:55 PM   #14
Forum Member




Join Date: Jan 2009
Location: Berlin, Germany
Posts: 62
Original Poster
ok, which is which: (all 6400ISO)

1st mail:
0049 (1/60, energy saving lamp)
0015 (dark frame; frying pan)
0002 (no artificial light; daylight shadow)
1/125, f4
1/90, f6.7

2nd mail:
1/90, f8
1/45, f11
1/15, f16
1/8, f22
01-25-2009, 05:03 PM   #15
Pentaxian
Wheatfield's Avatar

Join Date: Apr 2008
Location: The wheatfields of Canada
Posts: 10,157
QuoteOriginally posted by kasv Quote
ok, which is which: (all 6400ISO)

1st mail:
0049 (1/60, energy saving lamp)
0015 (dark frame; frying pan)
0002 (no artificial light; daylight shadow)
1/125, f4
1/90, f6.7

2nd mail:
1/90, f8
1/45, f11
1/15, f16
1/8, f22

Ummm, you are shooting at ISO 6400 and your wondering about why you are getting noise?
Get used to it instead.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, dslr, frame, iso, k20d, noise, photography, settings
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Yellow Tint chilihead Troubleshooting and Beginner Help 9 10-18-2009 03:41 PM
K20D RAW tint corrections jeffkrol Pentax DSLR Discussion 0 08-20-2009 10:39 AM
K100 Super Manual Lens Yellow Tint/Overexposed??? Grzldvt Pentax SLR Lens Discussion 8 06-09-2009 05:13 PM
what's causing this weird yellow tint ? chiem Pentax DSLR Discussion 17 03-11-2009 06:43 AM
Green spot in the middle of the frame elijahkagan Pentax SLR Lens Discussion 9 03-06-2008 10:49 AM



All times are GMT -7. The time now is 11:16 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top