K20D - pattern noise: show me your worst please

chse · 10-01-2008, 07:42 PM

I just became proud owner of a K20D. With all the talk about sample variation of the sensor I am now worried about mine. So please tell me (and show me samples) of how much pattern noise or banding you see with yours. When looking very hard (meaning really very hard, after a glass of wine) I can see some banding at iso 800 it becomes more pronounced at iso 1600 and is visible at iso 3200.
Please don't get this wrong- the camera is very capable and produces perfectly usable pictures up to iso 1600 (see my 'first impressions post'). I am just a bit worried if other samples do not show pattern noise at all at high iso. The banding mostly appears in pictures which contain a lot of dark areas. So does anyone have some similar night shots at high iso? (all images are raw converted with lightroom, no adjustments)

Iso 1600:

crop iso 1600:

iso 3200:

and here what the camera can do at iso1600 in a standart situation:

*Canada_Rockies* · 10-01-2008, 09:54 PM

I think I hear you asking about "banding" - correct me if I have misunderstood the "pattern noise" - in which case, you can reduce it immensely by ever so slightly increasing the exposure. My k10d will band in underexposed areas when I have to push the shadows up in post processing. I have my under/over exposure "blinkies" turned on at all times, and am very concerned at the slightest yellow flashing (under exposure). At the same time, I try to keep the red flashing down to specular highlights. When in doubt, pull up a histogram. Do a search on the forum on ETTR, or on Google. I have found in the 10 months I have had my k10d, that ETTR works for digital images. I also shoot only RAW, and find that I can "recover" highlights and darks to nearly a full stop on either end. The display on the LCD is based on the jpeg conversion by the camera - it really has nothing else to go on, after all - and thus using RAW gets you a bit more "wiggle room."

Hope this helps!

RiceHigh · 10-02-2008, 01:44 AM

More samples, info and discussion here:

RiceHigh's Pentax Blog: K20D Banding Problem Reported at Low ISO Speed (ISO 200)

**Damn Brit** · 10-02-2008, 01:48 AM

Ignore him.

**Damn Brit** · 10-02-2008, 01:49 AM

What lens were you using?

**Damn Brit** · 10-02-2008, 01:49 AM

What lens were you using and what is the other exif please.

marlon · 10-02-2008, 02:11 AM

When I pixel Peep I get about the same thing from 800 up, only in underexposed areas like yours, there is nothing wrong there in my opinion, it lookes quite good and probbaly better than the xxxxxx I used yesterday in rainy dark weather.
The only problem I had was the below (which happened 3 times in 1000 photos, but Pentax exchanged it for me without questions, 2 minutes (although it might even have been flash interference)

I wouldnt worry about that, it looks great man. Just expose right!

chse · 10-02-2008, 09:15 AM

Originally Posted by Canada_Rockies

I think I hear you asking about "banding" - correct me if I have misunderstood the "pattern noise"

Yes, as far I understand, banding is lines running over the image (mostly horizontally) while pattern noise is noise forming a checker like pattern, which than can also look like banding.

- in which case, you can reduce it immensely by ever so slightly increasing the exposure. My k10d will band in underexposed areas when I have to push the shadows up in post processing.

That is very similar to what I see, if there are enough bright areas in the image there is no banding or patterns.
I realize that the images look very dark, at my other computer they look much brighter. I will check the exposure. Looks like my camera tends to underexpose- thats something new for Pentax!

Do a search on the forum on ETTR, or on Google. I have found in the 10 months I have had my k10d, that ETTR works for digital images.

ETTR- Expose To The RIGHT (?), in a low light situation that is hard to do, though, since it requires an even longer exposure.

chse · 10-02-2008, 09:33 AM

Originally Posted by Damn Brit

Ignore him.

Originally Posted by Damn Brit

What lens were you using?

Originally Posted by Damn Brit

What lens were you using and what is the other exif please.

Thanks for not following your own advice.

I notice now that the images appear very dark and the banding was much more prominent on the computer I originally used (a 24" white imac compared to a 17" imac G5). I will try to fix it tonight, together with attaching the exif (I wonder where it got lost - flickr?).
The lens I used for these was the 18-55 kit lens (the original one, not the DA II), but I can see clear banding at iso3200 in dark areas also with a 16-45 f4.

Concerning your first comment: again, this happens only in images with lots of very dark areas, I find the camera very capable and usable up to iso 1600.

Gooshin · 10-02-2008, 09:42 AM

i dunno, banding on my K20D is subjective..

like, this is ISO6400...

another ISO6400, hard to see, but easily masked by increasing the blacks

also ISO6400

not bad ehh? but then check this out

ISO3200.. for some reason is worse...

so it really depends on some factors i think, exposure, steady hands, etc... how hot the sensor is from the previous shots, etc.

OTOH, this is my K100D at ISO3200...

Miserere · 10-02-2008, 04:06 PM

chse, I'm not sure I see any banding in your picture, apart from a band of clouds...

**Marc Sabatella** · 10-02-2008, 04:20 PM

The "ignore him" comment wasn't saying that people should ingore you - it was saying that you should ignore the person who had responded just previously.