K7 Green Banding

Started Oct 17, 2009 | Discussions
chupachup New Member • Posts: 13
K7 Green Banding

Hi all,

I like Pentax so much that i hate to talk bad about it.. but...

i just bought a k7 and on my first day of use, i had some horrible green banding in my photos. i have upgrade to the latest 1.01.xxx13 firmware which should have removed the green LINE issue. Is this a separate problem that warrants a trip to the service center?

points to note:

  • there was no visible green banding in the first few shots of the night

  • the green banding, once it started to appear, was there at all ISOs (i tested it because i thought it was an issue with ISO3200). but i 'think' it's more visible at high ISO than low ISO

  • the green banding was visible only in the shots of the night sky. in slightly brighter situations, there was not visible banding.

  • when i got home i tested the camera in low light and in darkness, on dark objects. there was no banding either.

i don't know if/when the situation will re-appear. sigh. hoping the someone can shed some light on this problem. it seems like someone else here ( http://forums.dpreview.com/forums/readflat.asp?forum=1036&message=32441243&q=k7+green+band&qf=m ) had the same problem. but just one.

Here's a sample of a photo with the green band. (Just a resized jpeg with no useful info)

john4160 Regular Member • Posts: 226
Re: K7 Green Banding

Are you using the kit lens? (18-55mm) Also, isn't this more likely a flare than a band? Do you have any other lens to try on it. Also I am guessing you could see this green in the viewfinder. If you can you should be able to raise and lower with the horizon to alter the green size. I'm just thinking to divide the problem between camera or lens.

OP chupachup New Member • Posts: 13
Re: K7 Green Banding

I'm using the FA31 and it's the only lens that i have..

the green banding is in the same position and of same size in all the photos, even though the view is varied slightly.

Below is a photo where i pointed higher towards the sky and the band is clearly still there..

*isteve Veteran Member • Posts: 9,509
Re: K7 Green Banding

You have a faulty sensor. You need to get your dealer to replace the camera.
--
Steve

Any fool can take a picture OF something. Its much harder to take a picture ABOUT something.

Britney Elvis Veteran Member • Posts: 5,256
Back it goes

As isteve says, that is a faulty sensor... get a new one.
--

Gus --- There are none so blind as those who had no chance to see... stop censoring photos!

OP chupachup New Member • Posts: 13
Re: Back it goes

ah, i was hoping that it was a smaller problem. i must be really unlucky.. hope it's gonna be a smooth process!

thanks! by the way, what are the usual things that you will check for when you first get a new camera? what can be checked on the spot in the shop (if you bought it in a brick n mortar shop) vs what needs to be checked when at home? this is my first dslr..

thanks in advance!

Bert v B Regular Member • Posts: 100
Re: Back it goes

This does not like the green banding problem the fix is meant for at all.
The green band is not a band but 1 line, centered.
It looks like a very different problem. You should return the camera.
--

  • Bert

Jadran Forum Member • Posts: 66
Re: Back it goes

This look just the same as my K-7. After trying several firmware updates, nothing changed much. Mine is on the way together with the guys from Croatia Pentax to Paris Pentax central for checking.

GordonBGood Veteran Member • Posts: 6,308
Re: Back it goes

Bert v B wrote:

This does not like the green banding problem the fix is meant for at all.
The green band is not a band but 1 line, centered.
It looks like a very different problem. You should return the camera.

The OP's vertical (in landscape orientation) green bands are common to some K20D's and K-7's and are due to some hot pixels in the black masked-to-light area along the bottom of the sensor, which photosites are used by the Pentax data acquisition algorithm to compensate for black offsets of the sensor. This is why the bands are always in the exact same position in the affected images: the hot pixels are always in the exact same position in the black bottom band of the sensor. The other mentioned vertical green line is somewhat related but due to the effect of the masked black area in the way the offsets are matched for the two sides of the green channel scans (a slight error in the algorithm), but this second problem is easier for Pentax to fix with firmware updates in that if affects very few photosites). The vertical banding is related to Vertical Pattern Noise (VPN) and banding as was found in the K10D's.

Although the OP's problem can be compensated in post processing if you are a raw shooter, you shouldn't have to and the easiest solution for a camera under warranty is to just return the camera for exchange or replacement of the sensor. If the hot photosites were to develop in a camera out of warranty, it would be more serious, but the chance of new hot pixels developing in the bottom 12 photosites as compared to the 3124 rows above it is very slight.

Regards, GordonBGood

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