Friday, January 30, 2009

Strange K20D Noise Patterns

Various K20D users at the PentaxForums have reported that they experienced strange pattern noises which appear in particular regions of a frame and are particularly noticeable at ISO speeds higher than ISO 1600:-

http://www.pentaxforums.com/forums/pentax-dslr-discussion/47584-strange-k20d-high-iso-noise-patterns.html


All the user reports in the above thread are self-explanatory, with sample pictures posted and the issues found are clearly described.

But yet a particular user who has a very careful mind found that "the K20D has a strange vertical bar at the left side of the image, visible (normally) only by extreme pushing the contrast and brightness" here, in his this reply post.

He further states that, "So far I was able to produce it with every K20D I saw."

Actually, this "vertical bar" can also be seen at ISO 100 at which the situation is the "best", see another follow-up post from the same poster. A histogram for shooting a dark frame is posted.

The strangest thing here is that the unevenly distributed pattern noises are appearing in particular regions, and particularly existent in the Blue channel. They appear at image corners, left side or at the top and bottom of the frame. They appear not only at high ISO speeds but also at lowest ISO 100. It is only that the noises are much more obvious at high ISO speeds whereas at low speeds, they are well hidden but push processing or any kinds of more "extreme" post processing will reveal all these.

So, the culprit? It should be an immature sensor and associated hardware (and may also be the associated software) used in the K20D, which are to be debugged!

Indeed, I hope Samsung will do their debug jobs quicker and faster so that it makes it possible for Pentax to roll out their K20D replacement model soonest (as it should be). If not, Pentax should really source and get another sensor unit to put it into the K20D replacement, IMHO. In fact, the K20D is essentially a dead model now, for what the limited number of sales and low popularity/availability as seen. There are less and less shops carry the K20D and it can be hardly found. And even for rare places where the K20D can be found, they are just sitting there for collecting dust despite the K20D are now selling for very little money (very close to the 450D kit price).

Read Also:-

K20D has VPN under Cold Temperature?

K20D Banding Problem Reported at Low ISO Speed

2 Comments:

Anonymous said...

Hi,

I also have this pattern an took a closer look at it:
http://www.dlip.de/?s=banding&submit=Go

It does not exist in every K20D to the same extend. Some are really bad others are fine...

Mike

RiceHigh said...

Maybe some factory hardware calibration will eliminate the problem? Dunno exactly but just my wild guess..

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