Monday, May 12, 2008

K20D Banding Problem Reported at Low ISO Speed (ISO 200)

A K20D user has just reported a "banding bug" of his K20D and posted a sample picture made by him which shows serious horizontal banding, at the DPR forum:-

Quoted:- "Each 1 of approx 50 images, taken with k20D, show very specific banding. I can't locate any regularities in there appearence. Other images are absolutely OK. The effect is visible even on the camera's screen."

And here is the direct link of his posted sample banding picture:-

Horizontal bandings are obvious in the whole image, especially at where near the pistils of the flowers which are having more textural details. I have examined the EXIF and it is discovered that the picture was actually taken at a low ISO speed of 200, plus a short exposure time of 1/200th of a second only, which is indeed the most worrisome thing afterall. Moreover, the exposure compensation was set to be -0.3 EV, which means that there should not be any underexposure and then push processing to exaggerate any potential artifact (if any), but the reverse is true, in contrast.

In fact, previously there have been a number of K20D user reports of banding found in pictures made at high ISO speeds and/or with long time exposure. But this time, it is the first time I have heard about banding could occur at such a low ISO speed, which is just an uncommon thing for most (or maybe all) DSLR models ever made and marketed.

I hope this case is just an isolated one rather than a common quality/manufacturing issue or even a design flaw or bug. Otherwise, it will be really a serious issue. Nonetheless, time will tell, when more and more users will report later if there is a real problem. Possibly and hopefully, we shall know about the truth within a few months' time to come.


Anonymous said...

I think the OP mentioned that it is most likely caused by electronic interferences.

kerriegibbo said...

I too have come across banding in my K20D images. So far I have only found 2 images (that I am aware of). These photos were taken in the same conditions using the same settings as approx. 18 other photos. These other photos do not show banding. The images were taken at 200 ISO, 1/180 sec, at f5.6 using a macro lens. The banding in my images is vertical. I have reported the issue to Pentax and am waiting for a reply.

RiceHigh said...

There is yet another user who reported the same problem here.

Marlon said...

As with Kerriegibbo's case, I have the same problem, only 2 or 3 images so far, and it SEEMS to be linked to the one's ive taken with my af360fgz flash... any more news on this?

RiceHigh said...

I have inspected the picture you posted over there and I think this maybe caused by some kinds of electrical interference just like what a K10D user verified and reported quite some times ago, when the vertical grip was used. See this:-

My suggestion is to try another flash unit or to try your flash unit on another body and to see if the same happens, or not. Of course, if problem persists, just contact Pentax directly to see if they can offer you some help.

kerriegibbo said...

Further to my post of 3 August, I have had many more images presenting with the banding. I have tested the camera with different lenses, different memory card, different settings, some with the on-camera flash, some without.

For some strange, unfathomable reason, ALL the banded images were taken in the morning - how weird is that!! If I pick the camera up in the morning and take shots some are bound to have banding. If I don't start the camera up until the afternoon (even after a couple of day without use), there is no banding in any of the images. I have had NOT ONE banded image which was taken in the afternoon.

I live in northern Australia so temperature should have no bearing as it is pretty warm most of the year.

I have sent my camera back to be repaired. I will let you know the outcome.

RiceHigh said...

This sounds very strange..

Maybe now Pentax have already opened a X-File to investigate the case! ;-)

Thanks for your update btw and I think many of us here will be eager to know about the findings by Pentax when your camera is back, if any discovered and told.

kerriegibbo said...

Well, I have my camera back from repair. Received it this morning so I haven't had a chance to test it out. The service note said they upgraded the firmware (which I had already done, unless they have issued yet another upgrade) and they cleaned the CCD Block. No other information was given.

I rang the repairer for further clarification, but the person I spoke to couldn't give me anything further. So I don't know if the issue presented when they tested it.

I have a couple of photography club outings this weekend so I will have a chance to test it out fully. Here's hoping.

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