Sunday, November 23, 2008

K20D has VPN under Cold Temperature?

A K20D professional user reported that his K20D produced annoying obvious vertical (stripping) pattern noise (VPN) when used under cold weather (that was not really extremely cold):-

http://forums.dpreview.com/forums/read.asp?forum=1036&message=30027850

As we can see from his artworks, which should have been great and nice ones, if these were not tampered by that superimposed VPN, which is very obvious. The poor models have just little clothes under a 2 degree Celsius working environment outdoor but I am afraid their scarification have yet been in vain, also. But anyway, their professional working attitude really makes them highly respectable and appreciatable. Bravo!

Furthermore, along the OP's own thread, it has been re-confirmed that it was not a RF or external power interference problem, nor a memory card issue, and neither a battery grip power interference problem (like what was confirmed with the K10D, which I reported very firstly when an user first confirmed that solidly, with good evidence). And finally, that K20D pro-user re-flashed his K20D and tested again, same thing once again re-confirmed, i.e., its *just* the cold temperature, but nothing else!

And, similar to another reported banding case much earlier before, this time pattern noise did also happen at low ISO speeds of 100, 200 and 400 (but the previous user didn't mention anything about cold temperature should be a factor).

Well, after all these, we may guess that the pro photographer's K20D has been defective. However, the very strange thing verified is that only lower temperature close to zero degree would create this problem. This maybe an isolated case and issue, but it could be in another extreme. Who knows?

3 Comments:

Male gorilla said...

I was the first to reply such issue on May 2008 on the dpreview. In my case Pentax engeneers refused to replace the camera, saying that they couldn't reproduce the effect and think on radio interference, so I still use tat camera. Now I can say:

1. No any interference.
2. Temperature trend exists but is not absolute - under 10 C the effect becomes 3-4 times more often.
3. The effect depends on composition and this is reproducable. If appears - I repeat the shot, stripes repeat. I turn the camera 20 degrees aside, shoot again - no stripes. I return the camera back to original, shoot - again stripees. Often (50% cases) changing ANYTHING (ISO, aperture, DR enchancement on/off etc) also stops striping.
4. Another trend noticed - low contrast shots, especially shots with fog, enforce the effect to appear 3-4 times more often.

RiceHigh said...

It very seems that the K20D doesn't like cold weather, below are two more similar reports by yet another two K20D users:-

http://www.pentaxforums.com/forums/pentax-dslr-discussion/46353-k20d-night-shooting-issue.html

So, including you and that pro photographer, there are already four K20D users who have reported the problem.

LORESTEGIULIA said...

http://farm4.static.flickr.com/3265/3217444680_af5580f305_b.jpg
I took this shot at -5 °c
ciao Lorenzo

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