Wave pattern in K20d photos

[ibargureni]

<p>Hi, everybody,<br>

I have been sooting and learning my new K20d these last weeks, and I'm really enjoying it so far. I have received my Tamron 17-50 today, so will be using it extensively in the following weeks...<br>

However, the last weekend I found something strange in two of my photos. A strange wave pattern was clearly visible in two of the photos taken in daylight at not very high ISO (ISO 400). It can be seen at 100% in the attached photo, and after two images with this pattern, it didn't appear again in any of the photos (the conditions were similar for the ongoing shots), nor have I found it in the previous photos (I have done around 1000 shots so far). At first I thought it could be owing to moiré effects, but it is clearly shown all around the image, so it isn't moiré. The photo I uploaded is from the jpg straight out of the camera, but the PEF shows the same effect (I shot PEF+jpg).<br>

It didn't bother me extremely, but I am curious to know if it happened before or if it is a common issue with this camera as I hadn't read about it before. If it didn't appear before, my thoughts were it could be induced by some kind of radio interference, as there were a high amount of policemen with their motorbikes around as well as many cars with their respective radio transmitters (it was a cycling race).<br>

Here is a 100% crop of the photo:<br>

Pentax k20d, DA18-55@55mm, f/5,6, 1/250 sec, ISO 400<br>

<img src="http://farm3.static.flickr.com/2424/3695331531_91db5bdcd8_o.jpg" alt="" /></p>

[jtk]

<p>Can you recreate this effect with the camera set for high performance (ie RAW)?</p>

 

[mithrandir]

<p>RF energy (radios and other sources) have been known to affect digital sensors producing results similar to what you experienced. I recently saw some photos taken by a Canon DSLR with similar interference patterns caused by powerful electromagnets in the vicinity of the camera. If the problem does not exist now that you are away from the race track, you probably were the victim of some strong RF interference.</p>

[jgredline]

<p>Send it back for warranty repair ''asap''</p>

[ibargureni]

<p>Thanks for the replies.<br>

John, the effect was also visible in the RAW files (they were shot in both formats, RAW+JPG), but I haven't been able to reproduce this effect in any other situation. In fact, it happened in just two images shot within maybe two seconds (yes,this kind of "burst" is possible even with the k20d, hehehe).<br>

Robert, I'm glad I'm not the only one thinking of external interferences. The fact is that that place was probably quite saturated of radio frequence waves, so if external interference could cause this kinds of effects, this place would be the perfect place to experience them.<br>

Javier, if this happened more regularly, I would sure send it back (it's just 2 weeks old...), but as this hasn't happened any more in the aproximately 1000 shots I've done so far and as I am not able to reproduce it, I will wait a bit before blaming the camera for this. However, I'll search for these "waves" in the photos I take from now on.<br>

Thanks for the answers and more ideas are welcome, of course!</p>

[michael_kuhne]

<p>Ioritz, that is a remarkable display of a situation most of us were unaware could possibly occur!! This is very educational to say the least, that radio interference can cause imaging abnormalities in a DSLR!!! </p>

<p>With film, you would not have this happen, but then you have to be careful regarding x-ray exposure from screening at airports.</p>

<p>Glad that you are enjoying your fine new camera!</p>

[ibargureni]

<p>Michael, as you said, each medium has its limits. There seems to be some kind of "issue" with RF waves in digital images. Moreover, digital information can be lost as a result of file corruption sometimes. However, film also has its limits. As you say, X-Ray scanners have always been problematic and film can't be stored for a long time undeveloped, whereas digital memory cards can hold the images a lot longer.<br>

They key is to know each medium's limits, as it has always been.</p>

[raybrizzi]

<p>Just think of what those RF rays might have done to your brain and family jewels!</p>

[Tim_Lookingbill]

<p>Anyone have an idea what causes these wave patterns shown in the image below shot with a Sigma 70-300mm f/4-5.6 DL Macro Super full frame zoom lens and K100D at 300mm?</p><div></div>

[jonathan_rush]

<p>Looks like distortion from hot air. Was this shot on a warm day, perhaps shooting over pavement?</p>

[Tim_Lookingbill]

<p>In Texas 100 degree heat I was thinking the same thing, but it doesn't seem to do it on all images. I'll have to do some further tests to be sure. </p>

<p>It does resemble a heat wave pattern. I don't get this with my old manual focus Sears 80-200 f/4 at 200mm.</p>