Black Noise

[joe_jackson4]

<p>IDEA: with no light hitting the sensor, a photo should be black. If not, the sensor is basically telling porkies. This may be seen as noise when boosting shadows in high contrast scenes, or when trying to correct underexposed piccies by cranking up the exposure slider in RAW. Something like that, anyway.</p>

<p>TEN-MINUTE TEST: K100D, K200D, K-x, kit lens, 1/15s, f/22, lens cap on, +4EV and max fill light in RAW converter. Extreme shadow boostage... :)</p>

<p>RESULTS: thumbnails of resulting uncropped images below...</p>

<p><img src="http://koti.welho.com/pwilkins/blacks.jpg" alt="" width="422" height="561" /><br>

<img src="I:\+ Lightroom Exports\Black Noise BW +4EV and Fill\blacks.jpg" alt="" /></p>

<p>CONCLUSIONS: K-x victory.</p>

<p>COMMENTS...</p>

<p>No ISO3200 on the K200D, so I put a base ISO shot there instead.</p>

<p>The K100D holds its own against the K-x in this (not-very-scientific-at-all-but-who-cares...) test up to ISO1600, but it's beaten by the K-x at ISO3200. The difference between ISO1600 and ISO3200 is much less noticeable on the K-x.</p>

<p>Pattern noise is much less visible on the K-x shots.</p>

<p>It's probably not a good idea to boost the shadows of a K-x ISO12800 shot in RAW... :)</p>

<p>The K200D@ISO1600, K100D@ISO3200 and K-x@ISO6400 pics are quite similar in terms of overall shade of grey. Strangely enough, these are the default max ISOs of these cams... Spooky... :)</p>

[joe_jackson4]

<p>Oh, I forgot to mention that I did a straight greyscale conversion on the pics...</p>

[joe_jackson4]

<p>One thing I'd add here is that in most real-world shooting situations a K200D ISO1600 shot will look much better than a K-x ISO6400 shot, despite what this "black noise" test may suggest... Why...? Because in most pics, not everything in the scene/frame is really, really dark... :)</p>

<p>If the light levels in various parts of a scene are very low, the K200D will suffer with shadow noise at ISO1600... So, no it's not a good pub cam, apart from the beer-sealing aspect... The K-x at ISO1600 handles such dimly lit, shadowy scenes much better... BUT... If the scene is reasonably well-lit overall and you're careful not to underexpose, ISO1600 on the K200D is just fine, IMHO. I use it a lot.</p>

[jpo3136b]

<p>Are you sure you're operating the lens cap correctly? </p>

[jpo3136b]

<p>Perhaps it is that "extreme shadow boostage." I have not noticed all black frames which have appeared that gray to me. I was kind of surprised by this. </p>

[joe_jackson4]

<p>John, yes, it's the shadow boostage... It just makes it easier to see the noise more clearly, to compare the sensors.</p>

<p>The greyness isn't caused by light entering the cam. It's caused by sensor noise, cranked up with a +4EV exposure shift in PP and max fill light just to make it even worse... The noise gets more noticeable as you increase the ISO, obviously, but no, it's certainly not what you'd see in real life, with normal exposure adjustments.</p>

<p>BTW, I had the lens cap on, f/22, the room light off, the door shut, and the camera under a heavy winter jacket... Pretty dark...</p>

[jpo3136b]

<p>I'm sure you got it right, Paul. I was just playing. It was <strong>level<em> and snapped on, right?</em></strong></p>

[joe_jackson4]

<p>Aye, 'twas level and snapped... Although even if it had fallen off completely, I doubt it would have made much difference... :)</p>

<p>Anyway, it's an easy test for to try if anyone's bored enough to wanna compare their own cams in this completely daft manner... :) A K100D vs K20D faceoff could be interesting... I've often wondered how the high MP (but more modern...) Samsung sensor compares to the old 6MP Sony...</p>

[laur1]

<p>Was SR on in those shots? ;)<br />One thing I find interesting is that for the K200 I see a vertical pattern to the noise, for the K100 a horizontal one, and finally, for the K-x the noise looks more uniform.</p>

[joe_jackson4]

<p>Yeah, the pattern noise isn't normally an issue with the older cams... It's just this extreme test bringing it out... Having said that, the K-x does very well in this regard, even at ISO12800.</p>

[andrew robertson]

<p>The way a CCD or CMOS sensor is read causes some small amount of noise, especially in long exposures.</p>

<p>This is just the way it is.</p>