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04-28-2009, 11:07 PM   #1
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High ISO Noise: How well do K20D / K200D clean-up?

Hey all,

After learning about the current Pentax dSLR offerings, I've been very heavily swayed from going Can***. I was initially thinking K200D, but I'm contemplating the 20D.

One real concern I have is the sensor noise of the 20D and 200D, especially at higher ISOs & low-light. While I realize some of the other guys are dealing with noise by doing filtering/processing in-camera, loosing details in the process(even if output is RAW), it seems as far as trends go the Pentax dSLRs are just noisier. My eyes are very sensitive to chroma noise -- I work in video electronics design, so I can easily tell Pentax vs. other guys.

Does anyone have examples of their 20D or 200D photos before and after de-noising / processing? I'm really wondering how good a Pentax low-light ISO800+ shot can look with the "best" software processing. My processing flow is usually minimal, just contrast/brightness adjustments, I'm usually light-handed with digital editing.

My aim is to use the SLR mostly for well-lit, outdoor landscapes / architecture / general shooting, but I do want to do low-light night photography and even astro-photography.

I'm really amazed at the friendliness and collaborative nature of the Pentax forums, that is also influencing my decision .

- slrl0ver

04-28-2009, 11:50 PM   #2
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QuoteOriginally posted by slrl0ver Quote
Hey all,

After learning about the current Pentax dSLR offerings, I've been very heavily swayed from going Can***. I was initially thinking K200D, but I'm contemplating the 20D.

One real concern I have is the sensor noise of the 20D and 200D, especially at higher ISOs & low-light. While I realize some of the other guys are dealing with noise by doing filtering/processing in-camera, loosing details in the process(even if output is RAW), it seems as far as trends go the Pentax dSLRs are just noisier. My eyes are very sensitive to chroma noise -- I work in video electronics design, so I can easily tell Pentax vs. other guys.

Does anyone have examples of their 20D or 200D photos before and after de-noising / processing? I'm really wondering how good a Pentax low-light ISO800+ shot can look with the "best" software processing. My processing flow is usually minimal, just contrast/brightness adjustments, I'm usually light-handed with digital editing.

My aim is to use the SLR mostly for well-lit, outdoor landscapes / architecture / general shooting, but I do want to do low-light night photography and even astro-photography.

I'm really amazed at the friendliness and collaborative nature of the Pentax forums, that is also influencing my decision .

- slrl0ver
It depends a lot of the image.

I have take a ISO 3200 image on my girlfriend where you barely noticed any noise at all
On the other hand, I have taken a ISO 1600 that was pretty noisy, so my advice to you is to NOT underexposure the photo.

K20d performs exellent on high ISO when not underexposure, so don't do that!

I think too that k20d keeps image details a lot better then canon and nikon, so if you have a good program to take away noise it can be a good alternative.

But yes the noise is bigger then in at least the better canon and nikon cameras, still not that bad people say. I think it compares well when not underexposure

//Emil
04-29-2009, 08:16 AM   #3
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Plus, you do have to factor in that the noise in Pentax images is replaced by bubbly watercolor blobbiness in Nikon and Canon. Personally, I can't STAND the way Canon processes noise.

DPReview actually has a pretty good series showing the trade offs.



50D, D300, K20 at 6400.

Obviously, settings can be tweaked to give different performance on all these cameras, as well as noise reduction later in post processing. The basic trade off is still immediately evident, and is really a matter of personal taste. Pentax is deliberately noiser, but the "quality" of that noise is much better.
04-29-2009, 10:35 AM   #4
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QuoteOriginally posted by slrl0ver Quote
Does anyone have examples of their 20D or 200D photos before and after de-noising / processing? I'm really wondering how good a Pentax low-light ISO800+ shot can look with the "best" software processing.
"Best" is subjective. To my eyes, "best" is processing that eliminates as much chroma noise as possible *without* causing a noticeable loss in detail. Others are more than happy to throw away detail in their efforts to purge noise - sounds like you might lean that way.

The appearance of noise levels can be affected by many factors, including the amount of contrast in the scene, the exposure, the color of the lighting, the sharpness of the picture, the nature of the detail in the picture, etc. Which is why sometimes you'll see a really good looking sample from one camera but also a very bad looking one from the same camera at the same ISO (eg, the various K20D ISO 6400 shots one can find in different reviews).

But FWIW, here's a full size image from my K200D, shot a stop and a third underexposed at ISO 1600 and pushed that much in RAW processing. This yields the equivalent of ISO 4000 or so. I processed it to my liking, which is to say, I was *extremely* light on the NR in order to not lose detail. Looking at it closely, I actually see more problems with what appear to be artifacts from the NR, sharpening, and/or JPEG compression than I do with noise per se:

http://marcsabatella.zenfolio.com/img/v7/p711839810.jpg

I chose this image not because it was especially good or especially bad in terms of noise, but because it's the most recent image for which I happened to have a full size version already online. I'd say this image is pretty good by K200D standards, but reasonably representative for pictures taken under similar lighting and with a similar level of detail. Light wasn't as highly colored as some stage spots, which helped maintain resolution and get a "decent" exposure without clipping the red channel, and having a closeup of a face like this gives one more detail to work with than a shot in which a person takes up less of the frame. All in all, this is what I expect ISO 4000 to look like on the K200D given similarly favorable conditions.

The K20D does somewhat better than the K200D at these higher ISO's, but in my experience, so much depends on the sort of factors I mentioned that it's really hard to make fair comparisons unless someone shoots the same scene with the same setting using both cameras.

BTW, when I've experimented with the idea of smearing away more noise, I was "impressed with", but didn't necessarily "like", the results produced by Neat Image.

04-29-2009, 10:47 AM   #5
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Thanks all for your responses.

I guess my problem is that even though the Pentax detail is better, my eyes are more distracting by the noise and I tend to ignore the extra detail and get turned off from the whole picture. Again, since I work with video electronics, I've unfortunately tuned my senses to unwanted abberations -- it makes watching TV and movies very hard sometimes!

Mark:

Thanks for your response. Do you have the RAW-->JPEG before any processing? That picture looks like it has "film grain" (pleasing) but unfortunately it's very heavily colored (chroma noise).

Maybe a better question, does someone have a RAW file with noticable amounts of noise that they are willing to post? Maybe the best option for me is to take such a RAW file and see if I can process it to remove noise to my liking, without decimating details or quality.

I haven't really used any de-noising programs, which is why I had hoped someone might have done this already and said "Here is a great example of an image that cleaned up!". But, as everyone says, this is very subjective.

Thanks!
-slrl0ver
04-29-2009, 11:17 AM   #6
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Well, you wouldn't want an "unprocessed" version of my image - it would be a stop and a third underexposed. And that push needs to be done in RAW to be effective. So you really need a processed JPEG to work with - either that or the RAW file itself.

Since I used so little NR on the JPEG as it is, and only the default sharpening as well, I really don't see any reason not to just take it as is and try running it through whatever NR processing you might like.

FWIW, I got curious and ran it through Neat Image using all default settings. *Way* too "smooshed" for my tastes, but as I said, impressive enough in its own way, I suppose:

http://www.marcsabatella.com/images/misc/MJS_090416_6130_filtered.jpg
04-29-2009, 11:32 AM   #7
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the k20d does wonderful at 400 and 800!

that's my 400 iso.



now 1600 iso



final results may vary!

Last edited by vitalsax; 04-29-2009 at 12:18 PM.
04-29-2009, 12:00 PM   #8
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I normally just get rid of or reduce the chroma (color) noise and leave the lumi noise as it is. That way it pretty much looks like regular grain. Also, I keep my 200's noise reduction on "weak". When I shoot at 500 or 640 ISO it can look like 200 on other cameras. I'm pretty impressed.

04-29-2009, 01:42 PM   #9
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QuoteOriginally posted by slrl0ver Quote
I do want to do low-light night photography and even astro-photography
The K20D has mandatory dark frame subtraction on long exposures, which might annoy you for things like astrophotography. This thread has a discussion on what that's about. It's generally considered to be a bit better than the other models in high ISO performance though.

I don't have a useful example image to share with you, but PM me if you're interested in getting the original files (89MB) for the K200D NR comparison I did in that thread, for processing yourself. Just keep in mind that scene was set up for a noise comparison, not necessarily because it was something you'd take a picture of...
05-05-2009, 02:52 PM   #10
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Here's an example of ISO 800 on my K20D. It's one from a set I did at my sister's wedding; it's not a very well lit picture, but it was more a test shot as she was sitting on the bed away from the window as she was getting ready, but it still shows the lack of perceptable noise at ISO 800 given that the lighting is far from ideal on the bottom of her bunch of flowers:

05-05-2009, 06:26 PM   #11
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You can get the "no chroma" plastic look of the Canon cadre anytime you want by picking the right denoiser. My current favourite is Wavelet Denoise by Marco Rossini. It is found in several imaging apps such as the Gimp. Decompose to LAB space, smush the red and blue channels and then do some noise touchup on the Luminance channel and Presto! as clean as a whistle. Individual aversion to such perversion is purely subjective.

Jack

Last edited by jbinpg; 05-05-2009 at 09:09 PM.
05-06-2009, 08:18 AM   #12
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Here is just an example of my K20D at ISO 6400 then after i run it through noiseware, i think it's very good,,





and then here is a couple of comparisions with my Canon 40D which i have sold now

K20D ISO 1600 NR OFF


40D ISO 1600


K20D ISO 3200 NR OFF


40D ISO 3200


also don't forget the K20D NR was set to OFF but if i turned it on, it would be better than the 40D, BTW still set to OFF i think it's the same as 40D so i don't know what the heck these reviews are talking about

lenses used were Pentax DA 17-70 which is a great lens, and Tamron 17-50 for the 40D that is also great but it is not as good as the Pentax DA 17-70, even the colors of the pentax are truer than the 40D.

Last edited by SpartanWarrior; 05-06-2009 at 08:24 AM.
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