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07-11-2009, 12:33 PM   #31
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QuoteOriginally posted by PentaxPoke Quote
My conclusion? Dang these cameras have good high iso performance.
ROFLMAO! Great summary line. Bravo!

They look *different*, but it's hard to pick a "winnah", I think. This is gonna be something, I think, that we'll just have to write off to personal preference.

07-11-2009, 03:00 PM   #32
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Thanks for a very nice piece of work, PP. My conclusion is that sensor output is not a differentiator between a K20D and K-7.

Thanks again.

Jer
07-11-2009, 06:50 PM   #33
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QuoteOriginally posted by PentaxPoke Quote
K-7 iso 3200 default NR:



k20d iso 3200 default NR:

What's interesting is the K7's image seems to have less chroma noise...take a look at the top of the pentax front cap...
07-11-2009, 07:32 PM   #34
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QuoteOriginally posted by kenyee Quote
What's interesting is the K7's image seems to have less chroma noise...take a look at the top of the pentax front cap...
Excellent point. I didn't really notice that until you mentioned it.

K-7

K20d


I agree with you. And it is chroma noise that is the most problematic of the two. Looking at the two closely, I see almost no chroma noise at all on the K-7 crop. If I had to describe K-7 noise, I would characterize it as "fine grain luminance noise." Nice catch kenyee!

07-11-2009, 07:57 PM   #35
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This is exactly what I like. Noise is fine, I just hate the chroma spots on my K20D.
07-11-2009, 08:17 PM   #36
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QuoteOriginally posted by PentaxPoke Quote
Excellent point. I didn't really notice that until you mentioned it.... And it is chroma noise that is the most problematic of the two.... Looking at the two closely, I see almost no chroma noise at all on the K-7 crop. If I had to describe K-7 noise, I would characterize it as "fine grain luminance noise." Nice catch kenyee!
Agree with that. My past high-iso shots always looked better when converted to B&W because the chroma noise was throwing up blotches of non-existent colours in the normal shots.
The K-7 handles this much better.
07-11-2009, 08:42 PM   #37
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Very informative post, PentaxPoke .. thank you and also to all that have contributed!

What strikes me is that everyone has their own threshold of acceptable noise .. and that is as it should be. I think we can all take solace in knowing that, to a certain degree, the amount of noise in an image is controllable by the photographer .. if you know what you're doing and you know the limitations of your camera's sensor.
07-11-2009, 08:43 PM   #38
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QuoteOriginally posted by jstevewhite Quote
Here are three images from my K20D. I don't have a k-7, sorry. These are ISO3200, tripod mounted, at -.3EV, 0EV, and +.3EV. Here's the grid view:



I corrected them in LR to 0EV in PP. They're shot RAW PEF, light from overcast coming from distant south window. I labeled each one. The noise is very clumpy and ugly at -0.3EV, a little better at 0EV, and best at +0.3EV. I think this illustrates what a sensor that was .3 stops more sensitive might mean to high-ISO noise profiles, and how important metering is to noise. I think the EXIF is preserved if you want to snoop it.

Here is - 0.3EV:



Here is 0EV:



and at last +0.3EV:

GREAT post, thank you.

i think many cameras have been more guilty of bad metering than bad ISO capability, very eye-opening.

07-12-2009, 10:27 AM   #39
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Great work there guys! I just did a quick comparison of my K20, GX20 and K7 at ISO 1600, with no NR and various NR setting. I'm basically getting similar results as the pictures posted here.

One thing that bug me on my K7 high iso picture is the size of the grain. It seems to be rough, and bigger than K20 or GX20, no matter which NR setting I choose. Eventhough I don't see noise like in K20, the rough grain seems to make the picture seems not as sharp as K20.

Maybe I peep too much?

Other than the grain, everything seems perfect for me so far.

Mike
07-12-2009, 11:42 AM   #40
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About the test in post #30 : it seems that K-7 is just desaturates image in noisy deep-black areas, same as Nikon D300. I don`t see any other reason for chroma noise absence in K-7 samples...
07-12-2009, 12:19 PM   #41
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QuoteOriginally posted by Om81 Quote
About the test in post #30 : it seems that K-7 is just desaturates image in noisy deep-black areas, same as Nikon D300. I don`t see any other reason for chroma noise absence in K-7 samples...
Is it desaturated or just a more neutral color balance? Looking at the whole images, the K20D pics are more yellow-red generally.

Rob
07-12-2009, 12:22 PM   #42
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QuoteOriginally posted by illdefined Quote
GREAT post, thank you.

i think many cameras have been more guilty of bad metering than bad ISO capability, very eye-opening.
Ya, it's always best to expose properly, but there are times when even properly exposed photos have deep shadows, and that is where noise is most likely to appear. Sometimes, it cannot be avoided.

Rob
07-12-2009, 04:11 PM   #43
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QuoteOriginally posted by PentaxPoke Quote
I agree with you. And it is chroma noise that is the most problematic of the two. Looking at the two closely, I see almost no chroma noise at all on the K-7 crop. If I had to describe K-7 noise, I would characterize it as "fine grain luminance noise." Nice catch kenyee!
What's interesting is they did this w/ the same 14-bit A/D converter...the theory was switching from the 22-bit A/D to the 14-bit caused this excessive shadow noise.

Out of curiosity, do you still get random hot pixels on the K-7? You'd have to pixel peep ISO800 or higher to see them. On the K20D, they randomly reappear on the sensor even after hot pixel mapping. I had thought hot pixel mapping fixed it, but only for a relatively short period (maybe a month) of time...
07-12-2009, 07:49 PM   #44
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More grist for the mill. Same caveats - quick and dirty high iso. What is interesting to me is how a few of the lenses look "different" between the two cameras (especially 77ltd). Mix of metering, awb and pixie dust?

k7k20d - Page 1
07-12-2009, 08:10 PM   #45
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QuoteOriginally posted by kenyee Quote
What's interesting is they did this w/ the same 14-bit A/D converter...the theory was switching from the 22-bit A/D to the 14-bit caused this excessive shadow noise.

Out of curiosity, do you still get random hot pixels on the K-7? You'd have to pixel peep ISO800 or higher to see them. On the K20D, they randomly reappear on the sensor even after hot pixel mapping. I had thought hot pixel mapping fixed it, but only for a relatively short period (maybe a month) of time...
Ken,
I havent seen any yet. [/fingers crossed]
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