My K-7 vs K-20d High ISO comparisons

PentaxPoke · 07-10-2009, 08:04 PM

I was interested in observing how the two cameras compare at high-iso with a highly detailed scene. I assume they should be close, because the sensor is essentially the same, but I wanted to do a quick comparison just the same. I know many have been doing this, but I thought I would add my tests to the forum.

Now this is not an entirely scientific comparison, but it is indicative of the results I have been seeing. I decided to just use the in-camera default NR settings for each camera. I also elected to output default jpeg files. I did keep the exposure settings identical for each camera since we all know how sensitive noise is to exposure, so I felt it was essential to keep that constant between the two cameras.

I also did another quick test that might interest some. It is 4 shots of the same subject at ISO 3200 with the K-7 at the 4 different NR settings.

UPDATE: jump to post # 30 for a more recent test I did: https://www.pentaxforums.com/forums/664653-post30.html

Here is the full set for the K-7 / K-20d comparisons:
K-7 and K20d Iso tests - a set on Flickr

Here is the full set for the NR variation tests on the K-7:
K-7 ISO 3200 with NR variation - a set on Flickr

Quick summary of my observations:

-White balance of k-7 is clearly superior. Maybe the best of any camera I have used. The tungsten lights in my house are very challenging for photography. I use commercial 130v bulbs instead of residential 120v. (The reason is they last a LOT longer, but as a trade-off, there is a bit less light, and it tends more toward yellow.) The K-7 has not had a single problem nailing the WB. I am quite impressed.

-As I have shown in similar tests here before, high-iso performance on the K20d is very good if you properly expose. When compared with the K-7, there are subtle differences, but nothing to suggest that the K-7 is worse or better. To me, that was to be expected.

-NR settings on the K-7 have an observable effect. Even on "high" there does not appear to be an objectionable loss in detail.

Did I mention that the K-7 is really fast?

For those that don't want to go to the link themselves, here is the k20d at ISO 3200:

And here is the K-7 at ISO 3200:

Last edited by PentaxPoke; 07-11-2009 at 12:28 PM.

Raybo · 07-10-2009, 08:51 PM

If the WB was equal how would the images compare?
I'm seeing less noise in the K20 images (IMHO).

Ray

**Ash** · 07-10-2009, 09:02 PM

Thanks for sharing these results.
Nice summary.
Indeed AWB is well refined in the K-7. Not too much of an issue if shooting RAW, but still a great advance for those who like JPEGs out of camera.

Though I agree that in order to make better comparisons in noise, ALL settings should be fixed between the cameras and using the same lens, including WB, particularly when shooting JPEG.
As you've proven, even at ISO 3200 both cameras produce useable images, despite some loss of detail as expected at such high ISO settings.

Who would have dreamed of getting such high ISO results in the film era?

nostatic · 07-10-2009, 10:20 PM

another quick and dirty. K7 vs K20d, 50-135* at 50mm. Crappy low light, f2.8, iso 1600, 1/4-1/5s shutter speed. Shot raw and developed in Aperture2. k7 is -0.3ev.

k20 - no correction

k7 - no correction

k20 AWB correction (basically click a button)

k7 AWB correction

k20 crop of AF point

k7 crop of AF point

PentaxPoke · 07-10-2009, 10:35 PM

Thanks for posting those static. They really add to the thread: Mine shows default out-of-the-camera results while holding exposure constant, and yours shows the WB constant processed from RAW. I noticed you said that the K-7 was -0.3ev. Was that to try and equalize the exposure differences between the two sensors?

Your crops are also very interesting. The K-7 shows more noise, but shows significantly more detail, like the grain of the wood, and the ridges of that white cup. I am wondering now if the K20d by default, has more NR? Even if the user NR is "off", there still is noise reduction in the image processing of any camera.

nostatic · 07-10-2009, 10:47 PM

I have the k7 at -0.3 because earlier in the day I was noticing that 0ev was a little "hot" for my tastes. It is a little dark in this photo and 0ev would have been closer to the K20d under these conditions I think.

That said I agree with your comments. What I'm seeing is more "noise" and more detail from the K7. For what I shoot and what I'm looking for, I actually like that combination a lot. I tend to go high iso and output b&w. Any sort of NR ends up looking like smears when I work the file. The k7 seems to put out a lot more of a rough grain at high iso.

Here are the crops with some sharpening, contrast increase but no definition increase or highlight/shadow tweak.

Raybo · 07-10-2009, 11:05 PM

Whatever that white thing is looks "whiter" on the K-7.

I'm still wondering if the WB is equal? K-7 image looks to be a bit larger IMHO.....

Raybo · 07-10-2009, 11:07 PM

Originally posted by nostatic

I have the k7 at -0.3 because earlier in the day I was noticing that 0ev was a little "hot" for my tastes. It is a little dark in this photo and 0ev would have been closer to the K20d under these conditions I think.

That said I agree with your comments. What I'm seeing is more "noise" and more detail from the K7. For what I shoot and what I'm looking for, I actually like that combination a lot. I tend to go high iso and output b&w. Any sort of NR ends up looking like smears when I work the file. The k7 seems to put out a lot more of a rough grain at high iso.

Here are the crops with some sharpening, contrast increase but no definition increase or highlight/shadow tweak.

You used different lenses........................Right?

PentaxPoke · 07-10-2009, 11:22 PM

In my set, the lenses are the same. I used the DA70 ltd.

Raybo · 07-10-2009, 11:33 PM

Originally posted by PentaxPoke

In my set, the lenses are the same. I used the DA70 ltd.

Something is amiss..................the second set of images is a tad bigger.

Raybo · 07-10-2009, 11:36 PM

My bad PP!

Your images are okee dokee, nostatic's images are a bit off.

Sorry,
Ray

nostatic · 07-10-2009, 11:44 PM

same lens. Roughly the same position but it is handheld so there is a little difference. Shot raw and processed with one-click AWB in Aperture. The crops are roughly the same amount of area but not identical.

Sorry, but I don't do the rigorous, scientifically controlled tests as I don't shoot that way in real life. This approximates the type of conditions I'd normally use (handheld, low light). And I'm lazy.

robgo2 · 07-10-2009, 11:56 PM

Originally posted by PentaxPoke

Your crops are also very interesting. The K-7 shows more noise, but shows significantly more detail, like the grain of the wood, and the ridges of that white cup. I am wondering now if the K20d by default, has more NR? Even if the user NR is "off", there still is noise reduction in the image processing of any camera.

In these examples, the top of the bottle shows more detail in the K-7 shot, because it is in perfect focus, while the K-20D shot is not. I don't know if sharp focus makes noise more apparent, but underexposure does. It looks to be more than -0.3EV, but I am not the one doing the measurement.

Rob

nostatic · 07-11-2009, 12:10 AM

Originally posted by robgo2

In these examples, the top of the bottle shows more detail in the K-7 shot, because it is in perfect focus, while the K-20D shot is not. I don't know if sharp focus makes noise more apparent, but underexposure does. It looks to be more than -0.3EV, but I am not the one doing the measurement.

Rob

-0.3 is what was set on the camera and shows in exif for the k7. As for AF, both shot with the same admittedly half-assed procedure but that might also say something about the AF capabilities of the two bodies. But it seems to be fairly consistent - the K7 and K20d files have a different "look" at high iso.

jstevewhite · 07-11-2009, 12:12 AM

Originally posted by robgo2

In these examples, the top of the bottle shows more detail in the K-7 shot, because it is in perfect focus, while the K-20D shot is not. I don't know if sharp focus makes noise more apparent, but underexposure does. It looks to be more than -0.3EV, but I am not the one doing the measurement.

Rob

As nostatic said: "another quick and dirty. K7 vs K20d, 50-135* at 50mm. Crappy low light, f2.8, iso 1600, 1/4-1/5s shutter speed. Shot raw and developed in Aperture2. k7 is -0.3ev."

This is the 50-135 DA*. It's *sharp* on the K20D. I think at those shutter speeds we probably have some camera motion involved. The K20D shot is either OOF as you said, or blurred by motion - quite possible at 1/4 -1/5 second.

07-10-2009, 08:04 PM	#1
PentaxPoke Veteran Member Join Date: Jan 2008 Location: Oklahoma Posts: 1,411	My K-7 vs K-20d High ISO comparisons I was interested in observing how the two cameras compare at high-iso with a highly detailed scene. I assume they should be close, because the sensor is essentially the same, but I wanted to do a quick comparison just the same. I know many have been doing this, but I thought I would add my tests to the forum. Now this is not an entirely scientific comparison, but it is indicative of the results I have been seeing. I decided to just use the in-camera default NR settings for each camera. I also elected to output default jpeg files. I did keep the exposure settings identical for each camera since we all know how sensitive noise is to exposure, so I felt it was essential to keep that constant between the two cameras. I also did another quick test that might interest some. It is 4 shots of the same subject at ISO 3200 with the K-7 at the 4 different NR settings. UPDATE: jump to post # 30 for a more recent test I did: https://www.pentaxforums.com/forums/664653-post30.html Here is the full set for the K-7 / K-20d comparisons: K-7 and K20d Iso tests - a set on Flickr Here is the full set for the NR variation tests on the K-7: K-7 ISO 3200 with NR variation - a set on Flickr Quick summary of my observations: -White balance of k-7 is clearly superior. Maybe the best of any camera I have used. The tungsten lights in my house are very challenging for photography. I use commercial 130v bulbs instead of residential 120v. (The reason is they last a LOT longer, but as a trade-off, there is a bit less light, and it tends more toward yellow.) The K-7 has not had a single problem nailing the WB. I am quite impressed. -As I have shown in similar tests here before, high-iso performance on the K20d is very good if you properly expose. When compared with the K-7, there are subtle differences, but nothing to suggest that the K-7 is worse or better. To me, that was to be expected. -NR settings on the K-7 have an observable effect. Even on "high" there does not appear to be an objectionable loss in detail. Did I mention that the K-7 is really fast? For those that don't want to go to the link themselves, here is the k20d at ISO 3200: And here is the K-7 at ISO 3200: Last edited by PentaxPoke; 07-11-2009 at 12:28 PM.

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07-10-2009, 08:51 PM	#2
Raybo Veteran Member Join Date: Dec 2007 Posts: 872	If the WB was equal how would the images compare? I'm seeing less noise in the K20 images (IMHO). Ray

07-10-2009, 09:02 PM	#3
Ash Loyal Site Supporter Join Date: Mar 2007 Location: Toowoomba, Queensland Photos: Gallery \| Albums Posts: 23,920	Thanks for sharing these results. Nice summary. Indeed AWB is well refined in the K-7. Not too much of an issue if shooting RAW, but still a great advance for those who like JPEGs out of camera. Though I agree that in order to make better comparisons in noise, ALL settings should be fixed between the cameras and using the same lens, including WB, particularly when shooting JPEG. As you've proven, even at ISO 3200 both cameras produce useable images, despite some loss of detail as expected at such high ISO settings. Who would have dreamed of getting such high ISO results in the film era?

07-10-2009, 10:20 PM	#4
nostatic Veteran Member Join Date: Feb 2008 Location: socal Photos: Gallery Posts: 1,575	another quick and dirty. K7 vs K20d, 50-135* at 50mm. Crappy low light, f2.8, iso 1600, 1/4-1/5s shutter speed. Shot raw and developed in Aperture2. k7 is -0.3ev. k20 - no correction k7 - no correction k20 AWB correction (basically click a button) k7 AWB correction k20 crop of AF point k7 crop of AF point

07-10-2009, 10:35 PM	#5
PentaxPoke Veteran Member Join Date: Jan 2008 Location: Oklahoma Posts: 1,411 Original Poster	Thanks for posting those static. They really add to the thread: Mine shows default out-of-the-camera results while holding exposure constant, and yours shows the WB constant processed from RAW. I noticed you said that the K-7 was -0.3ev. Was that to try and equalize the exposure differences between the two sensors? Your crops are also very interesting. The K-7 shows more noise, but shows significantly more detail, like the grain of the wood, and the ridges of that white cup. I am wondering now if the K20d by default, has more NR? Even if the user NR is "off", there still is noise reduction in the image processing of any camera.

07-10-2009, 10:47 PM	#6
nostatic Veteran Member Join Date: Feb 2008 Location: socal Photos: Gallery Posts: 1,575	I have the k7 at -0.3 because earlier in the day I was noticing that 0ev was a little "hot" for my tastes. It is a little dark in this photo and 0ev would have been closer to the K20d under these conditions I think. That said I agree with your comments. What I'm seeing is more "noise" and more detail from the K7. For what I shoot and what I'm looking for, I actually like that combination a lot. I tend to go high iso and output b&w. Any sort of NR ends up looking like smears when I work the file. The k7 seems to put out a lot more of a rough grain at high iso. Here are the crops with some sharpening, contrast increase but no definition increase or highlight/shadow tweak.

07-10-2009, 11:05 PM	#7
Raybo Veteran Member Join Date: Dec 2007 Posts: 872	Whatever that white thing is looks "whiter" on the K-7. I'm still wondering if the WB is equal? K-7 image looks to be a bit larger IMHO.....

07-10-2009, 11:07 PM	#8
Raybo Veteran Member Join Date: Dec 2007 Posts: 872	Originally posted by nostatic I have the k7 at -0.3 because earlier in the day I was noticing that 0ev was a little "hot" for my tastes. It is a little dark in this photo and 0ev would have been closer to the K20d under these conditions I think. That said I agree with your comments. What I'm seeing is more "noise" and more detail from the K7. For what I shoot and what I'm looking for, I actually like that combination a lot. I tend to go high iso and output b&w. Any sort of NR ends up looking like smears when I work the file. The k7 seems to put out a lot more of a rough grain at high iso. Here are the crops with some sharpening, contrast increase but no definition increase or highlight/shadow tweak. You used different lenses........................Right?

07-10-2009, 11:22 PM	#9
PentaxPoke Veteran Member Join Date: Jan 2008 Location: Oklahoma Posts: 1,411 Original Poster	In my set, the lenses are the same. I used the DA70 ltd.

07-10-2009, 11:33 PM	#10
Raybo Veteran Member Join Date: Dec 2007 Posts: 872	Originally posted by PentaxPoke In my set, the lenses are the same. I used the DA70 ltd. Something is amiss..................the second set of images is a tad bigger.

07-10-2009, 11:36 PM	#11
Raybo Veteran Member Join Date: Dec 2007 Posts: 872	My bad PP! Your images are okee dokee, nostatic's images are a bit off. Sorry, Ray

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07-10-2009, 11:44 PM	#12
nostatic Veteran Member Join Date: Feb 2008 Location: socal Photos: Gallery Posts: 1,575	same lens. Roughly the same position but it is handheld so there is a little difference. Shot raw and processed with one-click AWB in Aperture. The crops are roughly the same amount of area but not identical. Sorry, but I don't do the rigorous, scientifically controlled tests as I don't shoot that way in real life. This approximates the type of conditions I'd normally use (handheld, low light). And I'm lazy.

07-10-2009, 11:56 PM	#13
robgo2 Veteran Member Join Date: Jan 2007 Location: New Mexico Photos: Albums Posts: 1,125	Originally posted by PentaxPoke Your crops are also very interesting. The K-7 shows more noise, but shows significantly more detail, like the grain of the wood, and the ridges of that white cup. I am wondering now if the K20d by default, has more NR? Even if the user NR is "off", there still is noise reduction in the image processing of any camera. In these examples, the top of the bottle shows more detail in the K-7 shot, because it is in perfect focus, while the K-20D shot is not. I don't know if sharp focus makes noise more apparent, but underexposure does. It looks to be more than -0.3EV, but I am not the one doing the measurement. Rob

07-11-2009, 12:10 AM	#14
nostatic Veteran Member Join Date: Feb 2008 Location: socal Photos: Gallery Posts: 1,575	Originally posted by robgo2 In these examples, the top of the bottle shows more detail in the K-7 shot, because it is in perfect focus, while the K-20D shot is not. I don't know if sharp focus makes noise more apparent, but underexposure does. It looks to be more than -0.3EV, but I am not the one doing the measurement. Rob -0.3 is what was set on the camera and shows in exif for the k7. As for AF, both shot with the same admittedly half-assed procedure but that might also say something about the AF capabilities of the two bodies. But it seems to be fairly consistent - the K7 and K20d files have a different "look" at high iso.

07-11-2009, 12:12 AM	#15
jstevewhite Veteran Member Join Date: Mar 2009 Location: Midwest Photos: Gallery Posts: 1,407	Originally posted by robgo2 In these examples, the top of the bottle shows more detail in the K-7 shot, because it is in perfect focus, while the K-20D shot is not. I don't know if sharp focus makes noise more apparent, but underexposure does. It looks to be more than -0.3EV, but I am not the one doing the measurement. Rob As nostatic said: "another quick and dirty. K7 vs K20d, 50-135* at 50mm. Crappy low light, f2.8, iso 1600, 1/4-1/5s shutter speed. Shot raw and developed in Aperture2. k7 is -0.3ev." This is the 50-135 DA. It's sharp* on the K20D. I think at those shutter speeds we probably have some camera motion involved. The K20D shot is either OOF as you said, or blurred by motion - quite possible at 1/4 -1/5 second.