getting the most noise free high iso from k7

opiedog · 03-24-2010, 07:50 AM

well, i played around with ISO3200 on my k7 last night and was surprised that the exposure was actually shorter than indicated by my kx.

interstingly enough, the "correct" exposure yielded an image with pronounced noise. so i tried EV+1 (which now matched my kx's exposure) and voila, a much, much cleaner image (jpg straight out of the camera)

i thought that the K7 should expose longer, not shorter as widely documented by others.

i'll post those images tonight.

GoremanX · 03-24-2010, 09:18 AM

Originally posted by RBellavance

Hmmm, care to elaborate on that, please ? What do you use for versioning ?

I don't use anything for versioning, I just use UFraw itself. Unfortunately, that means I can only use UFraw's features in a "non-destructive" way (and I use the term very loosely here), things like sharpening aren't available yet. I tend to use UFraw in standalone mode for the most part, not as a Gimp import plugin.

When I'm processing a RAW file with UFraw, on the Save tab, I have "Create ID file" set to "Also". So when I save a resulting image after selecting my settings, UFraw creates a .ufraw file alongside the JPG or TIF file. Opening that .ufraw file opens up UFraw with the same RAW original file and the same settings pre-loaded.

So I can do my basic processing (exposure compensation, white balance, etc.), save it as a pair of jpg+ufraw files (say, image-original.jpg + image-original.ufraw), then open up the .ufraw and continue editing differently. That one I can save as something else (image-saturated.jpg + image-saturated.ufraw). Then I can go back to the first .ufraw file and go in another direction instead (image-grayscale.jpg + image-grayscale.ufraw, or image-cropped.jpg + image-cropped.ufraw). And so on, and so forth. Everytime I save as a new filename, I'm saving a new jpg file, but I'm also saving a new .ufraw file which allows me to step back to that editing stage with a pristine RAW file and all my settings saved. Then I can use a simple image viewer (like Gwenview) to flip through the resulting pictures until I find the one I prefer, open up that picture's .ufraw file, and send it straight to Gimp without having to go through an intermediate file format. There I can do sharpening and stuff.

Sure, it's not elegant like Lightroom, but it works for me. I'd love to propose some simple features on the UFraw mailing list to make this workflow more efficient, but I don't want to add to the dev's burdens right now, I'd rather see the lensfun stuff get ironed out properly (and perhaps some built-in sharpening get added) before I bother them with my silly ideas.

RBellavance · 03-24-2010, 09:32 AM

Originally posted by GoremanX

So I can do my basic processing (exposure compensation, white balance, etc.), save it as a pair of jpg+ufraw files (say, image-original.jpg + image-original.ufraw), then open up the .ufraw and continue editing differently. That one I can save as something else (image-saturated.jpg + image-saturated.ufraw).

Gotcha, thanks !

I've used UFRaw almost exclusively as a Gimp plug-in so far, so I have not played much with .ufraw files. But your strategy sounds good to me.

dlacouture · 03-24-2010, 09:48 AM

From experience, the k7 (and the k20 and k10 before it, don't know for other pentaxes) underexposes under tungsten...
I use a +1Ev comp (by aperture or speed, not iso!) under tungsten, and have much better results, without blown highlights.

Now, for really clean high-iso shots, I'll definitively invest in LR3 for my post-processing needs! Noise Reduction simply rocks in this version, and my K7's 6400 iso shots looks like they came from a Kx!

Ira · 03-24-2010, 10:00 AM

According to the documentation, it's supposed to kick in AT the number, not above it.

GoremanX · 03-24-2010, 10:13 AM

Originally posted by Ira

According to the documentation, it's supposed to kick in AT the number, not above it.

The only documentation I've found (in my K-7 manual) states the following:

Page 92:
"You can change the sensitivity at which to activate Noise Reduction in [20. High-ISO NR Start Level] in the [C Custom Setting 3] menu (p. 86)."

Page 86:
"High-ISO Noise Reduction is activated when shooting with a higher sensitivity than the set sensitivity."

I'm not sure what documentation you're referring to.

Ira · 03-24-2010, 10:28 AM

I misspoke twice, because I was referring to the KX, which I thought would be the same.

And looking at the menu, it does indeed say "above."

**jpzk** · 03-24-2010, 10:45 AM

Nice to see I am finding answers to questions I have not thought of!

Now that I know how this NR thing works on my K7.... the settings, that is ....
can someone actually CONFIRM that this NR will automatically kick in at ISO3200 only, when shooting RAW,
and that there is not much or no NR at all done by the camera at ISO 1600 or less, as long as you shoot RAW ...

sorry, lost the question mark when I type ... gives me this: ^ instead!

JP

GoremanX · 03-24-2010, 10:57 AM

Originally posted by jpzk

Nice to see I am finding answers to questions I have not thought of!

Now that I know how this NR thing works on my K7.... the settings, that is ....
can someone actually CONFIRM that this NR will automatically kick in at ISO3200 only, when shooting RAW,
and that there is not much or no NR at all done by the camera at ISO 1600 or less, as long as you shoot RAW ...

Honestly, I'm not sure how we can confirm or deny this claim. Since there's no way to have a RAW file at ISO 3200 that doesn't have noise reduction, we have nothing to compare it to. I'm sure there's some technical reason why GordonBGood made that claim, but I'm not aware what it is.

Originally posted by jpzk

sorry, lost the question mark when I type ... gives me this: ^ instead!

Your keyboard is set to English/US. The question mark is found at the bottom-right, where the é key is. You need to hold shift while pressing that key. (consequently, you've lost the é key). Switch back to a French/CA keyboard layout to put the keys back where they belong.

dlacouture · 03-24-2010, 12:54 PM

Originally posted by GoremanX

Since there's no way to have a RAW file at ISO 3200 that doesn't have noise reduction, we have nothing to compare it to. I'm sure there's some technical reason why GordonBGood made that claim, but I'm not aware what it is.

Well, on the DxO site, there is an explanation to this. In fact, it can be found by using some mathematical models analyzing the noise... Cannot explain more, but that was a really interesting reading.

Here it is : DxO - Noise reduction

Ira · 03-24-2010, 01:16 PM

On the Kx, i think it automatically kicks in at 3200 whether you want it or not, but you can still choose the level amongst three choices.

My high iso start pref is set for 800, which means mine kicks in at 1600, and I have it set to medium.

But maybe I should change it to low.

GoremanX · 03-24-2010, 01:30 PM

Originally posted by Ira

My high iso start pref is set for 800, which means mine kicks in at 1600, and I have it set to medium.

Wow, you actually restrict yourself that much on purpose? I have ISO 1000 and 1250 between 800 and 1600.

Custom Function #2: Sensitivity Steps (I have it set to "as EV")

Even the K-x has this option. That way you get the full spectrum of ISO choices instead of only bumping it by full stops. In my case, since EV steps is set to 1/3 steps (Custom Function #1), that means I end up with 1/3 ISO steps too.

Ira · 03-24-2010, 02:28 PM

Originally posted by GoremanX

Wow, you actually restrict yourself that much on purpose? I have ISO 1000 and 1250 between 800 and 1600.

Custom Function #2: Sensitivity Steps (I have it set to "as EV")

Even the K-x has this option. That way you get the full spectrum of ISO choices instead of only bumping it by full stops. In my case, since EV steps is set to 1/3 steps (Custom Function #1), that means I end up with 1/3 ISO steps too.

Really? I had no idea those two settings were connected. I guess I didn't notice the ISO changes when I changed the EV steps.

Thanks for THAT info!

And for those newbies who are nubier than me:

Take notes!!!!!!!!!!'n

Ira · 03-24-2010, 02:37 PM

Originally posted by GoremanX

Wow, you actually restrict yourself that much on purpose? I have ISO 1000 and 1250 between 800 and 1600.

Custom Function #2: Sensitivity Steps (I have it set to "as EV")

Even the K-x has this option. That way you get the full spectrum of ISO choices instead of only bumping it by full stops. In my case, since EV steps is set to 1/3 steps (Custom Function #1), that means I end up with 1/3 ISO steps too.

Well gee, THAT was hard to change, huh?

On the kx, you select "As EV steps" to mirror your EV steps. The other option, which I was using, is obviously the default one--"EV Step," which gives you full stops.

Thanks AGAIN! THIS was an important lesson!!!

GoremanX · 03-24-2010, 02:38 PM

Originally posted by Ira

I guess I didn't notice the ISO changes when I changed the EV steps.

You wouldn't have noticed, the "full" ISO steps stay the same regardless of whether you're using 1/2 or 1/3 steps. The series of ISO sensitivities goes like this:

In 1/3 EV steps:
100 - 125 - 160 - 200 - 250 - 320 - 400 - 500 - 640 - 800 - 1000 - 1250 - 1600 - 2000 - 2500 - 3200 - 4000 - 5000 - 6400

In 1/2 EV steps:
100 - 140 - 200 - 280 - 400 - 560 - 800 - 1100 - 1600 - 2200 - 3200 - 4500 - 6400

(the full ISO steps are bolded)

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03-24-2010, 07:50 AM	#16
opiedog Inactive Account Join Date: Jan 2008 Location: NC Posts: 787 Original Poster	well, i played around with ISO3200 on my k7 last night and was surprised that the exposure was actually shorter than indicated by my kx. interstingly enough, the "correct" exposure yielded an image with pronounced noise. so i tried EV+1 (which now matched my kx's exposure) and voila, a much, much cleaner image (jpg straight out of the camera) i thought that the K7 should expose longer, not shorter as widely documented by others. i'll post those images tonight.

03-24-2010, 09:18 AM	#17
GoremanX Veteran Member Join Date: Dec 2009 Location: Georgia, VT Photos: Albums Posts: 1,657	Originally posted by RBellavance Hmmm, care to elaborate on that, please ? What do you use for versioning ? I don't use anything for versioning, I just use UFraw itself. Unfortunately, that means I can only use UFraw's features in a "non-destructive" way (and I use the term very loosely here), things like sharpening aren't available yet. I tend to use UFraw in standalone mode for the most part, not as a Gimp import plugin. When I'm processing a RAW file with UFraw, on the Save tab, I have "Create ID file" set to "Also". So when I save a resulting image after selecting my settings, UFraw creates a .ufraw file alongside the JPG or TIF file. Opening that .ufraw file opens up UFraw with the same RAW original file and the same settings pre-loaded. So I can do my basic processing (exposure compensation, white balance, etc.), save it as a pair of jpg+ufraw files (say, image-original.jpg + image-original.ufraw), then open up the .ufraw and continue editing differently. That one I can save as something else (image-saturated.jpg + image-saturated.ufraw). Then I can go back to the first .ufraw file and go in another direction instead (image-grayscale.jpg + image-grayscale.ufraw, or image-cropped.jpg + image-cropped.ufraw). And so on, and so forth. Everytime I save as a new filename, I'm saving a new jpg file, but I'm also saving a new .ufraw file which allows me to step back to that editing stage with a pristine RAW file and all my settings saved. Then I can use a simple image viewer (like Gwenview) to flip through the resulting pictures until I find the one I prefer, open up that picture's .ufraw file, and send it straight to Gimp without having to go through an intermediate file format. There I can do sharpening and stuff. Sure, it's not elegant like Lightroom, but it works for me. I'd love to propose some simple features on the UFraw mailing list to make this workflow more efficient, but I don't want to add to the dev's burdens right now, I'd rather see the lensfun stuff get ironed out properly (and perhaps some built-in sharpening get added) before I bother them with my silly ideas.

03-24-2010, 09:32 AM	#18
RBellavance Veteran Member Join Date: Nov 2006 Location: Near Montréal, Canada Photos: Gallery Posts: 1,716	Originally posted by GoremanX So I can do my basic processing (exposure compensation, white balance, etc.), save it as a pair of jpg+ufraw files (say, image-original.jpg + image-original.ufraw), then open up the .ufraw and continue editing differently. That one I can save as something else (image-saturated.jpg + image-saturated.ufraw). Gotcha, thanks ! I've used UFRaw almost exclusively as a Gimp plug-in so far, so I have not played much with .ufraw files. But your strategy sounds good to me.

03-24-2010, 09:48 AM	#19
dlacouture Veteran Member Join Date: Jul 2008 Location: Var, South of France Photos: Albums Posts: 1,074	From experience, the k7 (and the k20 and k10 before it, don't know for other pentaxes) underexposes under tungsten... I use a +1Ev comp (by aperture or speed, not iso!) under tungsten, and have much better results, without blown highlights. Now, for really clean high-iso shots, I'll definitively invest in LR3 for my post-processing needs! Noise Reduction simply rocks in this version, and my K7's 6400 iso shots looks like they came from a Kx!

03-24-2010, 10:00 AM	#20
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	According to the documentation, it's supposed to kick in AT the number, not above it.

03-24-2010, 10:13 AM	#21
GoremanX Veteran Member Join Date: Dec 2009 Location: Georgia, VT Photos: Albums Posts: 1,657	Originally posted by Ira According to the documentation, it's supposed to kick in AT the number, not above it. The only documentation I've found (in my K-7 manual) states the following: Page 92: "You can change the sensitivity at which to activate Noise Reduction in [20. High-ISO NR Start Level] in the [C Custom Setting 3] menu (p. 86)." Page 86: "High-ISO Noise Reduction is activated when shooting with a higher sensitivity than the set sensitivity." I'm not sure what documentation you're referring to.

03-24-2010, 10:28 AM	#22
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	I misspoke twice, because I was referring to the KX, which I thought would be the same. And looking at the menu, it does indeed say "above."

03-24-2010, 10:45 AM	#23
jpzk Site Supporter Join Date: Jan 2009 Location: Québec Photos: Gallery \| Albums Posts: 8,251	Nice to see I am finding answers to questions I have not thought of! Now that I know how this NR thing works on my K7.... the settings, that is .... can someone actually CONFIRM that this NR will automatically kick in at ISO3200 only, when shooting RAW, and that there is not much or no NR at all done by the camera at ISO 1600 or less, as long as you shoot RAW ... sorry, lost the question mark when I type ... gives me this: ^ instead! JP

03-24-2010, 10:57 AM	#24
GoremanX Veteran Member Join Date: Dec 2009 Location: Georgia, VT Photos: Albums Posts: 1,657	Originally posted by jpzk Nice to see I am finding answers to questions I have not thought of! Now that I know how this NR thing works on my K7.... the settings, that is .... can someone actually CONFIRM that this NR will automatically kick in at ISO3200 only, when shooting RAW, and that there is not much or no NR at all done by the camera at ISO 1600 or less, as long as you shoot RAW ... Honestly, I'm not sure how we can confirm or deny this claim. Since there's no way to have a RAW file at ISO 3200 that doesn't have noise reduction, we have nothing to compare it to. I'm sure there's some technical reason why GordonBGood made that claim, but I'm not aware what it is. Originally posted by jpzk sorry, lost the question mark when I type ... gives me this: ^ instead! Your keyboard is set to English/US. The question mark is found at the bottom-right, where the é key is. You need to hold shift while pressing that key. (consequently, you've lost the é key). Switch back to a French/CA keyboard layout to put the keys back where they belong.

03-24-2010, 12:54 PM	#25
dlacouture Veteran Member Join Date: Jul 2008 Location: Var, South of France Photos: Albums Posts: 1,074	Originally posted by GoremanX Since there's no way to have a RAW file at ISO 3200 that doesn't have noise reduction, we have nothing to compare it to. I'm sure there's some technical reason why GordonBGood made that claim, but I'm not aware what it is. Well, on the DxO site, there is an explanation to this. In fact, it can be found by using some mathematical models analyzing the noise... Cannot explain more, but that was a really interesting reading. Here it is : DxO - Noise reduction

03-24-2010, 01:16 PM	#26
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	On the Kx, i think it automatically kicks in at 3200 whether you want it or not, but you can still choose the level amongst three choices. My high iso start pref is set for 800, which means mine kicks in at 1600, and I have it set to medium. But maybe I should change it to low.

03-24-2010, 01:30 PM	#27
GoremanX Veteran Member Join Date: Dec 2009 Location: Georgia, VT Photos: Albums Posts: 1,657	Originally posted by Ira My high iso start pref is set for 800, which means mine kicks in at 1600, and I have it set to medium. Wow, you actually restrict yourself that much on purpose? I have ISO 1000 and 1250 between 800 and 1600. Custom Function #2: Sensitivity Steps (I have it set to "as EV") Even the K-x has this option. That way you get the full spectrum of ISO choices instead of only bumping it by full stops. In my case, since EV steps is set to 1/3 steps (Custom Function #1), that means I end up with 1/3 ISO steps too.

03-24-2010, 02:28 PM	#28
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Originally posted by GoremanX Wow, you actually restrict yourself that much on purpose? I have ISO 1000 and 1250 between 800 and 1600. Custom Function #2: Sensitivity Steps (I have it set to "as EV") Even the K-x has this option. That way you get the full spectrum of ISO choices instead of only bumping it by full stops. In my case, since EV steps is set to 1/3 steps (Custom Function #1), that means I end up with 1/3 ISO steps too. Really? I had no idea those two settings were connected. I guess I didn't notice the ISO changes when I changed the EV steps. Thanks for THAT info! And for those newbies who are nubier than me: Take notes!!!!!!!!!!'n

03-24-2010, 02:37 PM	#29
Ira Inactive Account Join Date: Mar 2009 Location: Coral Springs, FL Photos: Gallery \| Albums Posts: 5,216	Originally posted by GoremanX Wow, you actually restrict yourself that much on purpose? I have ISO 1000 and 1250 between 800 and 1600. Custom Function #2: Sensitivity Steps (I have it set to "as EV") Even the K-x has this option. That way you get the full spectrum of ISO choices instead of only bumping it by full stops. In my case, since EV steps is set to 1/3 steps (Custom Function #1), that means I end up with 1/3 ISO steps too. Well gee, THAT was hard to change, huh? On the kx, you select "As EV steps" to mirror your EV steps. The other option, which I was using, is obviously the default one--"EV Step," which gives you full stops. Thanks AGAIN! THIS was an important lesson!!!

03-24-2010, 02:38 PM	#30
GoremanX Veteran Member Join Date: Dec 2009 Location: Georgia, VT Photos: Albums Posts: 1,657	Originally posted by Ira I guess I didn't notice the ISO changes when I changed the EV steps. You wouldn't have noticed, the "full" ISO steps stay the same regardless of whether you're using 1/2 or 1/3 steps. The series of ISO sensitivities goes like this: In 1/3 EV steps: 100 - 125 - 160 - 200 - 250 - 320 - 400 - 500 - 640 - 800 - 1000 - 1250 - 1600 - 2000 - 2500 - 3200 - 4000 - 5000 - 6400 In 1/2 EV steps: 100 - 140 - 200 - 280 - 400 - 560 - 800 - 1100 - 1600 - 2200 - 3200 - 4500 - 6400 (the full ISO steps are bolded)