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08-24-2009, 02:23 PM   #31
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QuoteOriginally posted by wll Quote
What is your technique for noise removal, you did a great job !


wll
I'll go through the steps later, when I get home.

08-24-2009, 02:35 PM   #32
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QuoteOriginally posted by attack11 Quote
not true at all. if you read up on the sensors (i don't know about the k7), they have a 'push' limit before you start degrading the image. the k10d for example can do 2 stops, i believe the k20d is only 1-1.5 stops.

these aren't full frame cameras, keep your iso below 800 if you want details.

histograms are generally useless. they're an output graph, not an input graph.
Ease up, there - it's not all that useless.
As a guide it's helpful to ascertain adequate exposure within reason.
Knowing how to interpret a histogram makes it a more useful tool - otherwise it's just a funky graph one can use to show off to others...
08-24-2009, 02:40 PM   #33
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QuoteOriginally posted by filorp Quote


and then again - who makes you set 0 exposure at iso 800? Sorry if i didn't get something - you can call me bone-head, but please explain.... if the conditions makes you to set iso3200, 1/5s, f4, EV+2 why not to set it at iso 800 and EV0 if you at both cases would obtain similar histogram on the final picture? Am i wrong?
You are not a bonehead at all. Asking questions is what the forum is for....it is much better than being damn ceratin of the wrong things and refuse to change.

I will not get the same histogram at both cases. At iso3200, 1/5, F4, EV+2 in Av mode gives the proper exposure and the perfect histogram in camera. If I do iso 800 and 0 EV with the same shutter and aperture then the scene will be 4 stops underexposed (2 for the iso, and 2 for the EV), and the histogram will look very different and had to be recovered later.......(I am done at work, I'll continue when i go home)
08-24-2009, 03:27 PM   #34
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QuoteOriginally posted by pcarfan Quote
You are not a bonehead at all.
Apparently i am... i'v missed the point thoroughly... it was supposed to be just the way about - a was thinking about situation: conditions according to indication of histogram: for instance M mode - 1st shoot: iso 800, 1/10s, f4, EV0 - 2nd shoot: settings of camera: iso 3200, 1/10s,f4, EV+2 - results: you have exactly the same indications on camera light meter; 2nd picture would be brighter so you need to lower 2EV during postprocessing; 1st is to dark so you increase EV +2 result is the same! exactly the same....!!!! So what's the point? One cannot cheak the light....

08-24-2009, 04:01 PM   #35
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QuoteOriginally posted by filorp Quote
Apparently i am... i'v missed the point thoroughly... it was supposed to be just the way about - a was thinking about situation: conditions according to indication of histogram: for instance M mode - 1st shoot: iso 800, 1/10s, f4, EV0 - 2nd shoot: settings of camera: iso 3200, 1/10s,f4, EV+2 - results: you have exactly the same indications on camera light meter; 2nd picture would be brighter so you need to lower 2EV during postprocessing; 1st is to dark so you increase EV +2 result is the same! exactly the same....!!!! So what's the point? One cannot cheak the light....
Sorry, I am not totally understanding what you are saying. But, exposure to the right is the correct exposure, I am not reducing the exposure in post processing, just getting it right in the first place. Does this help?, I am not reducing exposure afterward.


What do you mean by "iso800, 1/10s, F4 EV0 and iso 3200, 1/10, F4 and EV+2 have exactly the same indications on camera light meter". Are you saying both those will give the same histogram. No, they will not. Like you say next, the first one will be two stops darker than the second, assuming identical scene, with different areas metered.

Last edited by pcarfan; 08-24-2009 at 04:29 PM.
08-24-2009, 04:20 PM   #36
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filorp

These are the histograms prior to any post-processing. So, they are ideal except for some clipping in the second one.



08-24-2009, 04:27 PM   #37
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QuoteOriginally posted by Gooshin Quote
you are right to a point, however keep in mind that "EV" compensation is basically you telling the camera

"whatever you are metering, you are wrong, so add a stop"

if you just set it to 800 and Ev 0, you will be one stop undre exposed still.

however, should this be used in manual mode, perhaps then you really are better off using lower ISO.
In manual mode the scene would definitely need 3200 iso for proper exposure given the aperture and shutter. iso 800 with the same shutter and aperture will under expose the scene by two stops and would need to be recovered PP. Recovering in PP will add more noise.
08-24-2009, 04:58 PM   #38
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QuoteOriginally posted by attack11 Quote
not true at all. if you read up on the sensors (i don't know about the k7), they have a 'push' limit before you start degrading the image. the k10d for example can do 2 stops, i believe the k20d is only 1-1.5 stops.

these aren't full frame cameras, keep your iso below 800 if you want details.

histograms are generally useless. they're an output graph, not an input graph.
On the internet sometimes things don't come across the right way, I will give you the benefit of the doubt and respond. But, if infact you are saying you know it all and are not interested in proper discussion then please stop reading.

First of all, no one needs to read up on sensor technology to understand any of this. But, it sure sounds cool saying it that way though, I will give you that.

The two stop advantage with the K10D in general terms is true. Of course the full two stop (or there abouts) advantage will be gained by using RAW and using a good RAW converter. Jpeg will give much less. Also, better RAW converters give better results. This two stop advantage is in gaining extra dynamic range, combined with both shadow and highlight recovery. But, if you think this shadow recovery is without increasing noise, then you are mistaken. There is no free lunch here. Yes, you can recover detail. but it is always by gaining noise. Also, it has been shown that in most cameras and in most situations pushing exposure in PP ads more noise than increasing iso in camera and exposing it right in the first place. Recovering highlights will affect color as some colors are clipped at different points.

Generalizations are ok, but they are not always true. Of course, Iso 800 is better than iso 3200. Lower iso is always better, if and only if the exposure is correct. But, your generalization of using only 800 or less with APS-C sensor is the reason these images are posted in the first place. Yes, higher the iso less the sharpness, but to me the severe reduction in DR with increasing iso is more troublesome. It goes without saying that it is best to use the lowest iso possible given proper exposure. But, as these examples show, the sharpness is not all that bad even at high iso like 3200 with the k-7. There are higher iso settings than 800 even in APS-C cameras, so why not look into it a little deeper and see what they can do, and not be bogged down by self-built restrictions of only wanting to use iso 800 or less.

Histograms are almost everything, the exact metering mode and EV compensation means nothing. Other than a light meter, the best way to evaluate exposure while shooting is the histogram. Again throwing things like histograms are output graph vs input graph sure sounds cool, but sadly it has no practical relevance in this discussion. Of course hitsograms show output and not input they afterall made form the JPEG file, and RAW images have no histograms, the histogram you see even when shooting RAW-only is the jpeg histogram. But, why is this relevant here? Histograms are the best way to evaluate exposure while shooting other than to carry around a light meter., whether it be an output graph or input graph.


Last edited by pcarfan; 08-24-2009 at 06:33 PM.
08-24-2009, 04:58 PM   #39
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QuoteOriginally posted by filorp Quote
Apparently i am... i'v missed the point thoroughly... it was supposed to be just the way about - a was thinking about situation: conditions according to indication of histogram: for instance M mode - 1st shoot: iso 800, 1/10s, f4, EV0 - 2nd shoot: settings of camera: iso 3200, 1/10s,f4, EV+2 - results: you have exactly the same indications on camera light meter; 2nd picture would be brighter so you need to lower 2EV during postprocessing; 1st is to dark so you increase EV +2 result is the same! exactly the same....!!!! So what's the point? One cannot cheak the light....
I see where you're getting at but this is not the issue here.
Your discussion is based on exposure equivalence - see these threads:
https://www.pentaxforums.com/forums/general-photography-techniques-styles/630...ake-sense.html
https://www.pentaxforums.com/forums/general-photography-techniques-styles/617...ose-right.html
https://www.pentaxforums.com/forums/general-photography-techniques-styles/615...tal-shots.html
and there are many more - this has been a highly discussed topic.

Where we're getting at is that the 'right' exposure (according to the artist) may need user intervention as the camera cannot work out what the artist is trying to expose for. Camera just says this should be 18% grey, and we say no, it really should look more like 50% - so the user adjusts EV. Then we're saying that once this is right, at ISO 3200, the images out of the K-7 are very acceptable - no more, no less.
08-24-2009, 05:08 PM   #40
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QuoteOriginally posted by Ash Quote
Ease up, there - it's not all that useless.
As a guide it's helpful to ascertain adequate exposure within reason.
Knowing how to interpret a histogram makes it a more useful tool - otherwise it's just a funky graph one can use to show off to others...
Thanks....

But, I wouldn't say "it is not all that useless"...rather given the limitations histograms are the most useful.
08-24-2009, 05:51 PM   #41
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QuoteOriginally posted by ivoire Quote
Excellent job and post. This should help me with my high iso shots... i'd be very grateful if you would post your noise reduction technique also. This is some of the best high iso tweaking i've seen
QuoteOriginally posted by wll Quote
What is your technique for noise removal, you did a great job !


wll

I use noisware professional plug-in for photoshop. It is ~$70, but IMO worth it.

-With this software, you can choose how much noise you want to remove form the shadows, how much you want to remove form the mid tones and how much you want to remove from the highlights. (My reason for picking this program)

-Also, you can choose to remove noise form certain colors as well (I don't use this but I will find use with certain images).

-Then you can choose how much detail you want to keep without introducing more noise. You choose the proper sharpness and contrast (maximum possible without adding more noise). You can also choose the level of edge smoothing .

- You can choose to reduce noise in the different frequencies too. The program analyzes the image and tells you which frequency has the most noise so you can choose to reduce more noise in those frequencies that has the most noise.

If you don't want to mess around with all this, then there is a pull down menu with varying noise reduction options with all this settings chosen for you. So you can pick one and the program will do it for you.

The individual controls may sound complex but very easy to use. They are done with sliders and you see changes in real time.

So, open the file, choose the luminance and chroma noise reduction amount to taste. Then go to tonal range and pick no noise reduction for highlights and medium for midtones (need to play around and see the image - look at areas with most noise and areas with fine detail) and choose close to max. reduction for shadows (again, check the noisy dark areas and fine detail areas and move the slider to taste). You can change the percentage of luminance noise and chroma noise as well as you do this. So, you go back and forth with these sliders constantly checking the dark zones for noise and fine detail areas for loss of detail.

Then you can change sharpness, contrast to taste as well. Going back and forth with these sliders until the darkest areas have most noise gone and yet the fine detail, area has detail left.

choosing noise reduction for various frequencies don't show much change. but as the program analyzes this, I just see the graph and reduce more in the frequencies that show the most noise.

Then I go to edge smoothing and see a sharp line in a dark area and chose the correct setting.

I am not that great at putting things into word as instructions. But, hopefully this helps.
08-24-2009, 06:20 PM   #42
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QuoteOriginally posted by pcarfan Quote
I use noisware professional plug-in for photoshop. It is ~$70, but IMO worth it.
wow alot of control there.. i'm using rawtherapee now as it seems to do better for K-7 DNG Raw than PS CS3 for me

08-24-2009, 07:13 PM   #43
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Here is a screen capture of noiseware pro, with some notes for clarification.

08-24-2009, 08:29 PM   #44
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0.3 seconds?

Thanks for the test. It probably is just my usage, but my only use for high ISO is to allow me a fast shutter speed.

I find that the situation calling for 0.3s ISO 3200 would not be different than that of 1 s at ISO 1000 because both are equally meaningless handheld (again, it's my shooting habit - I find myself needing to freeze action more, and exposures of 0.3 s and 1 s usually don't make any difference to me). When I put the camera on a tripod, it's usually the situation where I don't need to freeze a motion (except for macros).

Do you find yourself in this situation more, or like I do, try to use high ISO to achieve shutter speeds that allow hand-held shots? In this case, a test with Tv=1/focal-length would be more realistic, even if it results in an underexposed picture that needs pushing - that is, if you turn up the ISO facing a choice of higher noise vs motion blur, which one would you take?

I'd take the noise over any motion blur. Just my preference.
08-24-2009, 10:15 PM   #45
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Yes, that's true wolfier, but I don't think that was the purpose of the test.
Out in the field, you want to know that going to ISO 3200 to allow you to hand hold the shot will not give you an unacceptably noisy exposure. So here we have good evidence that if adequately exposed, an ISO 3200 image has plenty of detail retained to make it useable.
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