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08-25-2009, 12:12 AM   #46
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I often use High ISO in situations where there is still a decent amount of light e.g. late afternoon, but need to keep the shutter speed up to capture a moving object.

So the High ISO usability in fairly decent lighting does have a practical angle to it.

08-25-2009, 04:58 AM   #47
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QuoteOriginally posted by wolfier Quote
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.

True. In dpreview I had mentioned how the 0.3 sec, makes it not applicable to real life situations. I see that I had skipped it here.

However, I think noise at 3200 is noise at 3200, what ever the shutter and aperture may be (with-in limits...not real long exposure). So, it is just a test to see what the noise is at iso3200.

Think of it this way. I wanted to make the room as dark as possible and do the test. If I turned on the table lamp, I could have gotten the shot at iso 3200, f4 and a healthy shutter speed like you would like (will be more applicable to real life situation). Now with that set-up, one might say, the room is not dark enough. Do you see where I am going.

So, given iso 3200 is iso 3200, and the aim of this test is to make the room as dark as possible and use a tripod to see what iso 3200 looks when ETTR, this is the ideal way to go about achieving those aims.

As iso 3200 is iso 3200, one would not gain any more knowledge by testing in a brighter room only to achieve a healthy shutter. It only introduces the notion that iso 3200 was used unnecessarily. Do you agree?

To answer your question. I use high iso exactly like you do, to get a good shutter speed. It is mostly in good light with thew 300mm attached to a 1.4 TC. Or available light indoor shoot where a much higher shutter tahn 1/3 will be required (could never do this with the K10D to my satisfaction, the K-7 handles it like a walk in the park below f2.8). So, an identical situation to the test will never occur in real life. Also, I will always choose noisier shot than a blurry shot exactly like what you say you would do.

P.S. Thank you for the civility in your question.

Last edited by pcarfan; 08-25-2009 at 05:34 AM.
08-25-2009, 05:01 AM   #48
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Interesting results pcarfan, I did some K20D ISO 3200 test shots with no NR and then using Noise Ninja NR. I won't hijack your thread, but I will start a new one and get your opinion on my test results?
08-25-2009, 07:11 AM   #49
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QuoteOriginally posted by Big G Quote
Interesting results pcarfan, I did some K20D ISO 3200 test shots with no NR and then using Noise Ninja NR. I won't hijack your thread, but I will start a new one and get your opinion on my test results?
Would love to see it. My work computer is quite bad, so I will respond later today.

08-25-2009, 08:03 AM   #50
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QuoteOriginally posted by Ash Quote
Probably that it's just easier to see on a black background, although it's still there amongst other colours, just less noticeable.

Wouldn't see it much with whites as the signal's already saturated. Just a guess - would this be right?
Yes, this is the general idea. It's the signal to noise ratio that is important. Basically, the amount of noise produced by shots from a certain camera doesn't change. What changes is where you look for the signal.

It's the same principle as with audio tape. If you record music on a cassette tape, and the music is fairly loud, you can play the tape back at a comfortable volume and not really notice the tape noise. If you record quiet music, what happens? When you play it back, you turn up the volume so you can hear the music better. When you do this, you also hear the tape noise better because at this volume it is audible. Now, wherever the music is the quietest, or where the music pauses altogether, is where you'll really hear the tape noise the best. The louder portions will tend to drown it out.

When you turn up the ISO setting on your camera to get what little light is available, it is like turning up the volume on a tape recorder to hear soft music. The noise is amplified just like the light signal. Wherever there is the least signal, that is, dark areas, is where you will see the noise the best. Where there is more signal, it will tend to "drown out" the noise. Using the camera on a low ISO setting is like keeping the volume down so that louder music will be heard at a comfortable level. The noise is still there, but you're not amplifying it to the point of being seen. You are looking for the image at the much higher point where the signal exists and where the noise is not readily visible. So the amount of noise visible in any given image is all about the signal to noise ratio.
08-25-2009, 08:08 AM   #51
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QuoteOriginally posted by Gooshin Quote
what is it with black and noise

...
or is that the caveat, that the only thing reflected is the noise?
There is no such a thing as "reflected noise". Noise is generated by the camera, not the light source.
08-25-2009, 08:09 AM   #52
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Good analogy - after all it's still an analog input converted to a digital output...
Nicely put.
08-25-2009, 08:18 AM   #53
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Seriously, you've been using Pentax for years and this is a surprise?

Unless i am shooting a black cat against a black wall at 2am in the desert ... i need positive Ev comp.

QuoteOriginally posted by k100d Quote
my concern is only because you have mentioned that you use ETTR technique, which involves overexposing without clipping and then bringing the exposure back down in post which reduces noise.

it is discouraging that you actually had to use +1.7 EV in (matrix metering?) to get an image that bright.

thanks for the tests, the results do look pretty clean.


08-25-2009, 08:22 AM   #54
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QuoteOriginally posted by Alfisti Quote
Seriously, you've been using Pentax for years and this is a surprise?

Unless i am shooting a black cat against a black wall at 2am in the desert ... i need positive Ev comp.
it's only been 1.5 years, any underexposure thread and i know you'll pipe in
08-25-2009, 08:33 AM   #55
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QuoteOriginally posted by pcarfan Quote
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.
i mean - exactly the same amount of light will hit the sensor at both cases so there is no way to expect that the firs option will give you worse picture - 2 stops higher you've said.... but you have obtained it just by pushing the sensor sensitivity, not by increasing the light amount so in my opinion you'v gain nothing... 2 stops higher doesn't equal 2 stop higher it depend what you are doing incres the light or increase sensitivity of the sensor.... actually you haven't even gain faster shutter speed but in some cases you can easy overburn some part of picture.... i have tried it.... SORRY EVERYONE FOR MY ENGLISH!!!!
08-25-2009, 08:49 AM   #56
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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....
One thing that is mixing you up is that you are thinking of exposure compensation backwards (which, depending on your way of looking at it could be interpreted either way, so this is understandable). EV0 at ISO 800 would be equivalent to EV-2 at ISO 3200, not EV+2.

The only way that attention called to the EV setting could have any validity is if he were overexposing the image by two stops in camera with the exposure compensation, and then pulling it back to correct exposure by using -2 stops of post processing exposure compensation (I'd hate to see how much clipping this would have). This is not happening. He is not reducing the exposure by two stops in post, so the EV setting in camera is a non-issue. It's pointless to even bring up.
08-25-2009, 09:34 AM   #57
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QuoteOriginally posted by filorp Quote
i mean - exactly the same amount of light will hit the sensor at both cases so there is no way to expect that the firs option will give you worse picture - 2 stops higher you've said.... but you have obtained it just by pushing the sensor sensitivity, not by increasing the light amount so in my opinion you'v gain nothing... 2 stops higher doesn't equal 2 stop higher it depend what you are doing incres the light or increase sensitivity of the sensor.... actually you haven't even gain faster shutter speed but in some cases you can easy overburn some part of picture.... i have tried it.... SORRY EVERYONE FOR MY ENGLISH!!!!
-Filorp, it is true that the same amount of light is hitting the sensor and only the sensitivity of the sensor is changed. But, this is the whole point with iso. Increasing iso increase sensitivity. Are you saying having differnet iso sensitivities is pointless and that all cameras should only have the base iso? What else can you mean by that you gain nothing by boosting iso.

- There is no overburn (over-exposure) as you can see in the histogram.

-Also, I am not too sure whether it's been established in this discussion, that exposure is only determined by shutter, aperture and iso. EV has nothing to do with exposure as such, it is just the instruction to the camera on how to come up with the exposure. i.e. EV is just metering instruction to the camera.
08-25-2009, 10:38 AM   #58
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QuoteOriginally posted by pcarfan Quote
Increasing iso increase sensitivity.
you dont phisycally increase sensitivity af the sensor but just the way it interprets the signal, so...
QuoteOriginally posted by pcarfan Quote
Are you saying having differnet iso sensitivities is pointless and that all cameras should only have the base iso? What else can you mean by that you gain nothing by boosting iso.
but we all have just the base iso.... and bunch of software which is deceiving us pretending that we have something different the main question is haw much light was cought by the sensor (answ: 1/5s and f4). I'm not just theorizing.... the same results we obtain with iso 800 pushed at silkypix, im shure about it... i'm not questioning the fact you'v showed i mean picture on high iso look better when you endeavour to get a proper exp acc to histogram

Last edited by filorp; 08-25-2009 at 10:49 AM.
08-25-2009, 10:47 AM   #59
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QuoteOriginally posted by pcarfan Quote
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.
and i'm the know it all? if you say so. you're talking about a reflective meter, not an incident meter. high iso sucks on pentax cameras, you can't get around it. iso3200 looks just as good on practically everything since the *ist dl, it all depends on the person using the camera.

the rest is just hilarious.

Last edited by attack11; 08-25-2009 at 10:52 AM.
08-25-2009, 11:09 AM   #60
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QuoteOriginally posted by filorp Quote
you dont phisycally increase sensitivity af the sensor but just the way it interprets the signal, so...

but we all have just the base iso.... and bunch of software which is deceiving us pretending that we have something different the main question is haw much light was cought by the sensor (answ: 1/5s and f4). I'm not just theorizing.... the same results we obtain with iso 800 pushed at silkypix, im shure about it... i'm not questioning the fact you'v showed i mean picture on high iso look better when you endeavour to get a proper exp acc to histogram
Are you saying iso 800 (underexposed by two stops), and recovered by pushing it two stops in post processing will get better results than shooting at iso 3200 and not needing any exposure change in post processing?

Is this true for iso 400 as well. If the proper exposure is obtained form iso 400, is it better to shoot at iso 100 and be underexposed by two stops and then recovering in the post process.

Thanks.
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