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07-03-2012, 07:24 PM   #16
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Falk did some response test and the response curve was different with ISO80 then with ISO100

Besides why would only pentax use ISO80 if it's standard comes with the sensor, it doesnt make sense.

Also look at other tests with dynamic range, you'll see the DR goes deeper into the shadows with pentax and less in the highlights compared to others so ISO80 might indeed be ISO100 but brought back in exposure and using the response what other use for ISO100.
Basicly creating a natural expose to the right situation.

For fun compare the graphs of the K5 and D7000 on imaging resource for a bit.


Last edited by Anvh; 07-03-2012 at 07:45 PM.
07-03-2012, 07:42 PM   #17
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Its just one of those mysteries of the universe.

Just use the camera more
07-03-2012, 08:22 PM   #18
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i never try to use iso 80, but IMHO i think just a little difference in DR.
07-04-2012, 03:55 AM   #19
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Sensor ISO isn't the same thing as film ISO, they just use the same measurement scales. In film it is the emulsion formulation's sensitivity to light - how quickly the silver salts will react to a given light level. On the sensor it is the amount of analog signal amplification: ISO 100 = little amplification, ISO 12,800 = a LOT of amplification. Any time you amplify a signal the amplification circuitry introduces noise, and that's why higher ISO settings result in higher noise levels in the image - essentially errors in signal strength.

The sensor is designed and spec'd by Sony to work from ISO 100 to ISO 12,800. The "extended" ranges offered by most camera manufacturers are the result of their customized amplification circuitry that is attached to the sensor, and depending on how "clean" these circuits are the extended ranges will give you more or less dynamic range and noise. Pentax seems to have very clean amplification, which is why you rarely see any chrominance noise below ISO 800 and why the K-5 is known for its excellent low luminance noise levels.

BUT - I have always wondered if software like Lightroom plays nice with extended ranges when processing RAW files. What does "ISO 80" mean to Lightroom? Does the ISO level matter to the software at all, or is it just dealing with 14-bit numbers and it doesn't care? Anyway, it's one of those features of the K-5 I haven't really investigated yet, since the quality of ISO 100 for daylight landscapes is so damned good, and that's mostly what I shoot. (I've had mine since Feb. and am just now feeling I have mastered the touchy/quirky AF system - the camera's only real rough spot aside from it's somewhat quirky mirror lockup system, IMHO).

07-04-2012, 06:27 AM   #20
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There are not many scenes where you actually take full advantage of iso80 instead of using iso100.
07-04-2012, 06:41 AM   #21
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I always use ISO 80, if it does not harm IQ, then I just use it.
the most useful case might be for off camera flash
simetimes to get the best exposure your shutter speed might be like 1/200 to 1/250 by using iso100. so it is slightly faster than 1/180, therefore can not trigger flash remotely
but by using iso 80, we can get shutter speed down to 1/180..

Last edited by liukaitc; 07-04-2012 at 06:46 AM.
07-04-2012, 07:00 AM   #22
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Has anyone used '80@16mp's?

Ron,

What type of scene would take advantage?
07-04-2012, 07:10 AM   #23
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QuoteOriginally posted by Anvh Quote
Falk did some response test and the response curve was different with ISO80 then with ISO100
Can you please provide a pointer?

QuoteOriginally posted by Anvh Quote
Besides why would only pentax use ISO80 if it's standard comes with the sensor, it doesnt make sense.
I offered a reason why Pentax may have "hidden" the ISO 80 setting in the extended range. Maybe other manufacturers have omitted it altogether for the same (or different) reason.

BTW, it is possible that the ISO 80 aren't native and that the corresponding increase in DR is achieved by some dark noise signal processing. Falk seems to have observed something like this with the K-x (although his findings weren't super conclusive in this instance).

But the fact that other manufactures didn't offer ISO 80 and that "ISO 80" is not the default low ISO value for the K-5 do not demonstrate that the above possibility is reality.

QuoteOriginally posted by Anvh Quote
Also look at other tests with dynamic range, you'll see the DR goes deeper into the shadows with pentax and less in the highlights compared to others so ISO80 might indeed be ISO100 but brought back in exposure and using the response what other use for ISO100.
You seem to be referring to DPReview tests and JPG tone curves. Both are irrelevant in this discussion. Note that RAW file DR is just a number, specifying a range. This range refers to a linear response, i.e., there are no shadow or highlight shoulders which could by asymmetrical. This is of course assuming that no low-level sensor trickery is performed, but you'll have to provide some evidence in order to suggest the latter happens.

07-04-2012, 07:44 AM   #24
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QuoteOriginally posted by tabl10s Quote
Has anyone used '80@16mp's?

Ron,

What type of scene would take advantage?
Well looking at the test from DxO: DxOMark - Pentax K-5 you can see different results for SNR - DR - TR - CS (different tabs in measurements). The step in Dynamic Range is with 0,42EV pretty large, so you do get some extra on this.

So you only benefit from that if you scene has a larger dynamic range then can be captured with iso100 and would fit into the iso80 range. So less highlightclipping or dark blacks without structure. The same is for tonal range or colour sensitivity.

For the highlightclipping we also have the tool Dynamic Range Expansion (DRon) (that is a plus of 1 EV for highlights) on our camera. With that you start at either iso160 or iso200 depending on your settings. This gives some help with preventing clipping in the highlights where we have less space (tolerance) then with the darks in our picturescene.

I think when you are looking for extra space in highlights either underexposing and developing RAW at home or DRon will help you more then the step from iso100 to iso80.

With iso160 and DRon:

In bright sun the DRon is helping you more I think. These are also jpg straight out of the camera since I didn't do RAW that weekend. You do loose some of your blacks and that is shown in the shirt, but for the balance in this scene it is probably for the best.

P.S. Don't drool on your computer, just click on the LIKE-button

With iso100:

There is a little highlightclipping (in the shirt) that might even be safed with using iso80, but this was my first walkaround with my K-5 Silver (and FA*85) and I didn't changed the settings yet.

Couldn't find any iso80 picture, but I did use it from time to time.

Last edited by RonHendriks1966; 07-04-2012 at 07:50 AM.
07-04-2012, 08:04 AM   #25
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QuoteOriginally posted by Class A Quote
Can you please provide a pointer?
Will try. had a look at it yesterday on my tablet but couldnt find it so quick.

ps ur right it was the Kx not the k5, sorry...

QuoteQuote:
I offered a reason why Pentax may have "hidden" the ISO 80 setting in the extended range. Maybe other manufacturers have omitted it altogether for the same (or different) reason.

BTW, it is possible that the ISO 80 aren't native and that the corresponding increase in DR is achieved by some dark noise signal processing. Falk seems to have observed something like this with the K-x (although his findings weren't super conclusive in this instance).

But the fact that other manufactures didn't offer ISO 80 and that "ISO 80" is not the default low ISO value for the K-5 do not demonstrate that the above possibility is reality.
yes you did, sorry i missed that but since it's native to the sensor it actually takes more resources to take it out then to leave it in so it still doesnt make sense.


QuoteQuote:
You seem to be referring to DPReview tests and JPG tone curves. Both are irrelevant in this discussion. Note that RAW file DR is just a number, specifying a range. This range refers to a linear response, i.e., there are no shadow or highlight shoulders which could by asymmetrical. This is of course assuming that no low-level sensor trickery is performed, but you'll have to provide some evidence in order to suggest the latter happens.
Nope, i wasnt, like i said look at imaging resource.

This one is RAW


this the D7000, funny enough more dynamic range.

Last edited by Anvh; 07-04-2012 at 08:18 AM.
07-05-2012, 01:37 AM   #26
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QuoteOriginally posted by Anvh Quote
This one is RAW
No, it isn't.

The description says "The illustration above shows the results from an Adobe Camera Raw 6.3 converted DNG file, using the Auto setting.".

You are seeing the tone curve applied by ACR with the "Auto" setting applied. That's basically equivalent to just another JPG (not in-camera, but "cooked" in post-processing), i.e. output referred image.

You can forget any comparisons done with ACR as Adobe is know to do behind the scenes processing depending on the camera model (and probably even ISO setting).

Even if ACR would do the same job for every sensor, you'd still be looking at RAW development tone curves, not the actual raw sensor response (which should be linear w.r.t. to scene intensity levels).
07-05-2012, 02:05 AM   #27
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QuoteOriginally posted by Class A Quote
Can you please provide a pointer?


I offered a reason why Pentax may have "hidden" the ISO 80 setting in the extended range. Maybe other manufacturers have omitted it altogether for the same (or different) reason.

BTW, it is possible that the ISO 80 aren't native and that the corresponding increase in DR is achieved by some dark noise signal processing. Falk seems to have observed something like this with the K-x (although his findings weren't super conclusive in this instance).

But the fact that other manufactures didn't offer ISO 80 and that "ISO 80" is not the default low ISO value for the K-5 do not demonstrate that the above possibility is reality.


You seem to be referring to DPReview tests and JPG tone curves. Both are irrelevant in this discussion. Note that RAW file DR is just a number, specifying a range. This range refers to a linear response, i.e., there are no shadow or highlight shoulders which could by asymmetrical. This is of course assuming that no low-level sensor trickery is performed, but you'll have to provide some evidence in order to suggest the latter happens.
Cellulite in the sun.
07-05-2012, 06:10 AM   #28
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QuoteOriginally posted by Class A Quote
No, it isn't.

The description says "The illustration above shows the results from an Adobe Camera Raw 6.3 converted DNG file, using the Auto setting.".

You are seeing the tone curve applied by ACR with the "Auto" setting applied. That's basically equivalent to just another JPG (not in-camera, but "cooked" in post-processing), i.e. output referred image.

You can forget any comparisons done with ACR as Adobe is know to do behind the scenes processing depending on the camera model (and probably even ISO setting).

Even if ACR would do the same job for every sensor, you'd still be looking at RAW development tone curves, not the actual raw sensor response (which should be linear w.r.t. to scene intensity levels).
Then show me a better test.
07-05-2012, 12:12 PM   #29
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this was taken at iso80 in RAW, this has been lightly pp'd but the RAW file wasnt much different. To me it seems like a great example of the excellent DR from the k-5


12-05-2013, 10:22 AM   #30
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ISO 80 and the full dynamic range very useful in astrophotography. I find this guy's work quite inspiring:

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