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02-17-2018, 10:15 PM   #316
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QuoteOriginally posted by ogl Quote
How do you know it? It's absolutely unfounded what you said.

ISO80 of K-5IIs is the best ISO for this camera.
Nikon D850 and 810's ISO64 are the same.
Better DR, SBR18%, Tonal range, Colour Sensitivity in all aspects and e.t.c.

Not much higher, but HIGHER.
It really depends on the sensor
If we take a look at some of the raw data a lot of times when we see camera with extended Iso to a lower iso setting really is a relaxation in the headroom or that buffer designers build into the camera from clipping Data.
When we look at the raw data for these setting you will see that the raw histogram is shifted to the right and this can increase the chances of clipping.

From my understanding there is really no inherent iso that is found on the sensor, different camera manufactures can program with some degree how the sensor works, They will decide how large the maximum exposure they will allow the Iso setting ( short of oversaturating the sensor). Some manufactures like to include more headroom to further reduce the risk of clipping while other will forgo with less headroom.

Remember that iso standard really is not a standard that regulates how camera companies are to use the sensor, the Iso regulates how the final jpg image is appear.

Some camera manufactures will use the same sensor very differently from camera model to camera model for better performance at different spectrums of the iso settings.

02-17-2018, 10:26 PM   #317
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QuoteOriginally posted by Ian Stuart Forsyth Quote
It really depends on the sensor
I say about real cameras with real ISO lower than ISO100. Nothing else. We have 3 samples. All 3 samples confirm my thoughts.
02-17-2018, 11:02 PM - 3 Likes   #318
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QuoteOriginally posted by ogl Quote
I say about real cameras with real ISO lower than ISO100. Nothing else. We have 3 samples. All 3 samples confirm my thoughts.
You have to remember that iso really is an exposure index, different manufactures will vary slightly from that standard as to how they want the final image to appear.

So when I set my Pentax camera to iso 100 that exposure is 2/3 of a stop larger than the very same iso is set to my Nikon camera. Iso is really an afterthought that is based really on how that camera manufacture is metering for their idea of a correct exposure within the confines of the Iso standard.

I really don’t like to use the term of base iso of a sensor as how low the sensor can be set is more determined by what the camera manufactures want to get out of the sensor short of clipping and how they program it.
Now if we take a look at the D810 and the K1 and look as to how both camera manufactures use that sensor you will see for the same iso the pentax is using a larger exposure.

If we take a look at the d810 and iso 64 when viewing the raw data we are still given the same headroom ( what Nikon like to use is around 1 2/3rd headroom) as iso 100, this to some degree confirms your assumption.
You also have to remember that iso100 to iso 64 is only 2/3rd of a stop

---------- Post added 02-18-2018 at 12:36 AM ----------

To further support your assumption we can look at the Saturation (e-) and the DR of the 2 camera
Sensorgen.info data for Nikon D800
Sensorgen.info data for Nikon D810

D800 Saturation (e-) 48818 DR13.4
D810 Saturation (e-) 78083 DR 13.8

Now if we want to increase the DR from 13.4 to 13.8 we will need to increase the size of the exposure which is just shy of half a stop which is very close to that 2/3rd of a stop we see from 100 to 64
If we also look at the Saturation (e-) value 48818/78083=0.62 stops again very close to that difference in iso 100-64
One of the reason why I don't think we see a full 2/3 of a stop increase to DR with the D810 over the D800 is that at iso 64 the D810 has 5.5 Read Noise (e-) while the D800 at iso 100 has 4.6 Read Noise (e-)

Sorry for using Nikon but that is all the information I have to sensors being used below iso 100

Last edited by Ian Stuart Forsyth; 02-17-2018 at 11:37 PM.
02-18-2018, 12:51 AM - 1 Like   #319
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QuoteOriginally posted by Kunzite Quote
So the technical expertise deciding that K-1 Mark II is no good can be resumed to two words: "baked" and "massaged".
Why are you putting words like "K-1 Mark II is no good" into my mouth?

I never said anything like it.
I only argued the case that post-processing should occur outside the camera, as faster hardware and new algorithms can provide continuous improvement over time. However, this only works optimally, if you have access to the raw data from the sensor. Any additional processing in the camera will "bake in" some correlation into the data that you cannot remove anymore after the fact. DxOMark has produced evidence for such RAW data tampering with some older Pentax cameras (for high ISO settings only). Luckily, this practice has never created any significant downsides as one can simply shoot at a lower ISO setting (ISO 1600 has been the threshold) and then push in post-production. Due to the "ISO less" nature of modern Sony sensors, there is no difference between pushing in post or using high ISO settings during shooting. The only downside of pushing in post is that visual feedback during shooting won't be available, as the back LCD will show a heavily underexposed image.

I never intended to create "some negative emotions regarding a new Pentax product". I love my Pentax gear and always wish Pentax the best. This doesn't make me close my eyes, though, and hail the addition of what appears to be a fast post-processing stage as an actual achievement for RAW shooters.

If anyone can explain how the "accelerator" unit is actually increasing the fidelity of the sensor data, rather than performing post-processing that should be left to a RAW converter, then I'd be most grateful. The architecture of modern Sony sensor appears to make it impossible to allow camera manufacturers to tweak their performance which appears to leave RAW data manipulation as the only form of achieving a better looking output.

QuoteOriginally posted by MMVIII Quote
Isn't that funny. Is not the 'look' the final deciding factor if an image from a sensor is better or not?
Sure, but see above for the optimal place to create a "look".

QuoteOriginally posted by Racer X 69 Quote
What happened to 80, like the K5 has?

And why can't we get even lower, say 50.
Providing meaningful low ISO values requires to increase the full-well capacity of sensor sensels. In other words, this requires different hardware as opposed to different software. A meaningful low ISO value -- as opposed to software-emulated ones, one where one simply underexposes, or those achieved by photon attenuation which increases noise -- directly translates into a higher dynamic range.

Note that the K-1 "only" offers ISO 100, unlike the D810, which offers ISO 64 (for simplicity, I'm using the manufacture figures here, not the measured values). It is therefore highly unlikely that the K-1 uses the same sensor as the D810, a "fact" that has often been purported. It is much more likely that the K-1 uses the same sensor (or a variant of it) as the D800. As Pentax has demonstrated with the K-5, they know how to exploit the option of lower ISO values (ISO 80, in this case) to their advantage. The "ISO 80" setting moved the K-5 considerably up the DxOMarK score ladder and obviously has real advantages to photographers as well.

To be clear, for me personally, the K-1 offers plenty enough dynamic range. I personally don't need a lower ISO setting and in my view the K-1 is an absolutely fantastic camera as it is. However, there are reasons why the D810 offers a lower ISO setting:
  1. meaningful low ISO settings translate into higher dynamic range.
  2. higher dynamic range is not only useful for photographers but also for achieving top positions in the DxoMark ranking (which has marketing implications).
  3. sensors with higher dynamic range are more expensive. Pentax did not use a Sony sensor similar to the D810's because either the sensor was too expensive (relative to the benefit) or potentially because it had some other characteristics they wanted to avoid. I wouldn't know, however, what those negative characteristics could have been.


02-18-2018, 01:28 AM   #320
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QuoteOriginally posted by ogl Quote
ISO80 of K-5IIs is the best ISO for this camera.
At least on the K5II+s it is ETTR done in camera. I can do the same with K1, overexpose 0.5 or 1 stop (depending on scene) and get lower noise.
That's why for the D850 for example, the SNR 18% at lowest ISO is improved over the SNR 18% at ISO100, but the DR is about the same for both ISO values, than means the lower ISO setting is mostly done in software.

---------- Post added 18-02-18 at 09:32 ----------

QuoteOriginally posted by ogl Quote
I say about real cameras with real ISO lower than ISO100.
For 18% grey target, overexposure followed by exposure reduction in software come out as a lower measured value of ISO.

---------- Post added 18-02-18 at 09:45 ----------

QuoteOriginally posted by Class A Quote
It is much more likely that the K-1 uses the same sensor (or a variant of it) as the D800.
D800 and D800E also support ISO settings lower than 100.

---------- Post added 18-02-18 at 09:50 ----------

QuoteOriginally posted by Class A Quote
meaningful low ISO settings translate into higher dynamic range.
K1 and D8xx have the same DR.

QuoteOriginally posted by Class A Quote
sensors with higher dynamic range are more expensive.
Can you give the prices of sensors?

Last edited by biz-engineer; 02-18-2018 at 01:34 AM.
02-18-2018, 02:40 AM   #321
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QuoteOriginally posted by Ian Stuart Forsyth Quote

D800 Saturation (e-) 48818 DR13.4
D810 Saturation (e-) 78083 DR 13.8

D810 has 14.76 EV DR at ISO64. D800 has 14.33 EV DR at ISO100 (D810 has 14.36)

0.43 EV is not much, but it's advantage.

D810 has 46.3 dB SNR18% at ISO64, D800 has 45 dB at ISO100.

Tonal range, 9.63 bits at ISO100 of D800 vs 9.83 bits of D810 at ISO64....

D850 has a bit higher specs with 45.7 MP sensor than D810.
02-18-2018, 03:05 AM - 1 Like   #322
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QuoteOriginally posted by Class A Quote
I only argued the case that post-processing should occur outside the camera, as faster hardware and new algorithms can provide continuous improvement over time.
So you know as a fact that you can do at least as good by processing a K-1 RAW, than the K-1 Mk II does with (supposedly) the same sensor and the Accelerator Unit?
Without seeing a single image taken with the Mk II?

QuoteOriginally posted by Class A Quote
I never intended to create "some negative emotions regarding a new Pentax product". I love my Pentax gear and always wish Pentax the best.
I'm sure you do, we're both posting here for a while; but still, this discussion about "baked" and "massaged" RAWs is designed to create negative emotions. Not as bad as "crippled", I'll give you that.

BTW. Am I right to notice that people who've seen the AU in action (either in the K-70 or KP) are happy with it?
02-18-2018, 03:23 AM   #323
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QuoteOriginally posted by ogl Quote
Real ISO50 or 64 are really good...I hope we can see someday in any camera... I can't dream about ISO25. But 50 or 64 are really good.
I think the dynamic range are good enough at ISO 100, all we need is an in camera or in sensor ND-filter that takes away the hassle of glass filters and optical faults that introduces. I would love to have a camera with built in ND that takes ISO 100 down to ISO 25 or 12 with a touch.

Let me add, at a sensor level, reducing ISO below 100 is hard to do. That means compromises. Higher saturation (per pixel) can mainly be acrhieved by increasing pixel size. Per area the saturation stays about the same. This is basicly the capisitance holding the electrons captured by the photodiode. Replacing 1 large pixel with 4 small will have the same combined saturation (#e-). The large one will have longer electron transport and thus be slower to read out. The large will have a larger chief ray angle, wich is good for large aperture lenses. The small pixels will have higher noise, also when binned, assuming a monochrome sensor. With RGGB sensors it will be more complicated.

Although the K-1 II probably will perform much like K-1, I think future sensors may get around the low ISO limitation by using global shutter and take two or more exposures almost without delay. Two expossure durations will be combined into one file with very high dynamic range. The range will be extended mainly in the high saturation end. Lenses have to be specifically designed to take advantage of the higher DR.


Last edited by Simen1; 02-18-2018 at 03:53 AM.
02-18-2018, 03:50 AM   #324
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QuoteOriginally posted by ogl Quote
I say about real cameras with real ISO lower than ISO100. Nothing else. We have 3 samples. All 3 samples confirm my thoughts.
I think the question is what the base iso of the sensor you get really is. With the K5, Pentax had a sensor that had a base iso of 75 and so it wasn't hard to create an iso 80. With the kx the base iso was 200 and while they did expand it to iso 100, the dynamic range was actually slightly worse at iso 100 than at iso 200.

Nikon did pay extra for a sensor with bigger photon wells for the D810 which allowed for a true lower base iso setting, but the difference is actually very minimal. DXO Mark measures the base iso of the D810 to be 47 with dynamic range of 4.76 EV and the base iso of the K-1 to be 95 with dynamic range of 4.6 EV. But that .16 difference in EV is very expensive to get to and you are better off in most situations using a one stop ND filter if you want to use a wider aperture with flash in bright light or something like that (this would not be nearly enough to allow for a long exposure in bright light and for that you would need a several stop darker ND filter).
02-18-2018, 04:40 AM   #325
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QuoteOriginally posted by biz-engineer Quote
D800 and D800E also support ISO settings lower than 100.
If you refer to their "ISO 50" setting, that is not a meaningful low ISO setting. It just creates an overexposed image. This will work fine, as long as the original scene could have been captured with ISO 100 as well. Otherwise, you'll get blown highlights. In other words, this "ISO 50" setting, does not result in more dynamic range compared to "ISO 100".

QuoteOriginally posted by biz-engineer Quote
K1 and D8xx have the same DR.
No, they don't. The K-1's DR is higher than that of the D800 and slightly lower than that of the D810.

QuoteOriginally posted by biz-engineer Quote
Can you give the prices of sensors?
I don't have a reliable source for which sensor exactly is used in the D810. In the D800, it is the IMX094AQP but a further complication would be to find out what the exact prices were at the time Pentax had to make a decision. It seems logical to me that Sony would charge more for a more capable product. If you can provide evidence that a sensor with more dynamic range does not command a higher price then I'll be happy to accept that I jumped to a conclusion. BTW, Nikon appears to work closely with Sony and sometimes do their own designs and/or dedicated D/A converters. This complicates this particular story quite a bit.

None of this matters for what I've been trying to say, i.e., that nominal IQ is created by the sensor, not by an image processor.
02-18-2018, 04:48 AM   #326
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QuoteOriginally posted by Kunzite Quote
So you know as a fact that you can do at least as good by processing a K-1 RAW, than the K-1 Mk II does with (supposedly) the same sensor and the Accelerator Unit?
Again, that's not what I said.

I won't respond to you anymore, as you keep putting words into my mouth.

QuoteOriginally posted by Kunzite Quote
...this discussion about "baked" and "massaged" RAWs is designed to create negative emotions.
Take it from the horse's mouth: My points about undesirable RAW manipulation was not "designed to create negative emotions". You are entitled to your ideas regarding my motivations and intentions, but they are 100% false.

QuoteOriginally posted by Kunzite Quote
BTW. Am I right to notice that people who've seen the AU in action (either in the K-70 or KP) are happy with it?
That's besides the point. I never said that the processing does not result in more pleasing or cleaning looking images.

I only said that it is smarter to leave any processing of the data to a later, out-of-camera, stage.

It seems a discussion here is no longer fruitful. If I don't respond anymore, this shouldn't be construed as tacit approval on my behalf.
02-18-2018, 05:45 AM   #327
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QuoteOriginally posted by Class A Quote
No, they don't. The K-1's DR is higher than that of the D800 and slightly lower than that of the D810.
They differ by something like 0.1ev. How many camera copies have been measured at different point in time, by different operator? What is the repeatability and reproducibility of the measurement of the dynamic range?
If we consider that the measurements are perfectly repeatable and reproducible from one camera to another, from DXO:
Pentax K1 has 38.4dB of SNR at ISO100, D810 has 39.7 dB at ISO 50, i.e 1.3dB of advantage to D810.
Pentax K1 has 13.5ev of DR at ISO100, D810 has 13.67 ev of DR at ISO 50, i.e 0.17 ev (0.51dB) of advantage to D810.
That mean Nikon D810 low ISO grabs 0.79dB () by overexposure of 0.263 ev at ISO settings lower than 100.
Dial +0.3ev of exposure compensation of your K1 at ISO 100 and you can match the D810 for SNR. As for DR, yes if the DXO measurement is perfect, D810 has 0.17ev advantage over Pentax K1, not sure with pixel shift how that holds true.

Last edited by biz-engineer; 02-18-2018 at 06:06 AM.
02-18-2018, 05:58 AM   #328
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@Class A:
You said: "post-processing should occur outside the camera". It's only logical to conclude that you believe one can get similar or better results outside the camera. The alternative doesn't make much sense.

I'm not discussing theoretically, I'm not discussing principles - I'm discussing results. Maybe that is the problem here. I'm expecting those concerned about the presence of an Accelerator Unit to point out to an image and say: "look, this is something I do not want applied on my images; I can do better without it". Like those investigating Sony's star eater were doing.

Sorry for getting you upset; but seeing what it does on APS-C, I would have liked it in my K-1.
02-18-2018, 07:02 AM   #329
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QuoteOriginally posted by Class A Quote
If you refer to their "ISO 50" setting, that is not a meaningful low ISO setting. It just creates an overexposed image. This will work fine, as long as the original scene could have been captured with ISO 100 as well. Otherwise, you'll get blown highlights. In other words, this "ISO 50" setting, does not result in more dynamic range compared to "ISO 100".


No, they don't. The K-1's DR is higher than that of the D800 and slightly lower than that of the D810.


I don't have a reliable source for which sensor exactly is used in the D810. In the D800, it is the IMX094AQP but a further complication would be to find out what the exact prices were at the time Pentax had to make a decision. It seems logical to me that Sony would charge more for a more capable product. If you can provide evidence that a sensor with more dynamic range does not command a higher price then I'll be happy to accept that I jumped to a conclusion. BTW, Nikon appears to work closely with Sony and sometimes do their own designs and/or dedicated D/A converters. This complicates this particular story quite a bit.

None of this matters for what I've been trying to say, i.e., that nominal IQ is created by the sensor, not by an image processor.
The difference in dynamic range values between the cameras is pretty small. .17 EV difference at base iso difference between the K-1 and the D810. I'm sure it is reproducible in the lab, but as to whether or not it has any real world significance, I sort of doubt it. The benefit comes if you are trying to using flash in decent light with large aperture lenses or trying to drag the shutter for, say, blurring water effect in decent light, but it is a one stop difference in that respect -- helpful, but probably not enough to preclude the use of ND filters.

I would like to see lower iso ranges, but mainly if it offers a real boost in dynamic range. At this point, I get more of a boost from using pixel shift than I would by buying a D810.
02-18-2018, 11:42 AM - 3 Likes   #330
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QuoteOriginally posted by Class A Quote
Why are you putting words like "K-1 Mark II is no good" into my mouth?

I never said anything like it.
I only argued the case that post-processing should occur outside the camera, as faster hardware and new algorithms can provide continuous improvement over time. However, this only works optimally, if you have access to the raw data from the sensor. Any additional processing in the camera will "bake in" some correlation into the data that you cannot remove anymore after the fact. DxOMark has produced evidence for such RAW data tampering with some older Pentax cameras (for high ISO settings only). Luckily, this practice has never created any significant downsides as one can simply shoot at a lower ISO setting (ISO 1600 has been the threshold) and then push in post-production. Due to the "ISO less" nature of modern Sony sensors, there is no difference between pushing in post or using high ISO settings during shooting. The only downside of pushing in post is that visual feedback during shooting won't be available, as the back LCD will show a heavily underexposed image.

I never intended to create "some negative emotions regarding a new Pentax product". I love my Pentax gear and always wish Pentax the best. This doesn't make me close my eyes, though, and hail the addition of what appears to be a fast post-processing stage as an actual achievement for RAW shooters.

If anyone can explain how the "accelerator" unit is actually increasing the fidelity of the sensor data, rather than performing post-processing that should be left to a RAW converter, then I'd be most grateful. The architecture of modern Sony sensor appears to make it impossible to allow camera manufacturers to tweak their performance
You are making these statements as a matter of faith, seemingly saying that some adjustments {'tweaking' formerly allowed by Sony or perhaps resistors or capacitors placed in the circuit} are OK, but all other changes to a "raw" file cause irreparable harm. No alternatives??

I can't find it right now, but several months ago there was a thread here at PF saying that Fuji allegedly was encouraged to go forward with their MF project after 'applying' their software to the 645Z; there was a strong suggestion that Fuji modifies data before creating their "raw" file ... but, yet, people highly respect Fuji's products. Nikon users nonchalantly talk about theit cameras being able to create several different size of "raw" file; how is this happening without modification?


Until regular users have a K-1ii in their hands, we won't know what is going on with it .... of someone could 'play' with a KP right now, something that should have happened a year ago.
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