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Revised Estimate of A9 Photographic Dynamic Range (PDR) at PhotonsToPhotos

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bclaff said:
PWPhotography said:
mmeerdam said:
Thanks for the data bill. Very interesting to see It's on par with a Canon sensor (1dxii and 5d4) :P even though it's bsi... a while ago the 5d4 got new revised data that shows it to be just a bit behind the a7rii and d810.
Click to expand...
If you check DPR lab scene , you will see 5D IV is about one stop behind A7r II at ISO 100 and 1.5 stops behind D810 at ISO 64.
Click to expand...
You're mistakenly interpreting ISO Invariance visualizations with dynamic range.
You need to compare the same ISO settings without any push.
Click to expand...
What's the point without push? To leverage high DR sensors in highly contrast scenes and protect highlight, you will need to underexpose photos and then push shadow back. That's what we have talked about in DPR forums for years that Canon used to lag behind Sony in large degree in this area but now Canon is capturing up but still lags behind.

Without push, even my old 5D III has adequate DR. But I want to preserve highlight, then 5D III's RAW files will be ugly after pushing shadow. That's the reason I only used A7r exclusively on tripod in evening cityscape then during my last EU trip when I carried both 5D3 and A7r. The difference after shadow push is huge.
bclaff said:
--
Bill ( Your trusted source for independent sensor data at http://www.photonstophotos.net )
Click to expand...
--
https://www.flickr.com/photos/55485085@N04/albums
http://pwphotography.zenfolio.com
 
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rogerjosem said:
My issue is that Auto ISO does not set to 640 (jumps from 400 to 800) thus a bit of the gain is lost if ISO is not set manually.
Click to expand...
i Just checked on my A7rii, and my ISO Auto can choose every third stop, 400, 500, 640, 800, when I change S or A by 1/3 stop.
 
bclaff said:
There's nothing special or "good" about ISO 1600 or ISO 3200.
Click to expand...
Looking at the red curve of your graph, we find local maximums at 100, 640, 1600, 3200. Yes, 640 stands out, and we can also see from your graph that 640 is better than 500, 400, 300, and 250, like you said.

We can also see that 1600 is better than 1250, and 3200 is better than 2500. That what I was thinking your chart shows---that there is something good about 1600 and 3200.

I wasn't clear enough in one of my questions, so I'll try to be better: What is measured in your graph is not the only variable that matters with ISO, and there could be ways in which ISO 250 is better than 640. These ways might include a more advantageous aperture or shutter speed, of course, which we shouldn't totally forget about. Also color depth or noise could be better at ISO 250 than 640, might they?
 
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rogerjosem said:
rogerjosem said:
bclaff wrote:...
Click to expand...
Click to expand...
rogerjosem said:
rogerjosem said:
Yes, ISO 640 is about as good as ISO 200-250 (so better than ISO 400 or 500 for sure).
In most situations you would either shoot as ISO 100 without ISO Auto or at ISO 640 with ISO Auto.
(Again, my advice, not everyone takes this approach).
Click to expand...
Thanks for your helpful findings Bill. That makes sense. My issue is that Auto ISO does not set to 640 (jumps from 400 to 800) thus a bit of the gain is lost if ISO is not set manually.
Click to expand...
I'm sure you can set for 1/3 stop rather than 1 stop increments.
But if you're using ISO Auto then you might as well start at ISO 640 not ISO 100 because ISO settings from 320 to 500 are not as good as ISO 640.

41c199a4d10d488291aff7e97d06fad6.jpg.png

It would be nice if you could set ISO 100 and the firmware was smart enough to skip those ISO settings; but it is not.

--
Bill ( Your trusted source for independent sensor data at http://www.photonstophotos.net )
 
bclaff said:
Everything that follows is a generalization for typical photography.
There are always exceptions.

[...]

In most situations you would either shoot as ISO 100 without ISO Auto or at ISO 640 with ISO Auto.
(Again, my advice, not everyone takes this approach).
Click to expand...
All your posts help, thanks so much!

Previously, I was confused as to the meaning of "shoot at [...] ISO 640 with ISO Auto." But I finally understand. You mean to use a new A9 setting: ISO Auto Min = 640. Right? (My a7r2 allows ISO Auto Min = 800, but not ISO Auto Min = 640.)

Are you thinking of using it with M, S, or A? Would you be most likely to use it with A (aperture priority) and an ISO Auto Min Shutter Speed?
 
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osv said:
that chart helps.

--
dan
Click to expand...
Yeap. But also if not more meaningful to me is DPR lab's exposure latitude to judge DR performance after pushing several stops back. Personally I found myself more and more prefer to underexpose photos a bit to preserve highlight, and then push shadow back that is more attractive than blown highlight. Hope Sony and Canon continue improve sensors in this area. DR is more important than amount of pixels in my priority list.

--
https://www.flickr.com/photos/55485085@N04/albums
http://pwphotography.zenfolio.com
 
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PWPhotography said:
bclaff said:
PWPhotography said:
If you check DPR lab scene , you will see 5D IV is about one stop behind A7r II at ISO 100 and 1.5 stops behind D810 at ISO 64.
Click to expand...
You're mistakenly interpreting ISO Invariance visualizations with dynamic range.
You need to compare the same ISO settings without any push.
Click to expand...
What's the point without push? To leverage high DR sensors in highly contrast scenes and protect highlight, you will need to underexpose photos and then push shadow back.
...
Click to expand...
My comment was regarding the confusion between ISO Invariance and dynamic range.
Yours seems to some defense of the use of ISO Invariance.

Regardless of ISO Invariance exposure should be set so as not to lose important highlights; sometimes this means under-exposing.
I never manually raise my ISO to do this (or for any reason); I use Exposure Compensation (EC).

I have found that some people abuse the ISO Invariance and under-expose by raising the ISO setting 3 stops rather than setting EC to -1 stop.
This is sub-optimal and you will lose 2 stops of dynamic range.
If the scene really is high contrast then you just need to nail your exposure and not rely on ISO Invariance to bail you out; it won't.
 
Jerry Fusselman said:
bclaff said:
Everything that follows is a generalization for typical photography.
There are always exceptions.

[...]

In most situations you would either shoot as ISO 100 without ISO Auto or at ISO 640 with ISO Auto.
(Again, my advice, not everyone takes this approach).
Click to expand...
All your posts help, thanks so much!
Click to expand...
Thanks.
Jerry Fusselman said:
Previously, I was confused as to the meaning of "shoot at [...] ISO 640 with ISO Auto." But I finally understand. You mean to use a new A9 setting: ISO Auto Min = 640. Right? (My a7r2 allows ISO Auto Min = 800, but not ISO Auto Min = 640.)
Click to expand...
Right. Surprised you can't set Min by 1/3 stops with the A7R2. Are you sure?
Jerry Fusselman said:
Are you thinking of using it with M, S, or A? Would you be most likely to use it with A (aperture priority) and an ISO Auto Min Shutter Speed?
Click to expand...
I would be most likely to use M but A might easily be more appropriate for your photographic needs.
 
bclaff said:
PWPhotography said:
bclaff said:
PWPhotography said:
If you check DPR lab scene , you will see 5D IV is about one stop behind A7r II at ISO 100 and 1.5 stops behind D810 at ISO 64.
Click to expand...
You're mistakenly interpreting ISO Invariance visualizations with dynamic range.
You need to compare the same ISO settings without any push.
Click to expand...
What's the point without push? To leverage high DR sensors in highly contrast scenes and protect highlight, you will need to underexpose photos and then push shadow back.
...
Click to expand...
My comment was regarding the confusion between ISO Invariance and dynamic range.
Yours seems to some defense of the use of ISO Invariance.

Regardless of ISO Invariance exposure should be set so as not to lose important highlights; sometimes this means under-exposing.
I never manually raise my ISO to do this (or for any reason); I use Exposure Compensation (EC).

I have found that some people abuse the ISO Invariance and under-expose by raising the ISO setting 3 stops rather than setting EC to -1 stop.
This is sub-optimal and you will lose 2 stops of dynamic range.
If the scene really is high contrast then you just need to nail your exposure and not rely on ISO Invariance to bail you out; it won't.
Click to expand...
Bill,

I am trying to understand what you mean raising ISO? I shoot at base ISO 100 and expose largely on highlight (by judge zebra pattern), then push shadow back a few stops. If this is what you mean 'raising ISO'? Otherwise what difference from you EC to -1 stop which equivalent to my exposure level (-1 EV less exposure than normal)? You'd still need to push back shadow areas or leave very dark areas intact, right? BTW, I also use EC virtually in every photo by checking zebra pattern as I said but usually -0.3 to -0.7 EV. I found A7r II's sensor is more sensitive to A7r and A7 II's which means I frequently need to dial down EC to negative, in comparison my old 5D III that I frequently need to dial up +1/3 ~+2/3 EV.
bclaff said:
--
Bill ( Your trusted source for independent sensor data at http://www.photonstophotos.net )
Click to expand...
--
https://www.flickr.com/photos/55485085@N04/albums
http://pwphotography.zenfolio.com
 
Last edited:
PWPhotography said:
osv said:
that chart helps.
Click to expand...
Yeap. But also if not more meaningful to me is DPR lab's exposure latitude to judge DR performance after pushing several stops back.
Click to expand...
The dpreview ISO Invariance widget using images that have been underexposed and then pushed is a good way to visualize information you can glean from one chart, my Shadow Improvement of Photographic Dynamic Range versus ISO Setting chart.

The ILCE-9 (A9) curve will be smoother with final measurements.
The ILCE-9 (A9) curve will be smoother with final measurements.

You actually get more information here.

Remember you cannot make a blanket statement that a particular camera can "recover" a certain amount of under-exposure; that is ISO setting dependent.
This error is often made by people using the widget because they don't see the "big picture" as provided by this chart.

--
Bill ( Your trusted source for independent sensor data at http://www.photonstophotos.net )
 
PWPhotography said:
bclaff said:
PWPhotography said:
bclaff said:
PWPhotography said:
If you check DPR lab scene , you will see 5D IV is about one stop behind A7r II at ISO 100 and 1.5 stops behind D810 at ISO 64.
Click to expand...
You're mistakenly interpreting ISO Invariance visualizations with dynamic range.
You need to compare the same ISO settings without any push.
Click to expand...
What's the point without push? To leverage high DR sensors in highly contrast scenes and protect highlight, you will need to underexpose photos and then push shadow back.
...
Click to expand...
My comment was regarding the confusion between ISO Invariance and dynamic range.
Yours seems to some defense of the use of ISO Invariance.

Regardless of ISO Invariance exposure should be set so as not to lose important highlights; sometimes this means under-exposing.
I never manually raise my ISO to do this (or for any reason); I use Exposure Compensation (EC).

I have found that some people abuse the ISO Invariance and under-expose by raising the ISO setting 3 stops rather than setting EC to -1 stop.
This is sub-optimal and you will lose 2 stops of dynamic range.
If the scene really is high contrast then you just need to nail your exposure and not rely on ISO Invariance to bail you out; it won't.
Click to expand...
I am trying to understand what you mean raising ISO? I shoot at base ISO 100 and expose largely on highlight (by judge zebra pattern), then push shadow back a few stops. If this is what you mean 'raising ISO'? Otherwise what difference from you EC to -1 stop which equivalent to my exposure level (-1 EV less exposure than normal)? You'd still need to push back shadow areas or leave very dark areas intact, right? BTW, I also use EC virtually in every photo by checking zebra pattern as I said but usually -0.3 to -0.7 EV.
Click to expand...
I have no quarrel with that shooting style.
But if you had said that instead of using a modest amount of negative EC you manually raised the ISO setting to ISO 400 (2 stops versus -0.7 steps of EC) then I would say that's a bad approach.
PWPhotography said:
I found A7r II's sensor is more sensitive to A7r and A7 II's which means I frequently need to dial down EC to negative, in comparison my old 5D III that I frequently need to dial up +1/3 ~+2/3 EV.
Click to expand...
I have no doubt your observation is correct but it's not related to sensor sensitivity.
I think this is probably a difference in metering and tone curve, not surprising across brands.
 
bclaff said:
PWPhotography said:
bclaff said:
PWPhotography said:
bclaff said:
PWPhotography said:
If you check DPR lab scene , you will see 5D IV is about one stop behind A7r II at ISO 100 and 1.5 stops behind D810 at ISO 64.
Click to expand...
You're mistakenly interpreting ISO Invariance visualizations with dynamic range.
You need to compare the same ISO settings without any push.
Click to expand...
What's the point without push? To leverage high DR sensors in highly contrast scenes and protect highlight, you will need to underexpose photos and then push shadow back.
...
Click to expand...
My comment was regarding the confusion between ISO Invariance and dynamic range.
Yours seems to some defense of the use of ISO Invariance.

Regardless of ISO Invariance exposure should be set so as not to lose important highlights; sometimes this means under-exposing.
I never manually raise my ISO to do this (or for any reason); I use Exposure Compensation (EC).

I have found that some people abuse the ISO Invariance and under-expose by raising the ISO setting 3 stops rather than setting EC to -1 stop.
This is sub-optimal and you will lose 2 stops of dynamic range.
If the scene really is high contrast then you just need to nail your exposure and not rely on ISO Invariance to bail you out; it won't.
Click to expand...
I am trying to understand what you mean raising ISO? I shoot at base ISO 100 and expose largely on highlight (by judge zebra pattern), then push shadow back a few stops. If this is what you mean 'raising ISO'? Otherwise what difference from you EC to -1 stop which equivalent to my exposure level (-1 EV less exposure than normal)? You'd still need to push back shadow areas or leave very dark areas intact, right? BTW, I also use EC virtually in every photo by checking zebra pattern as I said but usually -0.3 to -0.7 EV.
Click to expand...
I have no quarrel with that shooting style.
But if you had said that instead of using a modest amount of negative EC you manually raised the ISO setting to ISO 400 (2 stops versus -0.7 steps of EC) then I would say that's a bad approach.
Click to expand...
Oh, that is misunderstanding. I never shoot landscape photos on tripod at ISO 200 or above, but always at base ISO 100 (except a few accidentally bumped to ISO 80 etc as I programmed back wheel to change ISO) and expose largely on highlight (use EC if necessary).
bclaff said:
bclaff said:
I found A7r II's sensor is more sensitive to A7r and A7 II's which means I frequently need to dial down EC to negative, in comparison my old 5D III that I frequently need to dial up +1/3 ~+2/3 EV.
Click to expand...
I have no doubt your observation is correct but it's not related to sensor sensitivity.
I think this is probably a difference in metering and tone curve, not surprising across brands.
Click to expand...
Pretty obvious. I remember original 5D sensor then has advantage over competitors that I need to permanently set -1/3 EC. But then years later Sony sensors exceed in this area, 5D2/5D3 sensors are less sensitive on my experience despite DPR lab tested they are correctly ISO marked. My A7-series sensors especially A7r II are obviously more sensitive than 5D2/5D3, not sure 5D IV as I have not owned it. I know what you mean but that is not my observation and experience.
bclaff said:
--
Bill ( Your trusted source for independent sensor data at http://www.photonstophotos.net )
Click to expand...
--
https://www.flickr.com/photos/55485085@N04/albums
http://pwphotography.zenfolio.com
 
Last edited:
Jerry Fusselman said:
bclaff said:
There's nothing special or "good" about ISO 1600 or ISO 3200.
Click to expand...
Looking at the red curve of your graph, we find local maximums at 100, 640, 1600, 3200. Yes, 640 stands out, and we can also see from your graph that 640 is better than 500, 400, 300, and 250, like you said.

We can also see that 1600 is better than 1250, and 3200 is better than 2500. That what I was thinking your chart shows---that there is something good about 1600 and 3200.
Click to expand...
This is what I suspected.

As I said earlier you're looking too closely at the graph; especially given that these values are estimates.
Jerry Fusselman said:
I wasn't clear enough in one of my questions, so I'll try to be better: What is measured in your graph is not the only variable that matters with ISO, and there could be ways in which ISO 250 is better than 640. These ways might include a more advantageous aperture or shutter speed, of course, which we shouldn't totally forget about. Also color depth or noise could be better at ISO 250 than 640, might they?
Click to expand...
If there is more advantage (or a need for) a particular aperture or shutter speed then that's what Aperture, Shutter, and Manual modes are for; right?
From a sensor performance standpoint ISO 250 and ISO 640 look the same.
(Dynamic range and noise are interrelated so this goes for noise too).

I doubt there's any difference in color depth, certainly nothing you would notice.
 
bclaff said:
PWPhotography said:
osv said:
that chart helps.
Click to expand...
Yeap. But also if not more meaningful to me is DPR lab's exposure latitude to judge DR performance after pushing several stops back.
Click to expand...
The dpreview ISO Invariance widget using images that have been underexposed and then pushed is a good way to visualize information you can glean from one chart, my Shadow Improvement of Photographic Dynamic Range versus ISO Setting chart.
Click to expand...
Sure DPR lab ISO Invariance widget is extreme that usually you don't underexpose that much. But it's a good lab test to show how far a sensor can lift shadow back.
bclaff said:
The ILCE-9 (A9) curve will be smoother with final measurements.
The ILCE-9 (A9) curve will be smoother with final measurements.

You actually get more information here.
Click to expand...
Thanks for info that certainly is useful.
bclaff said:
Remember you cannot make a blanket statement that a particular camera can "recover" a certain amount of under-exposure; that is ISO setting dependent.
Click to expand...
I only talk at respective base ISO. High ISO DR and high ISO noise are less important to me as I basically no longer shoot high ISO photos in evening but virtually exclusively on tripod at base ISO.

We all know there is no much difference between Sony and Canon sensors in high ISOs regarding DR or noise. But to serious photographers, base ISO performance matters. That's why Nikon D810 base ISO 64 really matters. Hope Sony and Canon will do the same to lower base native ISO.
bclaff said:
This error is often made by people using the widget because they don't see the "big picture" as provided by this chart.
Click to expand...
I am sure for people to shoot at all ISO levels. But personally DPR ISO latitude widget is very meaningful to me as I only shoot at base ISO on tripod and I don't care much high ISO so I can judge how far I could push shadow back if necessary while still retain quality noise and detail level. In scenarios that I cannot use tripod under low light I'd leverage IBIS and lens' OSS/IS to shoot as close to base ISO as possible, even resort to multiple tries.
bclaff said:
--
Bill ( Your trusted source for independent sensor data at http://www.photonstophotos.net )
Click to expand...
--
https://www.flickr.com/photos/55485085@N04/albums
http://pwphotography.zenfolio.com
 
Last edited:
bclaff said:
Jerry Fusselman said:
bclaff said:
There's nothing special or "good" about ISO 1600 or ISO 3200.
Click to expand...
Looking at the red curve of your graph, we find local maximums at 100, 640, 1600, 3200. Yes, 640 stands out, and we can also see from your graph that 640 is better than 500, 400, 300, and 250, like you said.

We can also see that 1600 is better than 1250, and 3200 is better than 2500. That what I was thinking your chart shows---that there is something good about 1600 and 3200.
Click to expand...
This is what I suspected.

As I said earlier you're looking too closely at the graph; especially given that these values are estimates.
bclaff said:
I wasn't clear enough in one of my questions, so I'll try to be better: What is measured in your graph is not the only variable that matters with ISO, and there could be ways in which ISO 250 is better than 640. These ways might include a more advantageous aperture or shutter speed, of course, which we shouldn't totally forget about. Also color depth or noise could be better at ISO 250 than 640, might they?
Click to expand...
If there is more advantage (or a need for) a particular aperture or shutter speed then that's what Aperture, Shutter, and Manual modes are for; right?
From a sensor performance standpoint ISO 250 and ISO 640 look the same.
(Dynamic range and noise are interrelated so this goes for noise too).

I doubt there's any difference in color depth, certainly nothing you would notice.
Click to expand...
Off topic question, Bill: how does one go about calculating color depth? I see the term all the time, but I don't really know what it means.

Jim

--
http://blog.kasson.com
 
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rogerjosem said:
bclaff said:
Jerry Fusselman said:
bclaff said:
Jerry Fusselman said:
...

Also, it appears that good choices for ISO when shadow detail matters with the A9 are 100, 640, 1600, 3200, 6400. Am I taking the right lesson from the results?
Click to expand...
You may be looking to closely at estimated values.
ISO 100 is where Low Conversion Gain (LCG) starts.
And ISO 640 is where High Conversion Gain (HCG) starts.
Other than that the normal advice applies, use the lowest ISO that you can given your conditions.
If you're shooting ISO Auto I think you might want to simply start at ISO 640.
Click to expand...
[bclaff] ISO 100 is where Low Conversion Gain (LCG) starts.

[JF] Sorry, I don't know the operational significance of that.

[bclaff] And ISO 640 is where High Conversion Gain (HCG) starts.

[JF] Does that mean that ISO 640 is better for most purposes than ISOs 500 and 400?

[bclaff] Other than that the normal advice applies, use the lowest ISO that you can given your conditions.

[JF] Not sure how to interpret that. Maybe an example or two would help.

[bclaff] If you're shooting ISO Auto I think you might want to simply start at ISO 640.

[JF] Is what you mean is that ISO Auto should with the A9 be used less often, and instead of ISO Auto it is often better to set the ISO, but at one of the good ISOs, 100, 640, 1600, 3200? Is also what you mean that setting at ISO 500 or 400 is generally a bad choice? If so, that is what I was trying to say.

[JF] I hope I am interpreting the information you're giving us correctly, but I'm happy to be corrected.
Click to expand...
Everything that follows is a generalization for typical photography.
There are always exceptions.

The best exposure strategy for any camera is to gather as much light as possible at the base/native ISO setting. (No, I'm not going to demonstrate this with examples.)

Then if the image will be too dark you raise the ISO setting.

Raising the ISO setting when necessary is what ISO Auto does for you.
I think ISO Auto is a great tool and preferable to raising ISO manually.
(My opinion, other disagree.)

Since this is a sensor with dual conversion gain technology there are actually two base/native ISO settings: ISO 100 and ISO 640.

Yes, ISO 640 is about as good as ISO 200-250 (so better than ISO 400 or 500 for sure).
In most situations you would either shoot as ISO 100 without ISO Auto or at ISO 640 with ISO Auto.
(Again, my advice, not everyone takes this approach).

There's nothing special or "good" about ISO 1600 or ISO 3200.

Hope this helps.

--
Bill ( Your trusted source for independent sensor data at http://www.photonstophotos.net )
Click to expand...
Thanks for your helpful findings Bill. That makes sense. My issue is that Auto ISO does not set to 640 (jumps from 400 to 800) thus a bit of the gain is lost if ISO is not set manually.
Click to expand...
I, personally, set Auto ISO limits from ISO100 to ISO6400 and in real life you either have a lot of light or not a lot at all - so intermediate ISOs from "not so good range below ISO640" are rarely selected by camera's firmware
 
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PWPhotography said:
PWPhotography said:
PWPhotography said:
I found A7r II's sensor is more sensitive to A7r and A7 II's which means I frequently need to dial down EC to negative, in comparison my old 5D III that I frequently need to dial up +1/3 ~+2/3 EV.
Click to expand...
I have no doubt your observation is correct but it's not related to sensor sensitivity.
I think this is probably a difference in metering and tone curve, not surprising across brands.
Click to expand...
Pretty obvious. I remember original 5D sensor then has advantage over competitors that I need to permanently set -1/3 EC. But then years later Sony sensors exceed in this area, 5D2/5D3 sensors are less sensitive on my experience despite DPR lab tested they are correctly ISO marked. My A7-series sensors especially A7r II are obviously more sensitive than 5D2/5D3, not sure 5D IV as I have not owned it. I know what you mean but that is not my observation and experience.
Click to expand...
I'm not communicating well (or you are resisting the concept :-) )

You're not observing sensor sensitivity which is specific to the pixel in the sensor but rather the entire system which includes a lot more electronics.
Furthermore, you could (are probably) seeing the effect of different metering.
 
bclaff said:
JimKasson said:
bclaff said:
...
Click to expand...
Off topic question, Bill: how does one go about calculating color depth? I see the term all the time, but I don't really know what it means.
Click to expand...
I don't do any color measurements but DxOMark does.

Try starting with Portrait photography: Color Depth and Testing protocol for color sensitivity.
Click to expand...
Thanks, Bill. I've seen those, but I can't figure our how to reproduce their measurements from them. I don't even know if what they're talking about is a property exclusively of the camera or or not. It would seem to be more useful if it were, but, as we both know, cameras don't capture colors.

Jim
 
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