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Archive 2014 · DualISO vs Exmor

  
 
kevindar
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p.3 #1 · p.3 #1 · DualISO vs Exmor


yeah, I tried it too. pretty impressive as others have posted.
Of course, for a landscape shooter, there are things to keep in mind. If you are have an entirely stationary landscape, no moving parts, you are still better off shooting two files 4 stops apart, use photoshop HDR funciton to fuse them in to a 32 bit TIF file. that way, you will still have much cleaner shadows and no resolution loss. and of course if the scene is amenable to just two exposures and simple layering, same is true.

At best, clean pushing of an exposure is about very low read noise which is not added during signal processing. so ineffect, wether you set the iso which is sensor amp in camera, or do it afterwards in software, you end up with the same amount of noise.

that means a scene shot with the same exposure (f stop/shutter speed), can be shot correctly at iso 1600, or shot at iso 100 and pushed 4 stops, and end up with same amount of noise. However, the shadows pushed 4 stops, under the best case scenario, still look like they were shot at iso 1600. However, if you take two exposure which are 4 stops apart, and use the shadows from the brighter exposure, it will have cleaner shadow.

I am probably stating the obvious, and using wrong terminology all along



Sep 06, 2014 at 08:57 PM
whumber
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p.3 #2 · p.3 #2 · DualISO vs Exmor


kezeka wrote:
Definitely mixed up the order. Too used to reading radiology scans these days . How does one enable 20-bit dng and -cs5x5?


If you're using the LR plugin then you can set those options in the export dialogue. If you're doing it through the command line then you need to use the 20-bit executable and the -cs5x5 flag.



Sep 06, 2014 at 09:09 PM
kezeka
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p.3 #3 · p.3 #3 · DualISO vs Exmor


kevindar wrote:
yeah, I tried it too. pretty impressive as others have posted.
Of course, for a landscape shooter, there are things to keep in mind. If you are have an entirely stationary landscape, no moving parts, you are still better off shooting two files 4 stops apart, use photoshop HDR funciton to fuse them in to a 32 bit TIF file. that way, you will still have much cleaner shadows and no resolution loss. and of course if the scene is amenable to just two exposures and simple layering, same is true.

At best, clean pushing of an exposure is about very low
...Show more

I believe you are incorrect. Signal amplification at the sensor level produces less noise than digital amplification in post processing (or using the "expanded" ISOs - both are digitally raised) in addition to preserving color and contrast better.



Sep 06, 2014 at 10:30 PM
kevindar
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p.3 #4 · p.3 #4 · DualISO vs Exmor


In fact, that is exactly what I am saying. In a perfect sensor with no read noise, it wont matter if the amplification is done initially on the sensor (ISO) or after it has gone through the ADC(post). of course there is no perfect sensor, but exmor is a lot closer to it than is canon. that is why you can push the shadows so much more before they fall apart. However, there remains photon noise. if you are pushing the shadows, either by amplifying the signal in camera (ISO) or in post, you will end up with more noise, than if your pixel wells were filled with more photons (higher exposure level). we of course know this as we know image shot at iso 1600 is noiser than one at iso 100.

If you are combining two separate exposures, you are taking advantage of photon wells (pixels) which are optimally filled for the shadow section of photograph in your longer exposure, and hence will have better shadow noise performance than pushing the shadows, regardless of doing so by ISO or in post.

From practical stand point however, you can push the shadows easily a couple of stops in modern sensors before you see much differnce (akin to a proper exposure at iso 400, if you are shooting at iso 100(



Sep 06, 2014 at 11:20 PM
Beni
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p.3 #5 · p.3 #5 · DualISO vs Exmor


Is it just me or is there significant vertical banding in the dual ISO shot?

The best trick with ML is to have it on a SD card then you can swap your CF cards and not have to reboot and also be able to format your CF cards as normal.

I tried Dual ISO about a year ago, it was awful with high key shots. I assume it has improved from the sound of this thread.



Sep 07, 2014 at 02:52 AM
whumber
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p.3 #6 · p.3 #6 · DualISO vs Exmor


Beni wrote:
Is it just me or is there significant vertical banding in the dual ISO shot?


The only vertical 'banding' like behavior I can see is from the window screen's bokeh, if you're referring to kezeka's shots. Can you point out where you're seeing it? I've been using it for ~18 months and I've never seen any sign of vertical banding.

Beni wrote:
I tried Dual ISO about a year ago, it was awful with high key shots. I assume it has improved from the sound of this thread.


Yeah, the improvement since the early versions is enormous. The early version were a neat trick but not really useable for anything over websize shots. With the new versions I've made several 13x19 prints that look great, even with your nose to the print. The remaining issue, as someone else mentioned is the startup time, but it's not really an issue for landscapes.



Sep 07, 2014 at 08:50 AM
kezeka
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p.3 #7 · p.3 #7 · DualISO vs Exmor


Beni wrote:
Is it just me or is there significant vertical banding in the dual ISO shot?

The best trick with ML is to have it on a SD card then you can swap your CF cards and not have to reboot and also be able to format your CF cards as normal.

I tried Dual ISO about a year ago, it was awful with high key shots. I assume it has improved from the sound of this thread.


The "banding" you are referring to is probably the window screen, there is no banding that I have found in my tests using dual ISO thus far. It definitely reduces the Canon staple chroma noise banding in the shadows when they are pushed, though.



Sep 07, 2014 at 12:54 PM
Beni
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p.3 #8 · p.3 #8 · DualISO vs Exmor


Looking at the second shot, wood on left, green on right, there seems to be significant banding in the green. Is that just the window?


Sep 08, 2014 at 12:04 AM
whumber
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p.3 #9 · p.3 #9 · DualISO vs Exmor


Beni wrote:
Looking at the second shot, wood on left, green on right, there seems to be significant banding in the green. Is that just the window?


The vertical banding in the green is definitely from a screen or something in the background, but I don't see any kind of banding in the wood, at least not in the dualISO shot.



Sep 08, 2014 at 08:09 AM
Beni
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p.3 #10 · p.3 #10 · DualISO vs Exmor


Cool.


Sep 08, 2014 at 11:32 AM
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