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Author Topic: 1Dx ISO100 high DR shadows SNR improvement  (Read 16341 times)

tron

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #60 on: November 14, 2012, 09:01:21 PM »
So I activate mirror lock just  before ME shot sequence  (done automatically after camera focused on the subject)  and then deactivate it after ME shot sequence  (using SET button - selectable option in mirror lock function) or it is deactivated itself later by camera itself .
Unfortunately this is not supported by my 5DMkIII that's why I was wondering how you can do that. So it's only Live View for me  :(  (OK I know it is sufficient and actually a super set of Mirror Lock for this purpose but still ...)

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #60 on: November 14, 2012, 09:01:21 PM »

slowcarIX

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #61 on: November 14, 2012, 09:03:06 PM »
Thank you!

Will single long exposure achieve the same effect keeping iso constant?

9 exposure with total integration of 2.5secs = smaller aperture and keeping shutter open for 2.5secs?


For me  to make it easy to use  I just registered ME  and Mirror lockup in the1Dx  custom menu (last tab).


Neutral: could you please give a step by step instruction how this can be done?

Thanks!!

This is how to  do this in 1Dx:
1.      Enable multi-exposure
1.1. Set ME mode to continuous .
1.2.  Set number of exposures to 9  (or any between 4 an 9 - smaller number will give less SNR improvement)
1.3.  Set multi-exposure control to  Average (to integrate over 9 images) ,
2.      (Optional) Switch on  mirror lock up function with the SET button deactivation to reduce camera vibration (will be deactivated  by SET button).  See explanation for this in my post above

3.      Switch on Long exposure NR - set it to auto - will be used for shots longer than 1 sec or set it ON -"forced" .  This adds additional SNR improvements and significantly reduce banding

4.      Put camera in high speed continuous shooting mode  ( optional - if you are shooting in high DR daylight environment to make ME shot very fast) ,  press shutter - mirror will be locked, press shutter again  to start ME shot  and keep it  pressed for each next shot in ME sequence until ME sequence is completed
 Camera will take quickly 9 images in less than 1 sec (that for daylight - at night will be longer ), stops and then merge it ( integrate)  into one image.
And you are done.
Now press set button to return mirror back (if mirror lock was used)  and then you could see the result.
Method is suitable for only still images.
In normal (daylight) conditions such kind of shot will take about 0.75 sec with FPS =12
And of course method should be used with strong stable tripod for camera and remote shutter control (to prevent image blurring due to camera vibrations and get highest possible resolution)

weixing

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #62 on: November 14, 2012, 11:31:34 PM »
Hi,
    This method is commonly use in Astrophotography to reduce noise (mainly to reduce random noise) and improve image quality.

    By the way, Panasonic had this feature built-in in some of their compact camera. 

   Have a nice day.

rpt

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #63 on: November 14, 2012, 11:45:19 PM »
Thank you!

Will single long exposure achieve the same effect keeping iso constant?

9 exposure with total integration of 2.5secs = smaller aperture and keeping shutter open for 2.5secs?


For me  to make it easy to use  I just registered ME  and Mirror lockup in the1Dx  custom menu (last tab).


Neutral: could you please give a step by step instruction how this can be done?

Thanks!!

This is how to  do this in 1Dx:
1.      Enable multi-exposure
1.1. Set ME mode to continuous .
1.2.  Set number of exposures to 9  (or any between 4 an 9 - smaller number will give less SNR improvement)
1.3.  Set multi-exposure control to  Average (to integrate over 9 images) ,
2.      (Optional) Switch on  mirror lock up function with the SET button deactivation to reduce camera vibration (will be deactivated  by SET button).  See explanation for this in my post above

3.      Switch on Long exposure NR - set it to auto - will be used for shots longer than 1 sec or set it ON -"forced" .  This adds additional SNR improvements and significantly reduce banding

4.      Put camera in high speed continuous shooting mode  ( optional - if you are shooting in high DR daylight environment to make ME shot very fast) ,  press shutter - mirror will be locked, press shutter again  to start ME shot  and keep it  pressed for each next shot in ME sequence until ME sequence is completed
 Camera will take quickly 9 images in less than 1 sec (that for daylight - at night will be longer ), stops and then merge it ( integrate)  into one image.
And you are done.
Now press set button to return mirror back (if mirror lock was used)  and then you could see the result.
Method is suitable for only still images.
In normal (daylight) conditions such kind of shot will take about 0.75 sec with FPS =12
And of course method should be used with strong stable tripod for camera and remote shutter control (to prevent image blurring due to camera vibrations and get highest possible resolution)
As I understand it, the pixel data will be averaged and not summed as that is what is selected in step 1.3. So my understanding is that the exposure should be sufficient to capture all the light for the subject. It is only in the dark areas that the random noise will be evened out.

Neutral, do correct me if I did not get it right.

Neutral

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #64 on: November 15, 2012, 10:30:07 AM »
    This method is commonly use in Astrophotography to reduce noise (mainly to reduce random noise) and improve image quality...
This correct. And they could use thousands and thousands of images for averaging to extract details that far below noise level.   And have supercomputers to do this using sophisticated processing algorithms – not just simple averaging

Neutral

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #65 on: November 15, 2012, 10:33:41 AM »
Thank you!
Will single long exposure achieve the same effect keeping iso constant?
9 exposure with total integration of 2.5secs = smaller aperture and keeping shutter open for 2.5secs?
Unfortunately this will not help.
 Basically by doing so you will be just reducing amount of light per time unit to the sensor to keep exposure longer  to obtain the same amount of light. 
    Mutli-Exposure  method is different  - it allows to capture more light - up 9 times more for 1Dx (and 10 times more for  Nikon D800) than in single shot and then averaging that  (normalizing)  to one single shot image . But random noise is not increased by 9 times but only  by  Sqrt(9)=3
 So after averaging 9 shots in ME sequence  (normalizing it to one shot) we will have  10*log(9/sqrt(9))=10*log(3)= 4.7dB  image SNR improvements.

 On the link below you can find detailed explanations - I was referring this in one of my previous post .
Found it when was searching for something that could answer all the questions.
http://www.cambridgeincolour.com/tutorials/image-averaging-noise.htm
 " In general, magnitude of noise<http://www.cambridgeincolour.com/tutorials/image-noise.htm> fluctuation drops by the square root of the number of images averaged, so you need to average 4 images in order to cut the magnitude in half."

Neutral

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #66 on: November 15, 2012, 10:36:51 AM »
  As I understand it, the pixel data will be averaged and not summed as that is what is selected in step 1.3. So my understanding is that the exposure should be sufficient to capture all the light for the subject. It is only in the dark areas that the random noise will be evened out.

Neutral, do correct me if I did not get it right.
Averaging is summing up all the values and then dividing result by number of samples.
Mathematically averaging is (A1+A2+A3 +...+AN)/N where N is number of samples.
  By using ME method Image SNR will be increased for every pixel on the image - regardless if this shadows or highlights where SNR is already high and will be even better.
As result of cleaner image you can use more aggressive sharpening without any visible problems on the image

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #66 on: November 15, 2012, 10:36:51 AM »

rpt

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #67 on: November 15, 2012, 10:46:33 AM »
  As I understand it, the pixel data will be averaged and not summed as that is what is selected in step 1.3. So my understanding is that the exposure should be sufficient to capture all the light for the subject. It is only in the dark areas that the random noise will be evened out.

Neutral, do correct me if I did not get it right.
Averaging is summing up all the values and then dividing result by number of samples.
Mathematically averaging is (A1+A2+A3 +...+AN)/N where N is number of samples.
  By using ME method Image SNR will be increased for every pixel on the image - regardless if this shadows or highlights where SNR is already high and will be even better.
As result of cleaner image you can use more aggressive sharpening without any visible problems on the image
You are right. The noise will be addressed for each pixel. It will be more noticeable in the shadows and darker areas of the image.

Neutral

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #68 on: November 15, 2012, 10:48:29 AM »
So I activate mirror lock just  before ME shot sequence  (done automatically after camera focused on the subject)  and then deactivate it after ME shot sequence  (using SET button - selectable option in mirror lock function) or it is deactivated itself later by camera itself .
Unfortunately this is not supported by my 5DMkIII that's why I was wondering how you can do that. So it's only Live View for me  :(  (OK I know it is sufficient and actually a super set of Mirror Lock for this purpose but still ...)
  Actually mirror lock is not required – just an option to get better image sharpness – reducing camera vibrations and preventing refocusing for each ME shot in sequence.
If for first one nothing could be done with 5DM3 but for second one it is possible to focus automatically then switch lens to manual focus to keep focus unchanged during  ME sequence

rpt

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #69 on: November 15, 2012, 12:14:37 PM »
Ok, I just tried it. Set it for 9 exposures. Set it on live view. After the first shot, I set the AF off and took the next 8. The noise reduction was significant. I shot decorative lights in the garden. The iso was 25600.
Yay!

Thanks Neutral :)

rpt

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #70 on: November 15, 2012, 01:11:39 PM »
Just tried another with iso 100. I am happy. No NR needed in LR :)

tron

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #71 on: November 15, 2012, 06:02:19 PM »
So I activate mirror lock just  before ME shot sequence  (done automatically after camera focused on the subject)  and then deactivate it after ME shot sequence  (using SET button - selectable option in mirror lock function) or it is deactivated itself later by camera itself .
Unfortunately this is not supported by my 5DMkIII that's why I was wondering how you can do that. So it's only Live View for me  :(  (OK I know it is sufficient and actually a super set of Mirror Lock for this purpose but still ...)
  Actually mirror lock is not required – just an option to get better image sharpness – reducing camera vibrations and preventing refocusing for each ME shot in sequence.
If for first one nothing could be done with 5DM3 but for second one it is possible to focus automatically then switch lens to manual focus to keep focus unchanged during  ME sequence
Mirror lock is required for sharpness. There is no point in trying to lower the noise merely to induce camera shake. But is is achieved with LiveView. Anyway for shots on tripod - when it is getting dark - I use Mirror Lock and 2 second delay. Focusing is either AF and then turned to manual or Live View (with manual focus and 10x). So the only additional function is the Multiple Exposure (Mirror is Locked in LV).

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #72 on: November 16, 2012, 02:04:35 AM »
Neutral - thanks for the in-depth explanation - I'm anxious to try out your ME method.

BTW - my 1DX is my first 1 series camera - I'm loving it but there is a learning - it's threads like yours that I find helpful - inspired me to register at canonrumors. Thanks again. :)

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #72 on: November 16, 2012, 02:04:35 AM »

Neutral

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #73 on: November 16, 2012, 02:19:55 AM »
Just tried another with iso 100. I am happy. No NR needed in LR :)
One more happy user  :)
 That's nice and gives some good feeling to me  :)

Neutral

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #74 on: November 16, 2012, 02:30:00 AM »
Neutral - thanks for the in-depth explanation - I'm anxious to try out your ME method.

BTW - my 1DX is my first 1 series camera - I'm loving it but there is a learning - it's threads like yours that I find helpful - inspired me to register at canonrumors. Thanks again. :)
Thanks for good words :)
My pleasure ))
 This is just illustration to what I was telling several times in some other posts – instead of useless arguments over subject(s)  that some most involved have no ideas or knowledge – better do something useful for others if you can do that )))
  And this was the reason I join forum recently – I got very tired of reading all that heated disputes about DXO sensor measurements  between people who do not understand that at all and wanted to show how  simple MATH is applied to real life.

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Re: 1Dx ISO100 high DR shadows SNR improvement
« Reply #74 on: November 16, 2012, 02:30:00 AM »