Exposure / Noise Epic-W problems - help is welcome

[Hans von Sonntag]

Blue channel. Of course!

Hans

 

[Michael Tiemann]

So, just for fun I applied my GIO LUT (see https://manifoldrecording.com/2017/12/20/gio_lut/) to your image. I set the ISO and WB to the "native" values (800 and 5600K) and then compared the results of the GIO_Max and GIO_Min functions. GIO_Max gives a GIO Scope reading on the maximum of the R, G, B channels and GIO_Min gives the reading based on the minimums. You can see just how wildly different are the brightest channels from the blue channel this way.

Max 1/2 @ 100%:

Min 1/2 @ 100%:

Max 1/2 @ 50%:

Min 1/2 @ 50%:

If you watch the clip in the max view, you see little noise. If you watch the clip in the min view, you see lots of noise. As others have said, a low K white balance means the blue channel is being amplified a lot, so you need to expose with a very low ISO (250-320) to give it a chance.

 

[David Moreno Belmonte]

Hi guys

Hi guys

May you please explain in short (to don't bother you) hhow exactly works the relation:

exposure / WB / noise

That you are mentioning, and how in summary best way to take care of different color channels to avoid noise?

I'm a random Dragon User and always had noise when I shot over 320ISO, but mostly I recall, in night environments with street lights, or different color lights, Eg. a scene with a fire and a blue moon light (5600k), where white balance was for the moon light to look not too cold, maybe 4800k the fire looked good in color, ISO was 400 but noise was horrible in shadows near the fire, even when exposure was better in those areas. I always wondered how that worked.... hope that make sense..

Just curious.

Thanks!

 

[Jake Wilganowski]

Basically in a nutshell the blue channel is way less sensitive than the other channels, so you need to feed it more blue light to reduce noise

 

[Tyler Besh]

So, just for fun I applied my GIO LUT (see https://manifoldrecording.com/2017/12/20/gio_lut/) to your image. I set the ISO and WB to the "native" values (800 and 5600K) and then compared the results of the GIO_Max and GIO_Min functions. GIO_Max gives a GIO Scope reading on the maximum of the R, G, B channels and GIO_Min gives the reading based on the minimums. You can see just how wildly different are the brightest channels from the blue channel this way.

Max 1/2 @ 100%:

Min 1/2 @ 100%:

Max 1/2 @ 50%:

Min 1/2 @ 50%:

If you watch the clip in the max view, you see little noise. If you watch the clip in the min view, you see lots of noise. As others have said, a low K white balance means the blue channel is being amplified a lot, so you need to expose with a very low ISO (250-320) to give it a chance.

Thanks for sharing this tool! I've looked into it and downloaded the LUT zip. I'm a little confused, even after reading, exactly what these LUTs show. Could you further explain your usage of it and what they reflect?