Canon R5C understanding Base ISO

[peterffm]

Hello Community. I have problems with understanding how works the ISO in R5C. 
When I choose cLog 3 the base ISO is 800/3200. I have a assignable button to change Base ISO between 800 and 3200 in clog3. Unfortunately when I change the ISO I have on tye screen Base 800 or Base 3200 but under is yet the work Iso and the value is not 800 or 3200. Why is this so that when I change the Base to 800/3200 O have a different value of Camera ISO? And then when I change the ISO in Camera the picture is brighter or darker but on the screen is set Base 800 or Base 3200. Can me someone explain please this because it's very annoying.

Please see a short footage on YouTube here

https://m.youtube.com/watch?v=0YrAZCv4PEY&pp=ygUSQ2Fub24gcjVjIGlzbyBiYXNl 

Thanks

[kvbarkley]

What a coinkidink! This just came up on the lens rentals blog:

https://www.lensrentals.com/blog/2023/08/decoding-the-language-of-videography-gear-an-equipment-term...

Your question is the last answered.

[peterffm]

Thank You for the answer, this thing with dual ISO I think that I understand my issue is that I don't understand why in R5C I see two ISO value one is Base ISO and another is the work iso of the camera. Please see the image. Base ISO is set to 800 and under is 6400. The 6400 I can change and the 800 is still visible. 

 

[rs-eos]

You can definitely dial in whatever ISO you need.  The base ISO is there so as to provide the ability to maximize the amount of dynamic range captured.

e.g. when using a base of ISO 800 and you keep your ISO at 800, your footage would have the highest amount of dynamic range.  You may still get the same range as you lower or raise that ISO a bit (you'd have to find charts that would reference that).  However, once you approach ISO 100, the dynamic range will most likely be lowered.  Same when using high ISO values.  And of course with the higher ISO values, you'll have extra noise as well.