Requesting Help with bmpcc6kpro / bad images always

Why? Personally the analogy made it much easier for me to understand the concept of exposing for raw when I got my first RED camera. I remember how many people on REDuser had to rethink exposing and how RED tried to educate everyone.

Michel, I think what John means is they are really very different; the analogies are sometimes just that. For example it was common to get a 'thick' negative, back in the day, by over exposing (conversely it was advisable to underexpose reversal stock); because negative film could be pushed and pulled in development considerably, and highlight fell off gracefully. Whereas digital is really video with a log curve and raw; but highlights will still clip eventually in an ugly way. And so here ETTR which may be considered a broadly similar and analogous approach may not be suitable, in the same way.

ISO is really a complete fiction, in the sense of photochemical equivalence, that is; it is really db digital gain simply, with fixed 1 or two ADC amplitudes. Your selection of ISO/db does obviously influence your exposure settings choice and raw allows more latitude in post, analogous to negative film, but that's where it ends with real ISO or ASA, or whatever. ISO comes mainly from stills anyway, from the DSLR craze; it was more common to think in ASA back in the film days.

The incredible latitude of of Digital film cameras now does approach film and in some ways exceeds it; and these terms have most certainly helped the almost total transition to digital, so you are right too, they can be very helpful in the end. But the terminology is strictly analogous not scientific.

Whenever I see threads like this it makes my head spin.

I'm still using the original Super-16 sensor BMD cameras: one 1080p Pocket Cinema Camera and two Micro Cinema Cameras. Their native ISO is 800, and when I first got the cameras the general consensus I got from online research and inquiries to cinematographers was "when shooting raw, always leave ISO set at 800, leave shutter angle at 180 unless you want to change it for creative reasons, choose your iris/aperture based on desired depth of field and/or your lens's sweet spot, and use ND filters to dial in exposure."

Then I became aware of a second faction of advice which was to use a lower ISO in low light when shooting raw (to reduce noise), and raise ISO in very bright situations (to protect highlights).

What I have trouble understanding is how these two strategies differ from point of view of the amount of light hitting the sensor. If I set my ISO at 800, apply a 1-stop ND filter and adjust iris to dial in exposure, isn't the sensor receiving the exact same amount of light as if I had set the ISO to 400 and adjusted iris to dial in exposure?

I can see an argument for limiting the amount of ND needed if you're using variable ND filters, but if you're using fixed ND filters I'm not sure why I shouldn't just keep shooting at ISO 800 and use filters and iris to manage exposure.

What I have trouble understanding is how these two strategies differ from point of view of the amount of light hitting the sensor. If I set my ISO at 800, apply a 1-stop ND filter and adjust iris to dial in exposure, isn't the sensor receiving the exact same amount of light as if I had set the ISO to 400 and adjusted iris to dial in exposure?

No. When shooting raw, think of ISO changes as nothing but making the monitor image brighter or dimmer. It does not do anything to the recorded light or the sensitivity of the sensor (with the exception of dual gain sensors that have a second "sensitivity").

Say your camera's base ISO is 400. Your image is exposed so it looks fine. Now you raise ISO to 800. Your preview monitor is now 1 stop brighter and the image looks to be overexposed. That will make you feel like closing down aperture by 1 stop. The image now looks good again, exactly like it did when exposing for ISO 400 - the difference is, you closed down aperture by 1 stop when exposing for ISO 800 compared to 400.
So 1 stop less oflight hits the sensor, even though both images looked the same on your monitor.

Tools like histogram, zebra, false color ect help with proper exposure more precisely. But dialing in an ISO according to the scene, can make it easier to expose for the actual image on the screen.

Personally I only lower ISO when shooting in low light to expose for cleaner shadows, otherwise I stay at base ISO.

Why? Personally the analogy made it much easier for me to understand the concept of exposing for raw when I got my first RED camera. I remember how many people on REDuser had to rethink exposing and how RED tried to educate everyone.

Michel, I think what John means is they are really very different; the analogies are sometimes just that. For example it was common to get a 'thick' negative, back in the day, by over exposing (conversely it was advisable to underexpose reversal stock); because negative film could be pushed and pulled in development considerably, and highlight fell off gracefully. Whereas digital is really video with a log curve and raw; but highlights will still clip eventually in an ugly way. And so here ETTR which may be considered a broadly similar and analogous approach may not be suitable, in the same way.

ISO is really a complete fiction, in the sense of photochemical equivalence, that is; it is really db digital gain simply, with fixed 1 or two ADC amplitudes. Your selection of ISO/db does obviously influence your exposure settings choice and raw allows more latitude in post, analogous to negative film, but that's where it ends with real ISO or ASA, or whatever. ISO comes mainly from stills anyway, from the DSLR craze; it was more common to think in ASA back in the film days.

The incredible latitude of of Digital film cameras now does approach film and in some ways exceeds it; and these terms have most certainly helped the almost total transition to digital, so you are right too, they can be very helpful in the end. But the terminology is strictly analogous not scientific.

Yes, I recently realized why the film analogy can easily confuse people.

For me it was helpful because I imagined the digital camera to be what my analog foto camera was when it was loaded with, say, an ASA 400 film. It had a sensitivity of 400 ASA and no matter what dials I turned, that would never change. When shooting raw on a digital camera, that analogy helped me understand that changing ISO does nothing to the sensitivity. Only what I chose to do with lighting, aperture, ND or shutter angle would change the recorded image, but not changing ISO. Now with analog film you could rate ASA higher or lower to intentionally push or pull the negative. Which again helped me understand the concept of changing ISO when shooting raw on digital.

But I realize the flaw of that analogy. It could easily be understood that replacing the ASA 400 film with, say, an ASA 1600 film is the equivalent of changing ISO. Instead of the film roll being the equivalent of the sensor itself. Probably other pitfalls, too.

I still remember how much the concept of exposing for raw capture was head spinning for new RED users, and how RED tried to educate people on that concept. It is something people had to learn (again) because it's so counterintuitive when used to shooting to codecs where camera gain is baked in.

I'm still using the original Super-16 sensor BMD cameras: one 1080p Pocket Cinema Camera and two Micro Cinema Cameras. Their native ISO is 800

Btw, I shot commercial work for several years on the OG Pocket and found "native ISO" to be closer to 400 than 800. BMD rated it 800 but that almost always left me with unused headroom and unnecessary noise while exposing for 400 generally produced nicer files.