Discussion: Do BMD cams really need more light than others?

Today I was at local filmmaker brunch in my town. There I got into an interesting discussion with a gaffer (who owns a light rental business and has worked on many feature films, TV series and corporate films). He told me that in his experience as a gaffer when BMD cameras were brought in as B cams (ARRI Alexa or RED, SONY CANON as A cams), he always had to put up more light to get the same look out of the BMD camera. As an example he named the PCC6k Pro.
He wasn't talking about noise - just about the "normal range" they want to bring in the picture.

I told him, that this would be contradictory to my own experience with BMD cameras I have used since 2013. Sure - the pockets do have less dynamic range than the Alexa or high-end REDs, Sonys and Canons. And BMD cameras do not have any internal noise reduction.

I asked him, if he was sure the DoPs were really familiar with the BMD cameras as in my experience when people bring in a B cam from another brand - they often do know less about that camera because they are used to their A cam system. He said he thinks the DoPs knew what they were doing but he had no idea if they shot in ProRes or BRAW on the pockets. My guess was maybe the wrong LUT or a too conservative setting in the camera or not enough knowledge what could be done in post with BRAW.

I tried to not come over as too defensive of BMD cameras, but also tried to get more in-detail information - but he only repeated what he had experienced from his job as the gaffer. Unfortunately we ran out of time to dive deeper into this topic.

So I'd like to discuss this here a bit further. Observations and experience of other users from this forum.
Please no personal attacks on those DoPs the gaffer worked for - there is just not enough information.

I will meet him again at a workshop in two weeks and would like to present some valid observations.

If shooting at a native ISO on the Pocket, maybe it's at 400 compared to an ARRI at typically 800?

My experience is with Bmpc4k, pocket4k,6k, Ursa Mini Pro g1, and I can tell with first and last require a bit of more light in shadow be cause are prone to present fpn sometimes, and I want to avoid it, but I used in many situations, from dark shooting to light and not more light than I used for Panasonic Gh series, fujifilm xt3/4/h2 and more.
I not have direct experience like dop with higher camera like arri.
I learn a great lesson from an old dop from film (Romano Albani, dop for Dario Argento and many other):
film strip or digital are the same, you study the media, you understanding latitude and light : shadow for your needs.
Every media had its weak and strong point, use both.


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I typically need more light for the Pockets over the UM4.6K sensor. And, since the 12K and UC12K have 800 ISO as well for a base, I'd say this primarily has to do with the 400 base ISO on Pockets. Usually I also have to stop down the UMPG2 to match the P6KPro even if I compensate with a stop on the lens for the ISO difference. Usually the UMPG2 needs to go from ISO 800 to 640, and, that's often closed down a full stop on the lens compared to the P4K. And, the UMPG2 has always had more highlight details than the P6K sensors.

My assumption is all Base ISO 800 BMD cameras are like this compared to the Base ISO 400 BMD cameras. This means that the UC12K and UC17K won't need as much light as the PYXIS 6K. But with the rise for higher ISOs in triple or dual ISO cameras I'm betting people are expecting more from modern cinema cameras. Yet, I still like to light like it's film.

By comparison the ISO 800 base is very comparable to ISO 500T film. 400 is just a bit slower, and needs that much more light. Arri has had 800 for years, and is often pushed to 1600 without major noise issues. I rarely push the UMPG2 to 1600, but the P4K, P6K, and PYXIS all lose a stop of light by 1600. So, maybe there's some factor there as well where Arri is proven its higher dynamic range superior despite not having dual ISO.

But that's my experience and guesses. Generally the 4.6K hasn't needed as much light as the P6K, and in general compensation has lead me to believe it's over 1.33X brighter by comparison to the lower dynamic range and lower base ISO sensor of the P6K.

I routinely shoot almost every BMD camera alongside other primary cameras such as the DXL2, Arri Alexa 35, Alexa Mini LF, Alexa Mini, Alexa SXT.

I never change the amount of light I use, I don’t change lighting ratios. The only change I sometimes would make is around the base ISO matching, or if I have a different brand lens that might not be the same iris despite what’s on the lens.

In other words, no, I do not meaningfully change lighting ratios or levels.

I recently did a job with a DIT with Alexa 35 and because I was the second DP on the show I didn’t set up the process or the look. It had a pretty heavy grade applied real time by the DIT. The DIT was also controlling all cameras exposure remotely. When I switched to using the BMD camera and was operating it myself the DIT routinely overexposed the camera bump a stop to two stops from where I would have set the exposure. When I queried him, he said that’s where the exposure needed to be to match the LUT as established on the Alexa 35.

That is not a methodology I agree with at all. But I wonder if this is what’s happening Robert?

I typically use false colour to determine in camera exposure and a light meter for ratios.

When rolling on these scenes I’d flick the FC button and the skin tones were sitting at plus one stop over green on white skin tones and that’s just not where Inwould center the exposure.

I would argue a well exposed image can be bent and graded to what ever look you want in final colour. Trying to expose though a LUT made for another camera based on your eyeballs and not trusting false colour is a path to massive problems. But it’s also going to change how you perceive the camera is working.

It’s hard for me to say more without offending, but this is one of the reasons I choose not to use a DIT in most situations.


JB

When rolling on these scenes I’d flick the FC button and the skin tones were sitting at plus one stop over green on white skin tones and that’s just not where Inwould center the exposure.

JB

Thanks for your thoughts, John. Where do you usually like to expose lighter skin tones on FC?

I don't think they need more light, I just think people are used to cameras that has high ISO sensitivity settings. They are naturally under lighting everything.

When rolling on these scenes I’d flick the FC button and the skin tones were sitting at plus one stop over green on white skin tones and that’s just not where Inwould center the exposure.

JB

Thanks for your thoughts, John. Where do you usually like to expose lighter skin tones on FC?

Typically green with a smidge or highlight of pink is a great sweet spot.

JB