BMMCC / BMPCC OG ISO 400 vs 800

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Texaco87

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BMMCC / BMPCC OG ISO 400 vs 800

PostMon Dec 04, 2023 2:36 pm

I’m still getting used to exposing for our BMMCC, ETTR (which is much different than our g85 which we would usually underexpose for our desired result) and trying to get a clean image, protecting highlights vs shadows etc

So far we’ve been doing 800 for exteriors or bright interiors w/visible windows, and 400 for dark interiors, the only exception being 800 for dark exteriors where light can’t be controlled

I would love to hear other people’s thoughts and strategies though and maybe learn more about how this affects overall DR, thanks in advanced!
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Michel Rabe

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostMon Dec 04, 2023 4:13 pm

I ended up exposing almost everything at ISO 400, including exterior day. I felt like it gave me 'thicker' mids every time. If that made some highlights blow out I considered if I can live with it on a case by case basis before exposing for 800.
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Texaco87

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostMon Dec 04, 2023 6:06 pm

Cool, thanks so much for responding-

As I was reading that I was thinking that I actually think I do it the same way, so it’s good to know that serves you well
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ShaheedMalik

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostMon Dec 04, 2023 7:40 pm

Grading for 800 exteriors and 400 interiors is backwards.

These cameras put out noise at 800.

Expose for 400 or 200 and use an ND filter to prevent clipping for outside scenes. You will require less ND and the image will be cleaner.
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Brad Hurley

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostMon Dec 04, 2023 9:38 pm

Much depends on whether you are shooting raw or ProRes.

If you are shooting CDNG raw you might as well expose for ISO 800, which is the native ISO for both the OG BMPCC and BMMCC and thus provides the greatest dynamic range, and then pull down to 400 in post if you want to reduce noise. You'll be using ND filters most of the time, which you'll probably want to do anyway since diffraction softening sets in early on these cameras due to their tiny sensors, so you shouldn't go above f5.6 or at most f8.

If you are shooting ProRes, the ISO is baked into the compressed footage (this might be true with the BMMCC's 3:1 compressed CDNG raw as well, but I don't think so), so if you want less noise in your footage you should shoot at ISO 400.

There's an informative thread about the original BMCC but also the OG BMPCC/BMMCC here: viewtopic.php?f=2&t=10892
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Michel Rabe

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostMon Dec 04, 2023 10:08 pm

I disagree about shooting cDNG at 800 and it being 'native', that might be what BMD states but results just didn't add up for me. ISO 400 consistently gave be equal (arguably better) DR but deeper color where it mattered, with less noise. There almost never was a scenario where 800 yielded better or even equally good results.
These sensors need light to really shine.
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Brad Hurley

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostMon Dec 04, 2023 10:18 pm

Michel Rabe wrote:I disagree about shooting cDNG at 800 and it being 'native', that might be what BMD states but results just didn't add up for me. ISO 400 consistently gave be equal (arguably better) DR but deeper color where it mattered, with less noise. There almost never was a scenario where 800 yielded better or even equally good results.
These sensors need light to really shine.


Sure, but if you're shooting at ISO 800 with a 1-stop ND filter you're effectively exposing at ISO 400 anyway. How is there a difference between setting the camera's ISO to 400 (which is just changing metadata if you're shooting raw) vs. shooting at 800 with a 1-stop ND filter? See viewtopic.php?f=2&t=10892#p115117

I keep my ISO at 800 and use ND filters to adjust exposure as needed; on the BMMCC it's easier to leave ISO the same all the time than to have to go into that awful menu and try to adjust it for the times when there's not enough light to shoot at 400. The answer is always "add more light," but unless you're only shooting cinema, with controlled lighting, adding more light isn't always an option.
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Michel Rabe

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostMon Dec 04, 2023 11:17 pm

I don't understand. Whether you use an ND or not depends on the scene, not the dialed in ISO. Exposing for ISO 400 vs 800 simply means that you let 1 stop of light more hit the sensor for the image on the screen to look right. As I mentioned above, these sensors want light to really shine.
Raising ISO to 800 and then cutting light with an ND to get the right exposure is not what yields the best "negative" for that Fairchild sensor in my experience.
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Anton_Shavlik

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostTue Dec 05, 2023 7:13 am

I would shoot 800iso most of the time and expose correctly. In film gamma at 800iso the zebras set at 95% will show where the sensor is clipping, and that's all you have to manage.

400iso for dark scenes or in tungsten lighting (and exposing correctly for 400) is also a good idea to protect yourself.

I find the noise at 800 pleasant and that it's usually minimized by the compression of the final output, and you gain a stop of highlights over shooting 400 which is typically the bigger problem.
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Michel Rabe

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostTue Dec 05, 2023 10:18 am

I found that rarely to be the problem though.

Setting ISO at 400 as default and only raising to 800 when I ran into trouble with highlights yielded thicker, superior results for me. You can mostly expose by eye on the screen (o.c. always check zebra/histo) and don't needlessly throw away a stop of light as you would in many situations when exposing for 800. If it was bright outside, 800 was usually a better starting point ( and ISO 200 for very low light).

Both ways are ok, but having shot commercials for years with the OG Pocket I cannot emphasize enough, this sensor wants as much light as it can get, so make sure you let it in and not potentially cripple it by defaulting to ISO 800.
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Michel Rabe

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostTue Dec 05, 2023 10:41 am

To add:
this is also a lot about personal preferences. I have colleagues who feel the need to prevent any highlights from clipping. If the middle of the lamp-shade from a practical clips, they'd lower exposure. Personally I'd be more likely to let it clip but keep shadow detail of the rest of the image. Sometimes a small area between clouds of the sky clips - do you protect it or expose the skin correctly? Or do you introduce a bounce that will likely make the shot not match with the previous one?

So there's not really a right or wrong but I found that it's a good idea to feed that Fairchild sensor as much light as possible.
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Howard Roll

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostTue Dec 05, 2023 6:36 pm

Interiors where more of the image is going to sit below mid grey it makes sense to shoot (and light) lower ISO.

Daylight exteriors where more of the image sits above mid grey it makes more sense to shoot high ISO.

DNG is raw in it’s purest sense so ultimately it only affects one’s exposure methodology.

Good Luck
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ShaheedMalik

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostWed Dec 06, 2023 12:44 am

Michel Rabe wrote:To add:
this is also a lot about personal preferences. I have colleagues who feel the need to prevent any highlights from clipping. If the middle of the lamp-shade from a practical clips, they'd lower exposure. Personally I'd be more likely to let it clip but keep shadow detail of the rest of the image. Sometimes a small area between clouds of the sky clips - do you protect it or expose the skin correctly? Or do you introduce a bounce that will likely make the shot not match with the previous one?

So there's not really a right or wrong but I found that it's a good idea to feed that Fairchild sensor as much light as possible.

Use an ND to prevent the video signal from clipping. It's no different than recording audio. You use NDs like you would use an audio limiter. It's all capturing a good signal.

If you turn up the gain on the signal, you are more likely to have the signal with noise.
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Michel Rabe

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostWed Dec 06, 2023 10:10 am

ShaheedMalik wrote:
If you turn up the gain on the signal, you are more likely to have the signal with noise.


Which is exactly what you do when exposing for ISO 800 although there are no highlights to protect.
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ShaheedMalik

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostWed Dec 06, 2023 10:14 am

Michel Rabe wrote:
ShaheedMalik wrote:
If you turn up the gain on the signal, you are more likely to have the signal with noise.


Which is exactly what you do when exposing for ISO 800 although there are no highlights to protect.


Turning up the gain to "protect the highlights" is a myth. The dynamic range of the camera does not change. If you are caputing something 6 stops above middle gray and your camera only captures 5, your image will clip. If your image is clipping, it's already blown out. Put an ND on and decrease the sensitivity by exposing for 200 or 400.
Last edited by ShaheedMalik on Wed Dec 06, 2023 10:17 am, edited 1 time in total.
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Michel Rabe

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostWed Dec 06, 2023 10:15 am

ShaheedMalik wrote:
Michel Rabe wrote:
ShaheedMalik wrote:
If you turn up the gain on the signal, you are more likely to have the signal with noise.


Which is exactly what you do when exposing for ISO 800 although there are no highlights to protect.


Turning up the gain to "protect the highlights" is a myth. The dynamic range of the camera does not change. If your image is clipping, it's already blown out. Put an ND on or decrease the sensitivity.


I think we're talking past each other or I'm misunderstanding your point. If the highlights aren't clipping, why would you put an ND on?
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Michel Rabe

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostWed Dec 06, 2023 10:21 am

ShaheedMalik wrote:Turning up the gain to "protect the highlights" is a myth. The dynamic range of the camera does not change.


Yes and no. The only thing that changes when changing ISO is how bright the screen interprets the signal. So by dialing in a higher ISO, the screen gets brighter. So when you expose by eye, on the image on your screen, you will let less light hit the sensor for it to look correct on the screen, which does 'protect the highlights' in a way. But at the same time you are right, the clipping point doesn't change.

It's a mix of choosing the right preview (ISO) and using the camera's exposure tools.
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ShaheedMalik

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostWed Dec 06, 2023 4:11 pm

Michel Rabe wrote:
I think we're talking past each other or I'm misunderstanding your point. If the highlights aren't clipping, why would you put an ND on?


I see you missed my edit. Read above, I made my post more clear.
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Texaco87

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Re: BMMCC / BMPCC OG ISO 400 vs 800

PostThu Dec 07, 2023 6:46 pm

Thanks everyone so much for weighing in on this!

It seems to me based on everyone’s feedback that it is best to treat ISO 400 as the cameras base ISO, using ISO 800 for shots featuring heavy highlights and ISO 200 for shots with heavy shadows, lighting permitting.

This is essentially what I have been doing, so it’s nice to hear that confirmed/reinforced by people who know more than me haha.

Thanks again all!

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