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Gerald Undone: Exposure Tips for the BMPCC4K & Why I Don’t Use ProRes

So, according to Gerald, there are several things with the P4K that I didn't know about that are very important:

1. Exposure with ProRes on the P4K can be problematic. To fix this you should use RAW, not ProRes, or be *very* careful when setting your exposure.

2. The maximum clipping point *changes* as you change the ISO, if you reduce your ISO from the "native" ISO levels (400, ~3200). At ISO 100, it clips at 83%! I am familiar with the chart showing the steps above and below middle gray, but I didn't realize they were just clipping the top at lower ISOs.

3. Highlight recovery seems to work differently than I had thought and should apparently not be used much of the time. Highlight recovery appears to cause problems with the image when you use it at ISOs >= native ISOs. I had heard that the highlight recovery used the data from other channels when a color had clipped to rebuild that clipped channel.

If you have a P4K you should watch this video! I am really curious to hear other's thoughts on this material. 

 

Thanks @kye for telling me how to embed the video! :) 

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1 hour ago, MeanRevert said:

Weren't you guys bagging on this dude's earlier P4K video where he blew out the highlights? 

I view Gerald Undone as more of a techy geek vlogger that talks about camera stuff than a filmmaker. But, I think that you are right that people were commenting about the visuals in one of his videos a few weeks back. 

The photo side of my brain is used to getting the ISO as low as possible to reduce noise. I shoot exclusively BRAW on the P4K, so this doesn't apply to me, but I would not have thought to avoid going below ISO 400 (or 3200) to avoid nuking the highlights. This means that NDs are pretty much necessary. 

UPDATE: Captain Hook added some clarifications to Gerald's YouTube video post, so make sure you read Captain Hook's comments as well.  Some of the clipping may be a Premier issue instead of clipping in ProRes. Hook says that Highlight Recovery (Highlight Rebuild) works as I thought. So, much of the earlier video may be a false alarm :grin:

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7 hours ago, MeanRevert said:

Weren't you guys bagging on this dude's earlier P4K video where he blew out the highlights? 

Maybe that's what prompted the discussion about exposure..  We all make mistakes, it's about learning from them that is what is important :) 

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Highlight recovery needs to be used at 400 iso still when ettr'ing, it seems super whites get clamped. Not sure if maybe Gerald's understanding is off, but you definitely need to use it at 400 iso in my testing.

 

These images are original, then lowered exposure and then lowered exposure with highlight recovery on.

Original.JPG

ExposureLowered.JPG

ExposureLowered_Unclamped.JPG

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10 hours ago, JeremyDulac said:

Highlight recovery needs to be used at 400 iso still when ettr'ing, it seems super whites get clamped. Not sure if maybe Gerald's understanding is off, but you definitely need to use it at 400 iso in my testing.

 

These images are original, then lowered exposure and then lowered exposure with highlight recovery on.

Original.JPG

ExposureLowered.JPG

ExposureLowered_Unclamped.JPG

Thanks for sharing. I have had blown out skies like that recovered when using Highlight Recovery as well. Captain Hook said that Highlight Recovery should really have been called "Highlight Rebuild" because it rebuilds the highlights from the other channels when one of the channels is clipped. He also said that the recovered area is only black/white because they don't know what color to make the recovered areas. So really, we should avoid using Highlight Recovery if we are interested in getting the most accurate image. In your footage, I would much rather have some detail in the sky rather than having it blown out.

At ISO 400, at least the clipping point is a full 100%. At ISOs below 400, the clipping point is lower. As you increase the ISO up to 1000, the area above middle gray increases. So, your sky shot with ISO 1000 should have more detail than the sky shot at ISO 400. I don't think that I have a sky shot handy. Have you tried 400 vs. 1000 on this scene to see if there are noticeable differences?

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8 hours ago, drm said:

Thanks for sharing. I have had blown out skies like that recovered when using Highlight Recovery as well. Captain Hook said that Highlight Recovery should really have been called "Highlight Rebuild" because it rebuilds the highlights from the other channels when one of the channels is clipped. He also said that the recovered area is only black/white because they don't know what color to make the recovered areas. So really, we should avoid using Highlight Recovery if we are interested in getting the most accurate image. In your footage, I would much rather have some detail in the sky rather than having it blown out.

At ISO 400, at least the clipping point is a full 100%. At ISOs below 400, the clipping point is lower. As you increase the ISO up to 1000, the area above middle gray increases. So, your sky shot with ISO 1000 should have more detail than the sky shot at ISO 400. I don't think that I have a sky shot handy. Have you tried 400 vs. 1000 on this scene to see if there are noticeable differences?

Right, so I suppose the highlight recovery tool serves two functions? In un-clamping highlights a lower than 400 iso value as Gerald said, and also rebuilding detail in certain clipped situations, but not all.

Does it help to change iso in post to get more highlight detail, or does that only work when exposing? I will try it right now and share.

Update: I just tried it and it doesn't seem to make a difference - in fact I think there may be less detail it seems... which I am wondering if that is because it is not "real" detail and therefore doesn't interact the same with iso in terms of detail in the stops the same?

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Every week a different thing..whats going on with this camera?

I do not mind using an ext batt, and for the price I ll use a vND, but it seems there are a few dos and donts.

What you guyd think, and what are the things we have to be careful when shooting with one?

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I’ve been sticking pretty strictly to iso 400 and 3200 and controlling my exposure with a vnd and have absolutely zero problems. 

I think the thing with the highlight recovery is that you can now compare two different options. With a lot of other cameras, if the highlights are blown, tough luck. Now you can compare, so there’s one more thing to consider while shooting. It’s far from a problem and if anything, I see it as a bonus. Just like many things, don’t rely on it and have it as an emergency backup.

It’s like a ‘don’t worry we’ll fix it in post’ kind of thing. Thinking that way about audio, lights or any other aspect of film making is a bad idea, so why do it with video? 

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27 minutes ago, Kisaha said:

Every week a different thing..whats going on with this camera?

I do not mind using an ext batt, and for the price I ll use a vND, but it seems there are a few dos and donts.

What you guyd think, and what are the things we have to be careful when shooting with one?

Well I know I could never do this on my A7III or EOS R. Try to concentrate on the sky ;)

 

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1 hour ago, alanpoiuyt said:

Well I know I could never do this on my A7III or EOS R. Try to concentrate on the sky ;)

 

That is a dramatic difference in the sky. This is where I use highlight recovery (rebuild) too. It makes the camera seem like it has a greater dynamic range than advertised. Since the clouds are already white, it doesn't hurt much that we can't recover all of the color detail in those sections.

Scenes with that much dynamic range are problems for most cameras, particularly at the P4K price point. I think you would have to spend at least 5K to get close to enough range for this (perhaps VLog on the S1). Even the C200 is limited to about 3 usable stops of over exposure and it costs about 4 times as much as the P4K.

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I always ETTR on the BMCC/BMPCC but not on the new BMPCC4K. I used the native ISOs and tried to get as close to the final exposure as I could in camera. With the new color science it's been a winning concept for me.

I still have never been able to create any type of "blue sky macro blocking", and I've owned two separate units.

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Thanks @Mattias Burling for your input but why not ETTR exactly going on P4K...? Puzzles me... : ) CS is working there, no doubts, but as Anthony posted, you blow up your results if not address any eventual trouble there with ETTR as much as the earlier models : -)

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1 hour ago, Mattias Burling said:

I always ETTR on the BMCC/BMPCC but not on the new BMPCC4K. I used the native ISOs and tried to get as close to the final exposure as I could in camera. With the new color science it's been a winning concept for me.

I still have never been able to create any type of "blue sky macro blocking", and I've owned two separate units.

Both CDNG units? Even compressed raw?

Exposing in the middle on my Braw unit, the macroblocking is clearly visible. Between 1 and 2 stops over you have to look hard for it but it's still there. It's there in ProRes too so it's not exclusively a Braw issue. BMD have been very quiet on this flaw, which is disappointing.

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19 minutes ago, Emanuel said:

Buddy, you know why you've always been one of my fav posters for years if not longer than a decade now, wherever you are ; ) a breeze welcome to any users community again, thanks to you too @Andrew Reid : -)

Thanks.

You get a punchier image with ETTR: more contrast and saturation, and less noise; but you'll get maximum latitude exposing in the middle @ 400 ISO, albeit with a bit more noise.

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