SIGMA FP with ProRes RAW and BRAW !

[mercer]

1 hour ago, Llaasseerr said:

Right. The issue is being unable to see clipping like you describe while monitoring, with the default profiles on the camera. It would be a good reason to consider underexposing at a fixed level with an ND, and having the ability to toggle a LUT on and off that included an exposure boost. Again, this is where a published Sigma log curve would be useful - for monitoring.

As for working with the image, just to be clear I'm not advocating working in Rec709. Personally I would work in either linear ACES or then convert the linear image to Arri logC. the DNG IDT is the most accurate DNG raw import available in Resolve since it's generated on the fly.

In the case of transforming to LogC, the ACES inverse Alexa IDT will do a pretty accurate transform from the linear image to Alexa. Arri's log color space is well documented and not confusing compared to BMD. Basically, I could round trip the image from LogC back to linear ACES and it would match the original imported DNG (via the ACES IDT), so then I know the image integrity has been maintained. My assumptions are based on sound DNG metadata though, as this is what Resolve relies on for accurate ACES input transform.

Interesting. Where do I find the CDNG IDT in Resolve?

[webrunner5]

 

[Llaasseerr]

57 minutes ago, mercer said:

Interesting. Where do I find the CDNG IDT in Resolve?

It's actually done under the hood, so all you have to do is import DNGs into an ACES project. 

If you then wanted to render out, say, Alexa LogC ProRes 4444, you would apply an ACES Transform node and keep the input transform as "no input transform" which means linear, and set the output transform to Alexa.

Also make sure regardless of whether you render linear EXRs or log Alexa footage that you don't have an output display transform set in the color management tab in the project settings, then render out and use in a new Resolve project. Or if you're going to stay in ACES, then that's unnecessary. 

[Llaasseerr]

38 minutes ago, webrunner5 said:

 

This is a little out of date, but that's the general idea.

[Llaasseerr]

1 hour ago, mercer said:

Interesting. Where do I find the CDNG IDT in Resolve?

Forgot to mention that you don't want an input transform applied in the color management tab either.

[mercer]

1 hour ago, Llaasseerr said:

Forgot to mention that you don't want an input transform applied in the color management tab either.

Thanks I'll have to do more research into using ACES. I'd like to test it with my ML Raw files. 

[Llaasseerr]

25 minutes ago, mercer said:

Thanks I'll have to do more research into using ACES. I'd like to test it with my ML Raw files. 

For the most flexibility, you can just use an ACES project to import the DNG files to Resolve, then export to a format you're familiar with (like Alexa LogC/Alexa wide gamut) and use in a non-ACES project. Depending on how the metadata is written in the ML raw files, it should work pretty well but obviously it's good to compare how well they work within the MLV app as well.

[OleB]

10 hours ago, Llaasseerr said:

Gotcha. I appreciate your work translating the scaled ISO values. It does seem crazy the inconsistency with internal vs external recording, and I would need to try both to fully get it.

My first impulse is that I would probably not apply PQ personally, but instead choose Native and create a custom LUT. But that is based on the assumption that the linear image as displayed by the Ninja V appeared to be the similar to the "None" profile on the camera, ie, flat-ish but not log. So in other words, they've scaled the linear image for display, because an actual linear image is super contrasty and clipped on a Rec709 monitor.

I'm basing that on watching the Atomos Sigma fp setup video on youtube. The LUT approach may not be a good idea if the highlights are getting clipped in the default Ninja V display, whereas with PQ they will be fully present and rolling off according to the PQ spec. But the overall appearance of PQ would not match my intended final image, so it's a trade-off.

Unfortunately in native the false colors of the Ninja V are not showing correct clipping values either. Tried that as well. All summed up left me with PQ. Agree it is not 100% a direct preview of how a potential Rec709 picture could look like. But at least it is a way to come closer to WYSIWYG compared to all other options available. 
 

Sorry for not being clear with the false color, only the ones from the Ninja V are correct in PQ with the mentioned ISO conversation. Internal is only working for ISO 100…

[Llaasseerr]

2 hours ago, OleB said:

Unfortunately in native the false colors of the Ninja V are not showing correct clipping values either. Tried that as well. All summed up left me with PQ. Agree it is not 100% a direct preview of how a potential Rec709 picture could look like. But at least it is a way to come closer to WYSIWYG compared to all other options available. 
 

Sorry for not being clear with the false color, only the ones from the Ninja V are correct in PQ with the mentioned ISO conversation. Internal is only working for ISO 100…

So when working with just the naked camera the false color preview in the new firmware 4.0 is only accurate when set to ISO 100?

[OleB]

47 minutes ago, Llaasseerr said:

So when working with just the naked camera the false color preview in the new firmware 4.0 is only accurate when set to ISO 100?

Yes, I am afraid that is the case. At least if you consider sensor clipping as the point which it should be at its maximum. 

[Llaasseerr]

52 minutes ago, OleB said:

Yes, I am afraid that is the case. At least if you consider sensor clipping as the point which it should be at its maximum. 

Okay, if I understand you correctly then that makes sense in that I was expecting the highlights to be clipped on the internal display (unfortunately). My evaluation of the "none" picture mode on the camera is that it's the raw image with a Rec709 curve applied, and then anything above 1.0 is clipped because there's no rolloff applied - since it has no image processing beyond the Rec709 adjustment. Where in reality, a log curve is required to keep everything normalized to the display space of 0-1.

But I had surmised that assuming a decent exposure, it would probably be accurate for checking a middle grey card across the ISO range. Is that a fair assumption?

[OleB]

19 minutes ago, Llaasseerr said:

Okay, if I understand you correctly then that makes sense in that I was expecting the highlights to be clipped on the internal display (unfortunately). My evaluation of the "none" picture mode on the camera is that it's the raw image with a Rec709 curve applied, and then anything above 1.0 is clipped because there's no rolloff applied - since it has no image processing beyond the Rec709 adjustment. Where in reality, a log curve is required to keep everything normalized to the display space of 0-1.

But I had surmised that assuming a decent exposure, it would probably be accurate for checking a middle grey card across the ISO range. Is that a fair assumption?

I am not too sure about middle grey either. Maybe that could be something you could try out, because I was focussing more on highlight protection and sensor clipping in my approach. 
 

When using my ISO conversion table the middle grey as shown in the Ninja V on PQ was matching what my incident meter said it should have been at the converted ISO value. Did not try this for internal metering in camera though. Can only assume that middle grey behaves like Sigma described in their manual.  

[Ryan Earl]

5 hours ago, Llaasseerr said:

So when working with just the naked camera the false color preview in the new firmware 4.0 is only accurate when set to ISO 100?

No, it's accurate across the ISO range. 

The camera's internal exposure meter is really good too, along with the auto white balance, it's one of the reasons why I like using the camera.  Next to the aperture number on the rear lcd screen you get a +/- exposure indicator and it works well if you don't have time to use false color.  You can then place a gray card in the scene if you have time or use a skin tone for false color measurements.

[Ryan Earl]

I think the main issue with exposing for highlights, as was already discussed, is that you don't get a sense of exactly where the camera is clipping.  I don't think it's a huge issue though and in practice I now use the camera's false color and the exposure meter, even in manual mode I just pay attention to whether or not I am under or over exposing and by how much.  Then put it through your chosen workflow to roll off the highlights. 

[Llaasseerr]

4 hours ago, OleB said:

I am not too sure about middle grey either. Maybe that could be something you could try out, because I was focussing more on highlight protection and sensor clipping in my approach. 
 

When using my ISO conversion table the middle grey as shown in the Ninja V on PQ was matching what my incident meter said it should have been at the converted ISO value. Did not try this for internal metering in camera though. Can only assume that middle grey behaves like Sigma described in their manual.  

I unfortunately don't have the camera on hand, but for the internal false color display the way I would check it is I would use my Sekonic incident light meter and grey card, and then see if the false color green is hitting the grey on the internal display when I set the exposure as per the light meter reading.

[OleB]

1 minute ago, Ryan Earl said:

No, it's accurate across the ISO range. 

The camera's exposure meter too along with the auto white balance, it's one of the reasons why I like using the camera.  Next to the aperture number on the rear lcd screen you get a +/- exposure indicator and it's very good if you don't have time to use false color.  You can then place a gray card in the scene if you have time or use a skin tone for false color measurements.

I can only speak for the ProRes RAW workflow. And for that this is not the case. Assume that CDNG works exactly the same, there a plenty of YouTube videos about this topic on how to dial in exposure, including how many stops you can open up the aperture after setting the exposure and it still being captured while the camera already shows it as clipping.

Only the false color screen on the Ninja V seems to be truly correct, at least for that workflow. It shows exactly the clipping points of the sensor for the mentioned ISO values. Preview picture, at least as good as it gets, is fitting the false colors only in PQ (Rec709 you are getting correct clipping values in false color but overblown picture, same as in camera). My assumption is that like Llaasseerr said, the camera is not doing anything in Rec709 to push the on top dynamic range into the picture, there is no log. That said only PQ seems to be quite close in resembling the dynamic range of the camera.

To be precise following example. You expose in ISO 100 to the exact clipping point via Ninja V false colors, you can increase up to ISO 800 without any change to the false color clipping limits. The camera preview meanwhile looks totally over, while in reality it is not. It stays in its dynamic range. Guess that has to do with the ISO invariance of the sensor per each its two native ISOs. But there I am not an expert.

Feel free to test this yourself if you have the chance to get hold of a Ninja V for ProRes RAW. However I have to say you could also use the camera your way of course. The image quality still is great if you go after what the camera says (and the Sigma manual) but in my opinion you are throwing away an even better image.

 

[Llaasseerr]

29 minutes ago, Ryan Earl said:

No, it's accurate across the ISO range. 

The camera's internal exposure meter is really good too, along with the auto white balance, it's one of the reasons why I like using the camera.  Next to the aperture number on the rear lcd screen you get a +/- exposure indicator and it works well if you don't have time to use false color.  You can then place a gray card in the scene if you have time or use a skin tone for false color measurements.

Nice to hear the false color and exposure indicator works well. I tend to shoot a grey card if possible, rather than white balance, especially with raw.

 

27 minutes ago, Ryan Earl said:

I think the main issue with exposing for highlights, as was already discussed, is that you don't get a sense of exactly where the camera is clipping.  I don't think it's a huge issue though and in practice I now use the camera's false color and the exposure meter, even in manual mode I just pay attention to whether or not I am under or over exposing and by how much.  Then put it through your chosen workflow to roll off the highlights. 

Right, it sounds like this camera can expose well, but we don't get the full nice preview across the whole image range. Appreciate you guys fleshing out the details here.

The workflow you describe is pretty much how someone would shoot with an Alexa - expose for middle grey, and the highlights fall where they do. The difference is that the Alexa has monstrous dynamic range so you don't need to worry really about highlights clipping too soon. Maybe underexposing with an ND and setting the exposure compensation would do the trick though?

There is this idea I've had in the back of my head that may be stupid, but fun. There's a tiny BMD micro converter that allows adding a LUT. So it's basically an affordable LUT box:

https://www.blackmagicdesign.com/products/microconverters/techspecs/W-CONU-18

I also have a 3.5" Ikan VL-35 monitor lying around, so I could see adding these two if I had a cage around the camera and it wouldn't dominate the size so much. Then a more correct viewer could be added. But it probably would not deal with the clipped highlights issue. It would just offer a closer image to the final graded image in Resolve.

[Llaasseerr]

26 minutes ago, OleB said:

I can only speak for the ProRes RAW workflow. And for that this is not the case. Assume that CDNG works exactly the same, there a plenty of YouTube videos about this topic on how to dial in exposure, including how many stops you can open up the aperture after setting the exposure and it still being captured while the camera already shows it as clipping.

Only the false color screen on the Ninja V seems to be truly correct, at least for that workflow. It shows exactly the clipping points of the sensor for the mentioned ISO values. Preview picture, at least as good as it gets, is fitting the false colors only in PQ (Rec709 you are getting correct clipping values in false color but overblown picture, same as in camera). My assumption is that like Llaasseerr said, the camera is not doing anything in Rec709 to push the on top dynamic range into the picture, there is no log. That said only PQ seems to be quite close in resembling the dynamic range of the camera.

To be precise following example. You expose in ISO 100 to the exact clipping point via Ninja V false colors, you can increase up to ISO 800 without any change to the false color clipping limits. The camera preview meanwhile looks totally over, while in reality it is not. It stays in its dynamic range. Guess that has to do with the ISO invariance of the sensor per each its two native ISOs. But there I am not an expert.

Feel free to test this yourself if you have the chance to get hold of a Ninja V for ProRes RAW. However I have to say you could also use the camera your way of course. The image quality still is great if you go after what the camera says (and the Sigma manual) but in my opinion you are throwing away an even better image.

 

Thanks for the distinction there with the inconsistency between internal vs ProRes RAW. I'm kind of wondering what the value proposition is of using the Ninja V if you don't need DCI 4k and can deal with the larger file sizes internally. But I'd still like to mess around with both of them if I do end up getting the camera.

It does though seem like you've got a bit of a system there with the PQ workaround to check the highlights on the Ninja V. It's a shame Sigma have not thought things through more carefully and have a more consistent solution without unknowns. I mean I noticed on their blog they have guest writers offering their own ad-hoc solutions as to how to develop the DNGs in Resolve, so it seems like they don't even really know what they're doing. That doesn't mean it's impossible though.

I was hoping maybe the linear image on the Ninja V without the PQ setting, but as per the Atomos setup video, would display the highlights in a flat-ish image like the "none" profile, but it appears not.

[OleB]

15 minutes ago, Llaasseerr said:

Thanks for the distinction there with the inconsistency between internal vs ProRes RAW. I'm kind of wondering what the value proposition is of using the Ninja V if you don't need DCI 4k and can deal with the larger file sizes internally. But I'd still like to mess around with both of them if I do end up getting the camera.

It does though seem like you've got a bit of a system there with the PQ workaround to check the highlights on the Ninja V. It's a shame Sigma have not thought things through more carefully and have a more consistent solution without unknowns. I mean I noticed on their blog they have guest writers offering their own ad-hoc solutions as to how to develop the DNGs in Resolve, so it seems like they don't even really know what they're doing. That doesn't mean it's impossible though.

I was hoping maybe the linear image on the Ninja V without the PQ setting, but as per the Atomos setup video, would display the highlights in a flat-ish image like the "none" profile, but it appears not.

Inconsistent truly is the word for this...You can use the native preview, it will indeed show correct highlights, BUT false colors are not working and you would need to set the zebras for every ISO value to something different...not exactly an easy workflow.

My goal was to have a workflow which gives me reproducible results and I am glad I have found one. Form factor etc and building a nice rig out of the camera with high quality parts (like the Sigma PL mount adapter and its shimming options) and all is perfect. Software connectivity between Sigma and Atomos is not...

Maybe they get this right in a future firmware release if the word spreads.

 

[Ryan Earl]

11 minutes ago, Llaasseerr said:

Thanks for the distinction there with the inconsistency between internal vs ProRes RAW. I'm kind of wondering what the value proposition is of using the Ninja V if you don't need DCI 4k and can deal with the larger file sizes internally.

I've been importing the cDNG through SlimRAW as 3:1 and they playback much better and I'm able to upscale slightly to DCI 4K for monitoring / exporting. 

 

39 minutes ago, OleB said:

Assume that CDNG works exactly the same, there a plenty of YouTube videos about this topic on how to dial in exposure, including how many stops you can open up the aperture after setting the exposure and it still being captured while the camera already shows it as clipping.

I should clarify that I think when working in CDNG and 'naked' without BRAW or ProRes RAW it does appear to show the correct false color values on the rear lcd screen with the new firmware, but that false color reading is in conflict with the waveform, zebras and preview.