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Sigma Fp review and interview / Cinema DNG RAW


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1 hour ago, rawshooter said:

It's not just that. A proper log profile also has a wider color gamut. If your log curve remains within Rec709, it won't make much sense (and will cause color banding when translated into non-logarithmic Rec709).

It looks as if Sigma has been unable to implement a wider color gamut with its current camera hardware/ASIC. So it was sensible of them to pull the promise (rather than delivering just a Rec709 profile with a log gamma).

Where is the direct information or test that the color gamut in RAW on the Sigma fp is not wider than REC709? My information is that it is closer to REC2020 than the gamut of the Sony Venice!

Here is the video comparing the gamuts of the Venice and the Sigma fp. You will also learn more about log:

Look at 15:33. Note that the Sony Venice and the Sigma fp are being used in the latest Avatar movie.

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So i said i'd post some stills, these are basically ungraded. This frame is in a sequence with car lights, i like the tonality of this very subdued moment. Shot 12bit to manage shadow tonality.

Modified Sigma's smaller grip to allow it to hold a T5; haven't printed it yet so not so sure how comfortable it is.

Ah gotcha. I'm not really directing this at you but just to anyone in general who isn't aware or wants to learn more, and I'm probably being a 'stickler for accuracy' here but obviously a sensor/

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4 minutes ago, markr041 said:

Where is the direct information or test that the color gamut in RAW on the Sigma fp is not wider than REC709? My information is that it is closer to REC2020 than the gamut of the Sony Venice!

In raw. But the h264 encoded .mov files are limited to Rec709. A log profile would only apply to h264/.mov.

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Just now, markr041 said:

Where is the direct information or test that the color gamut in RAW on the Sigma fp is not wider than REC709? My information is that it is closer to REC2020 than the gamut of the Sony Venice!

No, we were talking about the MOV h.264 output, not raw. Raw should match Rec.2020 almost perfectly as you mentioned.

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8 minutes ago, rawshooter said:

In raw. But the h264 encoded .mov files are limited to Rec709. A log profile would only apply to h264/.mov.

Ok. That is certainly correct. Again, I do not understand why anyone would use this camera to shoot anything but RAW - that is its key advantage over almost all cameras - full-frame pure (no sharpening, no noise reduction), uncompressed, unprocessed, no chroma subsampling, wide color gamut, 12bit 4K with no overheating in a tiny form. Log is just totally irrelevant (I understand the question was why not log), but the discussion of log in my view for the fp is basically besides the point, the point being - RAW!

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1 minute ago, markr041 said:

Ok. That is certainly correct. Again, I do not understand why anyone would use this camera to shoot anything but RAW - that is its key advantage over almost all cameras - full-frame pure, uncompressed, unprocessed, no chroma subsampling, wide color gamut, 12bit 4K with no overheating in a tiny form. Log is just totally irrelevant 

Log would still be nice to have as a display profile to be able to properly monitor dynamic range and exposure of the camera in CinemaDNG - which now is guess work, especially at the second native ISO (3200).

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1 minute ago, rawshooter said:

Log would still be nice to have as a display profile to be able to properly monitor dynamic range and exposure of the camera in CinemaDNG - which now is guess work, especially at the second native ISO (3200).

As I understand it, using the Color Profile: Off results in correct reading on the waveform when shooting RAW.

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4 minutes ago, markr041 said:

As I understand it, using the Color Profile: Off results in correct reading on the waveform when shooting RAW.

Unfortunately, it doesn't. "Color Profile: Off" is still a Rec709 curve, it only switches off the grading/styling. Otherwise, you'd had a much lower contrast picture on the camera's internal sRGB display.  

And if you have the camera set to the second native ISO 3200 and rely on its exposure tools - waveform, meter, zebras -, you will underexpose it by 2 stops. (You can easily control that by shooting 3200 with what the camera thinks is clipped exposure and importing the material into Resolve.)

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3 minutes ago, rawshooter said:

Unfortunately, it doesn't. "Color Profile: Off" is still a Rec709 curve. And if you have the camera set to the second native ISO 3200 and rely on its exposure tools - waveform, meter, zebras -, you will underexpose it by 2 stops. (You can easily control that by shooting 3200 with what the camera thinks is clipped exposure and importing the material into Resolve.)

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OK, thanks. Then for the first native (<800 as I understand it), the displayed waveform is ok? I use Resolve, so this sounds like good advice.

 

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Yes, but only at ISO 100. All waveforms above ISO 100 actually meter sRGB/Rec709 for JPEGs/.mov instead of raw sensor exposure. If you rely on them, you'll underexpose the sensor/CinemaDNG material.

To correctly expose the second native ISO 3200, you need to switch the camera to ISO 800 first, set exposure according to zebras/waveform/meter, leave aperture, shutter and ND as they are and switch ISO to 3200 (and live with a two stops overexposed camera display while recording :-(( ).

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Just now, rawshooter said:

Yes, but only at ISO 100. All waveforms above ISO 100 do not meter raw sensor exposure. If you rely on them, you'll underexpose the sensor.

To correctly expose the second native ISO 3200, you need to switch the camera to ISO 800 first, set exposure according to zebras/waveform/meter, leave aperture, shutter and ND as they are and switch ISO to 3200 (and live with a two stops overexposed camera display while recording :-(( ).

Gotcha. Thanks.

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7 hours ago, rawshooter said:

Log would still be nice to have as a display profile to be able to properly monitor dynamic range and exposure of the camera in CinemaDNG - which now is guess work, especially at the second native ISO (3200).

This is another thing that Sigma can easily fix in firmware. As it stands currently the waveform is not very useful. I would go as far as to call it buggy. it just doesn't work correctly, but should be easily fixable with firmware upgrade. It's just a math problem in software.

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Has anyone seen any posts showing video shot using internal h.264 w/ 'Color Profile Off' ? I know its suboptimal given the camera can record Raw, but im very interested in how much can be done (latitude) in a pinch with internal recording on Color Profile Off. Everyone is posting these crazy raw videos but managing that amount of content is a bit much for day to day fun shooting. I dont use my BMPCC4K because its not quite pocket size, and yet I dont see myself needing Raw DNGs for fun and gun.

Curious!

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Was not able to extract more DR using Timur's workflow when compared to BMD film -> REC709 color space transform. But DR is very good and Sigma FP is still attractive to me as a travel cinema camera. Smaller form factor will let me take it with me more often than BMPCC 4K. Especially at this point when we know more or less what Canon and Sony will offer with new models. Willing to trade 4K 60P and BRAW for smaller form factor.

Saw a polish review. According to the reviewer in APS-C / Super 35 4K image quality is still not optimal. But if in Full Frame 4K Sigma FP has to do pixel binning / line skipping, APS-C is perfect for 1:1 pixel reading. Why then picture quality is still not as good as it should be ? Any experience and / or ideas ?  

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Really need waveforms and zebras based on the raw data, like raw shooter said - it's currently close enough at iso100 to gauge raw exposure. Above that it is incorrect. Magic lantern could do it, Sigma should do it.

Has anyone had issues with external SSD after the new firmware - My sandisk extreme is now putting my FP into a reboot cycle. Gah.

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13 hours ago, Roogii said:

Has anyone had issues with external SSD after the new firmware - My sandisk extreme is now putting my FP into a reboot cycle. Gah.

I have had no problems with my Samsung 2TB T5 SSD, the brand recommended by Sigma and by BlackMagic. Interestingly, Z-Cam recommends the Sandisk Extreme SSD.

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Without details from Sigma, here's a quick look at perhaps making sense of footage shot with the new "none" profile, and how they could be used for internal raw monitoring. I grabbed the images from this page:

https://blog.sigmaphoto.com/2020/the-sigma-fp-evolves-firmware-2-0-for-the-cinema-crowd/

I assumed they are linear 1.0 in a rec2020 type of gamut, but that they have had a rec709 curve applied. So I took them into Nuke in an ACES color managed script, and I inverted the rec709 curve so that they are again linear 1.0 gamma. I then transformed the rec2020 gamut to ACES. The default ACES rrt/odt film look is applied, and I rendered out jpegs in sRGB, which I'm attaching here. Of course the highlights are completely clipped, but the midtones can be useful for accurately exposing with a grey card.

I'm not sure if they will display correctly in the browser window, but they look "correct" in Nuke.

EDIT: they look too dark in a Chomium-based browser compared to Nuke, but it may be because my screen is currently set to P3D65. YMMV.

 

02.jpg

03.jpg

01.jpg

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