Sigma Fp review and interview / Cinema DNG RAW

[redepicguy]

3 hours ago, paulinventome said:

I've cycled through all my settings, on 8, 10 and 12 bit. 180 degree shutter. My findings are consistent across bit depths, so that's something solid. I flicked at 400ISO and i think 320 but it might just be an odd flicker at the start. The flash frames seem to be an ISO setting incorrect. Flash frames happen for me 125, 160, 200 and 250 but seems solid after that.

What i was talking about was whether everyone sees a skew towards green in 8 and 10 bit modes at the bottom end? I have reported this and mentioned on this thread.

This is a side effect of reduced shadow bit depth you can see clearly below. But i still think it's a bug because there's no need for it to be green. 

Shoot at a low ISO and push the exposure up 3 in Resolve, it's very clear then (as below), these are ISO 160

So firstly if we're going to report this

1) Are we all happy that the depth setting doesn't change things?
2) Can we confirm what our own flicker ISOs are (and include shutter speed and frame rate)

 

Are you just lifting blacks or doing a universal exposure increase? Looks like you're just using the lift slider. Looks great though. I need to try and make a LUT that will allow for under exposure to protect highlights but not make it impossible to get focus when capturing. Obviously, this would be for external monitors only. 

[paulinventome]

3 minutes ago, redepicguy said:

Are you just lifting blacks or doing a universal exposure increase? Looks like you're just using the lift slider. Looks great though. I need to try and make a LUT that will allow for under exposure to protect highlights but not make it impossible to get focus when capturing. Obviously, this would be for external monitors only. 

Just a default +3 on DNG exposure so that i can see the shadows. 

I really don't think you need anything like that with RAW files. If you are recording 8 bit DNG then expose naturally, both the shadows and highlights have less data to give to the mids.

If you are exposing 10 or 12 (especially 10) then expose as far right whilst not clipping what you need. The shadows have a lot less detail in them so it's better to shoot over and then take it down in post. You get an extra stop or two if you do highlight reconstruction, which is plenty for spec hits (try to avoid clipping faces though)

If you are using with Red footage (username...) Set Resolve up to use IPP2 and a red workflow. Then when you add a DNG, do some exposure/ G/M adjustment and highlight options and you'll find that the linear data matches red fairly well and you get the nice roll off in IPP2 which is much better than normal DNG handling. If you are trying to match EpicW and the camera then the ISO is 4 times higher on the sigma. The fp is at least 2 stops less than the red.

You can get lovely images from the sigma. 

cheers
Paul

[redepicguy]

5 minutes ago, paulinventome said:

Just a default +3 on DNG exposure so that i can see the shadows. 

I really don't think you need anything like that with RAW files. If you are recording 8 bit DNG then expose naturally, both the shadows and highlights have less data to give to the mids.

If you are exposing 10 or 12 (especially 10) then expose as far right whilst not clipping what you need. The shadows have a lot less detail in them so it's better to shoot over and then take it down in post. You get an extra stop or two if you do highlight reconstruction, which is plenty for spec hits (try to avoid clipping faces though)

If you are using with Red footage (username...) Set Resolve up to use IPP2 and a red workflow. Then when you add a DNG, do some exposure/ G/M adjustment and highlight options and you'll find that the linear data matches red fairly well and you get the nice roll off in IPP2 which is much better than normal DNG handling. If you are trying to match EpicW and the camera then the ISO is 4 times higher on the sigma. The fp is at least 2 stops less than the red.

You can get lovely images from the sigma. 

cheers
Paul

Yea..I'm definitely loving the image...minus the audio and black bouncing issues. If you clip in cam though, it's pretty gone though. Yea, a tiny bit can potentially be recovered, but not like 2-3 stops of highlight recovery if they are already blown. With the FP, I find underexposure works best to preserve highlight detail since the blacks are so clean working with the CDNG files. 

[paulinventome]

4 minutes ago, redepicguy said:

Yea..I'm definitely loving the image...minus the audio and black bouncing issues. If you clip in cam though, it's pretty gone though. Yea, a tiny bit can potentially be recovered, but not like 2-3 stops of highlight recovery if they are already blown. With the FP, I find underexposure works best to preserve highlight detail since the blacks are so clean working with the CDNG files. 

There's clip and there's specular clip. The camera really has around 11.5 stops so you need to be mindful of that.

The highlight recovery depends on what you're shooting. Skies recover well, people not so much. Recovery is based on one channel *not* clipping where the others have.

If you grade under a decent roll-off curve like IPP2 or an ACES ODT then what happens is you get much nicer colour handling as you head up to clip whereas the default process (in Resolve anyway) starts going a bit wonky with odd cyan clipping and salmon highlights.

The shadows are good if you are doing 12 bit. Not so much in 10 or 8.

And as described above the very nature of linear means that the bottom 3 stops are always represented with just 7 values.

cheers
Paul

 

[Chris Whitten]

I have recorded two short clips in 4K (UHD) 10 bit, 25fps.

One at ISO125 and one at ISO320. The 125 clip I exposed dark, underexposed. The 320 clip I exposed as correctly as I could.

Loading both into Davinci Resolve 16 and selecting > colour page: camera settings: clip: Blackmagic Design film.

Both clips have the brighter first frame.

I see no flickering. My scopes are static as the clip plays. I bumped up the ISO125 clip by 3 stops exposure. I see no green tinge or tendency to green.

I am uploading the two clips to Dropbox and will share the link for anyone to download. You can send them to anyone else if it helps fix these matters (including Sigma).

It is taking me 3hrs to upload 10 seconds of DNG to Dropbox (weeps), so bear with me.

[Scott_Warren]

21 minutes ago, Chris Whitten said:

I have recorded two short clips in 4K (UHD) 10 bit, 25fps.

One at ISO125 and one at ISO320. The 125 clip I exposed dark, underexposed. The 320 clip I exposed as correctly as I could.

Loading both into Davinci Resolve 16 and selecting > colour page: camera settings: clip: Blackmagic Design film.

Both clips have the brighter first frame.

I see no flickering. My scopes are static as the clip plays. I bumped up the ISO125 clip by 3 stops exposure. I see no green tinge or tendency to green.

I am uploading the two clips to Dropbox and will share the link for anyone to download. You can send them to anyone else if it helps fix these matters (including Sigma).

It is taking me 3hrs to upload 10 seconds of DNG to Dropbox (weeps), so bear with me.

At least from what I've seen, the flickering will occur at ISOs just outside of that range. For whatever reason, 100-400 seems to be a fairly "safe" zone with no flickering. 

Why? Well... X-Files theme begins playing

[paulinventome]

28 minutes ago, Chris Whitten said:

I have recorded two short clips in 4K (UHD) 10 bit, 25fps.

One at ISO125 and one at ISO320. The 125 clip I exposed dark, underexposed. The 320 clip I exposed as correctly as I could.

Loading both into Davinci Resolve 16 and selecting > colour page: camera settings: clip: Blackmagic Design film.

Both clips have the brighter first frame.

I see no flickering. My scopes are static as the clip plays. I bumped up the ISO125 clip by 3 stops exposure. I see no green tinge or tendency to green.

I am uploading the two clips to Dropbox and will share the link for anyone to download. You can send them to anyone else if it helps fix these matters (including Sigma).

It is taking me 3hrs to upload 10 seconds of DNG to Dropbox (weeps), so bear with me.

Great, although it is 400 that flickers for me!!

Look forward to taking a look at those shadows.

cheers
Paul

[redepicguy]

Finally getting my rig finalized. Zacuto is sending me a new Zwiss plate (noticed this one is mounted upside down) since the rod receiver was tweaked...but I'm absolutely loving this setup. It allows for power all day and powering my SmallHD ultra bright monitor along with the camera and any other potential accessory I may attach down the road. It adds the weight to make things really stable handheld. The battery just goes right into my shoulder/chest area as I use the Smallrig grip with my right hand and pull focus with my left gripping the rods/lens. 

Leaving the Zfinder attached allows for quick mobility by removing system from rails (quick release plate) and going really discrete while still maintaining stability. The z-finder frame that originally was included sucked and popped right off, so I improvised. Works well and doesn't flop around at all. 

Will always be recording CDNG in 1080 or UHD 12 bit...don't see this cam being used any other way. If sigma can just fix a couple of the issues...I'd love it even more! 

 

 

[Chris Whitten]

Oh, I got myself confused and I slightly wasted my time. Although when I first got the camera I shot two short films with a lot of clips all at ISO640 and no flicker. I just went through the DNG's disabling the grade and the scopes are static.

[Chris Whitten]

Try this:

https://www.dropbox.com/sh/sjdd2nld9ey1i0m/AADDsukizgYbSYZewFBZsra5a?dl=0

[imagesfromobjects]

Could the flicker perhaps indicate something wonky with "dual gain" or similar? If the true base ISO is 400, it would attest to the overexposed first frame in ISOs below 400, because those would involve a different gain, or else some software juju to "underexpose" the sensor. It could also explain why ISOs over 400 give the flicker - if the software is struggling to "decide" which gain to use. Just a thought. 

 

You'd have to ask Jim Kasson or Bill Claff, or one of those guys. Jim had an exhaustive writeup on the Sony a7S where he mapped the specific ISOs where secondary gain kicked in, but tbh most of that stuff is way over my head and involves time, knowledge and equipment I do not possess. 

 

All I know is that the flickering is *visible* on the LCD when you are shooting low light in MOV. It's also visible in stills, shooting all-manual on a dumb adapter. The camera I was using was a rental, but I have purchased one (against my better judgment) which will be here shortly. Rental camera was on v1.02 and I'll be doing the same sort of shooting with the new one. Time permitting, I'll have a chance to dig deeper into what is going on, but as I already mentioned, my goal is to optimize my setup for run'n'gun, minimal grading type stuff, so I'll only be using SD cards - and likely MOV - to test. 

 

Other bugs/annoyances I noticed even after the firmware update were that:

*C1 / C2 / C3 - some settings were not being saved 

*Color shading was only storing the first entry 

*Cannot turn sharpening or noise reduction off completely, so MOV files show moire and artifacts. Could just be the lack of AA filter, but I wish there were more LOG-like profile adjustments one could make (eg Black Gamma level etc.) 

 

*Can we PLEASE gain the ability to assign ISO to the wheel in Manual mode. Shooting with manual lenses, you obviously don't need aperture control via camera, and the Q menu process of changing the ISO is annoying. 

*Can we also get rid of the white focusing square in stills mode? Also annoying that it's always there. 

 

 

Other than that, yeah. Camera is awesome and when it's on, it's ON. Keep it up, Sigma!! 

 

Ok, now back to your regularly scheduled crumbling of civilization as we know it. Happy shooting! 

[Chris Whitten]

MOV looks to be very poor compared to the UHD modes. My rig is very small using the Wise portable SSD attached to Sigma's included hot shoe attachment.

[Chris Whitten]

I shot a short clip at 4K UHD 10bit 25fps. ISO 640

No first frame blowout. Absolutely definitely no flicker, the scopes are rock solid, not moving at all. No green tinge. Attached is a screen shot of the colour page with just LUT dropped on the clip (Crimson Engine Aries lut). I will try and upload the clip to Dropbox at some point today.

ISO 640 seems clean and stable to me.

[paulinventome]

16 hours ago, Chris Whitten said:

I have recorded two short clips in 4K (UHD) 10 bit, 25fps.

One at ISO125 and one at ISO320. The 125 clip I exposed dark, underexposed. The 320 clip I exposed as correctly as I could.

Loading both into Davinci Resolve 16 and selecting > colour page: camera settings: clip: Blackmagic Design film.

Both clips have the brighter first frame.

I see no flickering. My scopes are static as the clip plays. I bumped up the ISO125 clip by 3 stops exposure. I see no green tinge or tendency to green.

I am uploading the two clips to Dropbox and will share the link for anyone to download. You can send them to anyone else if it helps fix these matters (including Sigma).

It is taking me 3hrs to upload 10 seconds of DNG to Dropbox (weeps), so bear with me.

Got them, thanks

Can confirm all of that but you do have green shadows at the very bottom. The scene still has quite a bit of light even at 125 ISO but i can see from the enclosed screenshot where you have a green/magenta at very lower shadow step. You can see it on the left edge in the shadow under the object and also on the darker reflective horn thingy.

In 10 bit if you shoot with something that is genuinely black in the scene and then shoot the same scene in 12 bit you can sometimes see by eye but if you raise the whole thing you can see very clearly (like my lenses one which was very very little light and high contrast). This shows the major difference between 12bit and the other modes - the shadow detail.

Now you've been using BlackMagic Film and actually that is reducing it a little which is perhaps why you're not seeing it. I'm not using BMDFilm but using the matrixes in the DNG via the normal DNG setting. I don't believe you get the best out of the camera with that setting but i suppose i need to look it that in greater detail. Maybe it does make sense. BMD Film seems to drop the exposure and take some of that tint off but BMD Film is expecting the colorimetry from a BMD camera, not a Sony sensor.

cheers
Paul

2 hours ago, Chris Whitten said:

MOV looks to be very poor compared to the UHD modes. My rig is very small using the Wise portable SSD attached to Sigma's included hot shoe attachment.

I wouldn't touch MOV with a bargepole. There are many better cameras which shoot MOV out there - this beauty is all about the RAW and no compression.

cheers
Paul

[Chris Whitten]

Dropbox link for the ISO640 clip:

https://www.dropbox.com/s/mwcegih2xdn1p4h/A001_003.zip?dl=0

[Chris Whitten]

24 minutes ago, paulinventome said:

 

Can confirm all of that but you do have green shadows at the very bottom. The scene still has quite a bit of light even at 125 ISO but i can see from the enclosed screenshot where you have a green/magenta at very lower shadow step. You can see it on the left edge in the shadow under the object and also on the darker reflective horn thingy.

 

Tell me what settings you have in Resolve that are making the green visible. I wouldn't;'t be boosting the exposure that much normally. In the screenshot of my clip you posted I can see green and magenta all over the frame, even in the light grey areas. I have not seen that.

It could be different equipment (computer OS, Resolve). It could be that I'm doing something wrong and therefore not creating the right conditions to see this issue.

[paulinventome]

6 hours ago, imagesfromobjects said:

Could the flicker perhaps indicate something wonky with "dual gain" or similar? If the true base ISO is 400, it would attest to the overexposed first frame in ISOs below 400, because those would involve a different gain, or else some software juju to "underexpose" the sensor. It could also explain why ISOs over 400 give the flicker - if the software is struggling to "decide" which gain to use. Just a thought. 

We don't know if this sensor is dual gain but it could be. 

I'd assumed that in the UI you see exposure changing (there's a setting for it to in terms of how fast) and i think there is a persistent bug somewhere in that firmware. In one of my 320 tests i saw not a flicker but a pulse of exposure change. So i think it's something linked to electronic exposure in the firmware.

The screen flicker happened with the original firmware but i still saw it in low light. I don't record MOV so can't confirm that. With MOV you're loosing so much of what this camera can do that IMHO i think it's crazy to do that. And SSD is cheap, and you can use SlimRAW to compress the DNGs as you copy them off the SSD.

But you're most likely right about base iso and compensation, just haven't quite figured out why.

+1 for ISO Wheel in cine mode!

cheers
Paul

[Chris Whitten]

I've just gone into Resolve and looked at my files in CinemaDNG and Blackmagic Film.

If I push the exposure to the extreme (in my opinion) the blotchy green and magenta is there in both Resolve settings. 

If I have exposed the clip correctly, and graded it subjectively correctly, I don't think it's viewable, but it might be.

Next I'm going to test with my IR Cut filter from there BMPCC4K. There was an issue with dark blacks and the BMD cameras.

[paulinventome]

6 minutes ago, Chris Whitten said:

Tell me what settings you have in Resolve that are making the green visible. I wouldn't;'t be boosting the exposure that much normally. In the screenshot of my clip you posted I can see green and magenta all over the frame, even in the light grey areas. I have not seen that.

 

I run Davinci Colour Managed all set to 709 2.4 gamma

In the DNG Settings it's Clip based on CinemaDNG. The Color Space and Gamma are greyed out in Davinci Colour Managed because it will do the 'right' thing. This is the 'native' image or as native as it can be. I see the same in RAW Digger for anaylsis of DNGs so i know it's an honest view.

There is a little more shadow latitude this way but not enough to make anything of it.

I run Davinci Colour Managed as part of a bigger workflow and pipeline so whatever i do is under that umbrella. And that umbrella also allows me to use IPP2 mapping which i think produces a lovely highlight roll off with DNG footage as well.

Screenshots show BMD Film against the above. You can see a bit more detail in the above compared to BMD Film which has a lower exposure.

IMHO BMD Film does seem wrong to me. The whole point of Resolve is that you're working in linear light space (photographic) and the purpose of that RAW tab is to move the camera data into linear data. If you choose BMD Film and it changes the curve (or rather it thinks the data coming from the camera has a specific tonality) then the camera isn't really being translated into linear. If you use the camera by itself and you're eyeballing then it doesn't really matter. But if you're using other cameras and need shots to match then it would be very difficult through BMD Film. Shot matching really needs all the cameras to be decoding in a single linear space so that exposure adjustments happen in the same way. And if you are doing any comping or vfx work then you *really* need to know that your data is linear.

But i know i'm looking at it from my perspective, so it's really just a IMHO - if you like the look then go for it

cheers
Paul

 

[Chris Whitten]

Here is the ISO125 clip I shot underexposed. The first clip just has light exposure adjustment using the lift, gamma and gain wheels in Resolve. On the second clip I pushed the exposure to extremes, like 5 stops. The green, purple blotch is visible in both clips IMO, and dramatic in the pushed clip.