Preview LUT, judging exposure and clipping indicator

Just testing a rented spark right now and trying to get a sense how I can judge exposure and whats actually in the RAWs.

For example thats how the clip comes in as Rec709 in Resolve: 

It was clearly clipped when I shot it but did not look quite as bad.  Once set to LOG and with my quick Slog3 transform + a creative LUT, things look really nice. No detail lost.

My question is: how can you confidentially exposure and know that your highlights are not clipped. Obviously underexposing until nothing is clipped in Rec709 preview would result in a massively underexposed image and create noise issues. 

  1. There needs to be a LOG preview that matches the BMD Film Log that Resolve gets.  

  2. Preferably a Cube LUT could be loaded - worst case the LUT could be applied in-monitor. 

  3. A highlight clipping indicator (like RED has with its goalpost or Sony coloring clipped areas of the image red) and a False Color a la EL Zone would be insanely helpful. 

Nothing worse than blown highlights and with cameras that already have a limited DR, really nailing exposure will be crucial.

Last but not least, I just ran a very rudimentary DR test and it appears that DR stays consistent between 400, 800 and 1600 ISO.  So the camera is indeed not what a traditional Dual-ISO camera would be.  Each is a native, analog ISO without any gamma-redistribution like you’d experience with most modern cameras (Alexa, Venice, REDs etc).  Need to do more testing but thought this was an interesting finding to share!

Cheers!

2 Likes

Yea so far I was using False color on Atomos which works in practise but it’s unclear if actual clipping levels match what camera can do.

On grading note for some clips I tried this and it produced more details than Blackmagic color space:

I hope true colorist nerds will eventually pick up on this to see what are the best settings to use :slight_smile:

1 Like

Yeah that’s what I was saying; the image (and your Atomos false color) will be clipped when the information is indeed still all there in the raw. So it’s an absolutely useless and unreliable way to judge your actual clipping point. 

interesting Re: linear.ill have to dig into it. Have you tried BMD Film Log + the colorspace transform to something like Slog3 or LogC3? That’s been my ticket so far! 

Possible, I would also like to know how to set that properly accurately, but for now I was happy with exposure results using False Color.

Have you tried BMD Film Log + the colorspace transform to something like Slog3 or LogC3? That’s been my ticket so far! 

I did try, but so far my shots were all physical objects and Linear sRGB gave drastically nicer midtone details.
Haven’t try yet on humans and skin.

Hey there, thanks for renting my camera and I hope you had fun with it! It’s pretty crazy just how much highlight information gets trashed with the current 709 implementation. I’m hoping, at a minimum, they’ll add some exposure tools to help us better judge when we’re actually clipping highlight detail. Giving us a LOG image (that we can add a LUT to ourselves) would be ideal.

3 Likes

Much appreciated - was very exciting to finally get to shoot with it… just as mine is landing in the US!! :) 

2 Likes

Hold up, when you say “raws”, are we talking actual raw files here? 

I was under the impression that raw hadn’t been implemented yet. 

We’ve shot a handful of shots on our Spark so far, and because the clipping is SO aggressive, we’re protecting our highlights like crazy. 

Did we miss a firmware update? Or have I missed the “raw” option in a menu somewhere on the Spark itself? 

Or have I just misunderstood altogether?

The LOG profile look is only accessible if you render out DNG files.

Check out this post for some tips: Davinci Processing, Send over your tips and tricks

1 Like

Shooting RAW was and is the corner stone of the SPARK - it’s been shooting RAW the entire time :D 

The RAW file is getting processed in their Pixboom Cine software, where you export RAW CineDNGs that then can be graded in Resolve.

1 Like

Ok, so I feel like the most basic person on the planet right now :joy: 

For some reason, I thought the camera was only capturing 10 bit for now, and that the raw capture was coming later (I think I was confusing this with the plans for internal ProRes Raw).

I completely ignored the CDNG option as I assumed it was just for people who… wanted to transcode the 10 bit footage into a CDNG sequence for some reason :man_facepalming:

So I’ve just re-exported one of my early test shots where the sky is largely blown out, and oh my word! The amount of highlight recovery in there is absolutely wild. 

Would love to know how many stops are captured above the rec709 clip point. Perhaps this could help us monitor the exposure in camera too? :thinking:

But for now, I just wanted to say that I’m an idiot! And thank you for clearing this up. Because this literally feels like a brand new camera now. This camera has affectively just gone from 6 stops to 13 stops in a heartbeat! My test footage has just been transformed from the early 2000s digi cams, to present day cinema cameras! 

Unbelievable “upgrade” I’ve just got for this camera :joy: Thanks so much for the heads up.

2 Likes

hahahhahahahha  too funny!!!

Raw does not imply any particular bit depth; it is 10-bit raw.

Interesting. I’m learning more with every comment on here :joy: 

Still, I’ll personally take increased dynamic range over extra colour information every day of the week. 10 bit with extra latitude is fine with me. 

1 Like

There is a 12-bit option in the works, though it will only be available for lower frame rates. The image quality even in 10-bit is very good though, so that’s at this point just icing on the cake. 

But it will also turn the camera from a viable to a rather nice A camera for smaller productions.

Even without on-board audio, it has time code, so it’s fine for filmmaking. Maybe not ideal for interviews, but that’s a pretty minor down side IMO.

1 Like

Do we know what sort of frame rates we’ll be looking at for the 12 bit raw? 

Somewhere around 600fps 12 bit raw would be lush.

They said frame rates in 12-bit would be approximately half of the current 10-bit speeds.