BMCC ProRes Exposure Tricks?

The place for questions about shooting with Blackmagic Cameras.
  • Author
  • Message
Offline

Jayson Rahmlow

  • Posts: 199
  • Joined: Sat Jul 27, 2013 6:33 am

BMCC ProRes Exposure Tricks?

PostFri Apr 25, 2014 6:05 am

Hey,
Is it me or do you really need to nail exposure in camera when shooting ProRes on the BMCC. I got used to shooting to the right when shooting raw. And had a rude awakening carrying this philosophy over to ProRes. I really tried to avoid bringing up the shadows because of noise so tend to want to slightly over expose shots. But have really been bitten by hot yellow skin tones that can't be normalized in post.

So is the rule of thumb for shooting ProRes to ETTL? Or do you really just need to nail the shot.

Anyone using zebra tricks, like setting zebras to a lower number and try to get skin tones just below the zebras? Or is it time I got a light meter?
Jayson Rahmlow
Applejackfilms.com
Los Angeles
Offline
User avatar

Thomas Schumacher

  • Posts: 709
  • Joined: Tue Nov 06, 2012 11:14 pm
  • Location: Germany

Re: BMCC ProRes Exposure Tricks?

PostFri Apr 25, 2014 10:21 am

Some people say ETTR even with ProRes but set your zebras to something around 80 - 85%, some expose half an or an extra f-stop above spot on so you avoid some of the noise in the shadows.

You gotta see what works best in which circumstances - at least that's what I'm still trying to figure out. But what I don't do anymore is ETTR in ProRes and to be honest, I don't care about a bit of noise and when I did some comparisons (mainly shooting outside) there was no siginifant difference in exposing spot on and overexposing a stop noise-wise.

But that's just me. I'm sure more experienced users will chime in.
https://www.gernemehrfilm.de/
Offline
User avatar

Tom

  • Posts: 1626
  • Joined: Wed Aug 22, 2012 5:08 am
  • Location: Manchester, UK

Re: BMCC ProRes Exposure Tricks?

PostFri Apr 25, 2014 10:39 am

Whilst it is generally always better to expose properly and in a controlled and consistent way -I have been able to successfully recover skin tones from ProRes, exposed to the right by 2.5 stops!

So I do not think ProRes is massively less flexible in that way compared to raw. You can still expose to the right, but make sure to set your ASA value in camera to the "correct" rating.

For example, if you want to ETTR by 1 stop, expose/light and film at 400.
ETTR by 2 stops - expose/light and film at 200.

In that, at those values the image should not require further exposure adjustment in post.
Tom Majerski
http://tetragrade.com/
http://www.imdb.com/name/nm5157752/
Offline

James Milner-Smyth

  • Posts: 22
  • Joined: Tue Sep 04, 2012 12:31 pm
  • Location: London, UK

Re: BMCC ProRes Exposure Tricks?

PostFri Apr 25, 2014 11:58 am

Jayson, given you mention hot yellow skin tones, it may also be worth looking at your post workflow?

If you were shooting RAW previously, presumably you are shooting prores with the film curve, not the video curve? If you are baking in the video look at the camera you are restricting your grading options somewhat.

If you are shooting film curve and using Resolve to grade, you'd be best avoiding the included LUTS to stretch the log back out: they seem very geared towards people who want a crunchy video look.

Best

James Milner-Smyth
Post Factory Group, London
Red Dragons, Sony FS7s, Blackmagic Ursa Minis, PC, PCC and 4K
Lomo Anamorphic, Canon K35, Super Baltar, EF, CP2s
Ronin Pro, Movi M10 M15
Post: DCP mastering and cinema delivery
http://postfactory.co.uk
http://gearfactory.co.uk
Offline
User avatar

AdrianSierkowski

  • Posts: 929
  • Joined: Sun Feb 17, 2013 4:59 pm
  • Location: Los Angeles.

Re: BMCC ProRes Exposure Tricks?

PostFri Apr 25, 2014 2:32 pm

I would assume you also properly balanced your camera and your lighting? E.g you were shooting 3200K under 3200K (or there abouts) lighting?
Adrian Sierkowski
Director of Photography
http://www.adriansierkowski.com
adrian@adriansierkowski.com
Offline

Jayson Rahmlow

  • Posts: 199
  • Joined: Sat Jul 27, 2013 6:33 am

Re: BMCC ProRes Exposure Tricks?

PostSat Apr 26, 2014 1:52 am

Thx for the tips everybody. And yeah, my white balance is right, or as close as the 6 wb settings can get. I was reading this thread from a shoot today. (A corporate media training gig so I was just staring at a static shot for about six hours.) And looking at the rec709 I realized there's no such thing as pink with the BMCC 2.5k rec709. This is probably why skin tends to look yellow and why red is orange. There's a yellow cast in rec709 or an absence of pink.

I took out my nexus 5 to compare how skin was represented and yup the pink of the persons arm looked right in the nexus 5 camera but jaundiced in the BMCC rec709. So I switched to film mode and while it's hard to tell because the saturation isn't there it seemed like it had a better chance of being graded back to looking like real skin.

This is unfortunate because I shoot about 3 times a week and edit about half the shoots and hand off the other half. And I really want to have a good in camera lut to save having to grade every edit or be able to hand off footage without telling clients they need to grade it. So I've been shooting everything with rec709 for the last month or so. Don't know what took me so long to see this yellow cast. I guess I always thought I'd just missed the WB by a few hundred degrees. But today I tested all the different wb's and I was on the right one.

Is there a corrected rec709 lut that people are using that has an ideal version of what the rec709 should look like out of the BMCC?

and thx again for posting everyone, looks like I won't be shooting rec709 anymore.

edit: I'll post two frames to show what I mean
Jayson Rahmlow
Applejackfilms.com
Los Angeles
Offline

Jayson Rahmlow

  • Posts: 199
  • Joined: Sat Jul 27, 2013 6:33 am

Re: BMCC ProRes Exposure Tricks?

PostSat Apr 26, 2014 7:06 am

Here's comparison frames from the corporate media training today. (it's just overhead lighting, I was asked not to light the shot because the camera's just there to show the person how often they say umm and like.)

The white balance is the same for both film and video mode (4500k)

There's a yellow cast over the rec709 shot.

So if I shoot in film mode what lut do I use? I don't see a lut in Resolve that applies a BlackMagic s-curve. I see Canon, Arri, Sony and yet BlackMagic, the makers of the software and the camera, only have one lut, the film to rec709 that makes everyone look like they have jaundice. Am I missing something?
Attachments
rec709-yellow.jpg
rec709-yellow.jpg (673.98 KiB) Viewed 7129 times
Jayson Rahmlow
Applejackfilms.com
Los Angeles
Offline
User avatar

AdrianSierkowski

  • Posts: 929
  • Joined: Sun Feb 17, 2013 4:59 pm
  • Location: Los Angeles.

Re: BMCC ProRes Exposure Tricks?

PostSat Apr 26, 2014 7:31 am

I've never seen results like that when lighting myself. Me thinks you may be dealing with poor cri bulbs. Try a test under tungsten or Kino lighting baldness accordingly.

That said you can make your own luts or look into the stuff from captain hook on here. I think that's the name. Another option is an flb filter on the camera. Test this first though as it may skew other things. If it's any consolation I hit this same problem using Kodak film sucks which was why I'd switch to Fuji when I could in such situations
Adrian Sierkowski
Director of Photography
http://www.adriansierkowski.com
adrian@adriansierkowski.com
Offline

Jayson Rahmlow

  • Posts: 199
  • Joined: Sat Jul 27, 2013 6:33 am

Re: BMCC ProRes Exposure Tricks?

PostSat Apr 26, 2014 8:29 am

Is there no official BlackMagic s-curve film LUT? I thought that was the idea behind flat profiles was to capture a compressed curve in camera and then decompress the curve with a manufacturer provided LUT.
Doesn't every other camera manufacturer with a flat profile have an official LUT? I know red, canon, arri and sony release them for their cameras.

Adrian, I'm seeing this yellow with all light sources, tungsten, daylight and flourescent.
Jayson Rahmlow
Applejackfilms.com
Los Angeles
Offline
User avatar

Dustin Boswell

  • Posts: 358
  • Joined: Tue Jan 21, 2014 11:16 pm
  • Location: Los Angeles

Re: BMCC ProRes Exposure Tricks?

PostSat Apr 26, 2014 9:02 am

I've been using CaptainHook's LUTS as a starting point, They do work quite well, there are also some other LUTs I've been playing with. I'd like to try out Filmconvert but unfortunately I'm a bit low on funds for it, but I've heard great things about it!

Rec709 is quite ugly, I did a nighttime test on my BMPCC w/RAW (to see how far I could bring the image up in extreme underexposure. I prefer real-world testing over traditional camera tests :geek: ). The Rec709 version falls apart completely into nasty-bayer pattern like noise, where as any of the LUTs I've used have produced a slightly finer noise pattern that is completely passable after some Noise Reduction (using the demo for NeatVideo, full version NR would probably be better).

Regarding Exposure, I'd think that slightly higher exposure levels (ETTR as some call it) as it would apply to RAW. I would advise to test this - as this method may not achieve the desired result. I would also think it would be a good idea to test the images difference from the correct exposure vs. slight overexposure.

I'd say the best way to achieve the best exposure would be with a Light Meter for the most precision, although they tend to be a bit expensive. The reason I say this is that many monitors aren't fully calibrated to the image that the camera is producing, as well as potential flaws in the users view of the image (light reflections, smudges on the screen, dust, screen brightness, lower resolution viewing).

Captain Hook's LUTs:
http://forum.blackmagicdesign.com/viewtopic.php?f=2&t=19731&hilit=luts

Film Print Emulation LUTs:
http://juanmelara.com.au/print-film-emulation-luts-for-download/

FilmConvert:
http://www.filmconvert.com/purchase/default.aspx

My Nighttime Test (Be Gentle):
https://www.dropbox.com/sh/d9co6qsy23mf7x3/ghL0Jd4xjM
"Fix it in Prep"- 1st A.D.'s Motto
Dustin Boswell
Director/Writer and periodically Camera Department.

Return to Cinematography

Who is online

Users browsing this forum: Jamie LeJeune and 18 guests