Adobe Premiere Pro Forum
Exposure question
Exposure question
by Duke Sweden on Aug 14, 2016 at 9:09:29 pm

I put this in Cinematography but after 3 days not one response. The Adobe forums seem to be the only active ones, so I thought I repost this here and hopefully one of my many mentors will jump in.
I'm just an amateur and I don't have a fancy lighting studio or outdoor equipment but the answer to my question might help others.

OK, when shooting a scene that will end up dark and moody, should one try to get exposure as close as possible to that look in camera, in other words underexpose to get the look I want before the final color grade, or should you try to get as bright an image as possible short of overexposure, and darken in post?

It seems to me that when I darken in post I get a lot of noise, even in the brighter areas. I'm using a Panasonic G7, btw, and I'm not entering anything at Cannes this year, if you catch my drift ;-)

Re: Exposure question
by Chris Paul on Aug 14, 2016 at 10:55:26 pm

Definitely get as close as you can to the look you want in camera. Amazing things can be done in post but it is unwise to rely on it.... Particularly as I do not think your camera shoots RAW video. If you do the look in camera you can see if you are getting what want as you shoot.

Chris Paul

Re: Exposure question
by Duke Sweden on Aug 15, 2016 at 1:11:17 am

Hey Chris, thanks for responding. No, the G7 doesn't shoot RAW. I'm shooting in 4K (100mbps). The problem it seems, is that when I do underexpose I don't get solid blacks, it's very blocky, not smooth.

I guess I'll try again, underexpose and overexpose, and then play with the clip in PPro.

Thanks again.

Re: Exposure question
by Tero Ahlfors on Aug 15, 2016 at 3:59:41 am

If your image doesn't have usable information (ie. it's insanely dark or blown out) then there's no use in grading it. I'd rather have some fill light and bring it down instead of trying to boost up nothing.

Re: Exposure question
by Chris Wright on Aug 15, 2016 at 5:28:34 am

I agree 100% with Tero.

If you look at the rec. 709 curve, most of the bits are spread toward the middle luma, because shadows and highlights have less bits to work with in 8 bit.

human eyes need a delta of 1% to not see banding. so linear light needs to be at least 14bits.

Since most cameras are only 8 bit, in the rec.709 gamma curve, the contrast ratio cannot exceed 50:1 or just a few f-stops.

With lower end cameras, the latitude range is less than 14 so you're having to share only around 8 f-stops, leaving about 3 and half above and below the middle!!!

So, as a rule of thumb, what you actually want to focus on is the f-stop difference between the middle and shadows so you can decide how to compromise on highlights being blown out without getting muddy blacks. You'll need a light meter to gauge the 3.5 f-stops from fill light to shadow light.

Hope this clears it up a little.

Re: Exposure question
by mark thompson on Aug 15, 2016 at 8:56:57 am

have you looked at the various "Day for night" tutorials?

unless you have a good low light camera, that might be a way to investigate at least.

Re: Exposure question
by Jon Doughtie on Aug 15, 2016 at 12:52:06 pm

Hi Duke. I know you do not have extensive lighting kit at your disposal, so I want you to know this is not a critique of your approach. You are having fun and enjoying the challenge of your personal projects and that is terrific.

Just a note here that this discussion emphasizes how important lighting is to production. The laws of physics can (and do) work against us in some situations such as yours, so we must bring tools to bear that give us the ability to "bend" those laws in our favor.

You will likely have to accept some quality compromises to get that look you are hoping for, given what you have to work with. Again, no critique, just conversing.

Dell Precision T7600 (x2)
Win 7 64-bit
Adobe CC 2015.02 (as of 6/2016)
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4 internal media drives RAID 5
Typically cutting short form from HD MP4 and P2 MXF.

Re: Exposure question
by Duke Sweden on Aug 15, 2016 at 3:10:24 pm

Hey Jon, no problem! I think that, once again, my original point is being misunderstood. After all these times I'm starting to think the problem is on my end. ;-)

Thanks to you guys I already knew a lot of what you were telling me here. But I wasn't asking how to light a scene or what vector to adjust my deltas to, or where to position my Johnson Crane ;-)

Tero came closest to answering my question, in fact I think he did. All I wanted to know, and you guys know the quality of my productions, is if I wanted to shoot, say, the big bad wolf in the Black Forest, should I light it as brightly as possible to get as much detail as I can, short of overexposing, and then creating the dark, spooky mood in post by bringing the exposure down (yes, I know about Day4Night, I've got like 4 different plugins), or should I lower the exposure in camera to get the look I'm going for. And the only reason I asked is that when I do under expose, I get nasty artifacts in the dark areas. Having experimented since I first asked, I've found that I can, indeed, lower a brightly lit scene and avoid ugly dark areas when lowering exposure in post. The key is to get it as evenly lit as possible. I can get spooky backgrounds but my face is still brighter than everything else. So I've got to work on that.

But, as always, I'm grateful that people with professional backgrounds like yourselves are quick to jump in and respond to my questions. I'm thinking, as a guitarist with 40 years experience, that if someone asked if it would be ok to pluck a G string rather than learn the chord, I don't think I'd be as patient as you guys are with me.

Re: Exposure question
by Tero Ahlfors on Aug 15, 2016 at 3:22:14 pm

[Duke Sweden] " The key is to get it as evenly lit as possible."

You don't need to even get it evenly lit. You'll just need to light what you need to see. If you have a pitch black background then that can probably stay black. If you have a guy in a black jacket in front of the image you'd want to light the guy so you can see the detail in the jacket.