Underexpose with filmgamma settings

Wikse · April 5, 2005

Hi.

I'm new in the scene-file-settings-world, and I'm a bit confused by the different info I get from more experienced scene-files-camera-people. One say that If I want to get the full effect of the Filmgamma setting, I have to underexpose my shots and adjust in post. The other guy says that I do not have to underexpose to get the effect. What is right? Wouldn't it be a lot of detail loss in the black areas if you underexpose and gains it up again in POST? (maybe a black stretch has to be added?)

Is it any difference between exposing by 100% zebra and 80/70%. As I believe - if you expose by 100% and you work with filmgamma, the image WILL get overexposed... And if you expose by 70% (skin tone zebra) it will be close to OK. correct me if I'm wrong - please.

(my camera has no lens at the moment, and the new lens will not arrive until next week... - so I am unable to test out this myself this week)

I'm shooting in PAL 50i.

Thank U :unsure:

John Ealer · April 5, 2005

Hi.
I'm new in the scene-file-settings-world, and I'm a bit confused by the different info I get from more experienced scene-files-camera-people. One say that If I want to get the full effect of the Filmgamma setting, I have to underexpose my shots and adjust in post. The other guy says that I do not have to underexpose to get the effect. What is right? Wouldn't it be a lot of detail loss in the black areas if you underexpose and gains it up again in POST? (maybe a black stretch has to be added?)

Is it any difference between exposing by 100% zebra and 80/70%. As I believe - if you expose by 100% and you work with filmgamma, the image WILL get overexposed... And if you expose by 70% (skin tone zebra) it will be close to OK. correct me if I'm wrong - please.

(my camera has no lens at the moment, and the new lens will not arrive until next week... - so I am unable to test out this myself this week)

I'm shooting in PAL 50i.

Thank U :unsure:

<{POST_SNAPBACK}>

I don't think there's one right answer to getting a "filmlook" with any camera, since that term is itself quite subjective. How you set the gamma slope and gamma mode on the SDX-900 really depends on what kind of filmic "look" you're going for and how much room for manipulation you want to have in post.

If you really want a film look, I'd suggest shooting in 25P mode rather than 50i.

Filmlike1 and Filmlike2 gamma modes roll off the toe and knee of the curve in increasing amounts, respectively, and preserve a lot of detail in shadow and highlight areas, especially if you use a modest slope of .50 or so. The advantage with this approach is that you have more room to manipulate in post. However, if you want to end up with a contrasty image with crushed blacks, you're going to have to add that back in post. If you shoot with STD gamma with a high slope of .65 or so, you'll have a contrasty image with solid blacks - but with less room for error on-set and less wiggle room later.

The other really important factor to consider is the detail settings. Too much detail will kill the film look with video sharpness no matter how the gamma is set. Exactly what detail settings to use depends on the lenses you're using, I personally usually end up between +4 and +8 with SD lenses, even less for HD glass.

Regarding your question about zebra settings: some people used to working with 100% zebras on other cameras can get thrown off in the Filmlike gamma modes (especially Filmlike2), as the knee of the curve rolls off so slowly that very little, if any, of the highlight areas hit 100%.

J

Gordon Highland · April 6, 2005

Regarding the Zebra modes, using one or the other doesn't mean you're going to overexpose, you just have to know what each is used for and expose accordingly. i'm basically an 80 zebra guy most of the time. i watch the skin for zebra, and as soon as i see it on the highlights, i iris down just a tick. if it's a complex shot, then i flip over to 100 zebra and check out the rest of the scene to see if i need to deal with anything else in the background, or just let certain sources blow out, depending. because if you only monitor at 80, you may have all kinds of stuff that all appears overexposed until you verify it. of course, with a good viewfinder properly set up, you can often judge the detail loss from overexposure even by eye. i hardly ever have a wavform monitor with me, else i'd just use that and be done with it. and the dual-mode zebra function is a little too obtuse for me, even though in theory it should work fine. if i had to pick just one, personally it wouldn't be the 100, because who knows what your subject is actually exposed at. it's easier for me to judge the other way around, but opinions vary greatly.

I shoot a lot of multimedia video that gets integrated against a solid white design on computer screens, and this techniue is perfect for that. i evenly-light a white background exposed to exactly 100 IRE, don't touch the iris, then bring in the talent and light and scrim as needed to get the right level on him, double checking on 80 zebra before i roll. it blends perfectly with no frame edges, looking like a chromakey.

My SDX900 footage (Filmlike2) is usually underexposed about half a stop, whether adjusted in post later or not. it's just a punchier, more saturated look that i generally prefer anyway. But you definitely don't want to overexpose with these cameras, because then that "video look" creeps back in.

Phil Rhodes · April 6, 2005

Hi,

Do you find yourself flashing out the white in post with Levels or whatever, to achieve your inserts?

I've shot stuff like that and have always had to, if only because the DV white isn't quite 255, and the graphic white inevitably is. Some codecs will remap this for you.

Phil

Gordon Highland · April 6, 2005

Yeah, it's usually pretty close, but sometimes there's a little pseudo-vignetting on a wide shot where the corners aren't quite as bright or a slight blue cast is in there. So I use the Limit part of FCP's color corrector to select just the whites, desaturate them, and turn them up a little if needed. (I don't use Levels for this because the subject is already exposed properly and it would bring that up, too.) Because almost all of my stuff is online and not broadcast, I work 0-255 instead of 16-235 range.

When shooting against white backgrounds, I'm almost always surprised how little illumination I'm using on the subject; it's because by the time I get the background up to 100, I'm irised wide open, and then I'm moving my foreground lights way way back for proper talent exposure.