"Levels" tied with "gaussian blur" (.001) for stills as needed.

curves
delete
and the make "cool" script


Logan5

Coffee!...and color corrector...

"best brain here save maybe Spot"

Here I'm reminded of a favourite quote from the miniseries "House of Cards", employed when revealing sensitive information to journalists: "Well might you think that, but I couldn't possibly comment". And in this case, I'm grateful for the observation and wish it were true.

To business: it's all about keeping the range of scene brightness within the range of the recording medium, and that you understand well because you asked. The smaller the range of the medium, the greater will be the situations where you must choose which parts of the scene must be let go. Using film negative you can achieve a range equivalent to 22 bits (still less than real world), which will let you expose for an indoor scene and yet still have detail recorded in the world outside the glass doors. Although the usable range in the theatre is only 10 or 12 bits, a wide latitude negative allows a lot more options in post as well as a great deal more tolerance for exposure and lighting deviations. Where the range of the medium cannot accommodate that of the scene you have the choice of discarding portions (letting them go all white or all black, in video) or of using additional light controls. On set you light to keep both shadow detail and highlight, so no problem. Outdoors you can light shadowed areas (eg.reflectors) and scrim down the sun, or in some cases graded filters will do it nicely. The basic graded filter is neutral grey, clear one edge and perhaps (your choice) 2 stops reduction at the opposite side. The gradient between the two occurs somewhere in the middle of the filter. In a typical nice simple scene with bright clouds and a straight horizon, you align filter so the stuff below the horizon is unfiltered and the stuff above is attenuated and brought within exposure range. A matt-box makes this easy because it allows the filter to be adjusted relative to the scene (up/down and rotation). For more complex horizons you might chose a softer gradient or take your scissors to a ND gel and shape it to suit. Do I hear you wondering about depth of field? A problem with using such filters with short focal length lenses, because the last thing you want to see is the filter edge or gradient. So you need to use big apertures (stop < f/4, say) and so probably will need to use a general ND filter on top of the grad (matt box!). Of course, most of this implies time to set up the shot. And a grad often just doesn't do exactly what you want (eg. sea scene with yacht's white sails above horizon).

What else can you do? Well the usual video gamma is a straight line (from black to white), but cinegamma introduces a little non-linearity to the top end of the curve which reduces contrast between the brightest elements and "softens" cut-off in the highlights. Somewhat similar in effect to the roll-off that film does towards over-exposure (remember the S shaped gamma curve). Cinegamma does influence overall contrast towards what some people call "film look". The Z1 also allows some user manipulation of gamma at the bottom end (shadows) -- black stretch. I think Spot's new HDV book includes details of these for the Z1, but I haven't received mine yet.
Then, if you've exposed your video to not clip highlights (such as clouds) you can find that your mid-tones are somewhat under-exposed. You can then work with filters in post to bring up those while retaining highlights, and generally I use curves for this. In fact generally the curve I apply is an S-curve because otherwise blacks get stretched too much (and get noisy if you're not careful).

To my eyes, it doesn't look like cinegamma introduces a non-linearity. It looks like that are just flattening the entirely image evenly... i.e. pop the brightness and contrast filter on a non-cinegamma clip and reduce contrast. It looks like that, except the highlight and shadow detail will keep going on.

Cinegamma characteristics: you need actual measurements. However I haven't made these myself but others have reported details.

I am just sooo pleased that an analogue item is squeezed in here amongst all the digital remedies. Get a Matte box, set of Solid and Grad NDs - not forgetting that pola too!! - For those of you who HAVE several NDs on their cameras, ignore the bit about solids - well, mostly.

Grazie