how to adjust for an iris change

[David Bogie]

It will be trial and error for you since your camera probably responds differently with varying sensor stimulation.

You need a set of scopes, waveform and vector, and to know how to read them. Levels and curves histograms help but only give you part of the whole video picture as a TV would see it.

You will need to drop the overall level of the shot but this wil not replace any blown out whites/brights. They may be completely gone although there are processes described in various AE forums to recover up to to two channels if there are pixels left in at least one.

bogiesan

This is my standard sigfile so do not take it personally: “For crying out loud, read the freakin’ manual.”

[Joey Foreman]

So hard to do, especially getting the keyframe ease to match the iris pull.

[Darby Edelen]

There will be a lot of trial and error involved. I recommend opening two comp preview windows, one with the correctly exposed footage and the other with the footage you’re trying to correct. Then your approach may use a combination of the Curves, Levels and Exposure effects.

In this case I might even recommend starting with the Exposure effect, since this uses photographic quantities/terms (although I can’t guarantee they’re entirely accurate). Then maybe followed by a Levels effect, which is usually easiest to use if you do it channel by channel. That is to say, look at the red channels in both the correct footage and the incorrect footage as you adjust the red levels of the incorrect footage to try and match the white/black points and gamma, from there move to the green and blue channels.

Finally, if you’re going to be doing primary and secondary color corrections on the entire feature this will help hide any subtle differences between scenes.

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA

[Kevin Dearing]

I’m just a noob to AE but:

“There will be a lot of trial and error involved. I recommend opening two comp preview windows, one with the correctly exposed footage and the other with the footage you’re trying to correct. Then your approach may use a combination of the Curves, Levels and Exposure effects. “

What about doing the adjustment in a precomp with the correctly exposed footage freeze framed in one layer with a hard edged mask showing the layer being adjusted (via curves, levels, etc..) Obviously the mask should try to be placed in a position that shares an object in both shots. When you cannot detect the mask edge then you’re probably close (though other things may be off of course..) Anyway, once happy with the adjustments copy the effects to the real layer and kill the precomp (or just use the precomp after removing the extra layer and all…)

–KTFA

[Darby Edelen]

One problem I see with that technique is that the footage will not be exactly the same unless a very sophisticated motion rig was used for the shots. So the ‘line’ benefits you less and less as the footage becomes less identical. Also if you adjust only for the line then you may be making elements that don’t lie on the line even worse.

Not necessarily a bad technique, but there are factors to consider while doing it.

Darby Edelen
Lead Designer
Left Coast Digital
Santa Cruz, CA

[Kevin Dearing]

Good points Darby, I was just thinking that it would possibly be better than eyeballing two separate windows..

–KTFA