 | | | 4/3 crop box on a 16/9 cam ? | 4/3 crop box on a 16/9 cam ? 2005-05-17 - By Marc Bourbonnais
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Ahhh, my kind of thread. FoV vs. lens.
The refresh issue is happening probably because
1) you are keying or controlling the lens value and the FoV values at the
same time. Aperture will not change but FoV and lens will merrily jump
around.
2) your aperture settings are changed and your camera format is not
"Custom". XSI will mess up a modified camera if the format is kept as one of
the standards after some refresh, for example after rendering or previewing
a frame.
Since Andre is mentionning changing aperture, it is probably 2). Just change
the camera format standard to "Custom"
Around here I hit people with sharp objects when they use anything but the
lens value for camera controls. No refresh issues. It simplifies everything
and as a bonus you're in synch with DOPs and camera reports; FoV doesn't
exist in real life. Aperture and lens do.
Fabrice:
The base magic formula for lens vs. FoV is
f = (0.5*Ap) / tan(0.5*FoV)
How to implement it with the setup you want to use would depend on how you
want to control your camera. I suppose you want to keep the vertical and
crop right and left? Are your camera(s) zooming or is the FoV constant?
Maybe too simple, but have you thought of using a simple rotoscopy pic, a
16:9 image with your 4:3 crop as a background image? Or as a camera
projection?
--
Marc Bourbonnais
3D TD
Hybride
(450)227-4245
-- -- Original Message -- --
From: "kim aldis" <kim@(protected)>
To: <XSI@(protected)>
Sent: Tuesday, May 17, 2005 1:41 PM
Subject: RE: 4/3 crop box on a 16/9 cam ?
> I have a script already, Andre, but thanks anyway. You're right, it does
> cause a refresh issue. Mine will probably do the same then. No cycle
> dependancies either. No idea.
>
> > -- --Original Message-- --
> > From: owner-xsi@(protected)
> > [mailto:owner-xsi@(protected)] On Behalf Of Andre DeAngelis
> > Sent: 17 May 2005 18:29
> > To: XSI@(protected)
> > Subject: RE: 4/3 crop box on a 16/9 cam ?
> >
> > Hi Kim,
> >
> > This is a script we created to do most of this. Pretty
> > simple, buit it does the trick.
> >
> > The script sets our cam parameters based on aspect ration of
> > the film aperture. You will want to make changes according
> > to your needs. To apply it, select your camera and run the script.
> >
> > The script also creates a PPG with lens presets. We did this
> > because changing the lens size created a refresh problem as
> > opposed to changing the FOV. Perhaps you could figure out
> > what is causing the refresh problem.
> >
> > Andre
> >
> > -- --Original Message-- --
> > From: owner-xsi@(protected)
> > [mailto:owner-xsi@(protected)] On Behalf Of kim aldis
> > Sent: Tuesday, May 17, 2005 1:04 PM
> > To: XSI@(protected)
> > Subject: RE: 4/3 crop box on a 16/9 cam ?
> >
> > What I do is build a rig with a bone parented to the camera
> > and a rectangle on the bone, scales expressed so it fits in
> > the camera view no matter where you slide the square on the
> > bone. I can post a rig if you want it in a hurry but I'm
> > thinking that the plugin I have to build it might make a good
> > Soup tool. What do you think, Maggie?
> >
> > > -- --Original Message-- --
> > > From: owner-xsi@(protected)
> > > [mailto:owner-xsi@(protected)] On Behalf Of Fabrice Altman
> > > Sent: 17 May 2005 14:27
> > > To: XSI@(protected)
> > > Subject: 4/3 crop box on a 16/9 cam ?
> > >
> > > Hi List,
> > >
> > > What's the best way to show a 4/3 semi-transparant "crop box"
> > > in a 16/9 cam viewport and capture ?
> > > Doing a post crop is not an option as I need a very fast solution.
> > > Just showing the field guide is not enough.
> > >
> > > Locking a grid in front of the camera is sort of what I need but is
> > > there a relationship between the cam FOV and the size of the grid ?
> > >
> > > I've looked into Xgs_slate but the bitmap has to be
> > different size in
> > > viewport and capture to work nicely, and the mask option
> > only seems to
> > > work only horizontaly.
> > >
> > > Thanks in advance,
> > > F.
> > >
> > > ---
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> > >
> >
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