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Shallow DOF in 3-D movies


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#1 Cesar Rubio

Cesar Rubio
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Posted 24 October 2011 - 04:27 PM

A few days ago I was discussing with a veteran “heavyweight” on 3-D, regarding DOF (Depth of Field) for 3-D movies.

He mentioned this: “In the 1980's we shot features with T/4 and T/5.6 lenses, and rarely used any aperture other than T/8 of T/11.In fact, of the thousands of stereo images I have shot over the years, I don't recall ever finding a shallow enough depth to warrant using such wide apertures.” (they used S35mm film)

All that discussion started because I said that sometimes I need to shoot at f1.4 in interiors.

In a normal house lighting environments I need ISO/ASA 800 1/60th shutter speed AND f1.4.

In order to use smaller lens apertures I have two choices:

1-Use gain (something like ISO 6400 to be able to use at least f4) but that increases noise in the images, I don't think that people like to see “flying mosquitos” in 3-D and out of sync BTW...Noise is one of the main enemies to fight with in 3-D movies.

2-Bring in more lights. I prefer this one over using gain, but sometimes it's not very practical for different reasons, like they produce a lot of heat and discomfort in peoples faces. And in most night time outdoors scenes they are not much practical either.

I told him that in order to “fight” the shallow DOF that such wide lens aperture (f1.4) produces, I like to use smaller sensors, like 2/3” for example.

f4 in a 2/3” sensor size gives the same DOF of T/8 in a S35mm sensor. So that lens aperture would be ideal in a 2/3” sensor, but until sensor technology advances and they can offer at least a clean “base” ISO 6400 at 0dB we have to compromise...

Then this morning I was reading about how a recent 3-D movie was shot at...they used S35mm sensors at T1.3 for most of the movie!: (Tron Legacy 3-D)

http://www.hdvideopr...echnologic.html


I don't agree in the “shallow DOF” approach for 3-D movies, but sometimes is something that we have to live with at present time...

Cesar Rubio.
Wisconsin & L.A.
http://dna-rubio-3d.blogspot.com/
http://dnarubio3d.wordpress.com/
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New Pro Video - New and Used Equipment