P3D Re: Dr. George A. Thernelis Reply

[fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)]

>Lets take the 1/30 formula: (160 * 30 = 4800)
>So, 4.8 meters from the nearest object. *Accepted*!
>But what if I'm using 28mm lens, and 50mm, and 200mm,
>Are they all the same? Seems ilogical to me, isn't it?

Instead of 1/30 use 1/FL. So for 28 mm lens use 1/28 and for a 200 mm
lens use 1/200.  (This comes directly from the formula you quoted by
setting parallax = 1.0 mm).

However, be aware that these rules are based on the distance of the
nearest object and the assumption that you have infinity in the picture.
When you use a wide angle lens you cannot help it but include a lot
of nearby foreground which limits your stereo base.  When using a long
angle lens you normally do not include infinity but concentrate on one
object and this gives you more freedom to translate the camera.  It might
be that at the end 1/30 might work well in both extreme situations!

Regards -- George Themelis


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