Lens used in 'Magnolia'
Posted 20 March 2009 - 08:41 AM
Watched Magnolia last night and noticed that the lens used produced a focus effect I've never seen before where everything that is out of focus is distorted vertically and as focus is pulled sharper the objects reduce in vertical size. For example glowing lights in the background will be vertically oval shaped and as focus is pulled they become circular again. Can anybody tell me what kind of lens is being used here and why this happens?
Posted 20 March 2009 - 10:51 AM
I'd read John Hora's article on anamorphic history in the ASC Manual.
The basic gist is that CinemaScope lenses, and current anamorphic lenses, have a 2X horizontal compression and anamorphic projector lenses have a 2X horizontal expansion. However, as you pull focus, the changing distance between elements can cause a change in the degree of the squeezing effect... but the amount of expansion during projection is a constant 2X.
In the early days of CinemaScope as you focused closer, the amount of compression would drop off (less than a 2X squeeze) making faces in close-up (often closer to the lens than an object in a wide shot) look fat once they were expanded by 2X in the theaters - called "anamorphic mumps". Panavision solved this problem by a change in the cams of the lens elements, so that rather than have the in-focus subject get too little squeezing as you focused closer and closer... the out-of-focus background now gets too much squeezing compared to the in-focus subject. So even though the expansion in the theater is a constant 2X, the out-of-focus backgrounds that got more than a 2X squeeze still look vertically compressed, skinny.
Posted 21 March 2009 - 01:46 AM
Posted 21 March 2009 - 01:42 PM
Panavision solved this problem by a change in the cams of the lens elements, so that rather than have the in-focus subject get too little squeezing as you focused closer and closer... the out-of-focus background now gets too much squeezing compared to the in-focus subject. So even though the expansion in the theater is a constant 2X, the out-of-focus backgrounds that got more than a 2X squeeze still look vertically compressed, skinny.
Panavision added a lens module called the variable astigmatizer, which has a positive cylindrical dioptre and a negative cylindrical dioptre rotating against each other, causing their squeeze to vary.
But the extra squeeze in the backgrounds, which effects the bokeh is due to the anamorphot having different horizontal and vertical depths of field.
Posted 21 March 2009 - 07:23 PM
Maybe I've watched a lot of films that weren't shot with anamorphic lenses...
Thanks a lot for your help!
Posted 22 March 2009 - 03:24 PM
Posted 22 March 2009 - 06:15 PM
'Cause won't that mean on the negative, the the light blobs will be even narrower than when they are "anamorphed" (if that's even a word)?
Yes, they are -- they are over-compressed, more than 2X, so they don't stretch back out to circles when uncompressed by 2X.
This is on the negative:
But this is how it looks stretched out by 2X:
This is also why you get red flattened horizontal rings on some older anamorphics -- the ring is due to an uncoated spherical element, which produces a circle on the negative, but it gets stretched out by 2X horizontally during projection.
And the blue horizontal line is due to the front surface of an anamorphic lens being barrel-shaped.