JerriK

290-350mm ISCO lens -- is that an anamorphic lens?

I'm wondering if a 290-350mm ISCO lens is an anamorphic lens.

John Whittle

The terminology you used is typical for a zoom lens range (specifing different focal lengths). Anamorphic lenses are specified by their compression ratio and have no focal length since it's taken from their "back up" lens. A typical theatre anamorphic is a 2x compression for Cinemascope/Panavision. Home movie lenses from the 50s were often 1.5x (Bolex, Vistascope and others).

If you look thru an anamorphic lens the image will be compressed and upright to you eye and if rotated 90 degrees, it will be expanded.

A 1.78 anamorphic lens should have a compression ratio of 1.33. This is want a typical movie lens.

Doesn't sound like your ISCO lens is anamorphic.

John

Mark Techer

That's not quite right. A cinema scope lens expands not compresses the image. The film strip contains an image just half as wide as it should be, IE it looks tall and thin. The cinema scope lens then expands that by 2x to restore the geometry.

HT anamorphic lens come in both VC (Vertical Compression) and lately there has been more attention to HE (Horizontal Expansion). The true benefit of a HE is that it allows the lens to be moved in and out of the light beam and maintain the Constant Image Height...

Mark