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Re: Wide lenses for 12x20 @ 300mm
Richard Knoppow wrote:
> I don't know the actual diagonal for 12 x 20 film. Most sheet film is a
>little smaller than the "nominal" size. However, assuming its pretty close
>it would require about a 90 degree coverage angle for a 300mm lens. This is
>beyond a Dagor. Dagors will do about 87 deg at f/45. A wide angle Dagor a
>little over 90 deg.
The actual diagonal of 12X20 is 590mm, slightly less if you measure only
the image area.
>The f/18 Zeiss Protar series V will cover 100 degrees
>but I suspect you are going to have to use a modern lens.
But is there a modern lens of 300mm or less will cover a circle of 590mm?
The Grandagons, Super Angulons and new Schneider SSXL are only made up to
210mm, and even at 105 degrees or more they miss covering 12X20.
> Goerz claimed 87 degree coverage for the Dagor at f/45. It will actually
>do this without vignetting but the image quality at the extremes is only
>fairly good.
Fairly good may be too generous to describe the image of a 12" Dagor at the
extreme corners of the 12X20 format.
Sandy King