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taking lens for 20x30?


jimdesu

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Hi there,

 

I know this's insane, but does anyone know of a lens that'll cover 20x30 at infinity? If my math's right, that's an image circle of 916mm w/ no movements!

 

I'm also wondering if I should just buy a single achromat cell, and, if that sort of thing works, if there are any rules of thumb for figuring out how to predict what the image circle of such a thing would be. Good idea? Bad idea? Dumb idea? =)

 

thanks,

 

Jim

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The APO ronars are not that wide of coverage...Our longest is a 36"/890mm which covers 24x36" at close ratios; but I'm not sure at infintiy......at 3x; the 24x36" negative would shoot an 72x108" field; taller than my vertical glass we place originals on........Maybe cutting a hole in the wall will give me the infinity coverage....:)<<BR><BR><img src="http://www.photo.net/photodb/image-display?photo_id=1238404&size=md">
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Armin ; our camera above has 7.6 feet of bellows; about 2.3 metres. the rails are about 17 feet long; 5.2 metres....To big to move; so it sits in one place! The negative, ground glass; and vacuum back is in another room; the camera is built into the wall...Maybe I should build a ULF portable camera; for my lenses....
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There is always the pinhole.

 

You have film that is 30 inches?

 

There is also a group (astronomy?) that grinds its own lenses on the net. They have shown up in my searches under Aplanat. At this scale you needn't worry about 1 micron precession in alignment. Maybe there is someone in the group that you could commission? I'd mimic an f 18 Protar V myself. Without going to these lengths you are stuck with searching for hens teeth or with luck, find a 900mm - 1200mm process lens. If you are thinking this big you must be a patient man. Good luck.

 

John

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