Re: Zero 2000 Zone Plate?

----- Original Message -----
From: "Chris Peregoy" <peregoy@gl.umbc.edu>
To: <pinhole-discussion@pinhole.com>
Sent: Monday, August 28, 2000 9:32 AM
Subject: Re: [pinhole-discussion] Zero 2000 Zone Plate?

> I thought so too but saw them advertising a zone lens back in Feb. or
March
> when there was a lot of talk about them on the list. Chris Patton's web
site
> has been updated since I looked at it back then,
> http://www.stanford.edu/~cpatton/zp.html. He has added a PDF file that has
6
> focal length zone plates ready for shooting which includes a 25mm plate.
> I've just started shooting with one and it works great.

In making very small focal length ZPs, the limit is set by both, the film
and the lens resolution. Assuming ZPs with 19 zones/rings and lens/film
resolution of 75 l/mm, Zone Plates of up to 6 or 7mm focal could be made,
smaller focal length are possible if the number of rings is reduced.

NOTE: I don't recall if resolution is measured in lines/mm or line_pairs/mm,
if it is the latter, then, ZPs of up to 2 mm focal length could be achieved
in theory!!

All the above is true when using analog imaging to make ZPs. Some people
make a digital file that then gets "printed" commercially (or not?) on very
high contrast film. I'd imaging there is a certain amount of jagged_ness to
the edged of the rings using this method. The smaller the ZP focal length,
the more it will be affected by that jagged_ness.

Guillermo
Received on Mon Aug 28 10:51:03 2000