Archived posting to the Leica Users Group, 2001/08/02

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Subject: Re: [Leica] mxsmanic and pinholes
From: "Mxsmanic" <mxsmanic@hotmail.com>
Date: Thu, 2 Aug 2001 15:58:32 +0200
References: <B78EBE20.14401%john@pinkheadedbug.com>

I agree; my mistake.  I should have researched it a bit more before making any
statements about it.

Unfortunately, I don't recall the context in which I made the statement, so I'm
unable to assess the impact of my error on whatever my original argument was.

- ----- Original Message -----
From: "Johnny Deadman" <john@pinkheadedbug.com>
To: "LUG" <leica-users@mejac.palo-alto.ca.us>
Sent: Thursday, August 02, 2001 14:21
Subject: Re: [Leica] mxsmanic and pinholes


> on 8/2/01 12:32 AM, Mxsmanic at mxsmanic@hotmail.com wrote:
>
> > Jimmy writes:
> >
> >> That is utter rubbish.
> >
> > In what way?  Pinholes have no aberrations or distortions at all; they are
> > diffraction-limited.  No glass lens can match that, no matter what its
design.
> > The only real reason to use a glass lens at all is that pinholes require
very
> > long exposure times.  Glass provides some other conveniences, also, but
better
> > image quality is not one of them.
>
> Sorry, you are really up the creek on this one. The image quality of a
> pinhole camera increases with diminishing size of the pinhole up to the
> point at which diffraction effects start to become more significant.
>
> This puts a clear limit on resolution.
>
> Contrary to what many people think the diffraction effects are significant
> even when the diameter of the pinhole is *much greater* than the wavelength
> of the light involved. The maths are not very difficult and agree well with
> experimental results. The maths also tell you that a pinhole of a certain
> diamter has an optimum focal length associated with it.
>
> So, what is the resolution of a pinhole lens in the best-case scenario of
> optimum diameter and optimum focal length? Some experimental results can be
> seen here:
>
>     http://www.pinhole.com/resources/articles/Young/
>
> They seem to me to show that the maximum possible resolution of a pinhole
> camera, is about 5 lp/mm. That is an order of magnitude less than not just
> Leica lenses but most commercially available 35mm lenses.
>
> --
> John Brownlow
>
> http://www.pinkheadedbug.com
>
> ICQ: 109343205
>

Replies: Reply from Nathan Wajsman <wajsman@webshuttle.ch> (Re: [Leica] mxsmanic and pinholes)
Reply from "Simon Lamb" <simon@sclamb.com> (Re: [Leica] mxsmanic and pinholes)
Reply from "Weifu Lin" <wflin@tp.silkera.net> ([Leica] LEICA DICOMAR lens for Panasonic DV)
In reply to: Message from Johnny Deadman <john@pinkheadedbug.com> (Re: [Leica] mxsmanic and pinholes)