Archived posting to the Leica Users Group, 2000/04/10

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Subject: Re: [Leica] Re: Leica Users digest V17 #3
From: Stephen Gandy <Stephen@CameraQuest.com>
Date: Mon, 10 Apr 2000 09:27:50 -0700

the Summicron Modern tested out at 105 l/mm was a 50 Dual Range

Stephen Gandy.

Stephen Gandy

LRZeitlin@aol.com wrote:

> I have been asked in private e-mails where my estimate of 9 megapixels as the
> digital equivalent of the 35 mm frame comes from. Here it is:
>
> In an oft quoted article "How Sharp Can You Get" published in the October
> 1976 issue of Modern Photography the editors used heroic measures to squeeze
> 100 lines/mm out of a number of high quality 35mm camera 50 mm lenses. The
> best performance was given by an older Leica Summicron (7 element) which
> reached 105 l/mm on High Contrast Copy film. Most lenses, including the
> Summicron reached 96 l/mm on Tech Pan. Faster films scored lower. Images on
> Kodachrome II peaked at 80 to 86 l/mm. To stay on the conservative side, I
> estimated the maximum usable resolution as 100 l/mm, fully realizing that
> most lens-film combinations would be less.
>
> The area of the 35mm frame is 864 sq. mm. Each sq. mm at 100 l/mm resolution
> requires 10,000 pixels, the total being 8,640,000 pixels. Hence the 9
> megapixel estimate as the digital equavalent of 35 mm. Using 24 bit color
> information, this works out to a file size of about 26 MB. Moderate JPEG
> compression at 1:4 will reduce this to a more manageable 6.5 MB file size.
>
> While this is a reasonable approximation of the amount of information stored
> on a 35 mm frame using today's methods, it is far lower than the maximum that
> could be stored given advances in lens/film technology. The theoretical
> resolution of an f2.0 lens is 882 l/mm in green light. This works out to 672
> megapixels and a file size of over 2 billion MB. Don't hold your breath
> waiting for Leica to offer lenses of this quality soon, however. All of the
> twentieth century efforts in camera lens design have only improved resolution
> for normal lenses by a factor of two.
>
> The LUG tends to place undue emphasis on resolution as the essential quality
> of imaging. In my youth, I worked for a Boston newspaper that never used
> finer than a 65 line halftone screen in its daily edition. We photographed
> sporting events with 4x5" Speed Graphics, not because of the high picture
> quality available from the large negative but pecause it could be fully
> processed in two minutes in concentrated developer and fixer and a printing
> plate could be made while the negative was still dripping wet. The paper was
> proud of the fact that it often had a paper on the streets showing the
> winning goal in a Celtics game before the crowd filed out of the Boston
> Arena.
>
> Today most of us watch hours of television whose images are formed by fewer
> than 0.3 megapixels or stare at computer screens which deliver their images
> at about 0.5 megapixels. A cheap low end digital camera can meet those
> requirements with ease. The vast majority of the world's pictures are never
> enlarged to a size greater than 4x6". A 1.5 megapixel camera and a basic ink
> jet printer will suffice. Timeliness, availability, flexibility and cost per
> image are often more important than resolution and tonal depth. A picture in
> the hand or on a electronic display screen is worth more than a dozen much
> finer images on a roll waiting to be developed.
>
> LarryZ