Archived posting to the Leica Users Group, 1999/10/13

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Subject: [Leica] Re: Leica Users digest V12 #64
From: Alexey Merz <>
Date: Wed, 13 Oct 1999 10:29:02 -0700

Anthony Atkielski typed:
> There is no need to make the pixels smaller than 5 um or so 
>(that's 250 lp/mm already).  

Bizarre way of doing arithmetic you have there, Anthony. 
'Specially for an engineer. 5 um pixels give at best 200 
lines per mm. And at best *100* lime pairs per mm. On top
of that you're looking at interpolation for color, degrading
the real resolution (in color) by another 2-fold or so. 50 
lp/mm. And real consumer-grade CCDs *don't* have 5 um pixels
at this time - more like 7-13 um. Whoops. We are down to 35-40
lp/mm. Maybe 50-60 per mm if the system is completely optimal. 
But as an engineer *you* know what it costs to get that 
last 20%. 

So instead of 250 lp/mm we are talking about - at best - 
50-60 lp/mm with a smaller detector than 24x36 mm, and 
hence fewer pixels. Yawn.

> What is really needed is to make the CCDs larger with the 
> _same_ pixel size, so that they can match the size of a 
> 24x36 film negative, and thereby use the same lenses.

Golly. What an insight. That's what I'd just written.
Like, Duh. 

Of course *you* know how to build, inexpensive, defect-free,
low-noise, gigantic CCD arrays. Right? Or are you just 
talking out your nether orifice?

- -Alexey