From: gsnow@clark.edu (Gary Snow)
Newsgroups: rec.video
Subject: Re: Film vs. tape
Date: 8 Sep 92 23:49:49 GMT
Organization: Clark College, Vancouver, Wa.  USA

In article <1992Sep8.192038.11193@clark.edu> gsnow@clark.edu (Gary Snow) writes:
>
>PhotoCD will have about half the resolution of a standard 100-400 ISO film.
>If you want, I can post a pretty informative post that describes the
>resolving capabilities of the PhotoCD.

Well, since I got a bunch of requests in mail for this, I guess I should
post it...:-)

Note that this is a post that was on rec.photo, and was not posted by me.
I post this without the knowledge of the original poster, and all typos
are his...-)

------- Originally posted on rec.photo by jay@metran.UUCP (Jay Ts) -------

>From: jay@metran.UUCP (Jay Ts)
>Newsgroups: rec.photo
>Subject: Re: Photo-CD - THE FACTS
>Date: 1 Sep 92 07:51:35 GMT
>Organization: Metran Technology, Tampa, Florida
>Lines: 70
 
Disclaimer: Please note that as far as "religion" goes, I am neither for
nor against Photo CD.  It has certain strengths that cannot easily be
produced using traditional media, and it has some weaknesses...
 
Disclaimer 2:  I am NOT a Photo CD expert!
 
rcoadh@kultarr.co.rmit.oz.AU (Alexander Doktorovich) writes:
: jgd@dixie.com (John De Armond) writes:
: 
: >Next question: "What is the resolution of the highest resolution image?"
: >Answer: "3072 X 2048", 24 bit color.  Yeehaaa!!!!!
 
3072 x 2048 is *great* for a computer, but compared even to the lowly
35mm format, it amounts to only 85.33 pixels/mm in the 24mm x 36mm frame.
Since a "line" is 2 pixels wide (including the space between) this is only
42.67 lines/mm.
 
: What is the effective spatial and colour resultions of Kodacolour 100?
 
I just tried to look this up and couldn't find the numbers for Kodacolor
Gold 100.  However, Kodacolor Gold 400 resolves 100 lines/mm!  In fact,
practically every 35mm film on the market outresolves Photo CD.  Here are
some examples of *low* resolution films (the lowest I could find numbers for):
 
film		resolving power
-------------------------------
Ektachrome 400		80 l/mm
Ektachrome P800/1600	63-80 l/mm, depending on EI
Ektar 1000		80 l/mm
Ektapress Gold 1600	80 l/mm
High Speed Infrared	80 l/mm
Ektachrome Infrared	63 l/mm
Scotchchrome 1000	67 l/mm
Scotchcolor 400		85 l/mm
 
Those are the really bad ones.  On the other extreme, there are films like:
 
film		resolving power
-------------------------------
Technical Pan		320 l/mm
Tmax 100		200 l/mm
Velvia			160 l/mm
Ektar 25		160 l/mm
 
Most films (including practically everything you can buy in a supermarket)
fall in between, at about 100-125 l/mm.
 
It could be argued that since most camera lenses don't come anywhere near
100 l/mm, Photo CD is really ok.  However, I would like to point out in
advance that:
 
1.  There are a good number of photographers using really good camera
    lenses -- Leica, Zeiss, and the better Nikon and Canon lenses, some
    of which are capable of over 100 l/mm resolution.
 
2.  There are a good number of photographers who consider 35mm to
    be a "toy" medium.  Stretch 3072x2048 pixels across medium or
    large format, and it doesn't work out as well.
 
3.  Camera lenses, especially at this point in history, are subject
    to incredible improvement.  A theoretically-perfect f/2 lens would
    be diffraction limited to over 500 l/mm, for example.  A small
    breakthrough in manufacturing technology, combined with good design,
    could make resolution like this quite possible in a few years.  At
    least, over 100 l/mm could become common!
 
I hope Kodak has left room for improvement in their spec.
 
---------------------------------- End ----------------------------------
-- 
-----
Gary Snow
uunet!clark!gsnow  or  gsnow@clark.edu
Newsgroups: rec.video