I would disagree with scanning negatives. Who wants to wait and wait for 30
meg files to scan, then dust and scratch removal, then photoshop, and on we
go. If I were to scan, I would scan slides, which the Epson 2450 does
beautifully. You save $ and time with a film scanner. People will use
digcams to get rid of teh intermediary scanning steps...I sure do.
-Bill
-----Original Message-----
From: Joe Gwinn [mailto:joegwinn@xxxxxxxxx]
Sent: December 30, 2002 10:17 AM
To: olympus@xxxxxxxxxxxxxxx
Subject: [OM] How many pixels in a 35mm film image - Pop Photo weighs in
On page 37 of the January 2003 issue of "Popolar Photography & Imaging"
magazine (the "& Imaging" part is new) there is a letter to the editor
("Proof: John B") where one John B questions Pop Photo's contention that the
information content of a 35mm frame is 20-30 Mpixels (these will be
marketing pixels), because he personally gets better photos with digital
cameras. One assumes that his camera has far fewer mpix, although this isn't
stated. The letter was in response to an editorial in the November 2002
issue of Pop Photo.
The Editors' answer more or less recapitulates our computations, albeit with
less math detail, summarizing that 24 Mpix is for handheld SLR shots, while
30 Mpix is for "optimal" situations. All this with ASA 100 color negative
and slide films and a top-of-the-line 50mm lens set to its optimum aperture,
with camera on a heavy tripod with remote cable release. No mention of
mirror lockup. Under less rigorous conditions, or with a 35mm point&shoot,
one gets 6-12 Mpix.
In my analyses, I used 50 line pairs per millimeter as the typical
performance of lenses, a conservative number, and ended up with 18 Mpix.
Pop Photo instead tried to estimate the best that could be done in practice,
and got about double that.
Assuming that the 30 Mpix is for a camera of 1:2:1 ratio, this is the
equivalent of 15 million tricolor pixels, and the frame will be about 4743 x
3162.
In all cases, the color accuracy of digital exceeds that of any film Pop
Photo has tested.
Pop Photo goes on to conclude that the lack of film grain plus the greater
color accuracy leads many to choose "digital enlargements" over "film-based
enlargements". This part threw me. Who was talking of enlargement only?
We were talking of the relative merits of film and digital cameras, and one
could read their conclusion to endorse scanning of the negatives, which is
not supported by their other points.
Perhaps the missing logical step is to note that at current price levels,
the cheaper route to digital is to use a 35mm film camera and scan the
negatives.
Joe Gwinn
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