Re: [Leica] RE: Calculations wrong?

[Johnny Deadman <john@pinkheadedbug.com>]

on 1/11/00 1:22 am, Jim Brick at jim@brick.org wrote:

> Erwin, the folks that read the advertising and news hype and spew vitriol
> at you (and probably me as a result of this) are simply ignorant about how
> it works and don't want to hear logic, reason, and of course, the clear and
> undisputable facts.

I assume you mean me and Austin, Jim. I wasn't aware that either of us had
'spewed vitriol'. In fact I think the phrase 'spewing vitriol' is the
closest anyone has got. Nor are either of us taken in by advertising hype.
What do you mean by that anyway? As for being ignorant and all the rest of
it... others can judge that better than me.

Very simply, Erwin argues that a 960x1440 pixel digital image is
functionally equivalent to the best hand-held image you can get with a
hand-held Leica (ie it has a similar resolution of around 20 lp/mm).

Austin can argue the theory of this much better than I so let me approach it
from the reverse angle and instead of accusing me of 'spewing vitriol' maybe
you could explain what I am missing in this practical example.

Let's assume for the purposes of this argument that we have a grain-free
image (tech pan or whatever... I think Delta 100 will do nicely). Let's also
assume that we'd like to make a nice 11x14 image of it... not unreasonable
from a 35mm handheld image if you are taking care and using a softy (for
example I just blew up a Toronto skyline which was 1/500 @ f8 on a 50mm...
it is wonderfully crisp).

Erwin's 960x1440 image will therefore be scaled up from 40 lines/mm (or
roughly 1000 ppi) to around 100 ppi.

Now this should be ringing alarm bells in the heads of anyone here who uses
Photoshop to make pictures. I could tell you that this just isn't going to
produce quality remotely like that of handheld 35mm film. At 11x14 from 35mm
on any high quality output medium you will see *very* visible differences
between 100, 200 and 300 ppi images.

Erwin says he doesn't care about this but it's the crux of the matter. I'm
not talking about inkdots, I'm talking about the quality of the image being
output. 

I suggest someone here who cares enough goes out and tries it. Shoot some, I
dunno, Delta 100 and develop in Xtol. Do it carefully, like I did my
skyline. If you have access to a megapixel camera shoot something side by
side. Go home and scan the delta neg at the highest rez you can - say 4000
ppi. Now downsample it to 1440 pixels across. Now put the three images (4000
ppi, 1440 pixels and the digicam together. What do you see?

As far as I can work out Erwin's argument seems to be that in terms of line
resolution these three are functionally equivalent. My experience tells me
that I need at least a 300 ppi image to print what I consider a high quality
35mm picture at 11x14. Erwin seems to say, no, 100 ppi will do fine.

I'm not saying anyone here's an idiot. They aren't. But to quote Erwin...

> I am confused!
> Can anyone explain?

- -- 
Johnny Deadman

http://www.pinkheadedbug.com