Re: DPI, was: filmscanners: OT (a bit): Publishing pictures :)

[SKID Photography <skid@bway.net>]

> > That depends on the film format, and what you
> > mean by poster-sized, and what your expected
> > quality is.
>
> It's pretty easy to calculate.  If the viewing distance is equal to or greater
> than 6875 multiplied by the size of a pixel, then the resolution is high 
>enough.
> That is _extremely_ conservative, however, and in fact about 2300 x pixel size
> would be sufficient.  At 150 lpi, that's a distance of 15 inches, and so 150 
>lpi
> is sufficient for use in things like magazines.  This would require 225 ppi in
> the image; at 2700 ppi, that would mean a maximum image size of about 11x17
> inches, easily enough for a full page or beyond.

Every magazine we have worked for insists on at least 300 dpi in any digital 
image (this includes the 'majors'
like Time).  IMO telling them that 150 dpi should suffice will only translate 
into not being hired by that
magazine again.

> Large enlargements of 35mm film are more likely to be limited by the grain
> structure of the film than by the resolution of the scan.

After going round and round on this subject on the colorsync list, the 
consensus seemed to be that the
limitation in enlarging (via scans) 35mm film is the 'noise' in the scan, not 
the grain.

I was always of the opinion that the only thing that gets in the way of 
*extreme* enlargements from 35mm film
are the tones, not the grain.  A positive example would the 8x10 foot color 
prints National Geographic does
from 35mm film (and that was in the dark ages, 15-20 years ago!).  :- )

That said, most magazines we work for, now want medium format film to scan from 
(again, I fear it's the
'noise' issue).  When we find ourselves in a situation where it makes more 
sense to shoot in 35mm format, we
shoot color neg., and then hand in 11x14 prints (to scan from), thereby 
bypassing the noise issue.  But we
also need to hand in 'enlarged 'contacts' for the editors to make their choices 
from.


Harvey Ferdschneider
partner, SKID Photography, NYC