[filmscanners] Re: Pixels and Prints

["" <focus@adnc.com>]

Sorry, there is no hard-and-fast print resolution answer--a lot of it depends 
on the
subject matter. I've gotten 11x17's I was very happy with from my 4MP Olympus 
E-10. I've
also gotten 8x10's that were awful, even though there were no actual problems 
like focus or
noise.

One example is people--a tight headshot is very tolerant of low resolution, 
because the
details that drop out are things like individual hairs, things we don't have a 
huge
objection to not seeing. 8x10s from my antique 1.4MP Sony DSC-770 look pretty 
good.

On the opposite end of the spectrum is a group shot with 20 people. Here low 
resolution
means faces with "monotooth" and missing nostrils and eye-whites--all things 
that are
visually disturbing. 8x10s off my 4MP E-10 look awful, even 8x10s off of 35mm 
don't look
that great, this is still the domain of MF.

Comparing digicam pixels to scanner pixels is misleading because scanner pixels 
are
second-generation--4000 scanner pixels=2700 digicam pixels seems empirically 
like a good
approximation, but I don't have research to prove this.

And comparing lines resolved between digicams and film is a little misleading
anyway--digicam generally have pretty decent MTF right down to their 
theoretical limit,
then fall off to zero. On film, the MTF starts to fall off sooner, but keeps 
going longer.
Assuming 3 pixels/line pair, 300 dpi can resolve a hair under 4 lp/mm. 200 dpi 
is 2.6
lp/mm. Both well under the "standards" for a fine enlarger print of 6-8 lp/mm. 
The catch is
that at the 3 lp/mm frequency, the 300 dpi digital probably has better MTF than 
the
enlarger print, even though it loses the ultimate resolution battle. The reason 
you "need"
6-8 lp/mm from an enlarger print is not so much that you can actually see that 
resolution
from a normal viewing distance, but that a 10% MTF at 6 lp/mm is a good 
predictor of a 80%+
MTF at 2-3 lp/mm, which is what really matters.

Roger Krueger


Eugene A La Lancette PhD MD wrote:

> 240 dpi is all that is needed.
>
> -----Original Message-----
> From: filmscanners_owner@halftone.co.uk
> [mailto:filmscanners_owner@halftone.co.uk] On Behalf Of HMSDOC@aol.com
> Sent: Monday, October 20, 2003 9:07 PM
> To: lalancet@massmed.org
> Subject: [filmscanners] Pixels and Prints
>
> I suspect I will 'go digital' sometime in the next year or two.  My question
> regards what type of print output quality I can expect from digital.
>
> I print on an Epson 2200 at sizes of up to 13x19 inches.  In reality, I tend
> to leave an inch margin or so around the image, so lets say an image size of
> 11x17 inches.  "Conventional" teaching with scans (and I suppose that this
> could be part of the answer..that the conventional holds with scans but not
> direct
> digital acquisition) is that for critical sharpness you should be able to
> send 300ppi to the printer.  Say this is overkill and you really only need
> 250
> ppi.  By my calculations you would still need 11 megapixels fo an 11x17
> image at
> 250ppi.   Yet everyone raves at the output of even the Canon 10D at
> significantly less resolution.  So is the conventional teaching incorrect
> when it comes
> to direct digital capture?  Perhaps more importantly, how many megapixels
> are
> needed for an extremely sharp 11x17 inch print?  I realize there are other
> benefits to digital capture as it translates to printing, such as lack of
> grain,
> but sharpness is quite important to me as well.  I would appreciate any help
> in how to look at this as I think about getting a digital body.  Right now I
> am using a 1V and a Polaroid Sprintscan 4000 Plus.  A DS1 at 14 or so
> megapixels and full frame sensor is way too expensive for me...but if a new
> Canon EOS 3
> type digital body were to come out I could see spending up to $2500 or so.
>
> Howard
>
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