Resolution -- 8x10" Prints

Dave wrote:


Well the print resolution may be the insolvable limitation to this
idea. I suppose the resolution of a print can only be so good and that
is why MF is not normally used for 8x10's. Yet I have no desire to
create posters. Is there any way around this? Slides certainly have
more detail per inch than prints do. Perhaps I should consider MF
slides(?) -- although viewing slides is rather clumsy. My desire is to
create "prints" (or equiv) that are so sharp that you would feel even
a magnifying glass could not reveal the grain. Thanks.


With both 6x6 and 4x5 I often have trouble finding grain with the focuser.
That's with a 25x focusser. That's not looking at the negative that's
looking at an enlarged image.

If you really want the sort of print that you can walk into the
image then move up to LF. Medium format is nice but LF is just that much
more. An 8x10 from a 4x5 negative provides something you'll never see with
smaller negatives.

Nick

In article ,
(Dave) wrote:

[...] My desire is to
create "prints" (or equiv) that are so sharp that you would feel even
a magnifying glass could not reveal the grain. Thanks.

Okay, now we have a better idea, but still not complete. First, the lack
of grain alone is not going to guarantee you sharp prints. Are you okay
with that truth?

In article , Stacey
wrote:

Are you digitizing your film like Rafe is? If so the limitation is going to
be your printer so might not be worth it. Optical prints will show the
difference as it's not being "dumbed down" in the conversion.

That may be true with contact prints, but any negative put through an
enlarging lens will loose accutance.

On Sat, 21 Feb 2004 01:42:05 GMT, Raphael Bustin
wrote:

On 20 Feb 2004 17:03:24 -0800, (Dave) wrote:

I'm interested in being able to create extremely sharp, but not
extremely large prints. At what print size does a medium format camera
provide any significant improvement over 35mm? Are there services
which can provide improved resolution prints? Thanks.


I'd say at any size beyond 8x10" and certainly
at 12 x 18", the advantages of MF film over 35 mm
are readily apparent.

There are some here who claim to see a big
difference even at 8x10".

The improvement isn't solely in detail or
sharpness, but in reduced grain and improved
tonality.

What exactly do you mean by "improved
resolution prints," anyway?


rafe b.
http://www.terrapinphoto.com

A 14 MP image from a 14n (full frame 35mm CCD) demonstrates that
digital images of up to about 12X18 rival those of film. That may
also apply to the Canon EOS 1Ds. These cameras are intended to rival
medium format film types, and they appear to succeed--and it's not
only the original image resolution that is the issue here.

With film you also have other gremlins at work to degrade the image,
most notably in the enlarging process where various scattering effects
and further degradation from the enlarging lens and illumination
system must be considered. The exquisite detail and gradation present
for large-format contact prints can be achieved with digital, since
you have far superior control over tonality, setting of white & black
points and gradation--and no gremlins or grain.

Under normal illumination the human eye can resolve about 230-300
lp/mm on a print, and that's just about what an inkjet print is
capable of. Image resolution beyond this has rapidly diminishing
returns. Print resolution and CCD megapixels cannot be directly
compared, but as a general rule of thumb a visually optimal 8X10 can
be produced by a 5 MP image. You can extrapolate from this to show
that a 12X18 requires about 14 MP.

"KBob" wrote in message
...

Print resolution and CCD megapixels cannot be directly
compared, but as a general rule of thumb a visually optimal 8X10 can
be produced by a 5 MP image. You can extrapolate from this to show
that a 12X18 requires about 14 MP.


Assuming an ideal of 300 pixels per inch, it would work out to (8 x 300 =
2400) x (10 x 300 = 3000) = 7,200,000 pixels, or just under 8 MP to produce
an excellent 8 x 10 print.

Using that same formula for a 12 x 18 the math would be as follows:

(12 x 300) x (18 x 300) = 19, 440,000 or about 20 MP.

The number of pixels increases by a factor of almost 3 when going from an
8x10 to a 12x18, if you want to maintain the same number of pixels per inch.
Right now, that is a major factor limiting digital's appeal in larger print
sizes.

Of course, I can get the same 300 pixel per inch resolution with my 2.3 MP
digicam--I'm just limited to 4x6 print size.

I do admit to having OFOTO make 5 x 7 and 8 x 10 from the same camera, with
very little loss of quality (but they may have some enhancement process
inherent in their processing--who knows?)

On Sat, 21 Feb 2004 22:43:36 GMT, KBob wrote:


A 14 MP image from a 14n (full frame 35mm CCD) demonstrates that
digital images of up to about 12X18 rival those of film. That may
also apply to the Canon EOS 1Ds. These cameras are intended to rival
medium format film types, and they appear to succeed--and it's not
only the original image resolution that is the issue here.

With film you also have other gremlins at work to degrade the image,
most notably in the enlarging process where various scattering effects
and further degradation from the enlarging lens and illumination
system must be considered. The exquisite detail and gradation present
for large-format contact prints can be achieved with digital, since
you have far superior control over tonality, setting of white & black
points and gradation--and no gremlins or grain.

Under normal illumination the human eye can resolve about 230-300
lp/mm on a print, and that's just about what an inkjet print is
capable of. Image resolution beyond this has rapidly diminishing
returns. Print resolution and CCD megapixels cannot be directly
compared, but as a general rule of thumb a visually optimal 8X10 can
be produced by a 5 MP image. You can extrapolate from this to show
that a 12X18 requires about 14 MP.


I think your numers are off in that last paragraph.

I've heard Bob M quote figures of 10 lp/mm for
prints, which is in the same ball park as typical
inkjet "resolutions" in the 250-350 lpi range.

FWIW, Lightjet's native (contone) resolution is
305 lpi, Durst Epsilon is 254.


rafe b.
http://www.terr

In article , KBob
wrote:

[...]

Under normal illumination the human eye can resolve about 230-300
lp/mm on a print [...]

Divide that figure by 50.

On Sun, 22 Feb 2004 01:21:10 GMT, Raphael Bustin
wrote:

On Sat, 21 Feb 2004 22:43:36 GMT, KBob wrote:


A 14 MP image from a 14n (full frame 35mm CCD) demonstrates that
digital images of up to about 12X18 rival those of film. That may
also apply to the Canon EOS 1Ds. These cameras are intended to rival
medium format film types, and they appear to succeed--and it's not
only the original image resolution that is the issue here.

With film you also have other gremlins at work to degrade the image,
most notably in the enlarging process where various scattering effects
and further degradation from the enlarging lens and illumination
system must be considered. The exquisite detail and gradation present
for large-format contact prints can be achieved with digital, since
you have far superior control over tonality, setting of white & black
points and gradation--and no gremlins or grain.

Under normal illumination the human eye can resolve about 230-300
lp/mm on a print, and that's just about what an inkjet print is
capable of. Image resolution beyond this has rapidly diminishing
returns. Print resolution and CCD megapixels cannot be directly
compared, but as a general rule of thumb a visually optimal 8X10 can
be produced by a 5 MP image. You can extrapolate from this to show
that a 12X18 requires about 14 MP.


I think your numers are off in that last paragraph.

I've heard Bob M quote figures of 10 lp/mm for
prints, which is in the same ball park as typical
inkjet "resolutions" in the 250-350 lpi range.

FWIW, Lightjet's native (contone) resolution is
305 lpi, Durst Epsilon is 254.


rafe b.
http://www.terr

Yes, of course you're right - what the hell was I thinking of?? The
human eye, under optimal viewing conditions can resolve up to 30 lp/mm
I understand, but under more normal conditions this drops to more like
10-15 lp/mm (as you noted). What I meant to say was that a printer
having 230-300 DPI (not lp/mm) provides an image that generally
corresponds with what the human eye can resolve under normal viewing
conditions.

In article , KBob
wrote:

On Sun, 22 Feb 2004 01:21:10 GMT, Raphael Bustin
wrote:

[...]
Yes, of course you're right - what the hell was I thinking of?? The
human eye, under optimal viewing conditions can resolve up to 30 lp/mm

Let us get realistic here. You are unlikely to discern 30 lp/mm except
perhaps under abstract and unrealistic conditions while viewing a very
uninteresting subject. The subject at hand is photographic prints and not
viewing line pairs in a lab under ideal conditions.

First, the eye resolves best at ten inches. Second, it discerns line-pairs
best if the are, in fact, like line pair (for example, three parallel
human hairs, at least three pixels) and of high contrast. Another big
issue is that the eye must have enough light to close the iris to about
2.5mm in diameter (a bit larger axial). That is not average or even an
ideal gallery condition.

So, unless you view prints in an exceedingly uncomfortable and abstract
circumstance, your "30 lp/mm" is meaningless.

6 to 12 is more realistic, FAPP.

On Sat, 21 Feb 2004 20:32:30 -0600, (jjs)
wrote:

In article , KBob
wrote:

[...]

Under normal illumination the human eye can resolve about 230-300
lp/mm on a print [...]

Divide that figure by 50.

I was wrong, thinking about 2 things at once I guess. The human eye
under ideal conditions is supposed to resolve up to 30 l/mm, but more
typically 10-20.