Resolution and Large Format Lenses

"jjs" <jjs.TakeThisOut@nospam.net> wrote in message
news:1123ugs5srcij36@news.supernews.com...

 > The simple, but incorrect math-approach says Yes if you want to do 33"x26"
 > prints on a common inkjet printer, but there is more to it than that.
 > Acutance is an issue and that is not strictly dependent upon PPI, but more
 > influenced by edge contrast so look to a combination of things. I find 4x5
 > at a nominal 1200ppi to be just adequate for 2x prints - but frankly, I
 > doubt I am getting even 600ppi (Epson 3200).

Are you suggesting that, instead of searching out a transparency equipped
flatbed scanner, I might be better off simply taking a photo of my 5x4 negs
using my 6MP EOS10D and the 100 f2.8 USM macro? (I've got suitable copying
gear, and flicker free rear lighting.)
Cheers,
--
M Stewart
Milton Keynes, UK
<a style='text-decoration: underline;' href="http://www.megalith.freeserve.co.uk/oddimage.htm" target="_blank">http://www.megalith.freeserve.co.uk/oddimage.htm</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses 

"Malcolm Stewart" <malcolm_stewart RemoveThis @megalith.freeserve.co.uk> wrote in
message news:cvt7ec$t8c$1@news7.svr.pol.co.uk...
 > "jjs" <jjs RemoveThis @nospam.net> wrote in message
 > news:1123ugs5srcij36@news.supernews.com...
 >
  >> The simple, but incorrect math-approach

 > Are you suggesting that, instead of searching out a transparency equipped
 > flatbed scanner, I might be better off simply taking a photo of my 5x4
 > negs
 > using my 6MP EOS10D and the 100 f2.8 USM macro?

No, of course not. I can't even understand how you came to consider such a
thing.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses 

On Sun, 27 Feb 2005 08:21:07 -0800, "None" <Nospam DeleteThis @none.com> wrote:

 >I have a question for the experts in this group:
 >
 >Are the newer large format lenses good enough to demand
 >scanner resolution of even 2500 DPI?

What I have to offer:

I quickly tested my SuperAngulon 65/8 and my Symmar 180/5.6 (not
exatly "newer large format lenses", you see) with a very rough test
chart (will do better next time), and found about 45-50 line pairs/mm
maximum resolving power on TMax 100, at f/13 (no results to show,
unfortunately; but I'll do another test when it stops raining here).
To correctly capture such details, you need, in theory, a minimum of
100 pixels/mm, or 2540 ppi.
Actually, no scanner has an ideal MTF curve: it will take a very good
3200 ppi scanner to do a good job on a 2540 ppi input signal...
Consumer flatbeds are not nearly "very good".
For example, the Epson 4180 flatbed that I MTF-tested, while having
4800x9600 ppi advertised hardware resolution, was only capable of
about 1500 ppi with sufficient contrast retained from the original.

Anyway, I'd guess that a 2500 ppi drum scanner, if correctly operated,
should suffice; and a decent consumer flatbed such as the Epson 4990
or Canon 9950 should do a reasonable job, at least on negative film
(lower density range), if you are not too picky.

Fernando<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses 

None wrote:
 > I have a question for the experts in this group:
 >
 > Are the newer large format lenses good enough to demand
 > scanner resolution of even 2500 DPI?
 >
 > Joe
 >
 >
No, its not and yes it is. Why do I answer like that - well if you want
to be on the safe side, scan as high as possible to have one masterscan.
I scan at maximum optical resolution and depending on the enlargement
size and purpose I resize the scan (copy of course) in Photoshop. To be
precise, with a 3200 Epson, you could do 3200 DPI theoreticall, but its
true optical resolution might be around 1800-2000dpi. With the 4870, it
is better, you could do around 3000dpi. Will be interesting to see how
good the new 3990 will be..
rgds George<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses 

Dr. Georg N.Nyman wrote:
 > None wrote:
 >
  >> I have a question for the experts in this group:
  >>
  >> Are the newer large format lenses good enough to demand
  >> scanner resolution of even 2500 DPI?
  >>
  >> Joe
  >>
  >>
 > No, its not and yes it is. Why do I answer like that - well if you want
 > to be on the safe side, scan as high as possible to have one masterscan.
 > I scan at maximum optical resolution and depending on the enlargement
 > size and purpose I resize the scan (copy of course) in Photoshop. To be
 > precise, with a 3200 Epson, you could do 3200 DPI theoreticall, but its
 > true optical resolution might be around 1800-2000dpi. With the 4870, it
 > is better, you could do around 3000dpi. Will be interesting to see how
 > good the new 3990 will be..
 > rgds George

I agree generally with all you say. However, the Epson 4870 can scan at
4800 or 2400 or ... If you set it to scan at 3000, it will scan at
4870 and resize afterwards to 3000. You might as well scan at 4870 and
rescale in Photoshop. Probably the best strategy is to scan at 2400 and
rescale in Photoshop as needed.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses 

"Leonard Evens" <len DeleteThis @math.northwestern.edu> wrote in message
news:bOqdnQZs0oKbvr7fRVn-tA@comcast.com...

 > I agree generally with all you say. However, the Epson 4870 can scan at
 > 4800 or 2400 or ... If you set it to scan at 3000, it will scan at
 > 4870 and resize afterwards to 3000. You might as well scan at 4870 and
 > rescale in Photoshop. Probably the best strategy is to scan at 2400 and
 > rescale in Photoshop as needed.

Which technique do you recommend for downsampling?<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses 

jjs wrote:

 >
 > Which technique do you recommend for downsampling?
 >
 >
I've had good luck with 'bicubric sharper'. Just go straight to the
resolution and size that you want. I've tried some of the fancier ways,
and I couldn't see any improvement. But I'm a photoshop duffer, and so YMMV.

-Peter
<a style='text-decoration: underline;' href="http://www.desmidt.net" target="_blank">www.desmidt.net</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses 

"jjs" <john@xstafford.net> wrote in message
news:1126b4jbii2hfa9@news.supernews.com...
SNIP
 > Which technique do you recommend for downsampling?

Take your pick:
<a style='text-decoration: underline;' href="http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/down_sample.htm" target="_blank">http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/down_sample.htm</a>

And for those that don't like revealing test objects, here's a scan
(35mm film, but the principle is the same, oh, and don't sharpen the
scan before re-sampling):
<a style='text-decoration: underline;' href="http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/example1.htm" target="_blank">http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/example1.htm</a>

You've guessed it, I prefer ImageMagick.

Bart<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses 

"Bart van der Wolf" <bvdwolf.TakeThisOut@no.spam> wrote in message
news:4223758a$0$28990$e4fe514c@news.xs4all.nl...
 >
 > "jjs" <john@xstafford.net> wrote in message
 > news:1126b4jbii2hfa9@news.supernews.com...
 > SNIP
  >> Which technique do you recommend for downsampling?
 >
 > Take your pick:
<font color=purple> > <a style='text-decoration: underline;' href="http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/down_sample.htm</font" target="_blank">http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/down_sample.htm</font</a>>
 >
 > And for those that don't like revealing test objects, here's a scan (35mm
 > film, but the principle is the same, oh, and don't sharpen the scan before
 > re-sampling):
<font color=purple> > <a style='text-decoration: underline;' href="http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/example1.htm</font" target="_blank">http://www.xs4all.nl/~bvdwolf/main/foto/down_sample/example1.htm</font</a>>
 >
 > You've guessed it, I prefer ImageMagick.

Bart, thanks very much for sharing your expertise in the great articles. I
will study them further tonight when I can relax in 'learn' mode.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Resolution and Large Format Lenses