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[OM] Re: First Try C41 process B&W film (3)

Subject: [OM] Re: First Try C41 process B&W film (3)
From: AG Schnozz <agschnozz@xxxxxxxxx>
Date: Mon, 14 Apr 2008 08:38:46 -0700 (PDT)
> Michael Wong wrote:
> Water front of Central & Sheung Wan, Hong Kong Island. Left hand
> side is Central & right hand side is Sheung Wan.
>
http://www.michaelphotography.net/TST_B&W20080407/images/IMG2934_ZF85.jpg

Something is a bit "off" in this scan. The midtones are all clumped
together as though the scan exposure was way off and the tonal
gradient is represented by too few bits.

A note about XP-2. If the film is not washed sufficiently, the base
is a bit dark. This isn't an issue with scanning, but is a major
issue for darkroom printing. I sometimes need to soak my film and
redry before enlarging to wash more of the dye away.  There can be an
entire stop of difference between densities based on the washing.

XP-2 does encourage you to overexpose slightly.  Some people shoot it
at ISO 200, but the problem with that is the fact XP-2 has almost no
straightline section and is all shoulder/toe.  By overexposing you
are leaning into the shoulder more and you and up with less tonal
seperation (blocked up midtones).  Effectively, it will also supress
skintones slightly too.  If I'm feeling punky I'll shoot it at ISO
320, but rarely at ISO 200.  ISO 200 makes the film almost impossible
to print in an enlarger.

When scanning, it is almost always better to scan in RGB and convert
to monochrome in an editor.

The grain in the reduced images points to an issue with your resize
algorithm of choice.  Avoid the newer algorithms that preserve
sharpness when downsizing. These cause the "grain" to go
over-the-top. I've found that a two or three-step resize process
using standard Bicubic does about the best job of downsizing XP-2.
And then apply a bit of edge-enhancement sharpening afterwards.

I used this technique on the images in "Christmas Outing with the
Olympus OM-4T on the www.zone-10.com website.

http://zone-10.com/cmsm/index.php?option=com_content&task=view&id=141&Itemid=1

Personally, my favorit B&W film remains Ilford Delta 400 processed in
Ilfotec DD-X. But convenience and cost usually dictates XP-2 these
days.

In my article "Call me Square", the photo was taken with either Delta
400 or HP5 pushed one stop.

http://zone-10.com/cmsm/index.php?option=com_content&task=view&id=88&Itemid=1&limit=1&limitstart=0

In another article "Chrome and Rust" I have downsized images taken
with the New Kodak Portra 400VC.  Again, little to no visible grain.

http://zone-10.com/cmsm/index.php?option=com_content&task=view&id=164&Itemid=1

The point is, that it is entirely possible to get nice grainless or
near-grainless images for web-display if you recognize that scans do
not resize the same way that digital camera images do.  GEM helps,
but is not the end-all, be-all.  In fact, GEM will do some really
gut-wrench things if you are not careful.

Oh, what about the prints?  Printing film scans is actually quite a
bit better than screen display because of "dot-gain".  Dot-gain on a
monitor is exactly the opposite as it is in a print.  On a screen,
luminance noise shows up more, whereas on a print chroma noise will
show up more.

AG


      
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