Digital BW, The Print

On 03/09/2012 David Kachel wrote:
> 4. Do not follow recommendations to use chromogenic B&W films (B&W 
> films
> processed in color chemistry), UNLESS you absolutely refuse to 
> process film
> yourself. Good machine processing is far more even and consistent 
> than badly
> done hand processing. In all other respects, chromogenic films are 
> markedly
> inferior to conventional B&W films. Think of it as VERY bad training 
> wheels
> for B&W photography.

I disagree pretty much completely:) I used XP-1 & 2 and TCN for many years 
out of preference. I didn't take it to a lab, and it was a PITA to process 
compared to trad B&W films, but the tonality was/is amazing in return for 
a little trade-off in sharpness.

Chromagenics were capable of tonality and extended highlight range that 
went way beyond normal ISO400 films. I did masses of testing of Tri X, 
HP5, Tmax400, Delta400 in different devs at different dilutions and ISO's, 
and used all of them for extended periods (years). They all had their good 
points, but chromagenics offered tonality that was simply impossible with 
trad ISO400.

If you just ran chromagenic through a Snappy Snaps and concluded it was 
junk, it's not a fair test. My only problem with XP1/2 was that it was 
occasionally prone to inexplicably filthy processing (using Ilford's 
custom dev) that would put a rash of tiny particulate crap across the odd 
frame. TCN never did that.

> 5. Most pointedly, DO NOT use chromogenic films if your plan is to 
> scan the
> negatives and print them digitally. Since they are in fact 
> single-color,
> color negatives, they will produce exactly the same noise problems 
> found
> when scanning standard color negatives. The noise can of course be 
> reduced,
> but why start with a film you know is going to create noise problems?

I couldn't agree less: chromagenics are REALLY well matched to scanning IME.

What noise problems "when scanning colour negatives"?

Noise is a lot LESS of an issue with chromagenics, IME, exactly because 
the sharp well-defined grain pattern has been replaced by more diffuse dye 
clouds.

Most noise seen in CCD-based scanning is grain aliasing artifacts at some 
critical interference frequency. Think of it as a chaotic version of 
moire, caused by grain spatial frequency being close to the sampling 
frequency of the CCD**.

Scanning at higher PPI is the answer. Most 2700ppi scanners could produce 
awful artifacts, especially the Nikons with semi-collimated LED sources. 
Many people mistook the horrid "grain" in colour neg blue sky for actual 
grain, but it was aliasing. Most 4000ppi scanners were largely immune.

** As far as I know I was the first to identify this problem, which was 
puzzling Polaroid engineers. They couldn't understand why a few customers 
were reporting excessive grain that was not in the emulsion.  John 
Brownlow's Photoscientia site went on to try and quantify this in greater 
depth.

-- 
Regards

Tony Sleep
http://tonysleep.co.uk (don't bother, currently broken)