Finer grain in cheap iso400 colour film than in iso100 b/w? Really?

[Emil]

Last night i printed my backlog of negatives from the last year, and i came across some colour negatives (a cheap kodak iso400 - store processed) and decided to print some of these too on b/w paper for the hell of it. I was stunned to see that the grain was an order of magnitude finer than on any of my carefully home developed b/w films! What's going on here?

 

[Anon Ymous]

There's a major difference between the traditional BW films and C41 films:

• 
  The granularity of classic BW films increases with density. It means that highlights are more grainy than shadows.

• 
  The granularity of C41 films decreases with density. It means that highlights are less grainy than shadows.

It's far more likely to spot grain at mid to light tones.

 

[polyglot]

C-41 has dye-clouds with soft edges. So while the grain doesn't look like much, the resolution may not be quite so great.

 

[markbarendt]

Nothing empirical but 400 and 800 speed C41 constantly amazes me.