It can be quite small, but I believe it largely depends on the ISO rating of the film. Larger grain = more light collected. I shoot wetplate collodion sometime

It can be quite small, but I believe it largely depends on the ISO rating of the film. Larger grain = more light collected. I shoot wetplate collodion sometimes and that has an effective ISO of under 2 and the detail is astounding - especially for a process that’s 150 years old.